--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/engine/sqlite/src/journal.cpp Thu Feb 25 14:29:19 2010 +0000
@@ -0,0 +1,238 @@
+/*
+** 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.cpp 1282 2008-11-13 09:31:33Z LarsPson $
+*/
+
+#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( size<p->iSize ){
+ p->iSize = size;
+ }
+ return rc;
+}
+
+/*
+** Sync the file.
+*/
+static int jrnlSync(sqlite3_file *pJfd, int flags){
+ int rc;
+ JournalFile *p = (JournalFile *)pJfd;
+ rc = createFile(p);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsSync(p->pReal, flags);
+ }
+ 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