diff -r 000000000000 -r 08ec8eefde2f persistentstorage/sql/SQLite/journal.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/persistentstorage/sql/SQLite/journal.c Fri Jan 22 11:06:30 2010 +0200 @@ -0,0 +1,239 @@ +/* +** 2007 August 22 +** +** 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. +** +************************************************************************* +** +** @(#) $Id: journal.c,v 1.8 2008/05/01 18:01:47 drh Exp $ +*/ + +#ifdef SQLITE_ENABLE_ATOMIC_WRITE + +/* +** This file implements a special kind of sqlite3_file object used +** by SQLite to create journal files if the atomic-write optimization +** is enabled. +** +** The distinctive characteristic of this sqlite3_file is that the +** actual on disk file is created lazily. When the file is created, +** the caller specifies a buffer size for an in-memory buffer to +** be used to service read() and write() requests. The actual file +** on disk is not created or populated until either: +** +** 1) The in-memory representation grows too large for the allocated +** buffer, or +** 2) The xSync() method is called. +*/ + +#include "sqliteInt.h" + + +/* +** A JournalFile object is a subclass of sqlite3_file used by +** as an open file handle for journal files. +*/ +struct JournalFile { + sqlite3_io_methods *pMethod; /* I/O methods on journal files */ + int nBuf; /* Size of zBuf[] in bytes */ + char *zBuf; /* Space to buffer journal writes */ + int iSize; /* Amount of zBuf[] currently used */ + int flags; /* xOpen flags */ + sqlite3_vfs *pVfs; /* The "real" underlying VFS */ + sqlite3_file *pReal; /* The "real" underlying file descriptor */ + const char *zJournal; /* Name of the journal file */ +}; +typedef struct JournalFile JournalFile; + +/* +** If it does not already exists, create and populate the on-disk file +** for JournalFile p. +*/ +static int createFile(JournalFile *p){ + int rc = SQLITE_OK; + if( !p->pReal ){ + sqlite3_file *pReal = (sqlite3_file *)&p[1]; + rc = sqlite3OsOpen(p->pVfs, p->zJournal, pReal, p->flags, 0); + if( rc==SQLITE_OK ){ + p->pReal = pReal; + if( p->iSize>0 ){ + assert(p->iSize<=p->nBuf); + rc = sqlite3OsWrite(p->pReal, p->zBuf, p->iSize, 0); + } + } + } + return rc; +} + +/* +** Close the file. +*/ +static int jrnlClose(sqlite3_file *pJfd){ + JournalFile *p = (JournalFile *)pJfd; + if( p->pReal ){ + sqlite3OsClose(p->pReal); + } + sqlite3_free(p->zBuf); + return SQLITE_OK; +} + +/* +** Read data from the file. +*/ +static int jrnlRead( + sqlite3_file *pJfd, /* The journal file from which to read */ + void *zBuf, /* Put the results here */ + int iAmt, /* Number of bytes to read */ + sqlite_int64 iOfst /* Begin reading at this offset */ +){ + int rc = SQLITE_OK; + JournalFile *p = (JournalFile *)pJfd; + if( p->pReal ){ + rc = sqlite3OsRead(p->pReal, zBuf, iAmt, iOfst); + }else{ + assert( iAmt+iOfst<=p->iSize ); + memcpy(zBuf, &p->zBuf[iOfst], iAmt); + } + return rc; +} + +/* +** Write data to the file. +*/ +static int jrnlWrite( + sqlite3_file *pJfd, /* The journal file into which to write */ + const void *zBuf, /* Take data to be written from here */ + int iAmt, /* Number of bytes to write */ + sqlite_int64 iOfst /* Begin writing at this offset into the file */ +){ + int rc = SQLITE_OK; + JournalFile *p = (JournalFile *)pJfd; + if( !p->pReal && (iOfst+iAmt)>p->nBuf ){ + rc = createFile(p); + } + if( rc==SQLITE_OK ){ + if( p->pReal ){ + rc = sqlite3OsWrite(p->pReal, zBuf, iAmt, iOfst); + }else{ + memcpy(&p->zBuf[iOfst], zBuf, iAmt); + if( p->iSize<(iOfst+iAmt) ){ + p->iSize = (iOfst+iAmt); + } + } + } + return rc; +} + +/* +** Truncate the file. +*/ +static int jrnlTruncate(sqlite3_file *pJfd, sqlite_int64 size){ + int rc = SQLITE_OK; + JournalFile *p = (JournalFile *)pJfd; + if( p->pReal ){ + rc = sqlite3OsTruncate(p->pReal, size); + }else if( sizeiSize ){ + p->iSize = size; + } + return rc; +} + +/* +** Sync the file. +*/ +static int jrnlSync(sqlite3_file *pJfd, int flags){ + int rc; + JournalFile *p = (JournalFile *)pJfd; + if( p->pReal ){ + rc = sqlite3OsSync(p->pReal, flags); + }else{ + rc = SQLITE_OK; + } + return rc; +} + +/* +** Query the size of the file in bytes. +*/ +static int jrnlFileSize(sqlite3_file *pJfd, sqlite_int64 *pSize){ + int rc = SQLITE_OK; + JournalFile *p = (JournalFile *)pJfd; + if( p->pReal ){ + rc = sqlite3OsFileSize(p->pReal, pSize); + }else{ + *pSize = (sqlite_int64) p->iSize; + } + return rc; +} + +/* +** Table of methods for JournalFile sqlite3_file object. +*/ +static struct sqlite3_io_methods JournalFileMethods = { + 1, /* iVersion */ + jrnlClose, /* xClose */ + jrnlRead, /* xRead */ + jrnlWrite, /* xWrite */ + jrnlTruncate, /* xTruncate */ + jrnlSync, /* xSync */ + jrnlFileSize, /* xFileSize */ + 0, /* xLock */ + 0, /* xUnlock */ + 0, /* xCheckReservedLock */ + 0, /* xFileControl */ + 0, /* xSectorSize */ + 0 /* xDeviceCharacteristics */ +}; + +/* +** Open a journal file. +*/ +int sqlite3JournalOpen( + sqlite3_vfs *pVfs, /* The VFS to use for actual file I/O */ + const char *zName, /* Name of the journal file */ + sqlite3_file *pJfd, /* Preallocated, blank file handle */ + int flags, /* Opening flags */ + int nBuf /* Bytes buffered before opening the file */ +){ + JournalFile *p = (JournalFile *)pJfd; + memset(p, 0, sqlite3JournalSize(pVfs)); + if( nBuf>0 ){ + p->zBuf = sqlite3MallocZero(nBuf); + if( !p->zBuf ){ + return SQLITE_NOMEM; + } + }else{ + return sqlite3OsOpen(pVfs, zName, pJfd, flags, 0); + } + p->pMethod = &JournalFileMethods; + p->nBuf = nBuf; + p->flags = flags; + p->zJournal = zName; + p->pVfs = pVfs; + return SQLITE_OK; +} + +/* +** If the argument p points to a JournalFile structure, and the underlying +** file has not yet been created, create it now. +*/ +int sqlite3JournalCreate(sqlite3_file *p){ + if( p->pMethods!=&JournalFileMethods ){ + return SQLITE_OK; + } + return createFile((JournalFile *)p); +} + +/* +** Return the number of bytes required to store a JournalFile that uses vfs +** pVfs to create the underlying on-disk files. +*/ +int sqlite3JournalSize(sqlite3_vfs *pVfs){ + return (pVfs->szOsFile+sizeof(JournalFile)); +} +#endif