diff -r 000000000000 -r 08ec8eefde2f persistentstorage/sql/SQLite/pager.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/persistentstorage/sql/SQLite/pager.c Fri Jan 22 11:06:30 2010 +0200 @@ -0,0 +1,5377 @@ +/* +** 2001 September 15 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** This is the implementation of the page cache subsystem or "pager". +** +** The pager is used to access a database disk file. It implements +** atomic commit and rollback through the use of a journal file that +** is separate from the database file. The pager also implements file +** locking to prevent two processes from writing the same database +** file simultaneously, or one process from reading the database while +** another is writing. +** +** @(#) $Id: pager.c,v 1.469 2008/08/02 03:50:39 drh Exp $ +*/ +#ifndef SQLITE_OMIT_DISKIO +#include "sqliteInt.h" +#include +#include + +/* +** Macros for troubleshooting. Normally turned off +*/ +#if 0 +#define sqlite3DebugPrintf printf +#define PAGERTRACE1(X) sqlite3DebugPrintf(X) +#define PAGERTRACE2(X,Y) sqlite3DebugPrintf(X,Y) +#define PAGERTRACE3(X,Y,Z) sqlite3DebugPrintf(X,Y,Z) +#define PAGERTRACE4(X,Y,Z,W) sqlite3DebugPrintf(X,Y,Z,W) +#define PAGERTRACE5(X,Y,Z,W,V) sqlite3DebugPrintf(X,Y,Z,W,V) +#else +#define PAGERTRACE1(X) +#define PAGERTRACE2(X,Y) +#define PAGERTRACE3(X,Y,Z) +#define PAGERTRACE4(X,Y,Z,W) +#define PAGERTRACE5(X,Y,Z,W,V) +#endif + +/* +** The following two macros are used within the PAGERTRACEX() macros above +** to print out file-descriptors. +** +** PAGERID() takes a pointer to a Pager struct as its argument. The +** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file +** struct as its argument. +*/ +#define PAGERID(p) ((int)(p->fd)) +#define FILEHANDLEID(fd) ((int)fd) + +/* +** The page cache as a whole is always in one of the following +** states: +** +** PAGER_UNLOCK The page cache is not currently reading or +** writing the database file. There is no +** data held in memory. This is the initial +** state. +** +** PAGER_SHARED The page cache is reading the database. +** Writing is not permitted. There can be +** multiple readers accessing the same database +** file at the same time. +** +** PAGER_RESERVED This process has reserved the database for writing +** but has not yet made any changes. Only one process +** at a time can reserve the database. The original +** database file has not been modified so other +** processes may still be reading the on-disk +** database file. +** +** PAGER_EXCLUSIVE The page cache is writing the database. +** Access is exclusive. No other processes or +** threads can be reading or writing while one +** process is writing. +** +** PAGER_SYNCED The pager moves to this state from PAGER_EXCLUSIVE +** after all dirty pages have been written to the +** database file and the file has been synced to +** disk. All that remains to do is to remove or +** truncate the journal file and the transaction +** will be committed. +** +** The page cache comes up in PAGER_UNLOCK. The first time a +** sqlite3PagerGet() occurs, the state transitions to PAGER_SHARED. +** After all pages have been released using sqlite_page_unref(), +** the state transitions back to PAGER_UNLOCK. The first time +** that sqlite3PagerWrite() is called, the state transitions to +** PAGER_RESERVED. (Note that sqlite3PagerWrite() can only be +** called on an outstanding page which means that the pager must +** be in PAGER_SHARED before it transitions to PAGER_RESERVED.) +** PAGER_RESERVED means that there is an open rollback journal. +** The transition to PAGER_EXCLUSIVE occurs before any changes +** are made to the database file, though writes to the rollback +** journal occurs with just PAGER_RESERVED. After an sqlite3PagerRollback() +** or sqlite3PagerCommitPhaseTwo(), the state can go back to PAGER_SHARED, +** or it can stay at PAGER_EXCLUSIVE if we are in exclusive access mode. +*/ +#define PAGER_UNLOCK 0 +#define PAGER_SHARED 1 /* same as SHARED_LOCK */ +#define PAGER_RESERVED 2 /* same as RESERVED_LOCK */ +#define PAGER_EXCLUSIVE 4 /* same as EXCLUSIVE_LOCK */ +#define PAGER_SYNCED 5 + +/* +** If the SQLITE_BUSY_RESERVED_LOCK macro is set to true at compile-time, +** then failed attempts to get a reserved lock will invoke the busy callback. +** This is off by default. To see why, consider the following scenario: +** +** Suppose thread A already has a shared lock and wants a reserved lock. +** Thread B already has a reserved lock and wants an exclusive lock. If +** both threads are using their busy callbacks, it might be a long time +** be for one of the threads give up and allows the other to proceed. +** But if the thread trying to get the reserved lock gives up quickly +** (if it never invokes its busy callback) then the contention will be +** resolved quickly. +*/ +#ifndef SQLITE_BUSY_RESERVED_LOCK +# define SQLITE_BUSY_RESERVED_LOCK 0 +#endif + +/* +** This macro rounds values up so that if the value is an address it +** is guaranteed to be an address that is aligned to an 8-byte boundary. +*/ +#define FORCE_ALIGNMENT(X) (((X)+7)&~7) + +typedef struct PgHdr PgHdr; + +/* +** Each pager stores all currently unreferenced pages in a list sorted +** in least-recently-used (LRU) order (i.e. the first item on the list has +** not been referenced in a long time, the last item has been recently +** used). An instance of this structure is included as part of each +** pager structure for this purpose (variable Pager.lru). +** +** Additionally, if memory-management is enabled, all unreferenced pages +** are stored in a global LRU list (global variable sqlite3LruPageList). +** +** In both cases, the PagerLruList.pFirstSynced variable points to +** the first page in the corresponding list that does not require an +** fsync() operation before its memory can be reclaimed. If no such +** page exists, PagerLruList.pFirstSynced is set to NULL. +*/ +typedef struct PagerLruList PagerLruList; +struct PagerLruList { + PgHdr *pFirst; /* First page in LRU list */ + PgHdr *pLast; /* Last page in LRU list (the most recently used) */ + PgHdr *pFirstSynced; /* First page in list with PgHdr.needSync==0 */ +}; + +/* +** The following structure contains the next and previous pointers used +** to link a PgHdr structure into a PagerLruList linked list. +*/ +typedef struct PagerLruLink PagerLruLink; +struct PagerLruLink { + PgHdr *pNext; + PgHdr *pPrev; +}; + +/* +** Each in-memory image of a page begins with the following header. +** This header is only visible to this pager module. The client +** code that calls pager sees only the data that follows the header. +** +** Client code should call sqlite3PagerWrite() on a page prior to making +** any modifications to that page. The first time sqlite3PagerWrite() +** is called, the original page contents are written into the rollback +** journal and PgHdr.inJournal and PgHdr.needSync are set. Later, once +** the journal page has made it onto the disk surface, PgHdr.needSync +** is cleared. The modified page cannot be written back into the original +** database file until the journal pages has been synced to disk and the +** PgHdr.needSync has been cleared. +** +** The PgHdr.dirty flag is set when sqlite3PagerWrite() is called and +** is cleared again when the page content is written back to the original +** database file. +** +** Details of important structure elements: +** +** needSync +** +** If this is true, this means that it is not safe to write the page +** content to the database because the original content needed +** for rollback has not by synced to the main rollback journal. +** The original content may have been written to the rollback journal +** but it has not yet been synced. So we cannot write to the database +** file because power failure might cause the page in the journal file +** to never reach the disk. It is as if the write to the journal file +** does not occur until the journal file is synced. +** +** This flag is false if the page content exactly matches what +** currently exists in the database file. The needSync flag is also +** false if the original content has been written to the main rollback +** journal and synced. If the page represents a new page that has +** been added onto the end of the database during the current +** transaction, the needSync flag is true until the original database +** size in the journal header has been synced to disk. +** +** inJournal +** +** This is true if the original page has been written into the main +** rollback journal. This is always false for new pages added to +** the end of the database file during the current transaction. +** And this flag says nothing about whether or not the journal +** has been synced to disk. For pages that are in the original +** database file, the following expression should always be true: +** +** inJournal = sqlite3BitvecTest(pPager->pInJournal, pgno) +** +** The pPager->pInJournal object is only valid for the original +** pages of the database, not new pages that are added to the end +** of the database, so obviously the above expression cannot be +** valid for new pages. For new pages inJournal is always 0. +** +** dirty +** +** When true, this means that the content of the page has been +** modified and needs to be written back to the database file. +** If false, it means that either the content of the page is +** unchanged or else the content is unimportant and we do not +** care whether or not it is preserved. +** +** alwaysRollback +** +** This means that the sqlite3PagerDontRollback() API should be +** ignored for this page. The DontRollback() API attempts to say +** that the content of the page on disk is unimportant (it is an +** unused page on the freelist) so that it is unnecessary to +** rollback changes to this page because the content of the page +** can change without changing the meaning of the database. This +** flag overrides any DontRollback() attempt. This flag is set +** when a page that originally contained valid data is added to +** the freelist. Later in the same transaction, this page might +** be pulled from the freelist and reused for something different +** and at that point the DontRollback() API will be called because +** pages taken from the freelist do not need to be protected by +** the rollback journal. But this flag says that the page was +** not originally part of the freelist so that it still needs to +** be rolled back in spite of any subsequent DontRollback() calls. +** +** needRead +** +** This flag means (when true) that the content of the page has +** not yet been loaded from disk. The in-memory content is just +** garbage. (Actually, we zero the content, but you should not +** make any assumptions about the content nevertheless.) If the +** content is needed in the future, it should be read from the +** original database file. +*/ +struct PgHdr { + Pager *pPager; /* The pager to which this page belongs */ + Pgno pgno; /* The page number for this page */ + PgHdr *pNextHash, *pPrevHash; /* Hash collision chain for PgHdr.pgno */ + PagerLruLink free; /* Next and previous free pages */ + PgHdr *pNextAll; /* A list of all pages */ + u8 inJournal; /* TRUE if has been written to journal */ + u8 dirty; /* TRUE if we need to write back changes */ + u8 needSync; /* Sync journal before writing this page */ + u8 alwaysRollback; /* Disable DontRollback() for this page */ + u8 needRead; /* Read content if PagerWrite() is called */ + short int nRef; /* Number of users of this page */ + PgHdr *pDirty, *pPrevDirty; /* Dirty pages */ +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + PgHdr *pPrevAll; /* A list of all pages */ + PagerLruLink gfree; /* Global list of nRef==0 pages */ +#endif +#ifdef SQLITE_CHECK_PAGES + u32 pageHash; +#endif + void *pData; /* Page data */ + /* Pager.nExtra bytes of local data appended to this header */ +}; + +/* +** For an in-memory only database, some extra information is recorded about +** each page so that changes can be rolled back. (Journal files are not +** used for in-memory databases.) The following information is added to +** the end of every EXTRA block for in-memory databases. +** +** This information could have been added directly to the PgHdr structure. +** But then it would take up an extra 8 bytes of storage on every PgHdr +** even for disk-based databases. Splitting it out saves 8 bytes. This +** is only a savings of 0.8% but those percentages add up. +*/ +typedef struct PgHistory PgHistory; +struct PgHistory { + u8 *pOrig; /* Original page text. Restore to this on a full rollback */ + u8 *pStmt; /* Text as it was at the beginning of the current statement */ + PgHdr *pNextStmt, *pPrevStmt; /* List of pages in the statement journal */ + u8 inStmt; /* TRUE if in the statement subjournal */ +}; + +/* +** A macro used for invoking the codec if there is one +*/ +#ifdef SQLITE_HAS_CODEC +# define CODEC1(P,D,N,X) if( P->xCodec!=0 ){ P->xCodec(P->pCodecArg,D,N,X); } +# define CODEC2(P,D,N,X) ((char*)(P->xCodec!=0?P->xCodec(P->pCodecArg,D,N,X):D)) +#else +# define CODEC1(P,D,N,X) /* NO-OP */ +# define CODEC2(P,D,N,X) ((char*)D) +#endif + +/* +** Convert a pointer to a PgHdr into a pointer to its data +** and back again. +*/ +#define PGHDR_TO_DATA(P) ((P)->pData) +#define PGHDR_TO_EXTRA(G,P) ((void*)&((G)[1])) +#define PGHDR_TO_HIST(P,PGR) \ + ((PgHistory*)&((char*)(&(P)[1]))[(PGR)->nExtra]) + +/* +** A open page cache is an instance of the following structure. +** +** Pager.errCode may be set to SQLITE_IOERR, SQLITE_CORRUPT, or +** or SQLITE_FULL. Once one of the first three errors occurs, it persists +** and is returned as the result of every major pager API call. The +** SQLITE_FULL return code is slightly different. It persists only until the +** next successful rollback is performed on the pager cache. Also, +** SQLITE_FULL does not affect the sqlite3PagerGet() and sqlite3PagerLookup() +** APIs, they may still be used successfully. +*/ +struct Pager { + sqlite3_vfs *pVfs; /* OS functions to use for IO */ + u8 journalOpen; /* True if journal file descriptors is valid */ + u8 journalStarted; /* True if header of journal is synced */ + u8 useJournal; /* Use a rollback journal on this file */ + u8 noReadlock; /* Do not bother to obtain readlocks */ + u8 stmtOpen; /* True if the statement subjournal is open */ + u8 stmtInUse; /* True we are in a statement subtransaction */ + u8 stmtAutoopen; /* Open stmt journal when main journal is opened*/ + u8 noSync; /* Do not sync the journal if true */ + u8 fullSync; /* Do extra syncs of the journal for robustness */ + u8 sync_flags; /* One of SYNC_NORMAL or SYNC_FULL */ + u8 state; /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */ + u8 tempFile; /* zFilename is a temporary file */ + u8 readOnly; /* True for a read-only database */ + u8 needSync; /* True if an fsync() is needed on the journal */ + u8 dirtyCache; /* True if cached pages have changed */ + u8 alwaysRollback; /* Disable DontRollback() for all pages */ + u8 memDb; /* True to inhibit all file I/O */ + u8 setMaster; /* True if a m-j name has been written to jrnl */ + u8 doNotSync; /* Boolean. While true, do not spill the cache */ + u8 exclusiveMode; /* Boolean. True if locking_mode==EXCLUSIVE */ + u8 journalMode; /* On of the PAGER_JOURNALMODE_* values */ + u8 dbModified; /* True if there are any changes to the Db */ + u8 changeCountDone; /* Set after incrementing the change-counter */ + u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */ + int errCode; /* One of several kinds of errors */ + int dbSize; /* Number of pages in the file */ + int origDbSize; /* dbSize before the current change */ + int stmtSize; /* Size of database (in pages) at stmt_begin() */ + int nRec; /* Number of pages written to the journal */ + u32 cksumInit; /* Quasi-random value added to every checksum */ + int stmtNRec; /* Number of records in stmt subjournal */ + int nExtra; /* Add this many bytes to each in-memory page */ + int pageSize; /* Number of bytes in a page */ + int nPage; /* Total number of in-memory pages */ + int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */ + int mxPage; /* Maximum number of pages to hold in cache */ + Pgno mxPgno; /* Maximum allowed size of the database */ + Bitvec *pInJournal; /* One bit for each page in the database file */ + Bitvec *pInStmt; /* One bit for each page in the database */ + char *zFilename; /* Name of the database file */ + char *zJournal; /* Name of the journal file */ + char *zDirectory; /* Directory hold database and journal files */ + sqlite3_file *fd, *jfd; /* File descriptors for database and journal */ + sqlite3_file *stfd; /* File descriptor for the statement subjournal*/ + BusyHandler *pBusyHandler; /* Pointer to sqlite.busyHandler */ + PagerLruList lru; /* LRU list of free pages */ + PgHdr *pAll; /* List of all pages */ + PgHdr *pStmt; /* List of pages in the statement subjournal */ + PgHdr *pDirty; /* List of all dirty pages */ + i64 journalOff; /* Current byte offset in the journal file */ + i64 journalHdr; /* Byte offset to previous journal header */ + i64 stmtHdrOff; /* First journal header written this statement */ + i64 stmtCksum; /* cksumInit when statement was started */ + i64 stmtJSize; /* Size of journal at stmt_begin() */ + int sectorSize; /* Assumed sector size during rollback */ +#ifdef SQLITE_TEST + int nHit, nMiss; /* Cache hits and missing */ + int nRead, nWrite; /* Database pages read/written */ +#endif + void (*xDestructor)(DbPage*,int); /* Call this routine when freeing pages */ + void (*xReiniter)(DbPage*,int); /* Call this routine when reloading pages */ +#ifdef SQLITE_HAS_CODEC + void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */ + void *pCodecArg; /* First argument to xCodec() */ +#endif + int nHash; /* Size of the pager hash table */ + PgHdr **aHash; /* Hash table to map page number to PgHdr */ +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + Pager *pNext; /* Doubly linked list of pagers on which */ + Pager *pPrev; /* sqlite3_release_memory() will work */ + volatile int iInUseMM; /* Non-zero if unavailable to MM */ + volatile int iInUseDB; /* Non-zero if in sqlite3_release_memory() */ +#endif + char *pTmpSpace; /* Pager.pageSize bytes of space for tmp use */ + char dbFileVers[16]; /* Changes whenever database file changes */ + i64 journalSizeLimit; /* Size limit for persistent journal files */ +}; + +/* +** The following global variables hold counters used for +** testing purposes only. These variables do not exist in +** a non-testing build. These variables are not thread-safe. +*/ +#ifdef SQLITE_TEST +int sqlite3_pager_readdb_count = 0; /* Number of full pages read from DB */ +int sqlite3_pager_writedb_count = 0; /* Number of full pages written to DB */ +int sqlite3_pager_writej_count = 0; /* Number of pages written to journal */ +int sqlite3_pager_pgfree_count = 0; /* Number of cache pages freed */ +# define PAGER_INCR(v) v++ +#else +# define PAGER_INCR(v) +#endif + +/* +** The following variable points to the head of a double-linked list +** of all pagers that are eligible for page stealing by the +** sqlite3_release_memory() interface. Access to this list is +** protected by the SQLITE_MUTEX_STATIC_MEM2 mutex. +*/ +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT +static Pager *sqlite3PagerList = 0; +static PagerLruList sqlite3LruPageList = {0, 0, 0}; +#endif + + +/* +** Journal files begin with the following magic string. The data +** was obtained from /dev/random. It is used only as a sanity check. +** +** Since version 2.8.0, the journal format contains additional sanity +** checking information. If the power fails while the journal is begin +** written, semi-random garbage data might appear in the journal +** file after power is restored. If an attempt is then made +** to roll the journal back, the database could be corrupted. The additional +** sanity checking data is an attempt to discover the garbage in the +** journal and ignore it. +** +** The sanity checking information for the new journal format consists +** of a 32-bit checksum on each page of data. The checksum covers both +** the page number and the pPager->pageSize bytes of data for the page. +** This cksum is initialized to a 32-bit random value that appears in the +** journal file right after the header. The random initializer is important, +** because garbage data that appears at the end of a journal is likely +** data that was once in other files that have now been deleted. If the +** garbage data came from an obsolete journal file, the checksums might +** be correct. But by initializing the checksum to random value which +** is different for every journal, we minimize that risk. +*/ +static const unsigned char aJournalMagic[] = { + 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7, +}; + +/* +** The size of the header and of each page in the journal is determined +** by the following macros. +*/ +#define JOURNAL_PG_SZ(pPager) ((pPager->pageSize) + 8) + +/* +** The journal header size for this pager. In the future, this could be +** set to some value read from the disk controller. The important +** characteristic is that it is the same size as a disk sector. +*/ +#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize) + +/* +** The macro MEMDB is true if we are dealing with an in-memory database. +** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set, +** the value of MEMDB will be a constant and the compiler will optimize +** out code that would never execute. +*/ +#ifdef SQLITE_OMIT_MEMORYDB +# define MEMDB 0 +#else +# define MEMDB pPager->memDb +#endif + +/* +** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is +** reserved for working around a windows/posix incompatibility). It is +** used in the journal to signify that the remainder of the journal file +** is devoted to storing a master journal name - there are no more pages to +** roll back. See comments for function writeMasterJournal() for details. +*/ +/* #define PAGER_MJ_PGNO(x) (PENDING_BYTE/((x)->pageSize)) */ +#define PAGER_MJ_PGNO(x) ((PENDING_BYTE/((x)->pageSize))+1) + +/* +** The maximum legal page number is (2^31 - 1). +*/ +#define PAGER_MAX_PGNO 2147483647 + +/* +** The pagerEnter() and pagerLeave() routines acquire and release +** a mutex on each pager. The mutex is recursive. +** +** This is a special-purpose mutex. It only provides mutual exclusion +** between the Btree and the Memory Management sqlite3_release_memory() +** function. It does not prevent, for example, two Btrees from accessing +** the same pager at the same time. Other general-purpose mutexes in +** the btree layer handle that chore. +*/ +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + static void pagerEnter(Pager *p){ + p->iInUseDB++; + if( p->iInUseMM && p->iInUseDB==1 ){ +#ifndef SQLITE_MUTEX_NOOP + sqlite3_mutex *mutex; + mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2); +#endif + p->iInUseDB = 0; + sqlite3_mutex_enter(mutex); + p->iInUseDB = 1; + sqlite3_mutex_leave(mutex); + } + assert( p->iInUseMM==0 ); + } + static void pagerLeave(Pager *p){ + p->iInUseDB--; + assert( p->iInUseDB>=0 ); + } +#else +# define pagerEnter(X) +# define pagerLeave(X) +#endif + +/* +** Add page pPg to the end of the linked list managed by structure +** pList (pPg becomes the last entry in the list - the most recently +** used). Argument pLink should point to either pPg->free or pPg->gfree, +** depending on whether pPg is being added to the pager-specific or +** global LRU list. +*/ +static void listAdd(PagerLruList *pList, PagerLruLink *pLink, PgHdr *pPg){ + pLink->pNext = 0; + pLink->pPrev = pList->pLast; + +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + assert(pLink==&pPg->free || pLink==&pPg->gfree); + assert(pLink==&pPg->gfree || pList!=&sqlite3LruPageList); +#endif + + if( pList->pLast ){ + int iOff = (char *)pLink - (char *)pPg; + PagerLruLink *pLastLink = (PagerLruLink *)(&((u8 *)pList->pLast)[iOff]); + pLastLink->pNext = pPg; + }else{ + assert(!pList->pFirst); + pList->pFirst = pPg; + } + + pList->pLast = pPg; + if( !pList->pFirstSynced && pPg->needSync==0 ){ + pList->pFirstSynced = pPg; + } +} + +/* +** Remove pPg from the list managed by the structure pointed to by pList. +** +** Argument pLink should point to either pPg->free or pPg->gfree, depending +** on whether pPg is being added to the pager-specific or global LRU list. +*/ +static void listRemove(PagerLruList *pList, PagerLruLink *pLink, PgHdr *pPg){ + int iOff = (char *)pLink - (char *)pPg; + +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + assert(pLink==&pPg->free || pLink==&pPg->gfree); + assert(pLink==&pPg->gfree || pList!=&sqlite3LruPageList); +#endif + + if( pPg==pList->pFirst ){ + pList->pFirst = pLink->pNext; + } + if( pPg==pList->pLast ){ + pList->pLast = pLink->pPrev; + } + if( pLink->pPrev ){ + PagerLruLink *pPrevLink = (PagerLruLink *)(&((u8 *)pLink->pPrev)[iOff]); + pPrevLink->pNext = pLink->pNext; + } + if( pLink->pNext ){ + PagerLruLink *pNextLink = (PagerLruLink *)(&((u8 *)pLink->pNext)[iOff]); + pNextLink->pPrev = pLink->pPrev; + } + if( pPg==pList->pFirstSynced ){ + PgHdr *p = pLink->pNext; + while( p && p->needSync ){ + PagerLruLink *pL = (PagerLruLink *)(&((u8 *)p)[iOff]); + p = pL->pNext; + } + pList->pFirstSynced = p; + } + + pLink->pNext = pLink->pPrev = 0; +} + +/* +** Add page pPg to the list of free pages for the pager. If +** memory-management is enabled, also add the page to the global +** list of free pages. +*/ +static void lruListAdd(PgHdr *pPg){ + listAdd(&pPg->pPager->lru, &pPg->free, pPg); +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + if( !pPg->pPager->memDb ){ + sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + listAdd(&sqlite3LruPageList, &pPg->gfree, pPg); + sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + } +#endif +} + +/* +** Remove page pPg from the list of free pages for the associated pager. +** If memory-management is enabled, also remove pPg from the global list +** of free pages. +*/ +static void lruListRemove(PgHdr *pPg){ + listRemove(&pPg->pPager->lru, &pPg->free, pPg); +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + if( !pPg->pPager->memDb ){ + sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + listRemove(&sqlite3LruPageList, &pPg->gfree, pPg); + sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + } +#endif +} + +/* +** This function is called just after the needSync flag has been cleared +** from all pages managed by pPager (usually because the journal file +** has just been synced). It updates the pPager->lru.pFirstSynced variable +** and, if memory-management is enabled, the sqlite3LruPageList.pFirstSynced +** variable also. +*/ +static void lruListSetFirstSynced(Pager *pPager){ + pPager->lru.pFirstSynced = pPager->lru.pFirst; +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + if( !pPager->memDb ){ + PgHdr *p; + sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + for(p=sqlite3LruPageList.pFirst; p && p->needSync; p=p->gfree.pNext); + assert(p==pPager->lru.pFirstSynced || p==sqlite3LruPageList.pFirstSynced); + sqlite3LruPageList.pFirstSynced = p; + sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + } +#endif +} + +/* +** Return true if page *pPg has already been written to the statement +** journal (or statement snapshot has been created, if *pPg is part +** of an in-memory database). +*/ +static int pageInStatement(PgHdr *pPg){ + Pager *pPager = pPg->pPager; + if( MEMDB ){ + return PGHDR_TO_HIST(pPg, pPager)->inStmt; + }else{ + return sqlite3BitvecTest(pPager->pInStmt, pPg->pgno); + } +} + +/* +** Change the size of the pager hash table to N. N must be a power +** of two. +*/ +static void pager_resize_hash_table(Pager *pPager, int N){ + PgHdr **aHash, *pPg; + assert( N>0 && (N&(N-1))==0 ); +#ifdef SQLITE_MALLOC_SOFT_LIMIT + if( N*sizeof(aHash[0])>SQLITE_MALLOC_SOFT_LIMIT ){ + N = SQLITE_MALLOC_SOFT_LIMIT/sizeof(aHash[0]); + } + if( N==pPager->nHash ) return; +#endif + pagerLeave(pPager); + if( pPager->aHash!=0 ) sqlite3BeginBenignMalloc(); + aHash = sqlite3MallocZero( sizeof(aHash[0])*N ); + if( pPager->aHash!=0 ) sqlite3EndBenignMalloc(); + pagerEnter(pPager); + if( aHash==0 ){ + /* Failure to rehash is not an error. It is only a performance hit. */ + return; + } + sqlite3_free(pPager->aHash); + pPager->nHash = N; + pPager->aHash = aHash; + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + int h; + if( pPg->pgno==0 ){ + assert( pPg->pNextHash==0 && pPg->pPrevHash==0 ); + continue; + } + h = pPg->pgno & (N-1); + pPg->pNextHash = aHash[h]; + if( aHash[h] ){ + aHash[h]->pPrevHash = pPg; + } + aHash[h] = pPg; + pPg->pPrevHash = 0; + } +} + +/* +** Read a 32-bit integer from the given file descriptor. Store the integer +** that is read in *pRes. Return SQLITE_OK if everything worked, or an +** error code is something goes wrong. +** +** All values are stored on disk as big-endian. +*/ +static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){ + unsigned char ac[4]; + int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset); + if( rc==SQLITE_OK ){ + *pRes = sqlite3Get4byte(ac); + } + return rc; +} + +/* +** Write a 32-bit integer into a string buffer in big-endian byte order. +*/ +#define put32bits(A,B) sqlite3Put4byte((u8*)A,B) + +/* +** Write a 32-bit integer into the given file descriptor. Return SQLITE_OK +** on success or an error code is something goes wrong. +*/ +static int write32bits(sqlite3_file *fd, i64 offset, u32 val){ + char ac[4]; + put32bits(ac, val); + return sqlite3OsWrite(fd, ac, 4, offset); +} + +/* +** If file pFd is open, call sqlite3OsUnlock() on it. +*/ +static int osUnlock(sqlite3_file *pFd, int eLock){ + if( !pFd->pMethods ){ + return SQLITE_OK; + } + return sqlite3OsUnlock(pFd, eLock); +} + +/* +** This function determines whether or not the atomic-write optimization +** can be used with this pager. The optimization can be used if: +** +** (a) the value returned by OsDeviceCharacteristics() indicates that +** a database page may be written atomically, and +** (b) the value returned by OsSectorSize() is less than or equal +** to the page size. +** +** If the optimization cannot be used, 0 is returned. If it can be used, +** then the value returned is the size of the journal file when it +** contains rollback data for exactly one page. +*/ +#ifdef SQLITE_ENABLE_ATOMIC_WRITE +static int jrnlBufferSize(Pager *pPager){ + int dc; /* Device characteristics */ + int nSector; /* Sector size */ + int szPage; /* Page size */ + sqlite3_file *fd = pPager->fd; + + if( fd->pMethods ){ + dc = sqlite3OsDeviceCharacteristics(fd); + nSector = sqlite3OsSectorSize(fd); + szPage = pPager->pageSize; + } + + assert(SQLITE_IOCAP_ATOMIC512==(512>>8)); + assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8)); + + if( !fd->pMethods || + (dc & (SQLITE_IOCAP_ATOMIC|(szPage>>8)) && nSector<=szPage) ){ + return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager); + } + return 0; +} +#endif + +/* +** This function should be called when an error occurs within the pager +** code. The first argument is a pointer to the pager structure, the +** second the error-code about to be returned by a pager API function. +** The value returned is a copy of the second argument to this function. +** +** If the second argument is SQLITE_IOERR, SQLITE_CORRUPT, or SQLITE_FULL +** the error becomes persistent. Until the persisten error is cleared, +** subsequent API calls on this Pager will immediately return the same +** error code. +** +** A persistent error indicates that the contents of the pager-cache +** cannot be trusted. This state can be cleared by completely discarding +** the contents of the pager-cache. If a transaction was active when +** the persistent error occured, then the rollback journal may need +** to be replayed. +*/ +static void pager_unlock(Pager *pPager); +static int pager_error(Pager *pPager, int rc){ + int rc2 = rc & 0xff; + assert( + pPager->errCode==SQLITE_FULL || + pPager->errCode==SQLITE_OK || + (pPager->errCode & 0xff)==SQLITE_IOERR + ); + if( + rc2==SQLITE_FULL || + rc2==SQLITE_IOERR || + rc2==SQLITE_CORRUPT + ){ + pPager->errCode = rc; + if( pPager->state==PAGER_UNLOCK && pPager->nRef==0 ){ + /* If the pager is already unlocked, call pager_unlock() now to + ** clear the error state and ensure that the pager-cache is + ** completely empty. + */ + pager_unlock(pPager); + } + } + return rc; +} + +/* +** If SQLITE_CHECK_PAGES is defined then we do some sanity checking +** on the cache using a hash function. This is used for testing +** and debugging only. +*/ +#ifdef SQLITE_CHECK_PAGES +/* +** Return a 32-bit hash of the page data for pPage. +*/ +static u32 pager_datahash(int nByte, unsigned char *pData){ + u32 hash = 0; + int i; + for(i=0; ipPager->pageSize, + (unsigned char *)PGHDR_TO_DATA(pPage)); +} + +/* +** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES +** is defined, and NDEBUG is not defined, an assert() statement checks +** that the page is either dirty or still matches the calculated page-hash. +*/ +#define CHECK_PAGE(x) checkPage(x) +static void checkPage(PgHdr *pPg){ + Pager *pPager = pPg->pPager; + assert( !pPg->pageHash || pPager->errCode || MEMDB || pPg->dirty || + pPg->pageHash==pager_pagehash(pPg) ); +} + +#else +#define pager_datahash(X,Y) 0 +#define pager_pagehash(X) 0 +#define CHECK_PAGE(x) +#endif + +/* +** When this is called the journal file for pager pPager must be open. +** The master journal file name is read from the end of the file and +** written into memory supplied by the caller. +** +** zMaster must point to a buffer of at least nMaster bytes allocated by +** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is +** enough space to write the master journal name). If the master journal +** name in the journal is longer than nMaster bytes (including a +** nul-terminator), then this is handled as if no master journal name +** were present in the journal. +** +** If no master journal file name is present zMaster[0] is set to 0 and +** SQLITE_OK returned. +*/ +static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, int nMaster){ + int rc; + u32 len; + i64 szJ; + u32 cksum; + u32 u; /* Unsigned loop counter */ + unsigned char aMagic[8]; /* A buffer to hold the magic header */ + + zMaster[0] = '\0'; + + rc = sqlite3OsFileSize(pJrnl, &szJ); + if( rc!=SQLITE_OK || szJ<16 ) return rc; + + rc = read32bits(pJrnl, szJ-16, &len); + if( rc!=SQLITE_OK ) return rc; + + if( len>=nMaster ){ + return SQLITE_OK; + } + + rc = read32bits(pJrnl, szJ-12, &cksum); + if( rc!=SQLITE_OK ) return rc; + + rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8); + if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc; + + rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len); + if( rc!=SQLITE_OK ){ + return rc; + } + zMaster[len] = '\0'; + + /* See if the checksum matches the master journal name */ + for(u=0; ujournalOff; + if( c ){ + offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager); + } + assert( offset%JOURNAL_HDR_SZ(pPager)==0 ); + assert( offset>=c ); + assert( (offset-c)journalOff = offset; +} + +/* +** Write zeros over the header of the journal file. This has the +** effect of invalidating the journal file and committing the +** transaction. +*/ +static int zeroJournalHdr(Pager *pPager, int doTruncate){ + int rc = SQLITE_OK; + static const char zeroHdr[28]; + + if( pPager->journalOff ){ + i64 iLimit = pPager->journalSizeLimit; + + IOTRACE(("JZEROHDR %p\n", pPager)) + if( doTruncate || iLimit==0 ){ + rc = sqlite3OsTruncate(pPager->jfd, 0); + }else{ + rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0); + } + if( rc==SQLITE_OK && !pPager->noSync ){ + rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->sync_flags); + } + + /* At this point the transaction is committed but the write lock + ** is still held on the file. If there is a size limit configured for + ** the persistent journal and the journal file currently consumes more + ** space than that limit allows for, truncate it now. There is no need + ** to sync the file following this operation. + */ + if( rc==SQLITE_OK && iLimit>0 ){ + i64 sz; + rc = sqlite3OsFileSize(pPager->jfd, &sz); + if( rc==SQLITE_OK && sz>iLimit ){ + rc = sqlite3OsTruncate(pPager->jfd, iLimit); + } + } + } + return rc; +} + +/* +** The journal file must be open when this routine is called. A journal +** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the +** current location. +** +** The format for the journal header is as follows: +** - 8 bytes: Magic identifying journal format. +** - 4 bytes: Number of records in journal, or -1 no-sync mode is on. +** - 4 bytes: Random number used for page hash. +** - 4 bytes: Initial database page count. +** - 4 bytes: Sector size used by the process that wrote this journal. +** - 4 bytes: Database page size. +** +** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space. +*/ +static int writeJournalHdr(Pager *pPager){ + int rc = SQLITE_OK; + char *zHeader = pPager->pTmpSpace; + int nHeader = pPager->pageSize; + int nWrite; + + if( nHeader>JOURNAL_HDR_SZ(pPager) ){ + nHeader = JOURNAL_HDR_SZ(pPager); + } + + if( pPager->stmtHdrOff==0 ){ + pPager->stmtHdrOff = pPager->journalOff; + } + + seekJournalHdr(pPager); + pPager->journalHdr = pPager->journalOff; + + memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic)); + + /* + ** Write the nRec Field - the number of page records that follow this + ** journal header. Normally, zero is written to this value at this time. + ** After the records are added to the journal (and the journal synced, + ** if in full-sync mode), the zero is overwritten with the true number + ** of records (see syncJournal()). + ** + ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When + ** reading the journal this value tells SQLite to assume that the + ** rest of the journal file contains valid page records. This assumption + ** is dangerous, as if a failure occured whilst writing to the journal + ** file it may contain some garbage data. There are two scenarios + ** where this risk can be ignored: + ** + ** * When the pager is in no-sync mode. Corruption can follow a + ** power failure in this case anyway. + ** + ** * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees + ** that garbage data is never appended to the journal file. + */ + assert(pPager->fd->pMethods||pPager->noSync); + if( (pPager->noSync) + || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND) + ){ + put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff); + }else{ + put32bits(&zHeader[sizeof(aJournalMagic)], 0); + } + + /* The random check-hash initialiser */ + sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit); + put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit); + /* The initial database size */ + put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbSize); + /* The assumed sector size for this process */ + put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize); + if( pPager->journalHdr==0 ){ + /* The page size */ + put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize); + } + + for(nWrite=0; rc==SQLITE_OK&&nWritejournalHdr, nHeader)) + rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff); + pPager->journalOff += nHeader; + } + + return rc; +} + +/* +** The journal file must be open when this is called. A journal header file +** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal +** file. See comments above function writeJournalHdr() for a description of +** the journal header format. +** +** If the header is read successfully, *nRec is set to the number of +** page records following this header and *dbSize is set to the size of the +** database before the transaction began, in pages. Also, pPager->cksumInit +** is set to the value read from the journal header. SQLITE_OK is returned +** in this case. +** +** If the journal header file appears to be corrupted, SQLITE_DONE is +** returned and *nRec and *dbSize are not set. If JOURNAL_HDR_SZ bytes +** cannot be read from the journal file an error code is returned. +*/ +static int readJournalHdr( + Pager *pPager, + i64 journalSize, + u32 *pNRec, + u32 *pDbSize +){ + int rc; + unsigned char aMagic[8]; /* A buffer to hold the magic header */ + i64 jrnlOff; + int iPageSize; + + seekJournalHdr(pPager); + if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){ + return SQLITE_DONE; + } + jrnlOff = pPager->journalOff; + + rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), jrnlOff); + if( rc ) return rc; + jrnlOff += sizeof(aMagic); + + if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){ + return SQLITE_DONE; + } + + rc = read32bits(pPager->jfd, jrnlOff, pNRec); + if( rc ) return rc; + + rc = read32bits(pPager->jfd, jrnlOff+4, &pPager->cksumInit); + if( rc ) return rc; + + rc = read32bits(pPager->jfd, jrnlOff+8, pDbSize); + if( rc ) return rc; + + rc = read32bits(pPager->jfd, jrnlOff+16, (u32 *)&iPageSize); + if( rc==SQLITE_OK + && iPageSize>=512 + && iPageSize<=SQLITE_MAX_PAGE_SIZE + && ((iPageSize-1)&iPageSize)==0 + ){ + u16 pagesize = iPageSize; + rc = sqlite3PagerSetPagesize(pPager, &pagesize); + } + if( rc ) return rc; + + /* Update the assumed sector-size to match the value used by + ** the process that created this journal. If this journal was + ** created by a process other than this one, then this routine + ** is being called from within pager_playback(). The local value + ** of Pager.sectorSize is restored at the end of that routine. + */ + rc = read32bits(pPager->jfd, jrnlOff+12, (u32 *)&pPager->sectorSize); + if( rc ) return rc; + + pPager->journalOff += JOURNAL_HDR_SZ(pPager); + return SQLITE_OK; +} + + +/* +** Write the supplied master journal name into the journal file for pager +** pPager at the current location. The master journal name must be the last +** thing written to a journal file. If the pager is in full-sync mode, the +** journal file descriptor is advanced to the next sector boundary before +** anything is written. The format is: +** +** + 4 bytes: PAGER_MJ_PGNO. +** + N bytes: length of master journal name. +** + 4 bytes: N +** + 4 bytes: Master journal name checksum. +** + 8 bytes: aJournalMagic[]. +** +** The master journal page checksum is the sum of the bytes in the master +** journal name. +** +** If zMaster is a NULL pointer (occurs for a single database transaction), +** this call is a no-op. +*/ +static int writeMasterJournal(Pager *pPager, const char *zMaster){ + int rc; + int len; + int i; + i64 jrnlOff; + i64 jrnlSize; + u32 cksum = 0; + char zBuf[sizeof(aJournalMagic)+2*4]; + + if( !zMaster || pPager->setMaster) return SQLITE_OK; + pPager->setMaster = 1; + + len = strlen(zMaster); + for(i=0; ifullSync ){ + seekJournalHdr(pPager); + } + jrnlOff = pPager->journalOff; + pPager->journalOff += (len+20); + + rc = write32bits(pPager->jfd, jrnlOff, PAGER_MJ_PGNO(pPager)); + if( rc!=SQLITE_OK ) return rc; + jrnlOff += 4; + + rc = sqlite3OsWrite(pPager->jfd, zMaster, len, jrnlOff); + if( rc!=SQLITE_OK ) return rc; + jrnlOff += len; + + put32bits(zBuf, len); + put32bits(&zBuf[4], cksum); + memcpy(&zBuf[8], aJournalMagic, sizeof(aJournalMagic)); + rc = sqlite3OsWrite(pPager->jfd, zBuf, 8+sizeof(aJournalMagic), jrnlOff); + jrnlOff += 8+sizeof(aJournalMagic); + pPager->needSync = !pPager->noSync; + + /* If the pager is in peristent-journal mode, then the physical + ** journal-file may extend past the end of the master-journal name + ** and 8 bytes of magic data just written to the file. This is + ** dangerous because the code to rollback a hot-journal file + ** will not be able to find the master-journal name to determine + ** whether or not the journal is hot. + ** + ** Easiest thing to do in this scenario is to truncate the journal + ** file to the required size. + */ + if( (rc==SQLITE_OK) + && (rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))==SQLITE_OK + && jrnlSize>jrnlOff + ){ + rc = sqlite3OsTruncate(pPager->jfd, jrnlOff); + } + return rc; +} + +/* +** Add or remove a page from the list of all pages that are in the +** statement journal. +** +** The Pager keeps a separate list of pages that are currently in +** the statement journal. This helps the sqlite3PagerStmtCommit() +** routine run MUCH faster for the common case where there are many +** pages in memory but only a few are in the statement journal. +*/ +static void page_add_to_stmt_list(PgHdr *pPg){ + Pager *pPager = pPg->pPager; + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + assert( MEMDB ); + if( !pHist->inStmt ){ + assert( pHist->pPrevStmt==0 && pHist->pNextStmt==0 ); + if( pPager->pStmt ){ + PGHDR_TO_HIST(pPager->pStmt, pPager)->pPrevStmt = pPg; + } + pHist->pNextStmt = pPager->pStmt; + pPager->pStmt = pPg; + pHist->inStmt = 1; + } +} + +/* +** Find a page in the hash table given its page number. Return +** a pointer to the page or NULL if not found. +*/ +static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){ + PgHdr *p; + if( pPager->aHash==0 ) return 0; + p = pPager->aHash[pgno & (pPager->nHash-1)]; + while( p && p->pgno!=pgno ){ + p = p->pNextHash; + } + return p; +} + +/* +** Clear the in-memory cache. This routine +** sets the state of the pager back to what it was when it was first +** opened. Any outstanding pages are invalidated and subsequent attempts +** to access those pages will likely result in a coredump. +*/ +static void pager_reset(Pager *pPager){ + PgHdr *pPg, *pNext; + if( pPager->errCode ) return; + for(pPg=pPager->pAll; pPg; pPg=pNext){ + IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno)); + PAGER_INCR(sqlite3_pager_pgfree_count); + pNext = pPg->pNextAll; + lruListRemove(pPg); + sqlite3PageFree(pPg->pData); + sqlite3_free(pPg); + } + assert(pPager->lru.pFirst==0); + assert(pPager->lru.pFirstSynced==0); + assert(pPager->lru.pLast==0); + pPager->pStmt = 0; + pPager->pAll = 0; + pPager->pDirty = 0; + pPager->nHash = 0; + sqlite3_free(pPager->aHash); + pPager->nPage = 0; + pPager->aHash = 0; + pPager->nRef = 0; +} + +/* +** Unlock the database file. +** +** If the pager is currently in error state, discard the contents of +** the cache and reset the Pager structure internal state. If there is +** an open journal-file, then the next time a shared-lock is obtained +** on the pager file (by this or any other process), it will be +** treated as a hot-journal and rolled back. +*/ +static void pager_unlock(Pager *pPager){ + if( !pPager->exclusiveMode ){ + if( !MEMDB ){ + int rc = osUnlock(pPager->fd, NO_LOCK); + if( rc ) pPager->errCode = rc; + pPager->dbSize = -1; + IOTRACE(("UNLOCK %p\n", pPager)) + + /* Always close the journal file when dropping the database lock. + ** Otherwise, another connection with journal_mode=delete might + ** delete the file out from under us. + */ + if( pPager->journalOpen ){ + sqlite3OsClose(pPager->jfd); + pPager->journalOpen = 0; + sqlite3BitvecDestroy(pPager->pInJournal); + pPager->pInJournal = 0; + } + + /* If Pager.errCode is set, the contents of the pager cache cannot be + ** trusted. Now that the pager file is unlocked, the contents of the + ** cache can be discarded and the error code safely cleared. + */ + if( pPager->errCode ){ + if( rc==SQLITE_OK ) pPager->errCode = SQLITE_OK; + pager_reset(pPager); + if( pPager->stmtOpen ){ + sqlite3OsClose(pPager->stfd); + sqlite3BitvecDestroy(pPager->pInStmt); + pPager->pInStmt = 0; + } + pPager->stmtOpen = 0; + pPager->stmtInUse = 0; + pPager->journalOff = 0; + pPager->journalStarted = 0; + pPager->stmtAutoopen = 0; + pPager->origDbSize = 0; + } + } + + if( !MEMDB || pPager->errCode==SQLITE_OK ){ + pPager->state = PAGER_UNLOCK; + pPager->changeCountDone = 0; + } + } +} + +/* +** Execute a rollback if a transaction is active and unlock the +** database file. If the pager has already entered the error state, +** do not attempt the rollback. +*/ +static void pagerUnlockAndRollback(Pager *p){ + /* assert( p->state>=PAGER_RESERVED || p->journalOpen==0 ); */ + if( p->errCode==SQLITE_OK && p->state>=PAGER_RESERVED ){ + sqlite3BeginBenignMalloc(); + sqlite3PagerRollback(p); + sqlite3EndBenignMalloc(); + } + pager_unlock(p); +#if 0 + assert( p->errCode || !p->journalOpen || (p->exclusiveMode&&!p->journalOff) ); + assert( p->errCode || !p->stmtOpen || p->exclusiveMode ); +#endif +} + +/* +** This routine ends a transaction. A transaction is ended by either +** a COMMIT or a ROLLBACK. +** +** When this routine is called, the pager has the journal file open and +** a RESERVED or EXCLUSIVE lock on the database. This routine will release +** the database lock and acquires a SHARED lock in its place if that is +** the appropriate thing to do. Release locks usually is appropriate, +** unless we are in exclusive access mode or unless this is a +** COMMIT AND BEGIN or ROLLBACK AND BEGIN operation. +** +** The journal file is either deleted or truncated. +** +** TODO: Consider keeping the journal file open for temporary databases. +** This might give a performance improvement on windows where opening +** a file is an expensive operation. +*/ +static int pager_end_transaction(Pager *pPager, int hasMaster){ + PgHdr *pPg; + int rc = SQLITE_OK; + int rc2 = SQLITE_OK; + assert( !MEMDB ); + if( pPager->statestmtOpen && !pPager->exclusiveMode ){ + sqlite3OsClose(pPager->stfd); + pPager->stmtOpen = 0; + } + if( pPager->journalOpen ){ + if( pPager->exclusiveMode + || pPager->journalMode==PAGER_JOURNALMODE_PERSIST + ){ + rc = zeroJournalHdr(pPager, hasMaster); + pager_error(pPager, rc); + pPager->journalOff = 0; + pPager->journalStarted = 0; + }else{ + sqlite3OsClose(pPager->jfd); + pPager->journalOpen = 0; + if( rc==SQLITE_OK && !pPager->tempFile ){ + rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0); + } + } + sqlite3BitvecDestroy(pPager->pInJournal); + pPager->pInJournal = 0; + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + pPg->inJournal = 0; + pPg->dirty = 0; + pPg->needSync = 0; + pPg->alwaysRollback = 0; +#ifdef SQLITE_CHECK_PAGES + pPg->pageHash = pager_pagehash(pPg); +#endif + } + pPager->pDirty = 0; + pPager->dirtyCache = 0; + pPager->nRec = 0; + }else{ + assert( pPager->pInJournal==0 ); + } + + if( !pPager->exclusiveMode ){ + rc2 = osUnlock(pPager->fd, SHARED_LOCK); + pPager->state = PAGER_SHARED; + }else if( pPager->state==PAGER_SYNCED ){ + pPager->state = PAGER_EXCLUSIVE; + } + pPager->origDbSize = 0; + pPager->setMaster = 0; + pPager->needSync = 0; + lruListSetFirstSynced(pPager); + pPager->dbSize = -1; + pPager->dbModified = 0; + + return (rc==SQLITE_OK?rc2:rc); +} + +/* +** Compute and return a checksum for the page of data. +** +** This is not a real checksum. It is really just the sum of the +** random initial value and the page number. We experimented with +** a checksum of the entire data, but that was found to be too slow. +** +** Note that the page number is stored at the beginning of data and +** the checksum is stored at the end. This is important. If journal +** corruption occurs due to a power failure, the most likely scenario +** is that one end or the other of the record will be changed. It is +** much less likely that the two ends of the journal record will be +** correct and the middle be corrupt. Thus, this "checksum" scheme, +** though fast and simple, catches the mostly likely kind of corruption. +** +** FIX ME: Consider adding every 200th (or so) byte of the data to the +** checksum. That way if a single page spans 3 or more disk sectors and +** only the middle sector is corrupt, we will still have a reasonable +** chance of failing the checksum and thus detecting the problem. +*/ +static u32 pager_cksum(Pager *pPager, const u8 *aData){ + u32 cksum = pPager->cksumInit; + int i = pPager->pageSize-200; + while( i>0 ){ + cksum += aData[i]; + i -= 200; + } + return cksum; +} + +/* Forward declaration */ +static void makeClean(PgHdr*); + +/* +** Read a single page from the journal file opened on file descriptor +** jfd. Playback this one page. +** +** If useCksum==0 it means this journal does not use checksums. Checksums +** are not used in statement journals because statement journals do not +** need to survive power failures. +*/ +static int pager_playback_one_page( + Pager *pPager, + sqlite3_file *jfd, + i64 offset, + int useCksum +){ + int rc; + PgHdr *pPg; /* An existing page in the cache */ + Pgno pgno; /* The page number of a page in journal */ + u32 cksum; /* Checksum used for sanity checking */ + u8 *aData = (u8 *)pPager->pTmpSpace; /* Temp storage for a page */ + + /* useCksum should be true for the main journal and false for + ** statement journals. Verify that this is always the case + */ + assert( jfd == (useCksum ? pPager->jfd : pPager->stfd) ); + assert( aData ); + + rc = read32bits(jfd, offset, &pgno); + if( rc!=SQLITE_OK ) return rc; + rc = sqlite3OsRead(jfd, aData, pPager->pageSize, offset+4); + if( rc!=SQLITE_OK ) return rc; + pPager->journalOff += pPager->pageSize + 4; + + /* Sanity checking on the page. This is more important that I originally + ** thought. If a power failure occurs while the journal is being written, + ** it could cause invalid data to be written into the journal. We need to + ** detect this invalid data (with high probability) and ignore it. + */ + if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){ + return SQLITE_DONE; + } + if( pgno>(unsigned)pPager->dbSize ){ + return SQLITE_OK; + } + if( useCksum ){ + rc = read32bits(jfd, offset+pPager->pageSize+4, &cksum); + if( rc ) return rc; + pPager->journalOff += 4; + if( pager_cksum(pPager, aData)!=cksum ){ + return SQLITE_DONE; + } + } + + assert( pPager->state==PAGER_RESERVED || pPager->state>=PAGER_EXCLUSIVE ); + + /* If the pager is in RESERVED state, then there must be a copy of this + ** page in the pager cache. In this case just update the pager cache, + ** not the database file. The page is left marked dirty in this case. + ** + ** An exception to the above rule: If the database is in no-sync mode + ** and a page is moved during an incremental vacuum then the page may + ** not be in the pager cache. Later: if a malloc() or IO error occurs + ** during a Movepage() call, then the page may not be in the cache + ** either. So the condition described in the above paragraph is not + ** assert()able. + ** + ** If in EXCLUSIVE state, then we update the pager cache if it exists + ** and the main file. The page is then marked not dirty. + ** + ** Ticket #1171: The statement journal might contain page content that is + ** different from the page content at the start of the transaction. + ** This occurs when a page is changed prior to the start of a statement + ** then changed again within the statement. When rolling back such a + ** statement we must not write to the original database unless we know + ** for certain that original page contents are synced into the main rollback + ** journal. Otherwise, a power loss might leave modified data in the + ** database file without an entry in the rollback journal that can + ** restore the database to its original form. Two conditions must be + ** met before writing to the database files. (1) the database must be + ** locked. (2) we know that the original page content is fully synced + ** in the main journal either because the page is not in cache or else + ** the page is marked as needSync==0. + ** + ** 2008-04-14: When attempting to vacuum a corrupt database file, it + ** is possible to fail a statement on a database that does not yet exist. + ** Do not attempt to write if database file has never been opened. + */ + pPg = pager_lookup(pPager, pgno); + PAGERTRACE4("PLAYBACK %d page %d hash(%08x)\n", + PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, aData)); + if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) + && pPager->fd->pMethods ){ + i64 offset = (pgno-1)*(i64)pPager->pageSize; + rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize, offset); + if( pPg ){ + makeClean(pPg); + } + } + if( pPg ){ + /* No page should ever be explicitly rolled back that is in use, except + ** for page 1 which is held in use in order to keep the lock on the + ** database active. However such a page may be rolled back as a result + ** of an internal error resulting in an automatic call to + ** sqlite3PagerRollback(). + */ + void *pData; + /* assert( pPg->nRef==0 || pPg->pgno==1 ); */ + pData = PGHDR_TO_DATA(pPg); + memcpy(pData, aData, pPager->pageSize); + if( pPager->xReiniter ){ + pPager->xReiniter(pPg, pPager->pageSize); + } +#ifdef SQLITE_CHECK_PAGES + pPg->pageHash = pager_pagehash(pPg); +#endif + /* If this was page 1, then restore the value of Pager.dbFileVers. + ** Do this before any decoding. */ + if( pgno==1 ){ + memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers)); + } + + /* Decode the page just read from disk */ + CODEC1(pPager, pData, pPg->pgno, 3); + } + return rc; +} + +/* +** Parameter zMaster is the name of a master journal file. A single journal +** file that referred to the master journal file has just been rolled back. +** This routine checks if it is possible to delete the master journal file, +** and does so if it is. +** +** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not +** available for use within this function. +** +** +** The master journal file contains the names of all child journals. +** To tell if a master journal can be deleted, check to each of the +** children. If all children are either missing or do not refer to +** a different master journal, then this master journal can be deleted. +*/ +static int pager_delmaster(Pager *pPager, const char *zMaster){ + sqlite3_vfs *pVfs = pPager->pVfs; + int rc; + int master_open = 0; + sqlite3_file *pMaster; + sqlite3_file *pJournal; + char *zMasterJournal = 0; /* Contents of master journal file */ + i64 nMasterJournal; /* Size of master journal file */ + + /* Open the master journal file exclusively in case some other process + ** is running this routine also. Not that it makes too much difference. + */ + pMaster = (sqlite3_file *)sqlite3Malloc(pVfs->szOsFile * 2); + pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile); + if( !pMaster ){ + rc = SQLITE_NOMEM; + }else{ + int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL); + rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0); + } + if( rc!=SQLITE_OK ) goto delmaster_out; + master_open = 1; + + rc = sqlite3OsFileSize(pMaster, &nMasterJournal); + if( rc!=SQLITE_OK ) goto delmaster_out; + + if( nMasterJournal>0 ){ + char *zJournal; + char *zMasterPtr = 0; + int nMasterPtr = pPager->pVfs->mxPathname+1; + + /* Load the entire master journal file into space obtained from + ** sqlite3_malloc() and pointed to by zMasterJournal. + */ + zMasterJournal = (char *)sqlite3Malloc(nMasterJournal + nMasterPtr); + if( !zMasterJournal ){ + rc = SQLITE_NOMEM; + goto delmaster_out; + } + zMasterPtr = &zMasterJournal[nMasterJournal]; + rc = sqlite3OsRead(pMaster, zMasterJournal, nMasterJournal, 0); + if( rc!=SQLITE_OK ) goto delmaster_out; + + zJournal = zMasterJournal; + while( (zJournal-zMasterJournal)state>=PAGER_EXCLUSIVE && pPager->fd->pMethods ){ + i64 currentSize, newSize; + rc = sqlite3OsFileSize(pPager->fd, ¤tSize); + newSize = pPager->pageSize*(i64)nPage; + if( rc==SQLITE_OK && currentSize!=newSize ){ + if( currentSize>newSize ){ + rc = sqlite3OsTruncate(pPager->fd, newSize); + }else{ + rc = sqlite3OsWrite(pPager->fd, "", 1, newSize-1); + } + } + } + if( rc==SQLITE_OK ){ + pPager->dbSize = nPage; + pager_truncate_cache(pPager); + } + return rc; +} + +/* +** Set the sectorSize for the given pager. +** +** The sector size is at least as big as the sector size reported +** by sqlite3OsSectorSize(). The minimum sector size is 512. +*/ +static void setSectorSize(Pager *pPager){ + assert(pPager->fd->pMethods||pPager->tempFile); + if( !pPager->tempFile ){ + /* Sector size doesn't matter for temporary files. Also, the file + ** may not have been opened yet, in whcih case the OsSectorSize() + ** call will segfault. + */ + pPager->sectorSize = sqlite3OsSectorSize(pPager->fd); + } + if( pPager->sectorSize<512 ){ + pPager->sectorSize = 512; + } +} + +/* +** Playback the journal and thus restore the database file to +** the state it was in before we started making changes. +** +** The journal file format is as follows: +** +** (1) 8 byte prefix. A copy of aJournalMagic[]. +** (2) 4 byte big-endian integer which is the number of valid page records +** in the journal. If this value is 0xffffffff, then compute the +** number of page records from the journal size. +** (3) 4 byte big-endian integer which is the initial value for the +** sanity checksum. +** (4) 4 byte integer which is the number of pages to truncate the +** database to during a rollback. +** (5) 4 byte big-endian integer which is the sector size. The header +** is this many bytes in size. +** (6) 4 byte big-endian integer which is the page case. +** (7) 4 byte integer which is the number of bytes in the master journal +** name. The value may be zero (indicate that there is no master +** journal.) +** (8) N bytes of the master journal name. The name will be nul-terminated +** and might be shorter than the value read from (5). If the first byte +** of the name is \000 then there is no master journal. The master +** journal name is stored in UTF-8. +** (9) Zero or more pages instances, each as follows: +** + 4 byte page number. +** + pPager->pageSize bytes of data. +** + 4 byte checksum +** +** When we speak of the journal header, we mean the first 8 items above. +** Each entry in the journal is an instance of the 9th item. +** +** Call the value from the second bullet "nRec". nRec is the number of +** valid page entries in the journal. In most cases, you can compute the +** value of nRec from the size of the journal file. But if a power +** failure occurred while the journal was being written, it could be the +** case that the size of the journal file had already been increased but +** the extra entries had not yet made it safely to disk. In such a case, +** the value of nRec computed from the file size would be too large. For +** that reason, we always use the nRec value in the header. +** +** If the nRec value is 0xffffffff it means that nRec should be computed +** from the file size. This value is used when the user selects the +** no-sync option for the journal. A power failure could lead to corruption +** in this case. But for things like temporary table (which will be +** deleted when the power is restored) we don't care. +** +** If the file opened as the journal file is not a well-formed +** journal file then all pages up to the first corrupted page are rolled +** back (or no pages if the journal header is corrupted). The journal file +** is then deleted and SQLITE_OK returned, just as if no corruption had +** been encountered. +** +** If an I/O or malloc() error occurs, the journal-file is not deleted +** and an error code is returned. +*/ +static int pager_playback(Pager *pPager, int isHot){ + sqlite3_vfs *pVfs = pPager->pVfs; + i64 szJ; /* Size of the journal file in bytes */ + u32 nRec; /* Number of Records in the journal */ + u32 u; /* Unsigned loop counter */ + Pgno mxPg = 0; /* Size of the original file in pages */ + int rc; /* Result code of a subroutine */ + int res = 1; /* Value returned by sqlite3OsAccess() */ + char *zMaster = 0; /* Name of master journal file if any */ + + /* Figure out how many records are in the journal. Abort early if + ** the journal is empty. + */ + assert( pPager->journalOpen ); + rc = sqlite3OsFileSize(pPager->jfd, &szJ); + if( rc!=SQLITE_OK || szJ==0 ){ + goto end_playback; + } + + /* Read the master journal name from the journal, if it is present. + ** If a master journal file name is specified, but the file is not + ** present on disk, then the journal is not hot and does not need to be + ** played back. + */ + zMaster = pPager->pTmpSpace; + rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1); + if( rc==SQLITE_OK && zMaster[0] ){ + rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res); + } + zMaster = 0; + if( rc!=SQLITE_OK || !res ){ + goto end_playback; + } + pPager->journalOff = 0; + + /* This loop terminates either when the readJournalHdr() call returns + ** SQLITE_DONE or an IO error occurs. */ + while( 1 ){ + + /* Read the next journal header from the journal file. If there are + ** not enough bytes left in the journal file for a complete header, or + ** it is corrupted, then a process must of failed while writing it. + ** This indicates nothing more needs to be rolled back. + */ + rc = readJournalHdr(pPager, szJ, &nRec, &mxPg); + if( rc!=SQLITE_OK ){ + if( rc==SQLITE_DONE ){ + rc = SQLITE_OK; + } + goto end_playback; + } + + /* If nRec is 0xffffffff, then this journal was created by a process + ** working in no-sync mode. This means that the rest of the journal + ** file consists of pages, there are no more journal headers. Compute + ** the value of nRec based on this assumption. + */ + if( nRec==0xffffffff ){ + assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ); + nRec = (szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager); + } + + /* If nRec is 0 and this rollback is of a transaction created by this + ** process and if this is the final header in the journal, then it means + ** that this part of the journal was being filled but has not yet been + ** synced to disk. Compute the number of pages based on the remaining + ** size of the file. + ** + ** The third term of the test was added to fix ticket #2565. + */ + if( nRec==0 && !isHot && + pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){ + nRec = (szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager); + } + + /* If this is the first header read from the journal, truncate the + ** database file back to its original size. + */ + if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){ + rc = pager_truncate(pPager, mxPg); + if( rc!=SQLITE_OK ){ + goto end_playback; + } + } + + /* Copy original pages out of the journal and back into the database file. + */ + for(u=0; ujfd, pPager->journalOff, 1); + if( rc!=SQLITE_OK ){ + if( rc==SQLITE_DONE ){ + rc = SQLITE_OK; + pPager->journalOff = szJ; + break; + }else{ + goto end_playback; + } + } + } + } + /*NOTREACHED*/ + assert( 0 ); + +end_playback: + if( rc==SQLITE_OK ){ + zMaster = pPager->pTmpSpace; + rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1); + } + if( rc==SQLITE_OK ){ + rc = pager_end_transaction(pPager, zMaster[0]!='\0'); + } + if( rc==SQLITE_OK && zMaster[0] ){ + /* If there was a master journal and this routine will return success, + ** see if it is possible to delete the master journal. + */ + rc = pager_delmaster(pPager, zMaster); + } + + /* The Pager.sectorSize variable may have been updated while rolling + ** back a journal created by a process with a different sector size + ** value. Reset it to the correct value for this process. + */ + setSectorSize(pPager); + return rc; +} + +/* +** Playback the statement journal. +** +** This is similar to playing back the transaction journal but with +** a few extra twists. +** +** (1) The number of pages in the database file at the start of +** the statement is stored in pPager->stmtSize, not in the +** journal file itself. +** +** (2) In addition to playing back the statement journal, also +** playback all pages of the transaction journal beginning +** at offset pPager->stmtJSize. +*/ +static int pager_stmt_playback(Pager *pPager){ + i64 szJ; /* Size of the full journal */ + i64 hdrOff; + int nRec; /* Number of Records */ + int i; /* Loop counter */ + int rc; + + szJ = pPager->journalOff; + + /* Set hdrOff to be the offset just after the end of the last journal + ** page written before the first journal-header for this statement + ** transaction was written, or the end of the file if no journal + ** header was written. + */ + hdrOff = pPager->stmtHdrOff; + assert( pPager->fullSync || !hdrOff ); + if( !hdrOff ){ + hdrOff = szJ; + } + + /* Truncate the database back to its original size. + */ + rc = pager_truncate(pPager, pPager->stmtSize); + assert( pPager->state>=PAGER_SHARED ); + + /* Figure out how many records are in the statement journal. + */ + assert( pPager->stmtInUse && pPager->journalOpen ); + nRec = pPager->stmtNRec; + + /* Copy original pages out of the statement journal and back into the + ** database file. Note that the statement journal omits checksums from + ** each record since power-failure recovery is not important to statement + ** journals. + */ + for(i=0; ipageSize); + rc = pager_playback_one_page(pPager, pPager->stfd, offset, 0); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK ) goto end_stmt_playback; + } + + /* Now roll some pages back from the transaction journal. Pager.stmtJSize + ** was the size of the journal file when this statement was started, so + ** everything after that needs to be rolled back, either into the + ** database, the memory cache, or both. + ** + ** If it is not zero, then Pager.stmtHdrOff is the offset to the start + ** of the first journal header written during this statement transaction. + */ + pPager->journalOff = pPager->stmtJSize; + pPager->cksumInit = pPager->stmtCksum; + while( pPager->journalOff < hdrOff ){ + rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK ) goto end_stmt_playback; + } + + while( pPager->journalOff < szJ ){ + u32 nJRec; /* Number of Journal Records */ + u32 dummy; + rc = readJournalHdr(pPager, szJ, &nJRec, &dummy); + if( rc!=SQLITE_OK ){ + assert( rc!=SQLITE_DONE ); + goto end_stmt_playback; + } + if( nJRec==0 ){ + nJRec = (szJ - pPager->journalOff) / (pPager->pageSize+8); + } + for(i=nJRec-1; i>=0 && pPager->journalOff < szJ; i--){ + rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK ) goto end_stmt_playback; + } + } + + pPager->journalOff = szJ; + +end_stmt_playback: + if( rc==SQLITE_OK) { + pPager->journalOff = szJ; + /* pager_reload_cache(pPager); */ + } + return rc; +} + +/* +** Change the maximum number of in-memory pages that are allowed. +*/ +void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){ + if( mxPage>10 ){ + pPager->mxPage = mxPage; + }else{ + pPager->mxPage = 10; + } +} + +/* +** Adjust the robustness of the database to damage due to OS crashes +** or power failures by changing the number of syncs()s when writing +** the rollback journal. There are three levels: +** +** OFF sqlite3OsSync() is never called. This is the default +** for temporary and transient files. +** +** NORMAL The journal is synced once before writes begin on the +** database. This is normally adequate protection, but +** it is theoretically possible, though very unlikely, +** that an inopertune power failure could leave the journal +** in a state which would cause damage to the database +** when it is rolled back. +** +** FULL The journal is synced twice before writes begin on the +** database (with some additional information - the nRec field +** of the journal header - being written in between the two +** syncs). If we assume that writing a +** single disk sector is atomic, then this mode provides +** assurance that the journal will not be corrupted to the +** point of causing damage to the database during rollback. +** +** Numeric values associated with these states are OFF==1, NORMAL=2, +** and FULL=3. +*/ +#ifndef SQLITE_OMIT_PAGER_PRAGMAS +void sqlite3PagerSetSafetyLevel(Pager *pPager, int level, int full_fsync){ + pPager->noSync = level==1 || pPager->tempFile; + pPager->fullSync = level==3 && !pPager->tempFile; + pPager->sync_flags = (full_fsync?SQLITE_SYNC_FULL:SQLITE_SYNC_NORMAL); + if( pPager->noSync ) pPager->needSync = 0; +} +#endif + +/* +** The following global variable is incremented whenever the library +** attempts to open a temporary file. This information is used for +** testing and analysis only. +*/ +#ifdef SQLITE_TEST +int sqlite3_opentemp_count = 0; +#endif + +/* +** Open a temporary file. +** +** Write the file descriptor into *fd. Return SQLITE_OK on success or some +** other error code if we fail. The OS will automatically delete the temporary +** file when it is closed. +*/ +static int sqlite3PagerOpentemp( + Pager *pPager, /* The pager object */ + sqlite3_file *pFile, /* Write the file descriptor here */ + int vfsFlags /* Flags passed through to the VFS */ +){ + int rc; + +#ifdef SQLITE_TEST + sqlite3_opentemp_count++; /* Used for testing and analysis only */ +#endif + + vfsFlags |= SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | + SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE; + rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0); + assert( rc!=SQLITE_OK || pFile->pMethods ); + return rc; +} + +/* +** Create a new page cache and put a pointer to the page cache in *ppPager. +** The file to be cached need not exist. The file is not locked until +** the first call to sqlite3PagerGet() and is only held open until the +** last page is released using sqlite3PagerUnref(). +** +** If zFilename is NULL then a randomly-named temporary file is created +** and used as the file to be cached. The file will be deleted +** automatically when it is closed. +** +** If zFilename is ":memory:" then all information is held in cache. +** It is never written to disk. This can be used to implement an +** in-memory database. +*/ +int sqlite3PagerOpen( + sqlite3_vfs *pVfs, /* The virtual file system to use */ + Pager **ppPager, /* Return the Pager structure here */ + const char *zFilename, /* Name of the database file to open */ + int nExtra, /* Extra bytes append to each in-memory page */ + int flags, /* flags controlling this file */ + int vfsFlags /* flags passed through to sqlite3_vfs.xOpen() */ +){ + u8 *pPtr; + Pager *pPager = 0; + int rc = SQLITE_OK; + int i; + int tempFile = 0; + int memDb = 0; + int readOnly = 0; + int useJournal = (flags & PAGER_OMIT_JOURNAL)==0; + int noReadlock = (flags & PAGER_NO_READLOCK)!=0; + int journalFileSize = sqlite3JournalSize(pVfs); + int szPageDflt = SQLITE_DEFAULT_PAGE_SIZE; + char *zPathname = 0; + int nPathname = 0; + + /* The default return is a NULL pointer */ + *ppPager = 0; + + /* Compute and store the full pathname in an allocated buffer pointed + ** to by zPathname, length nPathname. Or, if this is a temporary file, + ** leave both nPathname and zPathname set to 0. + */ + if( zFilename && zFilename[0] ){ + nPathname = pVfs->mxPathname+1; + zPathname = sqlite3Malloc(nPathname*2); + if( zPathname==0 ){ + return SQLITE_NOMEM; + } +#ifndef SQLITE_OMIT_MEMORYDB + if( strcmp(zFilename,":memory:")==0 ){ + memDb = 1; + zPathname[0] = 0; + }else +#endif + { + rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname); + } + if( rc!=SQLITE_OK ){ + sqlite3_free(zPathname); + return rc; + } + nPathname = strlen(zPathname); + } + + /* Allocate memory for the pager structure */ + pPager = sqlite3MallocZero( + sizeof(*pPager) + /* Pager structure */ + journalFileSize + /* The journal file structure */ + pVfs->szOsFile * 3 + /* The main db and two journal files */ + 3*nPathname + 40 /* zFilename, zDirectory, zJournal */ + ); + if( !pPager ){ + sqlite3_free(zPathname); + return SQLITE_NOMEM; + } + pPtr = (u8 *)&pPager[1]; + pPager->vfsFlags = vfsFlags; + pPager->fd = (sqlite3_file*)&pPtr[pVfs->szOsFile*0]; + pPager->stfd = (sqlite3_file*)&pPtr[pVfs->szOsFile*1]; + pPager->jfd = (sqlite3_file*)&pPtr[pVfs->szOsFile*2]; + pPager->zFilename = (char*)&pPtr[pVfs->szOsFile*2+journalFileSize]; + pPager->zDirectory = &pPager->zFilename[nPathname+1]; + pPager->zJournal = &pPager->zDirectory[nPathname+1]; + pPager->pVfs = pVfs; + if( zPathname ){ + memcpy(pPager->zFilename, zPathname, nPathname+1); + sqlite3_free(zPathname); + } + + /* Open the pager file. + */ + if( zFilename && zFilename[0] && !memDb ){ + if( nPathname>(pVfs->mxPathname - sizeof("-journal")) ){ + rc = SQLITE_CANTOPEN; + }else{ + int fout = 0; + rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd, + pPager->vfsFlags, &fout); + readOnly = (fout&SQLITE_OPEN_READONLY); + + /* If the file was successfully opened for read/write access, + ** choose a default page size in case we have to create the + ** database file. The default page size is the maximum of: + ** + ** + SQLITE_DEFAULT_PAGE_SIZE, + ** + The value returned by sqlite3OsSectorSize() + ** + The largest page size that can be written atomically. + */ + if( rc==SQLITE_OK && !readOnly ){ + int iSectorSize = sqlite3OsSectorSize(pPager->fd); + if( szPageDfltfd); + int ii; + assert(SQLITE_IOCAP_ATOMIC512==(512>>8)); + assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8)); + assert(SQLITE_MAX_DEFAULT_PAGE_SIZE<=65536); + for(ii=szPageDflt; ii<=SQLITE_MAX_DEFAULT_PAGE_SIZE; ii=ii*2){ + if( iDc&(SQLITE_IOCAP_ATOMIC|(ii>>8)) ) szPageDflt = ii; + } + } +#endif + if( szPageDflt>SQLITE_MAX_DEFAULT_PAGE_SIZE ){ + szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE; + } + } + } + }else if( !memDb ){ + /* If a temporary file is requested, it is not opened immediately. + ** In this case we accept the default page size and delay actually + ** opening the file until the first call to OsWrite(). + */ + tempFile = 1; + pPager->state = PAGER_EXCLUSIVE; + } + + if( pPager && rc==SQLITE_OK ){ + pPager->pTmpSpace = sqlite3PageMalloc(szPageDflt); + } + + /* If an error occured in either of the blocks above. + ** Free the Pager structure and close the file. + ** Since the pager is not allocated there is no need to set + ** any Pager.errMask variables. + */ + if( !pPager || !pPager->pTmpSpace ){ + sqlite3OsClose(pPager->fd); + sqlite3_free(pPager); + return ((rc==SQLITE_OK)?SQLITE_NOMEM:rc); + } + + PAGERTRACE3("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename); + IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename)) + + /* Fill in Pager.zDirectory[] */ + memcpy(pPager->zDirectory, pPager->zFilename, nPathname+1); + for(i=strlen(pPager->zDirectory); i>0 && pPager->zDirectory[i-1]!='/'; i--){} + if( i>0 ) pPager->zDirectory[i-1] = 0; + + /* Fill in Pager.zJournal[] */ + if( zPathname ){ + memcpy(pPager->zJournal, pPager->zFilename, nPathname); + memcpy(&pPager->zJournal[nPathname], "-journal", 9); + }else{ + pPager->zJournal = 0; + } + + /* pPager->journalOpen = 0; */ + pPager->useJournal = useJournal && !memDb; + pPager->noReadlock = noReadlock && readOnly; + /* pPager->stmtOpen = 0; */ + /* pPager->stmtInUse = 0; */ + /* pPager->nRef = 0; */ + pPager->dbSize = memDb-1; + pPager->pageSize = szPageDflt; + /* pPager->stmtSize = 0; */ + /* pPager->stmtJSize = 0; */ + /* pPager->nPage = 0; */ + pPager->mxPage = 100; + pPager->mxPgno = SQLITE_MAX_PAGE_COUNT; + /* pPager->state = PAGER_UNLOCK; */ + assert( pPager->state == (tempFile ? PAGER_EXCLUSIVE : PAGER_UNLOCK) ); + /* pPager->errMask = 0; */ + pPager->tempFile = tempFile; + assert( tempFile==PAGER_LOCKINGMODE_NORMAL + || tempFile==PAGER_LOCKINGMODE_EXCLUSIVE ); + assert( PAGER_LOCKINGMODE_EXCLUSIVE==1 ); + pPager->exclusiveMode = tempFile; + pPager->memDb = memDb; + pPager->readOnly = readOnly; + /* pPager->needSync = 0; */ + pPager->noSync = pPager->tempFile || !useJournal; + pPager->fullSync = (pPager->noSync?0:1); + pPager->sync_flags = SQLITE_SYNC_NORMAL; + /* pPager->pFirst = 0; */ + /* pPager->pFirstSynced = 0; */ + /* pPager->pLast = 0; */ + pPager->nExtra = FORCE_ALIGNMENT(nExtra); + pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT; + assert(pPager->fd->pMethods||memDb||tempFile); + if( !memDb ){ + setSectorSize(pPager); + } + /* pPager->pBusyHandler = 0; */ + /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */ + *ppPager = pPager; +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + pPager->iInUseMM = 0; + pPager->iInUseDB = 0; + if( !memDb ){ +#ifndef SQLITE_MUTEX_NOOP + sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2); +#endif + sqlite3_mutex_enter(mutex); + pPager->pNext = sqlite3PagerList; + if( sqlite3PagerList ){ + assert( sqlite3PagerList->pPrev==0 ); + sqlite3PagerList->pPrev = pPager; + } + pPager->pPrev = 0; + sqlite3PagerList = pPager; + sqlite3_mutex_leave(mutex); + } +#endif + return SQLITE_OK; +} + +/* +** Set the busy handler function. +*/ +void sqlite3PagerSetBusyhandler(Pager *pPager, BusyHandler *pBusyHandler){ + pPager->pBusyHandler = pBusyHandler; +} + +/* +** Set the destructor for this pager. If not NULL, the destructor is called +** when the reference count on each page reaches zero. The destructor can +** be used to clean up information in the extra segment appended to each page. +** +** The destructor is not called as a result sqlite3PagerClose(). +** Destructors are only called by sqlite3PagerUnref(). +*/ +void sqlite3PagerSetDestructor(Pager *pPager, void (*xDesc)(DbPage*,int)){ + pPager->xDestructor = xDesc; +} + +/* +** Set the reinitializer for this pager. If not NULL, the reinitializer +** is called when the content of a page in cache is restored to its original +** value as a result of a rollback. The callback gives higher-level code +** an opportunity to restore the EXTRA section to agree with the restored +** page data. +*/ +void sqlite3PagerSetReiniter(Pager *pPager, void (*xReinit)(DbPage*,int)){ + pPager->xReiniter = xReinit; +} + +/* +** Set the page size to *pPageSize. If the suggest new page size is +** inappropriate, then an alternative page size is set to that +** value before returning. +*/ +int sqlite3PagerSetPagesize(Pager *pPager, u16 *pPageSize){ + int rc = SQLITE_OK; + u16 pageSize = *pPageSize; + assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) ); + if( pageSize && pageSize!=pPager->pageSize + && !pPager->memDb && pPager->nRef==0 + ){ + char *pNew = (char *)sqlite3PageMalloc(pageSize); + if( !pNew ){ + rc = SQLITE_NOMEM; + }else{ + pagerEnter(pPager); + pager_reset(pPager); + pPager->pageSize = pageSize; + setSectorSize(pPager); + sqlite3PageFree(pPager->pTmpSpace); + pPager->pTmpSpace = pNew; + pagerLeave(pPager); + } + } + *pPageSize = pPager->pageSize; + return rc; +} + +/* +** Return a pointer to the "temporary page" buffer held internally +** by the pager. This is a buffer that is big enough to hold the +** entire content of a database page. This buffer is used internally +** during rollback and will be overwritten whenever a rollback +** occurs. But other modules are free to use it too, as long as +** no rollbacks are happening. +*/ +void *sqlite3PagerTempSpace(Pager *pPager){ + return pPager->pTmpSpace; +} + +/* +** Attempt to set the maximum database page count if mxPage is positive. +** Make no changes if mxPage is zero or negative. And never reduce the +** maximum page count below the current size of the database. +** +** Regardless of mxPage, return the current maximum page count. +*/ +int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){ + if( mxPage>0 ){ + pPager->mxPgno = mxPage; + } + sqlite3PagerPagecount(pPager, 0); + return pPager->mxPgno; +} + +/* +** The following set of routines are used to disable the simulated +** I/O error mechanism. These routines are used to avoid simulated +** errors in places where we do not care about errors. +** +** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops +** and generate no code. +*/ +#ifdef SQLITE_TEST +extern int sqlite3_io_error_pending; +extern int sqlite3_io_error_hit; +static int saved_cnt; +void disable_simulated_io_errors(void){ + saved_cnt = sqlite3_io_error_pending; + sqlite3_io_error_pending = -1; +} +void enable_simulated_io_errors(void){ + sqlite3_io_error_pending = saved_cnt; +} +#else +# define disable_simulated_io_errors() +# define enable_simulated_io_errors() +#endif + +/* +** Read the first N bytes from the beginning of the file into memory +** that pDest points to. +** +** No error checking is done. The rational for this is that this function +** may be called even if the file does not exist or contain a header. In +** these cases sqlite3OsRead() will return an error, to which the correct +** response is to zero the memory at pDest and continue. A real IO error +** will presumably recur and be picked up later (Todo: Think about this). +*/ +int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){ + int rc = SQLITE_OK; + memset(pDest, 0, N); + assert(MEMDB||pPager->fd->pMethods||pPager->tempFile); + if( pPager->fd->pMethods ){ + IOTRACE(("DBHDR %p 0 %d\n", pPager, N)) + rc = sqlite3OsRead(pPager->fd, pDest, N, 0); + if( rc==SQLITE_IOERR_SHORT_READ ){ + rc = SQLITE_OK; + } + } + return rc; +} + +/* +** Return the total number of pages in the disk file associated with +** pPager. +** +** If the PENDING_BYTE lies on the page directly after the end of the +** file, then consider this page part of the file too. For example, if +** PENDING_BYTE is byte 4096 (the first byte of page 5) and the size of the +** file is 4096 bytes, 5 is returned instead of 4. +*/ +int sqlite3PagerPagecount(Pager *pPager, int *pnPage){ + i64 n = 0; + int rc; + assert( pPager!=0 ); + if( pPager->errCode ){ + return pPager->errCode; + } + if( pPager->dbSize>=0 ){ + n = pPager->dbSize; + } else { + assert(pPager->fd->pMethods||pPager->tempFile); + if( (pPager->fd->pMethods) + && (rc = sqlite3OsFileSize(pPager->fd, &n))!=SQLITE_OK ){ + pPager->nRef++; + pager_error(pPager, rc); + pPager->nRef--; + return rc; + } + if( n>0 && npageSize ){ + n = 1; + }else{ + n /= pPager->pageSize; + } + if( pPager->state!=PAGER_UNLOCK ){ + pPager->dbSize = n; + } + } + if( n==(PENDING_BYTE/pPager->pageSize) ){ + n++; + } + if( n>pPager->mxPgno ){ + pPager->mxPgno = n; + } + if( pnPage ){ + *pnPage = n; + } + return SQLITE_OK; +} + + +#ifndef SQLITE_OMIT_MEMORYDB +/* +** Clear a PgHistory block +*/ +static void clearHistory(PgHistory *pHist){ + sqlite3PageFree(pHist->pOrig); + sqlite3PageFree(pHist->pStmt); + pHist->pOrig = 0; + pHist->pStmt = 0; +} +#else +#define clearHistory(x) +#endif + +/* +** Forward declaration +*/ +static int syncJournal(Pager*); + +/* +** Unlink pPg from its hash chain. Also set the page number to 0 to indicate +** that the page is not part of any hash chain. This is required because the +** sqlite3PagerMovepage() routine can leave a page in the +** pNextFree/pPrevFree list that is not a part of any hash-chain. +*/ +static void unlinkHashChain(Pager *pPager, PgHdr *pPg){ + if( pPg->pgno==0 ){ + assert( pPg->pNextHash==0 && pPg->pPrevHash==0 ); + return; + } + if( pPg->pNextHash ){ + pPg->pNextHash->pPrevHash = pPg->pPrevHash; + } + if( pPg->pPrevHash ){ + assert( pPager->aHash[pPg->pgno & (pPager->nHash-1)]!=pPg ); + pPg->pPrevHash->pNextHash = pPg->pNextHash; + }else{ + int h = pPg->pgno & (pPager->nHash-1); + pPager->aHash[h] = pPg->pNextHash; + } + if( MEMDB ){ + clearHistory(PGHDR_TO_HIST(pPg, pPager)); + } + pPg->pgno = 0; + pPg->pNextHash = pPg->pPrevHash = 0; +} + +/* +** Unlink a page from the free list (the list of all pages where nRef==0) +** and from its hash collision chain. +*/ +static void unlinkPage(PgHdr *pPg){ + Pager *pPager = pPg->pPager; + + /* Unlink from free page list */ + lruListRemove(pPg); + + /* Unlink from the pgno hash table */ + unlinkHashChain(pPager, pPg); +} + +/* +** This routine is used to truncate the cache when a database +** is truncated. Drop from the cache all pages whose pgno is +** larger than pPager->dbSize and is unreferenced. +** +** Referenced pages larger than pPager->dbSize are zeroed. +** +** Actually, at the point this routine is called, it would be +** an error to have a referenced page. But rather than delete +** that page and guarantee a subsequent segfault, it seems better +** to zero it and hope that we error out sanely. +*/ +static void pager_truncate_cache(Pager *pPager){ + PgHdr *pPg; + PgHdr **ppPg; + int dbSize = pPager->dbSize; + + ppPg = &pPager->pAll; + while( (pPg = *ppPg)!=0 ){ + if( pPg->pgno<=dbSize ){ + ppPg = &pPg->pNextAll; + }else if( pPg->nRef>0 ){ + memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize); + ppPg = &pPg->pNextAll; + }else{ + *ppPg = pPg->pNextAll; +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + if( *ppPg ){ + (*ppPg)->pPrevAll = pPg->pPrevAll; + } +#endif + IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno)); + PAGER_INCR(sqlite3_pager_pgfree_count); + unlinkPage(pPg); + makeClean(pPg); + sqlite3PageFree(pPg->pData); + sqlite3_free(pPg); + pPager->nPage--; + } + } +} + +/* +** Try to obtain a lock on a file. Invoke the busy callback if the lock +** is currently not available. Repeat until the busy callback returns +** false or until the lock succeeds. +** +** Return SQLITE_OK on success and an error code if we cannot obtain +** the lock. +*/ +static int pager_wait_on_lock(Pager *pPager, int locktype){ + int rc; + + /* The OS lock values must be the same as the Pager lock values */ + assert( PAGER_SHARED==SHARED_LOCK ); + assert( PAGER_RESERVED==RESERVED_LOCK ); + assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK ); + + /* If the file is currently unlocked then the size must be unknown */ + assert( pPager->state>=PAGER_SHARED || pPager->dbSize<0 || MEMDB ); + + if( pPager->state>=locktype ){ + rc = SQLITE_OK; + }else{ + if( pPager->pBusyHandler ) pPager->pBusyHandler->nBusy = 0; + do { + rc = sqlite3OsLock(pPager->fd, locktype); + }while( rc==SQLITE_BUSY && sqlite3InvokeBusyHandler(pPager->pBusyHandler) ); + if( rc==SQLITE_OK ){ + pPager->state = locktype; + IOTRACE(("LOCK %p %d\n", pPager, locktype)) + } + } + return rc; +} + +/* +** Truncate the file to the number of pages specified. +*/ +int sqlite3PagerTruncate(Pager *pPager, Pgno nPage){ + int rc; + assert( pPager->state>=PAGER_SHARED || MEMDB ); + sqlite3PagerPagecount(pPager, 0); + if( pPager->errCode ){ + rc = pPager->errCode; + return rc; + } + if( nPage>=(unsigned)pPager->dbSize ){ + return SQLITE_OK; + } + if( MEMDB ){ + pPager->dbSize = nPage; + pager_truncate_cache(pPager); + return SQLITE_OK; + } + pagerEnter(pPager); + rc = syncJournal(pPager); + pagerLeave(pPager); + if( rc!=SQLITE_OK ){ + return rc; + } + + /* Get an exclusive lock on the database before truncating. */ + pagerEnter(pPager); + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK); + pagerLeave(pPager); + if( rc!=SQLITE_OK ){ + return rc; + } + + rc = pager_truncate(pPager, nPage); + return rc; +} + +/* +** Shutdown the page cache. Free all memory and close all files. +** +** If a transaction was in progress when this routine is called, that +** transaction is rolled back. All outstanding pages are invalidated +** and their memory is freed. Any attempt to use a page associated +** with this page cache after this function returns will likely +** result in a coredump. +** +** This function always succeeds. If a transaction is active an attempt +** is made to roll it back. If an error occurs during the rollback +** a hot journal may be left in the filesystem but no error is returned +** to the caller. +*/ +int sqlite3PagerClose(Pager *pPager){ +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + if( !MEMDB ){ +#ifndef SQLITE_MUTEX_NOOP + sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2); +#endif + sqlite3_mutex_enter(mutex); + if( pPager->pPrev ){ + pPager->pPrev->pNext = pPager->pNext; + }else{ + sqlite3PagerList = pPager->pNext; + } + if( pPager->pNext ){ + pPager->pNext->pPrev = pPager->pPrev; + } + sqlite3_mutex_leave(mutex); + } +#endif + + disable_simulated_io_errors(); + sqlite3BeginBenignMalloc(); + pPager->errCode = 0; + pPager->exclusiveMode = 0; + pager_reset(pPager); + pagerUnlockAndRollback(pPager); + enable_simulated_io_errors(); + sqlite3EndBenignMalloc(); + PAGERTRACE2("CLOSE %d\n", PAGERID(pPager)); + IOTRACE(("CLOSE %p\n", pPager)) + if( pPager->journalOpen ){ + sqlite3OsClose(pPager->jfd); + } + sqlite3BitvecDestroy(pPager->pInJournal); + if( pPager->stmtOpen ){ + sqlite3OsClose(pPager->stfd); + } + sqlite3OsClose(pPager->fd); + /* Temp files are automatically deleted by the OS + ** if( pPager->tempFile ){ + ** sqlite3OsDelete(pPager->zFilename); + ** } + */ + + sqlite3_free(pPager->aHash); + sqlite3PageFree(pPager->pTmpSpace); + sqlite3_free(pPager); + return SQLITE_OK; +} + +#if !defined(NDEBUG) || defined(SQLITE_TEST) +/* +** Return the page number for the given page data. +*/ +Pgno sqlite3PagerPagenumber(DbPage *p){ + return p->pgno; +} +#endif + +/* +** The page_ref() function increments the reference count for a page. +** If the page is currently on the freelist (the reference count is zero) then +** remove it from the freelist. +** +** For non-test systems, page_ref() is a macro that calls _page_ref() +** online of the reference count is zero. For test systems, page_ref() +** is a real function so that we can set breakpoints and trace it. +*/ +static void _page_ref(PgHdr *pPg){ + if( pPg->nRef==0 ){ + /* The page is currently on the freelist. Remove it. */ + lruListRemove(pPg); + pPg->pPager->nRef++; + } + pPg->nRef++; +} +#ifdef SQLITE_DEBUG + static void page_ref(PgHdr *pPg){ + if( pPg->nRef==0 ){ + _page_ref(pPg); + }else{ + pPg->nRef++; + } + } +#else +# define page_ref(P) ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++) +#endif + +/* +** Increment the reference count for a page. The input pointer is +** a reference to the page data. +*/ +int sqlite3PagerRef(DbPage *pPg){ + pagerEnter(pPg->pPager); + page_ref(pPg); + pagerLeave(pPg->pPager); + return SQLITE_OK; +} + +/* +** Sync the journal. In other words, make sure all the pages that have +** been written to the journal have actually reached the surface of the +** disk. It is not safe to modify the original database file until after +** the journal has been synced. If the original database is modified before +** the journal is synced and a power failure occurs, the unsynced journal +** data would be lost and we would be unable to completely rollback the +** database changes. Database corruption would occur. +** +** This routine also updates the nRec field in the header of the journal. +** (See comments on the pager_playback() routine for additional information.) +** If the sync mode is FULL, two syncs will occur. First the whole journal +** is synced, then the nRec field is updated, then a second sync occurs. +** +** For temporary databases, we do not care if we are able to rollback +** after a power failure, so no sync occurs. +** +** If the IOCAP_SEQUENTIAL flag is set for the persistent media on which +** the database is stored, then OsSync() is never called on the journal +** file. In this case all that is required is to update the nRec field in +** the journal header. +** +** This routine clears the needSync field of every page current held in +** memory. +*/ +static int syncJournal(Pager *pPager){ + PgHdr *pPg; + int rc = SQLITE_OK; + + /* Sync the journal before modifying the main database + ** (assuming there is a journal and it needs to be synced.) + */ + if( pPager->needSync ){ + if( !pPager->tempFile ){ + int iDc = sqlite3OsDeviceCharacteristics(pPager->fd); + assert( pPager->journalOpen ); + + if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){ + /* Write the nRec value into the journal file header. If in + ** full-synchronous mode, sync the journal first. This ensures that + ** all data has really hit the disk before nRec is updated to mark + ** it as a candidate for rollback. + ** + ** This is not required if the persistent media supports the + ** SAFE_APPEND property. Because in this case it is not possible + ** for garbage data to be appended to the file, the nRec field + ** is populated with 0xFFFFFFFF when the journal header is written + ** and never needs to be updated. + */ + i64 jrnlOff; + if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){ + PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager)); + IOTRACE(("JSYNC %p\n", pPager)) + rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags); + if( rc!=0 ) return rc; + } + + jrnlOff = pPager->journalHdr + sizeof(aJournalMagic); + IOTRACE(("JHDR %p %lld %d\n", pPager, jrnlOff, 4)); + rc = write32bits(pPager->jfd, jrnlOff, pPager->nRec); + if( rc ) return rc; + } + if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){ + PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager)); + IOTRACE(("JSYNC %p\n", pPager)) + rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags| + (pPager->sync_flags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0) + ); + if( rc!=0 ) return rc; + } + pPager->journalStarted = 1; + } + pPager->needSync = 0; + + /* Erase the needSync flag from every page. + */ + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + pPg->needSync = 0; + } + lruListSetFirstSynced(pPager); + } + +#ifndef NDEBUG + /* If the Pager.needSync flag is clear then the PgHdr.needSync + ** flag must also be clear for all pages. Verify that this + ** invariant is true. + */ + else{ + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + assert( pPg->needSync==0 ); + } + assert( pPager->lru.pFirstSynced==pPager->lru.pFirst ); + } +#endif + + return rc; +} + +/* +** Merge two lists of pages connected by pDirty and in pgno order. +** Do not both fixing the pPrevDirty pointers. +*/ +static PgHdr *merge_pagelist(PgHdr *pA, PgHdr *pB){ + PgHdr result, *pTail; + pTail = &result; + while( pA && pB ){ + if( pA->pgnopgno ){ + pTail->pDirty = pA; + pTail = pA; + pA = pA->pDirty; + }else{ + pTail->pDirty = pB; + pTail = pB; + pB = pB->pDirty; + } + } + if( pA ){ + pTail->pDirty = pA; + }else if( pB ){ + pTail->pDirty = pB; + }else{ + pTail->pDirty = 0; + } + return result.pDirty; +} + +/* +** Sort the list of pages in accending order by pgno. Pages are +** connected by pDirty pointers. The pPrevDirty pointers are +** corrupted by this sort. +*/ +#define N_SORT_BUCKET_ALLOC 25 +#define N_SORT_BUCKET 25 +#ifdef SQLITE_TEST + int sqlite3_pager_n_sort_bucket = 0; + #undef N_SORT_BUCKET + #define N_SORT_BUCKET \ + (sqlite3_pager_n_sort_bucket?sqlite3_pager_n_sort_bucket:N_SORT_BUCKET_ALLOC) +#endif +static PgHdr *sort_pagelist(PgHdr *pIn){ + PgHdr *a[N_SORT_BUCKET_ALLOC], *p; + int i; + memset(a, 0, sizeof(a)); + while( pIn ){ + p = pIn; + pIn = p->pDirty; + p->pDirty = 0; + for(i=0; ipPager; + + /* At this point there may be either a RESERVED or EXCLUSIVE lock on the + ** database file. If there is already an EXCLUSIVE lock, the following + ** calls to sqlite3OsLock() are no-ops. + ** + ** Moving the lock from RESERVED to EXCLUSIVE actually involves going + ** through an intermediate state PENDING. A PENDING lock prevents new + ** readers from attaching to the database but is unsufficient for us to + ** write. The idea of a PENDING lock is to prevent new readers from + ** coming in while we wait for existing readers to clear. + ** + ** While the pager is in the RESERVED state, the original database file + ** is unchanged and we can rollback without having to playback the + ** journal into the original database file. Once we transition to + ** EXCLUSIVE, it means the database file has been changed and any rollback + ** will require a journal playback. + */ + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK); + if( rc!=SQLITE_OK ){ + return rc; + } + + pList = sort_pagelist(pList); + for(p=pList; p; p=p->pDirty){ + assert( p->dirty ); + p->dirty = 0; + } + while( pList ){ + + /* If the file has not yet been opened, open it now. */ + if( !pPager->fd->pMethods ){ + assert(pPager->tempFile); + rc = sqlite3PagerOpentemp(pPager, pPager->fd, pPager->vfsFlags); + if( rc ) return rc; + } + + /* If there are dirty pages in the page cache with page numbers greater + ** than Pager.dbSize, this means sqlite3PagerTruncate() was called to + ** make the file smaller (presumably by auto-vacuum code). Do not write + ** any such pages to the file. + */ + if( pList->pgno<=pPager->dbSize ){ + i64 offset = (pList->pgno-1)*(i64)pPager->pageSize; + char *pData = CODEC2(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6); + PAGERTRACE4("STORE %d page %d hash(%08x)\n", + PAGERID(pPager), pList->pgno, pager_pagehash(pList)); + IOTRACE(("PGOUT %p %d\n", pPager, pList->pgno)); + rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset); + PAGER_INCR(sqlite3_pager_writedb_count); + PAGER_INCR(pPager->nWrite); + if( pList->pgno==1 ){ + memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers)); + } + } +#ifndef NDEBUG + else{ + PAGERTRACE3("NOSTORE %d page %d\n", PAGERID(pPager), pList->pgno); + } +#endif + if( rc ) return rc; +#ifdef SQLITE_CHECK_PAGES + pList->pageHash = pager_pagehash(pList); +#endif + pList = pList->pDirty; + } + return SQLITE_OK; +} + +/* +** Collect every dirty page into a dirty list and +** return a pointer to the head of that list. All pages are +** collected even if they are still in use. +*/ +static PgHdr *pager_get_all_dirty_pages(Pager *pPager){ + +#ifndef NDEBUG + /* Verify the sanity of the dirty list when we are running + ** in debugging mode. This is expensive, so do not + ** do this on a normal build. */ + int n1 = 0; + int n2 = 0; + PgHdr *p; + for(p=pPager->pAll; p; p=p->pNextAll){ if( p->dirty ) n1++; } + for(p=pPager->pDirty; p; p=p->pDirty){ n2++; } + assert( n1==n2 ); +#endif + + return pPager->pDirty; +} + +/* +** Return 1 if there is a hot journal on the given pager. +** A hot journal is one that needs to be played back. +** +** If the current size of the database file is 0 but a journal file +** exists, that is probably an old journal left over from a prior +** database with the same name. Just delete the journal. +** +** Return negative if unable to determine the status of the journal. +** +** This routine does not open the journal file to examine its +** content. Hence, the journal might contain the name of a master +** journal file that has been deleted, and hence not be hot. Or +** the header of the journal might be zeroed out. This routine +** does not discover these cases of a non-hot journal - if the +** journal file exists and is not empty this routine assumes it +** is hot. The pager_playback() routine will discover that the +** journal file is not really hot and will no-op. +*/ +static int hasHotJournal(Pager *pPager, int *pExists){ + sqlite3_vfs *pVfs = pPager->pVfs; + int rc = SQLITE_OK; + *pExists = 0; + if( pPager->useJournal && pPager->fd->pMethods ){ + int exists; + int locked; + + rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists); + if( rc==SQLITE_OK && exists ){ + rc = sqlite3OsCheckReservedLock(pPager->fd, &locked); + } + + if( rc==SQLITE_OK && exists && !locked ){ + int nPage; + rc = sqlite3PagerPagecount(pPager, &nPage); + if( rc==SQLITE_OK ){ + if( nPage==0 ){ + sqlite3OsDelete(pVfs, pPager->zJournal, 0); + }else{ + *pExists = 1; + } + } + } + } + + return rc; +} + +/* +** Try to find a page in the cache that can be recycled. +** +** This routine may return SQLITE_IOERR, SQLITE_FULL or SQLITE_OK. It +** does not set the pPager->errCode variable. +*/ +static int pager_recycle(Pager *pPager, PgHdr **ppPg){ + PgHdr *pPg; + *ppPg = 0; + + /* It is illegal to call this function unless the pager object + ** pointed to by pPager has at least one free page (page with nRef==0). + */ + assert(!MEMDB); + assert(pPager->lru.pFirst); + + /* Find a page to recycle. Try to locate a page that does not + ** require us to do an fsync() on the journal. + */ + pPg = pPager->lru.pFirstSynced; + + /* If we could not find a page that does not require an fsync() + ** on the journal file then fsync the journal file. This is a + ** very slow operation, so we work hard to avoid it. But sometimes + ** it can't be helped. + */ + if( pPg==0 && pPager->lru.pFirst ){ + if( !pPager->errCode ){ + int iDc = sqlite3OsDeviceCharacteristics(pPager->fd); + int rc = syncJournal(pPager); + if( rc!=0 ){ + return rc; + } + if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){ + /* If in full-sync mode, write a new journal header into the + ** journal file. This is done to avoid ever modifying a journal + ** header that is involved in the rollback of pages that have + ** already been written to the database (in case the header is + ** trashed when the nRec field is updated). + */ + pPager->nRec = 0; + assert( pPager->journalOff > 0 ); + assert( pPager->doNotSync==0 ); + rc = writeJournalHdr(pPager); + if( rc!=0 ){ + return rc; + } + } + } + pPg = pPager->lru.pFirst; + } + + assert( pPg->nRef==0 ); + + /* Write the page to the database file if it is dirty. + */ + if( pPg->dirty && !pPager->errCode ){ + int rc; + assert( pPg->needSync==0 ); + makeClean(pPg); + pPg->dirty = 1; + pPg->pDirty = 0; + rc = pager_write_pagelist( pPg ); + pPg->dirty = 0; + if( rc!=SQLITE_OK ){ + return rc; + } + } + assert( pPg->dirty==0 || pPager->errCode ); + + /* If the page we are recycling is marked as alwaysRollback, then + ** set the global alwaysRollback flag, thus disabling the + ** sqlite3PagerDontRollback() optimization for the rest of this transaction. + ** It is necessary to do this because the page marked alwaysRollback + ** might be reloaded at a later time but at that point we won't remember + ** that is was marked alwaysRollback. This means that all pages must + ** be marked as alwaysRollback from here on out. + */ + if( pPg->alwaysRollback ){ + IOTRACE(("ALWAYS_ROLLBACK %p\n", pPager)) + pPager->alwaysRollback = 1; + } + + /* Unlink the old page from the free list and the hash table + */ + unlinkPage(pPg); + assert( pPg->pgno==0 ); + + *ppPg = pPg; + return SQLITE_OK; +} + +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT +/* +** This function is called to free superfluous dynamically allocated memory +** held by the pager system. Memory in use by any SQLite pager allocated +** by the current thread may be sqlite3_free()ed. +** +** nReq is the number of bytes of memory required. Once this much has +** been released, the function returns. The return value is the total number +** of bytes of memory released. +*/ +int sqlite3PagerReleaseMemory(int nReq){ + int nReleased = 0; /* Bytes of memory released so far */ + Pager *pPager; /* For looping over pagers */ + BusyHandler *savedBusy; /* Saved copy of the busy handler */ + int rc = SQLITE_OK; + + /* Acquire the memory-management mutex + */ +#ifndef SQLITE_MUTEX_NOOP + sqlite3_mutex *mutex; /* The MEM2 mutex */ + mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2); +#endif + sqlite3_mutex_enter(mutex); + + /* Signal all database connections that memory management wants + ** to have access to the pagers. + */ + for(pPager=sqlite3PagerList; pPager; pPager=pPager->pNext){ + pPager->iInUseMM = 1; + } + + while( rc==SQLITE_OK && (nReq<0 || nReleasedneedSync || pPg->pPager->iInUseDB) ){ + pPg = pPg->gfree.pNext; + } + if( !pPg ){ + pPg = sqlite3LruPageList.pFirst; + while( pPg && pPg->pPager->iInUseDB ){ + pPg = pPg->gfree.pNext; + } + } + sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU)); + + /* If pPg==0, then the block above has failed to find a page to + ** recycle. In this case return early - no further memory will + ** be released. + */ + if( !pPg ) break; + + pPager = pPg->pPager; + assert(!pPg->needSync || pPg==pPager->lru.pFirst); + assert(pPg->needSync || pPg==pPager->lru.pFirstSynced); + + savedBusy = pPager->pBusyHandler; + pPager->pBusyHandler = 0; + rc = pager_recycle(pPager, &pRecycled); + pPager->pBusyHandler = savedBusy; + assert(pRecycled==pPg || rc!=SQLITE_OK); + if( rc==SQLITE_OK ){ + /* We've found a page to free. At this point the page has been + ** removed from the page hash-table, free-list and synced-list + ** (pFirstSynced). It is still in the all pages (pAll) list. + ** Remove it from this list before freeing. + ** + ** Todo: Check the Pager.pStmt list to make sure this is Ok. It + ** probably is though. + */ + PgHdr *pTmp; + assert( pPg ); + if( pPg==pPager->pAll ){ + assert(pPg->pPrevAll==0); + assert(pPg->pNextAll==0 || pPg->pNextAll->pPrevAll==pPg); + pPager->pAll = pPg->pNextAll; + if( pPager->pAll ){ + pPager->pAll->pPrevAll = 0; + } + }else{ + assert(pPg->pPrevAll); + assert(pPg->pPrevAll->pNextAll==pPg); + pTmp = pPg->pPrevAll; + pTmp->pNextAll = pPg->pNextAll; + if( pTmp->pNextAll ){ + pTmp->pNextAll->pPrevAll = pTmp; + } + } + nReleased += ( + sizeof(*pPg) + pPager->pageSize + + sizeof(u32) + pPager->nExtra + + MEMDB*sizeof(PgHistory) + ); + IOTRACE(("PGFREE %p %d *\n", pPager, pPg->pgno)); + PAGER_INCR(sqlite3_pager_pgfree_count); + sqlite3PageFree(pPg->pData); + sqlite3_free(pPg); + pPager->nPage--; + }else{ + /* An error occured whilst writing to the database file or + ** journal in pager_recycle(). The error is not returned to the + ** caller of this function. Instead, set the Pager.errCode variable. + ** The error will be returned to the user (or users, in the case + ** of a shared pager cache) of the pager for which the error occured. + */ + assert( + (rc&0xff)==SQLITE_IOERR || + rc==SQLITE_FULL || + rc==SQLITE_BUSY + ); + assert( pPager->state>=PAGER_RESERVED ); + pager_error(pPager, rc); + } + } + + /* Clear the memory management flags and release the mutex + */ + for(pPager=sqlite3PagerList; pPager; pPager=pPager->pNext){ + pPager->iInUseMM = 0; + } + sqlite3_mutex_leave(mutex); + + /* Return the number of bytes released + */ + return nReleased; +} +#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */ + +/* +** Read the content of page pPg out of the database file. +*/ +static int readDbPage(Pager *pPager, PgHdr *pPg, Pgno pgno){ + int rc; + i64 offset; + assert( MEMDB==0 ); + assert(pPager->fd->pMethods||pPager->tempFile); + if( !pPager->fd->pMethods ){ + return SQLITE_IOERR_SHORT_READ; + } + offset = (pgno-1)*(i64)pPager->pageSize; + rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg), pPager->pageSize, offset); + PAGER_INCR(sqlite3_pager_readdb_count); + PAGER_INCR(pPager->nRead); + IOTRACE(("PGIN %p %d\n", pPager, pgno)); + if( pgno==1 ){ + memcpy(&pPager->dbFileVers, &((u8*)PGHDR_TO_DATA(pPg))[24], + sizeof(pPager->dbFileVers)); + } + CODEC1(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3); + PAGERTRACE4("FETCH %d page %d hash(%08x)\n", + PAGERID(pPager), pPg->pgno, pager_pagehash(pPg)); + return rc; +} + + +/* +** This function is called to obtain the shared lock required before +** data may be read from the pager cache. If the shared lock has already +** been obtained, this function is a no-op. +** +** Immediately after obtaining the shared lock (if required), this function +** checks for a hot-journal file. If one is found, an emergency rollback +** is performed immediately. +*/ +static int pagerSharedLock(Pager *pPager){ + int rc = SQLITE_OK; + int isErrorReset = 0; + + /* If this database is opened for exclusive access, has no outstanding + ** page references and is in an error-state, now is the chance to clear + ** the error. Discard the contents of the pager-cache and treat any + ** open journal file as a hot-journal. + */ + if( !MEMDB && pPager->exclusiveMode && pPager->nRef==0 && pPager->errCode ){ + if( pPager->journalOpen ){ + isErrorReset = 1; + } + pPager->errCode = SQLITE_OK; + pager_reset(pPager); + } + + /* If the pager is still in an error state, do not proceed. The error + ** state will be cleared at some point in the future when all page + ** references are dropped and the cache can be discarded. + */ + if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){ + return pPager->errCode; + } + + if( pPager->state==PAGER_UNLOCK || isErrorReset ){ + sqlite3_vfs *pVfs = pPager->pVfs; + if( !MEMDB ){ + int isHotJournal; + assert( pPager->nRef==0 ); + if( !pPager->noReadlock ){ + rc = pager_wait_on_lock(pPager, SHARED_LOCK); + if( rc!=SQLITE_OK ){ + assert( pPager->state==PAGER_UNLOCK ); + return pager_error(pPager, rc); + } + assert( pPager->state>=SHARED_LOCK ); + } + + /* If a journal file exists, and there is no RESERVED lock on the + ** database file, then it either needs to be played back or deleted. + */ + if( !isErrorReset ){ + rc = hasHotJournal(pPager, &isHotJournal); + if( rc!=SQLITE_OK ){ + goto failed; + } + } + if( isErrorReset || isHotJournal ){ + /* Get an EXCLUSIVE lock on the database file. At this point it is + ** important that a RESERVED lock is not obtained on the way to the + ** EXCLUSIVE lock. If it were, another process might open the + ** database file, detect the RESERVED lock, and conclude that the + ** database is safe to read while this process is still rolling it + ** back. + ** + ** Because the intermediate RESERVED lock is not requested, the + ** second process will get to this point in the code and fail to + ** obtain its own EXCLUSIVE lock on the database file. + */ + if( pPager->statefd, EXCLUSIVE_LOCK); + if( rc!=SQLITE_OK ){ + rc = pager_error(pPager, rc); + goto failed; + } + pPager->state = PAGER_EXCLUSIVE; + } + + /* Open the journal for read/write access. This is because in + ** exclusive-access mode the file descriptor will be kept open and + ** possibly used for a transaction later on. On some systems, the + ** OsTruncate() call used in exclusive-access mode also requires + ** a read/write file handle. + */ + if( !isErrorReset && pPager->journalOpen==0 ){ + int res; + rc = sqlite3OsAccess(pVfs,pPager->zJournal,SQLITE_ACCESS_EXISTS,&res); + if( rc==SQLITE_OK ){ + if( res ){ + int fout = 0; + int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL; + assert( !pPager->tempFile ); + rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout); + assert( rc!=SQLITE_OK || pPager->jfd->pMethods ); + if( fout&SQLITE_OPEN_READONLY ){ + rc = SQLITE_BUSY; + sqlite3OsClose(pPager->jfd); + } + }else{ + /* If the journal does not exist, that means some other process + ** has already rolled it back */ + rc = SQLITE_BUSY; + } + } + } + if( rc!=SQLITE_OK ){ + if( rc!=SQLITE_NOMEM && rc!=SQLITE_IOERR_UNLOCK + && rc!=SQLITE_IOERR_NOMEM + ){ + rc = SQLITE_BUSY; + } + goto failed; + } + pPager->journalOpen = 1; + pPager->journalStarted = 0; + pPager->journalOff = 0; + pPager->setMaster = 0; + pPager->journalHdr = 0; + + /* Playback and delete the journal. Drop the database write + ** lock and reacquire the read lock. + */ + rc = pager_playback(pPager, 1); + if( rc!=SQLITE_OK ){ + rc = pager_error(pPager, rc); + goto failed; + } + assert(pPager->state==PAGER_SHARED || + (pPager->exclusiveMode && pPager->state>PAGER_SHARED) + ); + } + + if( pPager->pAll ){ + /* The shared-lock has just been acquired on the database file + ** and there are already pages in the cache (from a previous + ** read or write transaction). Check to see if the database + ** has been modified. If the database has changed, flush the + ** cache. + ** + ** Database changes is detected by looking at 15 bytes beginning + ** at offset 24 into the file. The first 4 of these 16 bytes are + ** a 32-bit counter that is incremented with each change. The + ** other bytes change randomly with each file change when + ** a codec is in use. + ** + ** There is a vanishingly small chance that a change will not be + ** detected. The chance of an undetected change is so small that + ** it can be neglected. + */ + char dbFileVers[sizeof(pPager->dbFileVers)]; + sqlite3PagerPagecount(pPager, 0); + + if( pPager->errCode ){ + rc = pPager->errCode; + goto failed; + } + + if( pPager->dbSize>0 ){ + IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers))); + rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24); + if( rc!=SQLITE_OK ){ + goto failed; + } + }else{ + memset(dbFileVers, 0, sizeof(dbFileVers)); + } + + if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){ + pager_reset(pPager); + } + } + } + assert( pPager->exclusiveMode || pPager->state<=PAGER_SHARED ); + if( pPager->state==PAGER_UNLOCK ){ + pPager->state = PAGER_SHARED; + } + } + + failed: + if( rc!=SQLITE_OK ){ + /* pager_unlock() is a no-op for exclusive mode and in-memory databases. */ + pager_unlock(pPager); + } + return rc; +} + +/* +** Allocate a PgHdr object. Either create a new one or reuse +** an existing one that is not otherwise in use. +** +** A new PgHdr structure is created if any of the following are +** true: +** +** (1) We have not exceeded our maximum allocated cache size +** as set by the "PRAGMA cache_size" command. +** +** (2) There are no unused PgHdr objects available at this time. +** +** (3) This is an in-memory database. +** +** (4) There are no PgHdr objects that do not require a journal +** file sync and a sync of the journal file is currently +** prohibited. +** +** Otherwise, reuse an existing PgHdr. In other words, reuse an +** existing PgHdr if all of the following are true: +** +** (1) We have reached or exceeded the maximum cache size +** allowed by "PRAGMA cache_size". +** +** (2) There is a PgHdr available with PgHdr->nRef==0 +** +** (3) We are not in an in-memory database +** +** (4) Either there is an available PgHdr that does not need +** to be synced to disk or else disk syncing is currently +** allowed. +*/ +static int pagerAllocatePage(Pager *pPager, PgHdr **ppPg){ + int rc = SQLITE_OK; + PgHdr *pPg; + int nByteHdr; + + /* Create a new PgHdr if any of the four conditions defined + ** above are met: */ + if( pPager->nPagemxPage + || pPager->lru.pFirst==0 + || MEMDB + || (pPager->lru.pFirstSynced==0 && pPager->doNotSync) + ){ + void *pData; + if( pPager->nPage>=pPager->nHash ){ + pager_resize_hash_table(pPager, + pPager->nHash<256 ? 256 : pPager->nHash*2); + if( pPager->nHash==0 ){ + rc = SQLITE_NOMEM; + goto pager_allocate_out; + } + } + pagerLeave(pPager); + nByteHdr = sizeof(*pPg) + sizeof(u32) + pPager->nExtra + + MEMDB*sizeof(PgHistory); + pPg = sqlite3Malloc( nByteHdr ); + if( pPg ){ + pData = sqlite3PageMalloc( pPager->pageSize ); + if( pData==0 ){ + sqlite3_free(pPg); + pPg = 0; + } + } + pagerEnter(pPager); + if( pPg==0 ){ + rc = SQLITE_NOMEM; + goto pager_allocate_out; + } + memset(pPg, 0, nByteHdr); + pPg->pData = pData; + pPg->pPager = pPager; + pPg->pNextAll = pPager->pAll; +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT + if( pPg->pNextAll ){ + pPg->pNextAll->pPrevAll = pPg; + } +#endif + pPager->pAll = pPg; + pPager->nPage++; + }else{ + /* Recycle an existing page with a zero ref-count. */ + rc = pager_recycle(pPager, &pPg); + if( rc==SQLITE_BUSY ){ + rc = SQLITE_IOERR_BLOCKED; + } + if( rc!=SQLITE_OK ){ + goto pager_allocate_out; + } + assert( pPager->state>=SHARED_LOCK ); + assert(pPg); + } + *ppPg = pPg; + +pager_allocate_out: + return rc; +} + +/* +** Make sure we have the content for a page. If the page was +** previously acquired with noContent==1, then the content was +** just initialized to zeros instead of being read from disk. +** But now we need the real data off of disk. So make sure we +** have it. Read it in if we do not have it already. +*/ +static int pager_get_content(PgHdr *pPg){ + if( pPg->needRead ){ + int rc = readDbPage(pPg->pPager, pPg, pPg->pgno); + if( rc==SQLITE_OK ){ + pPg->needRead = 0; + }else{ + return rc; + } + } + return SQLITE_OK; +} + +/* +** Acquire a page. +** +** A read lock on the disk file is obtained when the first page is acquired. +** This read lock is dropped when the last page is released. +** +** This routine works for any page number greater than 0. If the database +** file is smaller than the requested page, then no actual disk +** read occurs and the memory image of the page is initialized to +** all zeros. The extra data appended to a page is always initialized +** to zeros the first time a page is loaded into memory. +** +** The acquisition might fail for several reasons. In all cases, +** an appropriate error code is returned and *ppPage is set to NULL. +** +** See also sqlite3PagerLookup(). Both this routine and Lookup() attempt +** to find a page in the in-memory cache first. If the page is not already +** in memory, this routine goes to disk to read it in whereas Lookup() +** just returns 0. This routine acquires a read-lock the first time it +** has to go to disk, and could also playback an old journal if necessary. +** Since Lookup() never goes to disk, it never has to deal with locks +** or journal files. +** +** If noContent is false, the page contents are actually read from disk. +** If noContent is true, it means that we do not care about the contents +** of the page at this time, so do not do a disk read. Just fill in the +** page content with zeros. But mark the fact that we have not read the +** content by setting the PgHdr.needRead flag. Later on, if +** sqlite3PagerWrite() is called on this page or if this routine is +** called again with noContent==0, that means that the content is needed +** and the disk read should occur at that point. +*/ +static int pagerAcquire( + Pager *pPager, /* The pager open on the database file */ + Pgno pgno, /* Page number to fetch */ + DbPage **ppPage, /* Write a pointer to the page here */ + int noContent /* Do not bother reading content from disk if true */ +){ + PgHdr *pPg; + int rc; + + assert( pPager->state==PAGER_UNLOCK || pPager->nRef>0 || pgno==1 ); + + /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page + ** number greater than this, or zero, is requested. + */ + if( pgno>PAGER_MAX_PGNO || pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){ + return SQLITE_CORRUPT_BKPT; + } + + /* Make sure we have not hit any critical errors. + */ + assert( pPager!=0 ); + *ppPage = 0; + + /* If this is the first page accessed, then get a SHARED lock + ** on the database file. pagerSharedLock() is a no-op if + ** a database lock is already held. + */ + rc = pagerSharedLock(pPager); + if( rc!=SQLITE_OK ){ + return rc; + } + assert( pPager->state!=PAGER_UNLOCK ); + + pPg = pager_lookup(pPager, pgno); + if( pPg==0 ){ + /* The requested page is not in the page cache. */ + int nMax; + int h; + PAGER_INCR(pPager->nMiss); + rc = pagerAllocatePage(pPager, &pPg); + if( rc!=SQLITE_OK ){ + return rc; + } + + pPg->pgno = pgno; + assert( !MEMDB || pgno>pPager->stmtSize ); + pPg->inJournal = sqlite3BitvecTest(pPager->pInJournal, pgno); + pPg->needSync = 0; + + makeClean(pPg); + pPg->nRef = 1; + + pPager->nRef++; + if( pPager->nExtra>0 ){ + memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra); + } + rc = sqlite3PagerPagecount(pPager, &nMax); + if( rc!=SQLITE_OK ){ + sqlite3PagerUnref(pPg); + return rc; + } + + /* Populate the page with data, either by reading from the database + ** file, or by setting the entire page to zero. + */ + if( nMax<(int)pgno || MEMDB || (noContent && !pPager->alwaysRollback) ){ + if( pgno>pPager->mxPgno ){ + sqlite3PagerUnref(pPg); + return SQLITE_FULL; + } + memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize); + pPg->needRead = noContent && !pPager->alwaysRollback; + IOTRACE(("ZERO %p %d\n", pPager, pgno)); + }else{ + rc = readDbPage(pPager, pPg, pgno); + if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){ + pPg->pgno = 0; + sqlite3PagerUnref(pPg); + return rc; + } + pPg->needRead = 0; + } + + /* Link the page into the page hash table */ + h = pgno & (pPager->nHash-1); + assert( pgno!=0 ); + pPg->pNextHash = pPager->aHash[h]; + pPager->aHash[h] = pPg; + if( pPg->pNextHash ){ + assert( pPg->pNextHash->pPrevHash==0 ); + pPg->pNextHash->pPrevHash = pPg; + } + +#ifdef SQLITE_CHECK_PAGES + pPg->pageHash = pager_pagehash(pPg); +#endif + }else{ + /* The requested page is in the page cache. */ + assert(pPager->nRef>0 || pgno==1); + PAGER_INCR(pPager->nHit); + if( !noContent ){ + rc = pager_get_content(pPg); + if( rc ){ + return rc; + } + } + page_ref(pPg); + } + *ppPage = pPg; + return SQLITE_OK; +} +int sqlite3PagerAcquire( + Pager *pPager, /* The pager open on the database file */ + Pgno pgno, /* Page number to fetch */ + DbPage **ppPage, /* Write a pointer to the page here */ + int noContent /* Do not bother reading content from disk if true */ +){ + int rc; + pagerEnter(pPager); + rc = pagerAcquire(pPager, pgno, ppPage, noContent); + pagerLeave(pPager); + return rc; +} + + +/* +** Acquire a page if it is already in the in-memory cache. Do +** not read the page from disk. Return a pointer to the page, +** or 0 if the page is not in cache. +** +** See also sqlite3PagerGet(). The difference between this routine +** and sqlite3PagerGet() is that _get() will go to the disk and read +** in the page if the page is not already in cache. This routine +** returns NULL if the page is not in cache or if a disk I/O error +** has ever happened. +*/ +DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){ + PgHdr *pPg = 0; + + assert( pPager!=0 ); + assert( pgno!=0 ); + + pagerEnter(pPager); + if( pPager->state==PAGER_UNLOCK ){ + assert( !pPager->pAll || pPager->exclusiveMode ); + }else if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){ + /* Do nothing */ + }else if( (pPg = pager_lookup(pPager, pgno))!=0 ){ + page_ref(pPg); + } + pagerLeave(pPager); + return pPg; +} + +/* +** Release a page. +** +** If the number of references to the page drop to zero, then the +** page is added to the LRU list. When all references to all pages +** are released, a rollback occurs and the lock on the database is +** removed. +*/ +int sqlite3PagerUnref(DbPage *pPg){ + Pager *pPager; + + if( pPg==0 ) return SQLITE_OK; + pPager = pPg->pPager; + + /* Decrement the reference count for this page + */ + assert( pPg->nRef>0 ); + pagerEnter(pPg->pPager); + pPg->nRef--; + + CHECK_PAGE(pPg); + + /* When the number of references to a page reach 0, call the + ** destructor and add the page to the freelist. + */ + if( pPg->nRef==0 ){ + + lruListAdd(pPg); + if( pPager->xDestructor ){ + pPager->xDestructor(pPg, pPager->pageSize); + } + + /* When all pages reach the freelist, drop the read lock from + ** the database file. + */ + pPager->nRef--; + assert( pPager->nRef>=0 ); + if( pPager->nRef==0 && (!pPager->exclusiveMode || pPager->journalOff>0) ){ + pagerUnlockAndRollback(pPager); + } + } + pagerLeave(pPager); + return SQLITE_OK; +} + +/* +** Create a journal file for pPager. There should already be a RESERVED +** or EXCLUSIVE lock on the database file when this routine is called. +** +** Return SQLITE_OK if everything. Return an error code and release the +** write lock if anything goes wrong. +*/ +static int pager_open_journal(Pager *pPager){ + sqlite3_vfs *pVfs = pPager->pVfs; + int flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_CREATE); + + int rc; + assert( !MEMDB ); + assert( pPager->state>=PAGER_RESERVED ); + assert( pPager->useJournal ); + assert( pPager->pInJournal==0 ); + sqlite3PagerPagecount(pPager, 0); + pagerLeave(pPager); + pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize); + pagerEnter(pPager); + if( pPager->pInJournal==0 ){ + rc = SQLITE_NOMEM; + goto failed_to_open_journal; + } + + if( pPager->journalOpen==0 ){ + if( pPager->tempFile ){ + flags |= (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL); + }else{ + flags |= (SQLITE_OPEN_MAIN_JOURNAL); + } +#ifdef SQLITE_ENABLE_ATOMIC_WRITE + rc = sqlite3JournalOpen( + pVfs, pPager->zJournal, pPager->jfd, flags, jrnlBufferSize(pPager) + ); +#else + rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0); +#endif + assert( rc!=SQLITE_OK || pPager->jfd->pMethods ); + pPager->journalOff = 0; + pPager->setMaster = 0; + pPager->journalHdr = 0; + if( rc!=SQLITE_OK ){ + if( rc==SQLITE_NOMEM ){ + sqlite3OsDelete(pVfs, pPager->zJournal, 0); + } + goto failed_to_open_journal; + } + } + pPager->journalOpen = 1; + pPager->journalStarted = 0; + pPager->needSync = 0; + pPager->alwaysRollback = 0; + pPager->nRec = 0; + if( pPager->errCode ){ + rc = pPager->errCode; + goto failed_to_open_journal; + } + pPager->origDbSize = pPager->dbSize; + + rc = writeJournalHdr(pPager); + + if( pPager->stmtAutoopen && rc==SQLITE_OK ){ + rc = sqlite3PagerStmtBegin(pPager); + } + if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && rc!=SQLITE_IOERR_NOMEM ){ + rc = pager_end_transaction(pPager, 0); + if( rc==SQLITE_OK ){ + rc = SQLITE_FULL; + } + } + return rc; + +failed_to_open_journal: + sqlite3BitvecDestroy(pPager->pInJournal); + pPager->pInJournal = 0; + return rc; +} + +/* +** Acquire a write-lock on the database. The lock is removed when +** the any of the following happen: +** +** * sqlite3PagerCommitPhaseTwo() is called. +** * sqlite3PagerRollback() is called. +** * sqlite3PagerClose() is called. +** * sqlite3PagerUnref() is called to on every outstanding page. +** +** The first parameter to this routine is a pointer to any open page of the +** database file. Nothing changes about the page - it is used merely to +** acquire a pointer to the Pager structure and as proof that there is +** already a read-lock on the database. +** +** The second parameter indicates how much space in bytes to reserve for a +** master journal file-name at the start of the journal when it is created. +** +** A journal file is opened if this is not a temporary file. For temporary +** files, the opening of the journal file is deferred until there is an +** actual need to write to the journal. +** +** If the database is already reserved for writing, this routine is a no-op. +** +** If exFlag is true, go ahead and get an EXCLUSIVE lock on the file +** immediately instead of waiting until we try to flush the cache. The +** exFlag is ignored if a transaction is already active. +*/ +int sqlite3PagerBegin(DbPage *pPg, int exFlag){ + Pager *pPager = pPg->pPager; + int rc = SQLITE_OK; + pagerEnter(pPager); + assert( pPg->nRef>0 ); + assert( pPager->state!=PAGER_UNLOCK ); + if( pPager->state==PAGER_SHARED ){ + assert( pPager->pInJournal==0 ); + if( MEMDB ){ + pPager->state = PAGER_EXCLUSIVE; + pPager->origDbSize = pPager->dbSize; + }else{ + rc = sqlite3OsLock(pPager->fd, RESERVED_LOCK); + if( rc==SQLITE_OK ){ + pPager->state = PAGER_RESERVED; + if( exFlag ){ + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK); + } + } + if( rc!=SQLITE_OK ){ + pagerLeave(pPager); + return rc; + } + pPager->dirtyCache = 0; + PAGERTRACE2("TRANSACTION %d\n", PAGERID(pPager)); + if( pPager->useJournal && !pPager->tempFile + && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){ + rc = pager_open_journal(pPager); + } + } + }else if( pPager->journalOpen && pPager->journalOff==0 ){ + /* This happens when the pager was in exclusive-access mode the last + ** time a (read or write) transaction was successfully concluded + ** by this connection. Instead of deleting the journal file it was + ** kept open and either was truncated to 0 bytes or its header was + ** overwritten with zeros. + */ + assert( pPager->nRec==0 ); + assert( pPager->origDbSize==0 ); + assert( pPager->pInJournal==0 ); + sqlite3PagerPagecount(pPager, 0); + pagerLeave(pPager); + pPager->pInJournal = sqlite3BitvecCreate( pPager->dbSize ); + pagerEnter(pPager); + if( !pPager->pInJournal ){ + rc = SQLITE_NOMEM; + }else{ + pPager->origDbSize = pPager->dbSize; + rc = writeJournalHdr(pPager); + } + } + assert( !pPager->journalOpen || pPager->journalOff>0 || rc!=SQLITE_OK ); + pagerLeave(pPager); + return rc; +} + +/* +** Make a page dirty. Set its dirty flag and add it to the dirty +** page list. +*/ +static void makeDirty(PgHdr *pPg){ + if( pPg->dirty==0 ){ + Pager *pPager = pPg->pPager; + pPg->dirty = 1; + pPg->pDirty = pPager->pDirty; + if( pPager->pDirty ){ + pPager->pDirty->pPrevDirty = pPg; + } + pPg->pPrevDirty = 0; + pPager->pDirty = pPg; + } +} + +/* +** Make a page clean. Clear its dirty bit and remove it from the +** dirty page list. +*/ +static void makeClean(PgHdr *pPg){ + if( pPg->dirty ){ + pPg->dirty = 0; + if( pPg->pDirty ){ + assert( pPg->pDirty->pPrevDirty==pPg ); + pPg->pDirty->pPrevDirty = pPg->pPrevDirty; + } + if( pPg->pPrevDirty ){ + assert( pPg->pPrevDirty->pDirty==pPg ); + pPg->pPrevDirty->pDirty = pPg->pDirty; + }else{ + assert( pPg->pPager->pDirty==pPg ); + pPg->pPager->pDirty = pPg->pDirty; + } + } +} + + +/* +** Mark a data page as writeable. The page is written into the journal +** if it is not there already. This routine must be called before making +** changes to a page. +** +** The first time this routine is called, the pager creates a new +** journal and acquires a RESERVED lock on the database. If the RESERVED +** lock could not be acquired, this routine returns SQLITE_BUSY. The +** calling routine must check for that return value and be careful not to +** change any page data until this routine returns SQLITE_OK. +** +** If the journal file could not be written because the disk is full, +** then this routine returns SQLITE_FULL and does an immediate rollback. +** All subsequent write attempts also return SQLITE_FULL until there +** is a call to sqlite3PagerCommit() or sqlite3PagerRollback() to +** reset. +*/ +static int pager_write(PgHdr *pPg){ + void *pData = PGHDR_TO_DATA(pPg); + Pager *pPager = pPg->pPager; + int rc = SQLITE_OK; + + /* Check for errors + */ + if( pPager->errCode ){ + return pPager->errCode; + } + if( pPager->readOnly ){ + return SQLITE_PERM; + } + + assert( !pPager->setMaster ); + + CHECK_PAGE(pPg); + + /* If this page was previously acquired with noContent==1, that means + ** we didn't really read in the content of the page. This can happen + ** (for example) when the page is being moved to the freelist. But + ** now we are (perhaps) moving the page off of the freelist for + ** reuse and we need to know its original content so that content + ** can be stored in the rollback journal. So do the read at this + ** time. + */ + rc = pager_get_content(pPg); + if( rc ){ + return rc; + } + + /* Mark the page as dirty. If the page has already been written + ** to the journal then we can return right away. + */ + makeDirty(pPg); + if( pPg->inJournal && (pageInStatement(pPg) || pPager->stmtInUse==0) ){ + pPager->dirtyCache = 1; + pPager->dbModified = 1; + }else{ + + /* If we get this far, it means that the page needs to be + ** written to the transaction journal or the ckeckpoint journal + ** or both. + ** + ** First check to see that the transaction journal exists and + ** create it if it does not. + */ + assert( pPager->state!=PAGER_UNLOCK ); + rc = sqlite3PagerBegin(pPg, 0); + if( rc!=SQLITE_OK ){ + return rc; + } + assert( pPager->state>=PAGER_RESERVED ); + if( !pPager->journalOpen && pPager->useJournal + && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){ + rc = pager_open_journal(pPager); + if( rc!=SQLITE_OK ) return rc; + } + pPager->dirtyCache = 1; + pPager->dbModified = 1; + + /* The transaction journal now exists and we have a RESERVED or an + ** EXCLUSIVE lock on the main database file. Write the current page to + ** the transaction journal if it is not there already. + */ + if( !pPg->inJournal && (pPager->journalOpen || MEMDB) ){ + if( (int)pPg->pgno <= pPager->origDbSize ){ + if( MEMDB ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + PAGERTRACE3("JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno); + assert( pHist->pOrig==0 ); + pHist->pOrig = sqlite3PageMalloc( pPager->pageSize ); + if( !pHist->pOrig ){ + return SQLITE_NOMEM; + } + memcpy(pHist->pOrig, PGHDR_TO_DATA(pPg), pPager->pageSize); + }else{ + u32 cksum; + char *pData2; + + /* We should never write to the journal file the page that + ** contains the database locks. The following assert verifies + ** that we do not. */ + assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) ); + pData2 = CODEC2(pPager, pData, pPg->pgno, 7); + cksum = pager_cksum(pPager, (u8*)pData2); + rc = write32bits(pPager->jfd, pPager->journalOff, pPg->pgno); + if( rc==SQLITE_OK ){ + rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, + pPager->journalOff + 4); + pPager->journalOff += pPager->pageSize+4; + } + if( rc==SQLITE_OK ){ + rc = write32bits(pPager->jfd, pPager->journalOff, cksum); + pPager->journalOff += 4; + } + IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno, + pPager->journalOff, pPager->pageSize)); + PAGER_INCR(sqlite3_pager_writej_count); + PAGERTRACE5("JOURNAL %d page %d needSync=%d hash(%08x)\n", + PAGERID(pPager), pPg->pgno, pPg->needSync, pager_pagehash(pPg)); + + /* An error has occured writing to the journal file. The + ** transaction will be rolled back by the layer above. + */ + if( rc!=SQLITE_OK ){ + return rc; + } + + pPager->nRec++; + assert( pPager->pInJournal!=0 ); + sqlite3BitvecSet(pPager->pInJournal, pPg->pgno); + pPg->needSync = !pPager->noSync; + if( pPager->stmtInUse ){ + sqlite3BitvecSet(pPager->pInStmt, pPg->pgno); + } + } + }else{ + pPg->needSync = !pPager->journalStarted && !pPager->noSync; + PAGERTRACE4("APPEND %d page %d needSync=%d\n", + PAGERID(pPager), pPg->pgno, pPg->needSync); + } + if( pPg->needSync ){ + pPager->needSync = 1; + } + pPg->inJournal = 1; + } + + /* If the statement journal is open and the page is not in it, + ** then write the current page to the statement journal. Note that + ** the statement journal format differs from the standard journal format + ** in that it omits the checksums and the header. + */ + if( pPager->stmtInUse + && !pageInStatement(pPg) + && (int)pPg->pgno<=pPager->stmtSize + ){ + assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize ); + if( MEMDB ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + assert( pHist->pStmt==0 ); + pHist->pStmt = sqlite3PageMalloc( pPager->pageSize ); + if( pHist->pStmt ){ + memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize); + } + PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno); + page_add_to_stmt_list(pPg); + }else{ + i64 offset = pPager->stmtNRec*(4+pPager->pageSize); + char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7); + rc = write32bits(pPager->stfd, offset, pPg->pgno); + if( rc==SQLITE_OK ){ + rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize, offset+4); + } + PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno); + if( rc!=SQLITE_OK ){ + return rc; + } + pPager->stmtNRec++; + assert( pPager->pInStmt!=0 ); + sqlite3BitvecSet(pPager->pInStmt, pPg->pgno); + } + } + } + + /* Update the database size and return. + */ + assert( pPager->state>=PAGER_SHARED ); + if( pPager->dbSize<(int)pPg->pgno ){ + pPager->dbSize = pPg->pgno; + if( !MEMDB && pPager->dbSize==PENDING_BYTE/pPager->pageSize ){ + pPager->dbSize++; + } + } + return rc; +} + +/* +** This function is used to mark a data-page as writable. It uses +** pager_write() to open a journal file (if it is not already open) +** and write the page *pData to the journal. +** +** The difference between this function and pager_write() is that this +** function also deals with the special case where 2 or more pages +** fit on a single disk sector. In this case all co-resident pages +** must have been written to the journal file before returning. +*/ +int sqlite3PagerWrite(DbPage *pDbPage){ + int rc = SQLITE_OK; + + PgHdr *pPg = pDbPage; + Pager *pPager = pPg->pPager; + Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize); + + pagerEnter(pPager); + if( !MEMDB && nPagePerSector>1 ){ + Pgno nPageCount; /* Total number of pages in database file */ + Pgno pg1; /* First page of the sector pPg is located on. */ + int nPage; /* Number of pages starting at pg1 to journal */ + int ii; + int needSync = 0; + + /* Set the doNotSync flag to 1. This is because we cannot allow a journal + ** header to be written between the pages journaled by this function. + */ + assert( pPager->doNotSync==0 ); + pPager->doNotSync = 1; + + /* This trick assumes that both the page-size and sector-size are + ** an integer power of 2. It sets variable pg1 to the identifier + ** of the first page of the sector pPg is located on. + */ + pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1; + + sqlite3PagerPagecount(pPager, (int *)&nPageCount); + if( pPg->pgno>nPageCount ){ + nPage = (pPg->pgno - pg1)+1; + }else if( (pg1+nPagePerSector-1)>nPageCount ){ + nPage = nPageCount+1-pg1; + }else{ + nPage = nPagePerSector; + } + assert(nPage>0); + assert(pg1<=pPg->pgno); + assert((pg1+nPage)>pPg->pgno); + + for(ii=0; iipgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){ + if( pg!=PAGER_MJ_PGNO(pPager) ){ + rc = sqlite3PagerGet(pPager, pg, &pPage); + if( rc==SQLITE_OK ){ + rc = pager_write(pPage); + if( pPage->needSync ){ + needSync = 1; + } + sqlite3PagerUnref(pPage); + } + } + }else if( (pPage = pager_lookup(pPager, pg))!=0 ){ + if( pPage->needSync ){ + needSync = 1; + } + } + } + + /* If the PgHdr.needSync flag is set for any of the nPage pages + ** starting at pg1, then it needs to be set for all of them. Because + ** writing to any of these nPage pages may damage the others, the + ** journal file must contain sync()ed copies of all of them + ** before any of them can be written out to the database file. + */ + if( needSync ){ + for(ii=0; iineedSync = 1; + } + assert(pPager->needSync); + } + + assert( pPager->doNotSync==1 ); + pPager->doNotSync = 0; + }else{ + rc = pager_write(pDbPage); + } + pagerLeave(pPager); + return rc; +} + +/* +** Return TRUE if the page given in the argument was previously passed +** to sqlite3PagerWrite(). In other words, return TRUE if it is ok +** to change the content of the page. +*/ +#ifndef NDEBUG +int sqlite3PagerIswriteable(DbPage *pPg){ + return pPg->dirty; +} +#endif + +/* +** A call to this routine tells the pager that it is not necessary to +** write the information on page pPg back to the disk, even though +** that page might be marked as dirty. +** +** The overlying software layer calls this routine when all of the data +** on the given page is unused. The pager marks the page as clean so +** that it does not get written to disk. +** +** Tests show that this optimization, together with the +** sqlite3PagerDontRollback() below, more than double the speed +** of large INSERT operations and quadruple the speed of large DELETEs. +** +** When this routine is called, set the alwaysRollback flag to true. +** Subsequent calls to sqlite3PagerDontRollback() for the same page +** will thereafter be ignored. This is necessary to avoid a problem +** where a page with data is added to the freelist during one part of +** a transaction then removed from the freelist during a later part +** of the same transaction and reused for some other purpose. When it +** is first added to the freelist, this routine is called. When reused, +** the sqlite3PagerDontRollback() routine is called. But because the +** page contains critical data, we still need to be sure it gets +** rolled back in spite of the sqlite3PagerDontRollback() call. +*/ +void sqlite3PagerDontWrite(DbPage *pDbPage){ + PgHdr *pPg = pDbPage; + Pager *pPager = pPg->pPager; + + if( MEMDB ) return; + pagerEnter(pPager); + pPg->alwaysRollback = 1; + if( pPg->dirty && !pPager->stmtInUse ){ + assert( pPager->state>=PAGER_SHARED ); + if( pPager->dbSize==(int)pPg->pgno && pPager->origDbSizedbSize ){ + /* If this pages is the last page in the file and the file has grown + ** during the current transaction, then do NOT mark the page as clean. + ** When the database file grows, we must make sure that the last page + ** gets written at least once so that the disk file will be the correct + ** size. If you do not write this page and the size of the file + ** on the disk ends up being too small, that can lead to database + ** corruption during the next transaction. + */ + }else{ + PAGERTRACE3("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)); + IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno)) + makeClean(pPg); +#ifdef SQLITE_CHECK_PAGES + pPg->pageHash = pager_pagehash(pPg); +#endif + } + } + pagerLeave(pPager); +} + +/* +** A call to this routine tells the pager that if a rollback occurs, +** it is not necessary to restore the data on the given page. This +** means that the pager does not have to record the given page in the +** rollback journal. +** +** If we have not yet actually read the content of this page (if +** the PgHdr.needRead flag is set) then this routine acts as a promise +** that we will never need to read the page content in the future. +** so the needRead flag can be cleared at this point. +*/ +void sqlite3PagerDontRollback(DbPage *pPg){ + Pager *pPager = pPg->pPager; + + pagerEnter(pPager); + assert( pPager->state>=PAGER_RESERVED ); + + /* If the journal file is not open, or DontWrite() has been called on + ** this page (DontWrite() sets the alwaysRollback flag), then this + ** function is a no-op. + */ + if( pPager->journalOpen==0 || pPg->alwaysRollback || pPager->alwaysRollback ){ + pagerLeave(pPager); + return; + } + assert( !MEMDB ); /* For a memdb, pPager->journalOpen is always 0 */ + +#ifdef SQLITE_SECURE_DELETE + if( pPg->inJournal || (int)pPg->pgno > pPager->origDbSize ){ + return; + } +#endif + + /* If SECURE_DELETE is disabled, then there is no way that this + ** routine can be called on a page for which sqlite3PagerDontWrite() + ** has not been previously called during the same transaction. + ** And if DontWrite() has previously been called, the following + ** conditions must be met. + ** + ** (Later:) Not true. If the database is corrupted by having duplicate + ** pages on the freelist (ex: corrupt9.test) then the following is not + ** necessarily true: + */ + /* assert( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ); */ + + assert( pPager->pInJournal!=0 ); + sqlite3BitvecSet(pPager->pInJournal, pPg->pgno); + pPg->inJournal = 1; + pPg->needRead = 0; + if( pPager->stmtInUse ){ + assert( pPager->stmtSize >= pPager->origDbSize ); + sqlite3BitvecSet(pPager->pInStmt, pPg->pgno); + } + PAGERTRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager)); + IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno)) + pagerLeave(pPager); +} + + +/* +** This routine is called to increment the database file change-counter, +** stored at byte 24 of the pager file. +*/ +static int pager_incr_changecounter(Pager *pPager, int isDirect){ + PgHdr *pPgHdr; + u32 change_counter; + int rc = SQLITE_OK; + +#ifndef SQLITE_ENABLE_ATOMIC_WRITE + assert( isDirect==0 ); /* isDirect is only true for atomic writes */ +#endif + if( !pPager->changeCountDone ){ + /* Open page 1 of the file for writing. */ + rc = sqlite3PagerGet(pPager, 1, &pPgHdr); + if( rc!=SQLITE_OK ) return rc; + + if( !isDirect ){ + rc = sqlite3PagerWrite(pPgHdr); + if( rc!=SQLITE_OK ){ + sqlite3PagerUnref(pPgHdr); + return rc; + } + } + + /* Increment the value just read and write it back to byte 24. */ + change_counter = sqlite3Get4byte((u8*)pPager->dbFileVers); + change_counter++; + put32bits(((char*)PGHDR_TO_DATA(pPgHdr))+24, change_counter); + +#ifdef SQLITE_ENABLE_ATOMIC_WRITE + if( isDirect && pPager->fd->pMethods ){ + const void *zBuf = PGHDR_TO_DATA(pPgHdr); + rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0); + } +#endif + + /* Release the page reference. */ + sqlite3PagerUnref(pPgHdr); + pPager->changeCountDone = 1; + } + return rc; +} + +/* +** Sync the pager file to disk. +*/ +int sqlite3PagerSync(Pager *pPager){ + int rc; + pagerEnter(pPager); + rc = sqlite3OsSync(pPager->fd, pPager->sync_flags); + pagerLeave(pPager); + return rc; +} + +/* +** Sync the database file for the pager pPager. zMaster points to the name +** of a master journal file that should be written into the individual +** journal file. zMaster may be NULL, which is interpreted as no master +** journal (a single database transaction). +** +** This routine ensures that the journal is synced, all dirty pages written +** to the database file and the database file synced. The only thing that +** remains to commit the transaction is to delete the journal file (or +** master journal file if specified). +** +** Note that if zMaster==NULL, this does not overwrite a previous value +** passed to an sqlite3PagerCommitPhaseOne() call. +** +** If parameter nTrunc is non-zero, then the pager file is truncated to +** nTrunc pages (this is used by auto-vacuum databases). +** +** If the final parameter - noSync - is true, then the database file itself +** is not synced. The caller must call sqlite3PagerSync() directly to +** sync the database file before calling CommitPhaseTwo() to delete the +** journal file in this case. +*/ +int sqlite3PagerCommitPhaseOne( + Pager *pPager, + const char *zMaster, + Pgno nTrunc, + int noSync +){ + int rc = SQLITE_OK; + + if( pPager->errCode ){ + return pPager->errCode; + } + + /* If no changes have been made, we can leave the transaction early. + */ + if( pPager->dbModified==0 && + (pPager->journalMode!=PAGER_JOURNALMODE_DELETE || + pPager->exclusiveMode!=0) ){ + assert( pPager->dirtyCache==0 || pPager->journalOpen==0 ); + return SQLITE_OK; + } + + PAGERTRACE4("DATABASE SYNC: File=%s zMaster=%s nTrunc=%d\n", + pPager->zFilename, zMaster, nTrunc); + pagerEnter(pPager); + + /* If this is an in-memory db, or no pages have been written to, or this + ** function has already been called, it is a no-op. + */ + if( pPager->state!=PAGER_SYNCED && !MEMDB && pPager->dirtyCache ){ + PgHdr *pPg; + +#ifdef SQLITE_ENABLE_ATOMIC_WRITE + /* The atomic-write optimization can be used if all of the + ** following are true: + ** + ** + The file-system supports the atomic-write property for + ** blocks of size page-size, and + ** + This commit is not part of a multi-file transaction, and + ** + Exactly one page has been modified and store in the journal file. + ** + ** If the optimization can be used, then the journal file will never + ** be created for this transaction. + */ + int useAtomicWrite = ( + !zMaster && + pPager->journalOpen && + pPager->journalOff==jrnlBufferSize(pPager) && + nTrunc==0 && + (0==pPager->pDirty || 0==pPager->pDirty->pDirty) + ); + assert( pPager->journalOpen || pPager->journalMode==PAGER_JOURNALMODE_OFF ); + if( useAtomicWrite ){ + /* Update the nRec field in the journal file. */ + int offset = pPager->journalHdr + sizeof(aJournalMagic); + assert(pPager->nRec==1); + rc = write32bits(pPager->jfd, offset, pPager->nRec); + + /* Update the db file change counter. The following call will modify + ** the in-memory representation of page 1 to include the updated + ** change counter and then write page 1 directly to the database + ** file. Because of the atomic-write property of the host file-system, + ** this is safe. + */ + if( rc==SQLITE_OK ){ + rc = pager_incr_changecounter(pPager, 1); + } + }else{ + rc = sqlite3JournalCreate(pPager->jfd); + } + + if( !useAtomicWrite && rc==SQLITE_OK ) +#endif + + /* If a master journal file name has already been written to the + ** journal file, then no sync is required. This happens when it is + ** written, then the process fails to upgrade from a RESERVED to an + ** EXCLUSIVE lock. The next time the process tries to commit the + ** transaction the m-j name will have already been written. + */ + if( !pPager->setMaster ){ + rc = pager_incr_changecounter(pPager, 0); + if( rc!=SQLITE_OK ) goto sync_exit; + if( pPager->journalMode!=PAGER_JOURNALMODE_OFF ){ +#ifndef SQLITE_OMIT_AUTOVACUUM + if( nTrunc!=0 ){ + /* If this transaction has made the database smaller, then all pages + ** being discarded by the truncation must be written to the journal + ** file. + */ + Pgno i; + int iSkip = PAGER_MJ_PGNO(pPager); + for( i=nTrunc+1; i<=pPager->origDbSize; i++ ){ + if( !sqlite3BitvecTest(pPager->pInJournal, i) && i!=iSkip ){ + rc = sqlite3PagerGet(pPager, i, &pPg); + if( rc!=SQLITE_OK ) goto sync_exit; + rc = sqlite3PagerWrite(pPg); + sqlite3PagerUnref(pPg); + if( rc!=SQLITE_OK ) goto sync_exit; + } + } + } +#endif + rc = writeMasterJournal(pPager, zMaster); + if( rc!=SQLITE_OK ) goto sync_exit; + rc = syncJournal(pPager); + } + } + if( rc!=SQLITE_OK ) goto sync_exit; + +#ifndef SQLITE_OMIT_AUTOVACUUM + if( nTrunc!=0 ){ + rc = sqlite3PagerTruncate(pPager, nTrunc); + if( rc!=SQLITE_OK ) goto sync_exit; + } +#endif + + /* Write all dirty pages to the database file */ + pPg = pager_get_all_dirty_pages(pPager); + rc = pager_write_pagelist(pPg); + if( rc!=SQLITE_OK ){ + assert( rc!=SQLITE_IOERR_BLOCKED ); + /* The error might have left the dirty list all fouled up here, + ** but that does not matter because if the if the dirty list did + ** get corrupted, then the transaction will roll back and + ** discard the dirty list. There is an assert in + ** pager_get_all_dirty_pages() that verifies that no attempt + ** is made to use an invalid dirty list. + */ + goto sync_exit; + } + pPager->pDirty = 0; + + /* Sync the database file. */ + if( !pPager->noSync && !noSync ){ + rc = sqlite3OsSync(pPager->fd, pPager->sync_flags); + } + IOTRACE(("DBSYNC %p\n", pPager)) + + pPager->state = PAGER_SYNCED; + }else if( MEMDB && nTrunc!=0 ){ + rc = sqlite3PagerTruncate(pPager, nTrunc); + } + +sync_exit: + if( rc==SQLITE_IOERR_BLOCKED ){ + /* pager_incr_changecounter() may attempt to obtain an exclusive + * lock to spill the cache and return IOERR_BLOCKED. But since + * there is no chance the cache is inconsistent, it is + * better to return SQLITE_BUSY. + */ + rc = SQLITE_BUSY; + } + pagerLeave(pPager); + return rc; +} + + +/* +** Commit all changes to the database and release the write lock. +** +** If the commit fails for any reason, a rollback attempt is made +** and an error code is returned. If the commit worked, SQLITE_OK +** is returned. +*/ +int sqlite3PagerCommitPhaseTwo(Pager *pPager){ + int rc; + PgHdr *pPg; + + if( pPager->errCode ){ + return pPager->errCode; + } + if( pPager->statedbModified==0 && + (pPager->journalMode!=PAGER_JOURNALMODE_DELETE || + pPager->exclusiveMode!=0) ){ + assert( pPager->dirtyCache==0 || pPager->journalOpen==0 ); + return SQLITE_OK; + } + pagerEnter(pPager); + PAGERTRACE2("COMMIT %d\n", PAGERID(pPager)); + if( MEMDB ){ + pPg = pager_get_all_dirty_pages(pPager); + while( pPg ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + clearHistory(pHist); + pPg->dirty = 0; + pPg->inJournal = 0; + pHist->inStmt = 0; + pPg->needSync = 0; + pHist->pPrevStmt = pHist->pNextStmt = 0; + pPg = pPg->pDirty; + } + pPager->pDirty = 0; +#ifndef NDEBUG + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + assert( !pPg->alwaysRollback ); + assert( !pHist->pOrig ); + assert( !pHist->pStmt ); + } +#endif + pPager->pStmt = 0; + pPager->state = PAGER_SHARED; + pagerLeave(pPager); + return SQLITE_OK; + } + assert( pPager->state==PAGER_SYNCED || !pPager->dirtyCache ); + rc = pager_end_transaction(pPager, pPager->setMaster); + rc = pager_error(pPager, rc); + pagerLeave(pPager); + return rc; +} + +/* +** Rollback all changes. The database falls back to PAGER_SHARED mode. +** All in-memory cache pages revert to their original data contents. +** The journal is deleted. +** +** This routine cannot fail unless some other process is not following +** the correct locking protocol or unless some other +** process is writing trash into the journal file (SQLITE_CORRUPT) or +** unless a prior malloc() failed (SQLITE_NOMEM). Appropriate error +** codes are returned for all these occasions. Otherwise, +** SQLITE_OK is returned. +*/ +int sqlite3PagerRollback(Pager *pPager){ + int rc; + PAGERTRACE2("ROLLBACK %d\n", PAGERID(pPager)); + if( MEMDB ){ + PgHdr *p; + for(p=pPager->pAll; p; p=p->pNextAll){ + PgHistory *pHist; + assert( !p->alwaysRollback ); + if( !p->dirty ){ + assert( !((PgHistory *)PGHDR_TO_HIST(p, pPager))->pOrig ); + assert( !((PgHistory *)PGHDR_TO_HIST(p, pPager))->pStmt ); + continue; + } + + pHist = PGHDR_TO_HIST(p, pPager); + if( pHist->pOrig ){ + memcpy(PGHDR_TO_DATA(p), pHist->pOrig, pPager->pageSize); + PAGERTRACE3("ROLLBACK-PAGE %d of %d\n", p->pgno, PAGERID(pPager)); + }else{ + PAGERTRACE3("PAGE %d is clean on %d\n", p->pgno, PAGERID(pPager)); + } + clearHistory(pHist); + p->dirty = 0; + p->inJournal = 0; + pHist->inStmt = 0; + pHist->pPrevStmt = pHist->pNextStmt = 0; + if( pPager->xReiniter ){ + pPager->xReiniter(p, pPager->pageSize); + } + } + pPager->pDirty = 0; + pPager->pStmt = 0; + pPager->dbSize = pPager->origDbSize; + pager_truncate_cache(pPager); + pPager->stmtInUse = 0; + pPager->state = PAGER_SHARED; + return SQLITE_OK; + } + + pagerEnter(pPager); + if( !pPager->dirtyCache || !pPager->journalOpen ){ + rc = pager_end_transaction(pPager, pPager->setMaster); + pagerLeave(pPager); + return rc; + } + + if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){ + if( pPager->state>=PAGER_EXCLUSIVE ){ + pager_playback(pPager, 0); + } + pagerLeave(pPager); + return pPager->errCode; + } + if( pPager->state==PAGER_RESERVED ){ + int rc2; + rc = pager_playback(pPager, 0); + rc2 = pager_end_transaction(pPager, pPager->setMaster); + if( rc==SQLITE_OK ){ + rc = rc2; + } + }else{ + rc = pager_playback(pPager, 0); + } + /* pager_reset(pPager); */ + pPager->dbSize = -1; + + /* If an error occurs during a ROLLBACK, we can no longer trust the pager + ** cache. So call pager_error() on the way out to make any error + ** persistent. + */ + rc = pager_error(pPager, rc); + pagerLeave(pPager); + return rc; +} + +/* +** Return TRUE if the database file is opened read-only. Return FALSE +** if the database is (in theory) writable. +*/ +int sqlite3PagerIsreadonly(Pager *pPager){ + return pPager->readOnly; +} + +/* +** Return the number of references to the pager. +*/ +int sqlite3PagerRefcount(Pager *pPager){ + return pPager->nRef; +} + +#ifdef SQLITE_TEST +/* +** This routine is used for testing and analysis only. +*/ +int *sqlite3PagerStats(Pager *pPager){ + static int a[11]; + a[0] = pPager->nRef; + a[1] = pPager->nPage; + a[2] = pPager->mxPage; + a[3] = pPager->dbSize; + a[4] = pPager->state; + a[5] = pPager->errCode; + a[6] = pPager->nHit; + a[7] = pPager->nMiss; + a[8] = 0; /* Used to be pPager->nOvfl */ + a[9] = pPager->nRead; + a[10] = pPager->nWrite; + return a; +} +int sqlite3PagerIsMemdb(Pager *pPager){ + return MEMDB; +} +#endif + +/* +** Set the statement rollback point. +** +** This routine should be called with the transaction journal already +** open. A new statement journal is created that can be used to rollback +** changes of a single SQL command within a larger transaction. +*/ +static int pagerStmtBegin(Pager *pPager){ + int rc; + assert( !pPager->stmtInUse ); + assert( pPager->state>=PAGER_SHARED ); + assert( pPager->dbSize>=0 ); + PAGERTRACE2("STMT-BEGIN %d\n", PAGERID(pPager)); + if( MEMDB ){ + pPager->stmtInUse = 1; + pPager->stmtSize = pPager->dbSize; + return SQLITE_OK; + } + if( !pPager->journalOpen ){ + pPager->stmtAutoopen = 1; + return SQLITE_OK; + } + assert( pPager->journalOpen ); + pagerLeave(pPager); + assert( pPager->pInStmt==0 ); + pPager->pInStmt = sqlite3BitvecCreate(pPager->dbSize); + pagerEnter(pPager); + if( pPager->pInStmt==0 ){ + /* sqlite3OsLock(pPager->fd, SHARED_LOCK); */ + return SQLITE_NOMEM; + } + pPager->stmtJSize = pPager->journalOff; + pPager->stmtSize = pPager->dbSize; + pPager->stmtHdrOff = 0; + pPager->stmtCksum = pPager->cksumInit; + if( !pPager->stmtOpen ){ + rc = sqlite3PagerOpentemp(pPager, pPager->stfd, SQLITE_OPEN_SUBJOURNAL); + if( rc ){ + goto stmt_begin_failed; + } + pPager->stmtOpen = 1; + pPager->stmtNRec = 0; + } + pPager->stmtInUse = 1; + return SQLITE_OK; + +stmt_begin_failed: + if( pPager->pInStmt ){ + sqlite3BitvecDestroy(pPager->pInStmt); + pPager->pInStmt = 0; + } + return rc; +} +int sqlite3PagerStmtBegin(Pager *pPager){ + int rc; + pagerEnter(pPager); + rc = pagerStmtBegin(pPager); + pagerLeave(pPager); + return rc; +} + +/* +** Commit a statement. +*/ +int sqlite3PagerStmtCommit(Pager *pPager){ + pagerEnter(pPager); + if( pPager->stmtInUse ){ + PgHdr *pPg, *pNext; + PAGERTRACE2("STMT-COMMIT %d\n", PAGERID(pPager)); + if( !MEMDB ){ + /* sqlite3OsTruncate(pPager->stfd, 0); */ + sqlite3BitvecDestroy(pPager->pInStmt); + pPager->pInStmt = 0; + }else{ + for(pPg=pPager->pStmt; pPg; pPg=pNext){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + pNext = pHist->pNextStmt; + assert( pHist->inStmt ); + pHist->inStmt = 0; + pHist->pPrevStmt = pHist->pNextStmt = 0; + sqlite3PageFree(pHist->pStmt); + pHist->pStmt = 0; + } + } + pPager->stmtNRec = 0; + pPager->stmtInUse = 0; + pPager->pStmt = 0; + } + pPager->stmtAutoopen = 0; + pagerLeave(pPager); + return SQLITE_OK; +} + +/* +** Rollback a statement. +*/ +int sqlite3PagerStmtRollback(Pager *pPager){ + int rc; + pagerEnter(pPager); + if( pPager->stmtInUse ){ + PAGERTRACE2("STMT-ROLLBACK %d\n", PAGERID(pPager)); + if( MEMDB ){ + PgHdr *pPg; + PgHistory *pHist; + for(pPg=pPager->pStmt; pPg; pPg=pHist->pNextStmt){ + pHist = PGHDR_TO_HIST(pPg, pPager); + if( pHist->pStmt ){ + memcpy(PGHDR_TO_DATA(pPg), pHist->pStmt, pPager->pageSize); + sqlite3PageFree(pHist->pStmt); + pHist->pStmt = 0; + } + } + pPager->dbSize = pPager->stmtSize; + pager_truncate_cache(pPager); + rc = SQLITE_OK; + }else{ + rc = pager_stmt_playback(pPager); + } + sqlite3PagerStmtCommit(pPager); + }else{ + rc = SQLITE_OK; + } + pPager->stmtAutoopen = 0; + pagerLeave(pPager); + return rc; +} + +/* +** Return the full pathname of the database file. +*/ +const char *sqlite3PagerFilename(Pager *pPager){ + return pPager->zFilename; +} + +/* +** Return the VFS structure for the pager. +*/ +const sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){ + return pPager->pVfs; +} + +/* +** Return the file handle for the database file associated +** with the pager. This might return NULL if the file has +** not yet been opened. +*/ +sqlite3_file *sqlite3PagerFile(Pager *pPager){ + return pPager->fd; +} + +/* +** Return the directory of the database file. +*/ +const char *sqlite3PagerDirname(Pager *pPager){ + return pPager->zDirectory; +} + +/* +** Return the full pathname of the journal file. +*/ +const char *sqlite3PagerJournalname(Pager *pPager){ + return pPager->zJournal; +} + +/* +** Return true if fsync() calls are disabled for this pager. Return FALSE +** if fsync()s are executed normally. +*/ +int sqlite3PagerNosync(Pager *pPager){ + return pPager->noSync; +} + +#ifdef SQLITE_HAS_CODEC +/* +** Set the codec for this pager +*/ +void sqlite3PagerSetCodec( + Pager *pPager, + void *(*xCodec)(void*,void*,Pgno,int), + void *pCodecArg +){ + pPager->xCodec = xCodec; + pPager->pCodecArg = pCodecArg; +} +#endif + +#ifndef SQLITE_OMIT_AUTOVACUUM +/* +** Move the page pPg to location pgno in the file. +** +** There must be no references to the page previously located at +** pgno (which we call pPgOld) though that page is allowed to be +** in cache. If the page previous located at pgno is not already +** in the rollback journal, it is not put there by by this routine. +** +** References to the page pPg remain valid. Updating any +** meta-data associated with pPg (i.e. data stored in the nExtra bytes +** allocated along with the page) is the responsibility of the caller. +** +** A transaction must be active when this routine is called. It used to be +** required that a statement transaction was not active, but this restriction +** has been removed (CREATE INDEX needs to move a page when a statement +** transaction is active). +** +** If the fourth argument, isCommit, is non-zero, then this page is being +** moved as part of a database reorganization just before the transaction +** is being committed. In this case, it is guaranteed that the database page +** pPg refers to will not be written to again within this transaction. +*/ +int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){ + PgHdr *pPgOld; /* The page being overwritten. */ + int h; + Pgno needSyncPgno = 0; + + pagerEnter(pPager); + assert( pPg->nRef>0 ); + + PAGERTRACE5("MOVE %d page %d (needSync=%d) moves to %d\n", + PAGERID(pPager), pPg->pgno, pPg->needSync, pgno); + IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno)) + + pager_get_content(pPg); + + /* If the journal needs to be sync()ed before page pPg->pgno can + ** be written to, store pPg->pgno in local variable needSyncPgno. + ** + ** If the isCommit flag is set, there is no need to remember that + ** the journal needs to be sync()ed before database page pPg->pgno + ** can be written to. The caller has already promised not to write to it. + */ + if( pPg->needSync && !isCommit ){ + needSyncPgno = pPg->pgno; + assert( pPg->inJournal || (int)pgno>pPager->origDbSize ); + assert( pPg->dirty ); + assert( pPager->needSync ); + } + + /* Unlink pPg from its hash-chain */ + unlinkHashChain(pPager, pPg); + + /* If the cache contains a page with page-number pgno, remove it + ** from its hash chain. Also, if the PgHdr.needSync was set for + ** page pgno before the 'move' operation, it needs to be retained + ** for the page moved there. + */ + pPg->needSync = 0; + pPgOld = pager_lookup(pPager, pgno); + if( pPgOld ){ + assert( pPgOld->nRef==0 ); + unlinkHashChain(pPager, pPgOld); + makeClean(pPgOld); + pPg->needSync = pPgOld->needSync; + }else{ + pPg->needSync = 0; + } + pPg->inJournal = sqlite3BitvecTest(pPager->pInJournal, pgno); + + /* Change the page number for pPg and insert it into the new hash-chain. */ + assert( pgno!=0 ); + pPg->pgno = pgno; + h = pgno & (pPager->nHash-1); + if( pPager->aHash[h] ){ + assert( pPager->aHash[h]->pPrevHash==0 ); + pPager->aHash[h]->pPrevHash = pPg; + } + pPg->pNextHash = pPager->aHash[h]; + pPager->aHash[h] = pPg; + pPg->pPrevHash = 0; + + makeDirty(pPg); + pPager->dirtyCache = 1; + pPager->dbModified = 1; + + if( needSyncPgno ){ + /* If needSyncPgno is non-zero, then the journal file needs to be + ** sync()ed before any data is written to database file page needSyncPgno. + ** Currently, no such page exists in the page-cache and the + ** "is journaled" bitvec flag has been set. This needs to be remedied by + ** loading the page into the pager-cache and setting the PgHdr.needSync + ** flag. + ** + ** If the attempt to load the page into the page-cache fails, (due + ** to a malloc() or IO failure), clear the bit in the pInJournal[] + ** array. Otherwise, if the page is loaded and written again in + ** this transaction, it may be written to the database file before + ** it is synced into the journal file. This way, it may end up in + ** the journal file twice, but that is not a problem. + ** + ** The sqlite3PagerGet() call may cause the journal to sync. So make + ** sure the Pager.needSync flag is set too. + */ + int rc; + PgHdr *pPgHdr; + assert( pPager->needSync ); + rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr); + if( rc!=SQLITE_OK ){ + if( pPager->pInJournal && (int)needSyncPgno<=pPager->origDbSize ){ + sqlite3BitvecClear(pPager->pInJournal, needSyncPgno); + } + pagerLeave(pPager); + return rc; + } + pPager->needSync = 1; + pPgHdr->needSync = 1; + pPgHdr->inJournal = 1; + makeDirty(pPgHdr); + sqlite3PagerUnref(pPgHdr); + } + + pagerLeave(pPager); + return SQLITE_OK; +} +#endif + +/* +** Return a pointer to the data for the specified page. +*/ +void *sqlite3PagerGetData(DbPage *pPg){ + return PGHDR_TO_DATA(pPg); +} + +/* +** Return a pointer to the Pager.nExtra bytes of "extra" space +** allocated along with the specified page. +*/ +void *sqlite3PagerGetExtra(DbPage *pPg){ + Pager *pPager = pPg->pPager; + return (pPager?PGHDR_TO_EXTRA(pPg, pPager):0); +} + +/* +** Get/set the locking-mode for this pager. Parameter eMode must be one +** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or +** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then +** the locking-mode is set to the value specified. +** +** The returned value is either PAGER_LOCKINGMODE_NORMAL or +** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated) +** locking-mode. +*/ +int sqlite3PagerLockingMode(Pager *pPager, int eMode){ + assert( eMode==PAGER_LOCKINGMODE_QUERY + || eMode==PAGER_LOCKINGMODE_NORMAL + || eMode==PAGER_LOCKINGMODE_EXCLUSIVE ); + assert( PAGER_LOCKINGMODE_QUERY<0 ); + assert( PAGER_LOCKINGMODE_NORMAL>=0 && PAGER_LOCKINGMODE_EXCLUSIVE>=0 ); + if( eMode>=0 && !pPager->tempFile ){ + pPager->exclusiveMode = eMode; + } + return (int)pPager->exclusiveMode; +} + +/* +** Get/set the journal-mode for this pager. Parameter eMode must be one +** of PAGER_JOURNALMODE_QUERY, PAGER_JOURNALMODE_DELETE or +** PAGER_JOURNALMODE_PERSIST. If the parameter is not _QUERY, then +** the journal-mode is set to the value specified. +** +** The returned value is either PAGER_JOURNALMODE_DELETE or +** PAGER_JOURNALMODE_PERSIST, indicating the current (possibly updated) +** journal-mode. +*/ +int sqlite3PagerJournalMode(Pager *pPager, int eMode){ + assert( eMode==PAGER_JOURNALMODE_QUERY + || eMode==PAGER_JOURNALMODE_DELETE + || eMode==PAGER_JOURNALMODE_PERSIST + || eMode==PAGER_JOURNALMODE_OFF ); + assert( PAGER_JOURNALMODE_QUERY<0 ); + assert( PAGER_JOURNALMODE_DELETE>=0 && PAGER_JOURNALMODE_PERSIST>=0 ); + if( eMode>=0 ){ + pPager->journalMode = eMode; + } + return (int)pPager->journalMode; +} + +/* +** Get/set the size-limit used for persistent journal files. +*/ +i64 sqlite3PagerJournalSizeLimit(Pager *pPager, i64 iLimit){ + if( iLimit>=-1 ){ + pPager->journalSizeLimit = iLimit; + } + return pPager->journalSizeLimit; +} + +#endif /* SQLITE_OMIT_DISKIO */