** file simultaneously, or one process from reading the database while
** another is writing.
**
-** @(#) $Id: pager.c,v 1.552 2009/01/16 15:21:06 danielk1977 Exp $
+** @(#) $Id: pager.c,v 1.553 2009/01/16 16:23:38 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
/*
** A open page cache is an instance of the following structure.
**
-** errCode
-**
-** 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.
-**
-** dbSizeValid, dbSize, dbOrigSize, dbFileSize
-**
-** Managing the size of the database file in pages is a little complicated.
-** The variable Pager.dbSize contains the number of pages that the database
-** image currently contains. As the database image grows or shrinks this
-** variable is updated. The variable Pager.dbFileSize contains the number
-** of pages in the database file. This may be different from Pager.dbSize
-** if some pages have been appended to the database image but not yet written
-** out from the cache to the actual file on disk. Or if the image has been
-** truncated by an incremental-vacuum operation. The Pager.dbOrigSize variable
-** contains the number of pages in the database image when the current
-** transaction was opened. The contents of all three of these variables is
-** only guaranteed to be correct if the boolean Pager.dbSizeValid is true.
-**
-** TODO: Under what conditions is dbSizeValid set? Cleared?
-**
-** changeCountDone
-**
-** This boolean variable is used to make sure that the change-counter
-** (the 4-byte header field at byte offset 24 of the database file) is
-** not updated more often than necessary.
-**
-** It is set to true when the change-counter field is updated, which
-** can only happen if an exclusive lock is held on the database file.
-** It is cleared (set to false) whenever an exclusive lock is
-** relinquished on the database file. Each time a transaction is committed,
-** The changeCountDone flag is inspected. If it is true, the work of
-** updating the change-counter is omitted for the current transaction.
-**
-** This mechanism means that when running in exclusive mode, a connection
-** need only update the change-counter once, for the first transaction
-** committed.
-**
-** dbModified
-**
-** The dbModified flag is set whenever a database page is dirtied.
-** It is cleared at the end of each transaction.
-**
-** It is used when committing or otherwise ending a transaction. If
-** the dbModified flag is clear then less work has to be done.
-**
-** TODO: Check some of the logic surrounding this optimization.
-**
-** journalStarted
-**
-** This flag is set whenever the the main journal is synced.
-**
-** The point of this flag is that it must be set after the
-** first journal header in a journal file has been synced to disk.
-** After this has happened, new pages appended to the database
-** do not need the PGHDR_NEED_SYNC flag set, as they do not need
-** to wait for a journal sync before they can be written out to
-** the database file (see function pager_write()).
-**
-** setMaster
-**
-** This variable is used to ensure that the master journal file name
-** (if any) is only written into the journal file once.
-**
-** When committing a transaction, the master journal file name (if any)
-** may be written into the journal file while the pager is still in
-** PAGER_RESERVED state (see CommitPhaseOne() for the action). It
-** then attempts to upgrade to an exclusive lock. If this attempt
-** fails, then SQLITE_BUSY may be returned to the user and the user
-** may attempt to commit the transaction again later (calling
-** CommitPhaseOne() again). This flag is used to ensure that the
-** master journal name is only written to the journal file the first
-** time CommitPhaseOne() is called.
-**
-** doNotSync
-**
-** This variable is set and cleared by sqlite3PagerWrite().
-**
-** needSync
-**
-** TODO: It might be easier to set this variable in writeJournalHdr()
-** and writeMasterJournal() only. Change its meaning to "unsynced data
-** has been written to the journal".
+** 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.
+**
+** Managing the size of the database file in pages is a little complicated.
+** The variable Pager.dbSize contains the number of pages that the database
+** image currently contains. As the database image grows or shrinks this
+** variable is updated. The variable Pager.dbFileSize contains the number
+** of pages in the database file. This may be different from Pager.dbSize
+** if some pages have been appended to the database image but not yet written
+** out from the cache to the actual file on disk. Or if the image has been
+** truncated by an incremental-vacuum operation. The Pager.dbOrigSize variable
+** contains the number of pages in the database image when the current
+** transaction was opened. The contents of all three of these variables is
+** only guaranteed to be correct if the boolean Pager.dbSizeValid is true.
*/
struct Pager {
sqlite3_vfs *pVfs; /* OS functions to use for IO */
- u8 exclusiveMode; /* Boolean. True if locking_mode==EXCLUSIVE */
- u8 journalMode; /* On of the PAGER_JOURNALMODE_* values */
+ 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 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 memDb; /* True to inhibit all file I/O */
-
- /* The following block contains those class members that are dynamically
- ** modified during normal operations. The other variables in this structure
- ** are either constant throughout the lifetime of the pager, or else
- ** used to store configuration parameters that affect the way the pager
- ** operates.
- **
- ** The 'state' variable is described in more detail along with the
- ** descriptions of the values it may take - PAGER_UNLOCK etc. Many of the
- ** other variables in this block are described in the comment directly
- ** above this class definition.
- */
- u8 state; /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */
- u8 dbModified; /* True if there are any changes to the Db */
u8 needSync; /* True if an fsync() is needed on the journal */
- u8 journalStarted; /* True if header of journal is synced */
- u8 changeCountDone; /* Set after incrementing the change-counter */
+ u8 dirtyCache; /* True if cached pages have changed */
+ 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 */
u8 dbSizeValid; /* Set when dbSize is correct */
Pgno dbSize; /* Number of pages in the database */
Pgno dbOrigSize; /* dbSize before the current transaction */
Pgno dbFileSize; /* Number of pages in the database file */
+ u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
int errCode; /* One of several kinds of errors */
- int nRec; /* Pages journalled since last j-header written */
+ int nRec; /* Number of pages written to the journal */
u32 cksumInit; /* Quasi-random value added to every checksum */
- u32 nSubRec; /* Number of records written to sub-journal */
- Bitvec *pInJournal; /* One bit for each page in the database file */
- sqlite3_file *fd; /* File descriptor for database */
- sqlite3_file *jfd; /* File descriptor for main journal */
- sqlite3_file *sjfd; /* File descriptor for sub-journal */
- i64 journalOff; /* Current write offset in the journal file */
- i64 journalHdr; /* Byte offset to previous journal header */
- PagerSavepoint *aSavepoint; /* Array of active savepoints */
- int nSavepoint; /* Number of elements in aSavepoint[] */
- char dbFileVers[16]; /* Changes whenever database file changes */
- u32 sectorSize; /* Assumed sector size during rollback */
-
+ int stmtNRec; /* Number of records in stmt subjournal */
int nExtra; /* Add this many bytes to each in-memory page */
- u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
int pageSize; /* Number of bytes in a page */
+ int nPage; /* Total number of in-memory pages */
+ 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 *pAlwaysRollback; /* One bit for each page marked always-rollback */
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 *sjfd; /* File descriptor for the sub-journal*/
int (*xBusyHandler)(void*); /* Function to call when busy */
void *pBusyHandlerArg; /* Context argument for xBusyHandler */
+ i64 journalOff; /* Current byte offset in the journal file */
+ i64 journalHdr; /* Byte offset to previous journal header */
+ u32 sectorSize; /* Assumed sector size during rollback */
#ifdef SQLITE_TEST
int nHit, nMiss; /* Cache hits and missing */
int nRead, nWrite; /* Database pages read/written */
void *pCodecArg; /* First argument to xCodec() */
#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 */
PCache *pPCache; /* Pointer to page cache object */
+ PagerSavepoint *aSavepoint; /* Array of active savepoints */
+ int nSavepoint; /* Number of elements in aSavepoint[] */
};
/*
};
/*
-** The size of the of each page record in the journal is given by
-** the following macro.
+** 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. This is usually the same
-** size as a single disk sector. See also setSectorSize().
+** 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)
# 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) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1))
+
/*
** The maximum legal page number is (2^31 - 1).
*/
return sqlite3OsWrite(fd, ac, 4, offset);
}
-/*
-** The argument to this macro is a file descriptor (type sqlite3_file*).
-** Return 0 if it is not open, or non-zero (but not 1) if it is.
-**
-** This is so that expressions can be written as:
-**
-** if( isOpen(pPager->jfd) ){ ...
-**
-** instead of
-**
-** if( pPager->jfd->pMethods ){ ...
-*/
-#define isOpen(pFd) ((pFd)->pMethods)
-
/*
** If file pFd is open, call sqlite3OsUnlock() on it.
*/
static int osUnlock(sqlite3_file *pFd, int eLock){
- if( !isOpen(pFd) ){
+ if( !pFd->pMethods ){
return SQLITE_OK;
}
return sqlite3OsUnlock(pFd, eLock);
** (b) the value returned by OsSectorSize() is less than or equal
** to the page size.
**
-** The optimization is also always enabled for temporary files. It is
-** an error to call this function if pPager is opened on an in-memory
-** database.
-**
** 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){
- assert( !MEMDB );
- if( !pPager->tempFile ){
- int dc; /* Device characteristics */
- int nSector; /* Sector size */
- int szPage; /* Page size */
+ int dc; /* Device characteristics */
+ int nSector; /* Sector size */
+ int szPage; /* Page size */
+ sqlite3_file *fd = pPager->fd;
- assert( isOpen(pPager->fd) );
- dc = sqlite3OsDeviceCharacteristics(pPager->fd);
+ if( fd->pMethods ){
+ dc = sqlite3OsDeviceCharacteristics(fd);
nSector = pPager->sectorSize;
szPage = pPager->pageSize;
-
- assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
- assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
- if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
- return 0;
- }
}
- return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
+ 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 IOERR, CORRUPT or FULL error
-** may have occured. 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.
+** 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,
** 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 to restore the contents of the database file (as if
-** it were a hot-journal).
+** to be replayed.
*/
static void pager_unlock(Pager *pPager);
static int pager_error(Pager *pPager, int rc){
/*
** When this is called the journal file for pager pPager must be open.
-** This function attempts to read a master journal file name from the
-** end of the file and, if successful, copies it into memory supplied
-** by the caller. See comments above writeMasterJournal() for the format
-** used to store a master journal file name at the end of a journal file.
+** 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
** nul-terminator), then this is handled as if no master journal name
** were present in the journal.
**
-** If a master journal file name is present at the end of the journal
-** file, then it is copied into the buffer pointed to by zMaster. A
-** nul-terminator byte is appended to the buffer following the master
-** journal file name.
-**
-** If it is determined that no master journal file name is present
-** zMaster[0] is set to 0 and SQLITE_OK returned.
-**
-** If an error occurs while reading from the journal file, an SQLite
-** error code is returned.
+** 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, u32 nMaster){
- int rc; /* Return code */
- u32 len; /* Length in bytes of master journal name */
- i64 szJ; /* Total size in bytes of journal file pJrnl */
- u32 cksum; /* MJ checksum value read from journal */
- u32 u; /* Unsigned loop counter */
- unsigned char aMagic[8]; /* A buffer to hold the magic header */
+ 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';
- if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
- || szJ<16
- || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
- || len>=nMaster
- || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
- || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
- || memcmp(aMagic, aJournalMagic, 8)
- || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len))
- ){
+ 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; u<len; u++){
cksum -= zMaster[u];
- }
+ }
if( cksum ){
/* If the checksum doesn't add up, then one or more of the disk sectors
** containing the master journal filename is corrupted. This means
** definitely roll back, so just return SQLITE_OK and report a (nul)
** master-journal filename.
*/
- len = 0;
+ zMaster[0] = '\0';
}
- zMaster[len] = '\0';
return SQLITE_OK;
}
/*
-** Return the offset of the sector boundary at or immediately
-** following the value in pPager->journalOff, assuming a sector
-** size of pPager->sectorSize bytes.
+** Seek the journal file descriptor to the next sector boundary where a
+** journal header may be read or written. Pager.journalOff is updated with
+** the new seek offset.
**
** i.e for a sector size of 512:
**
-** Pager.journalOff Return value
-** ---------------------------------------
-** 0 0
-** 512 512
-** 100 512
-** 2000 2048
+** Input Offset Output Offset
+** ---------------------------------------
+** 0 0
+** 512 512
+** 100 512
+** 2000 2048
**
*/
static i64 journalHdrOffset(Pager *pPager){
assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
return offset;
}
+static void seekJournalHdr(Pager *pPager){
+ pPager->journalOff = journalHdrOffset(pPager);
+}
/*
-** The journal file must be open when this function is called.
-**
-** This function is a no-op if the journal file has not been written to
-** within the current transaction (i.e. if Pager.journalOff==0).
-**
-** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
-** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
-** zero the 28-byte header at the start of the journal file. In either case,
-** if the pager is not in no-sync mode, sync the journal file immediately
-** after writing or truncating it.
-**
-** If Pager.journalSizeLimit is set to a positive, non-zero value, and
-** following the truncation or zeroing described above the size of the
-** journal file in bytes is larger than this value, then truncate the
-** journal file to Pager.journalSizeLimit bytes. The journal file does
-** not need to be synced following this operation.
-**
-** If an IO error occurs, abandon processing and return the IO error code.
-** Otherwise, return SQLITE_OK.
+** 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; /* Return code */
- assert( isOpen(pPager->jfd) );
+ int rc = SQLITE_OK;
+ static const char zeroHdr[28] = {0};
+
if( pPager->journalOff ){
- const i64 iLimit = pPager->journalSizeLimit; /* Local cache of jsl */
+ i64 iLimit = pPager->journalSizeLimit;
IOTRACE(("JZEROHDR %p\n", pPager))
if( doTruncate || iLimit==0 ){
rc = sqlite3OsTruncate(pPager->jfd, 0);
}else{
- static const char zeroHdr[28] = {0};
rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
}
if( rc==SQLITE_OK && !pPager->noSync ){
** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
*/
static int writeJournalHdr(Pager *pPager){
- int rc = SQLITE_OK; /* Return code */
- char *zHeader = pPager->pTmpSpace; /* Temporary space used to build header */
- u32 nHeader = pPager->pageSize; /* Size of buffer pointed to by zHeader */
- u32 nWrite; /* Bytes of header sector written */
- int ii; /* Loop counter */
-
- assert( isOpen(pPager->jfd) ); /* Journal file must be open. */
+ int rc = SQLITE_OK;
+ char *zHeader = pPager->pTmpSpace;
+ u32 nHeader = pPager->pageSize;
+ u32 nWrite;
+ int ii;
if( nHeader>JOURNAL_HDR_SZ(pPager) ){
nHeader = JOURNAL_HDR_SZ(pPager);
}
- /* If there are active savepoints and any of them were created
- ** since the most recent journal header was written, update the
- ** PagerSavepoint.iHdrOffset fields now.
+ /* If there are active savepoints and any of them were created since the
+ ** most recent journal header was written, update the PagerSavepoint.iHdrOff
+ ** fields now.
*/
for(ii=0; ii<pPager->nSavepoint; ii++){
if( pPager->aSavepoint[ii].iHdrOffset==0 ){
}
}
- pPager->journalHdr = pPager->journalOff = journalHdrOffset(pPager);
+ seekJournalHdr(pPager);
+ pPager->journalHdr = pPager->journalOff;
+
memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
/*
** * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
** that garbage data is never appended to the journal file.
*/
- assert( isOpen(pPager->fd) || pPager->noSync );
+ assert(pPager->fd->pMethods||pPager->noSync);
if( (pPager->noSync) || (pPager->journalMode==PAGER_JOURNALMODE_MEMORY)
|| (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
){
/* The assumed sector size for this process */
put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
- /* The page size */
- put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
-
/* Initializing the tail of the buffer is not necessary. Everything
** works find if the following memset() is omitted. But initializing
** the memory prevents valgrind from complaining, so we are willing to
** take the performance hit.
*/
- memset(&zHeader[sizeof(aJournalMagic)+20], 0,
- nHeader-(sizeof(aJournalMagic)+20));
-
- /* In theory, it is only necessary to write the 28 bytes that the
- ** journal header consumes to the journal file here. Then increment the
- ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next
- ** record is written to the following sector (leaving a gap in the file
- ** that will be implicitly filled in by the OS).
- **
- ** However it has been discovered that on some systems this pattern can
- ** be significantly slower than contiguously writing data to the file,
- ** even if that means explicitly writing data to the block of
- ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
- ** is done.
- **
- ** The loop is required here in case the sector-size is larger than the
- ** database page size. Since the zHeader buffer is only Pager.pageSize
- ** bytes in size, more than one call to sqlite3OsWrite() may be required
- ** to populate the entire journal header sector.
- */
+ memset(&zHeader[sizeof(aJournalMagic)+16], 0,
+ nHeader-(sizeof(aJournalMagic)+16));
+
+ if( pPager->journalHdr==0 ){
+ /* The page size */
+ put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
+ }
+
for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
** 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. The current location in the journal file is given by
-** pPager->journalOff. See comments above function writeJournalHdr() for
+** pPager->journalOff. See comments above function writeJournalHdr() for
** a description of the journal header format.
**
-** If the header is read successfully, *pNRec is set to the number of
-** page records following this header and *pDbSize is set to the size of the
+** 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 *pNRec and *PDbSize are undefined. If JOURNAL_HDR_SZ bytes
+** returned and *nRec and *dbSize are undefined. If JOURNAL_HDR_SZ bytes
** cannot be read from the journal file an error code is returned.
*/
static int readJournalHdr(
- Pager *pPager, /* Pager object */
- i64 journalSize, /* Size of the open journal file in bytes */
- u32 *pNRec, /* OUT: Value read from the nRec field */
- u32 *pDbSize /* OUT: Value of original database size field */
+ Pager *pPager,
+ i64 journalSize,
+ u32 *pNRec,
+ u32 *pDbSize
){
- int rc; /* Return code */
- unsigned char aMagic[8]; /* A buffer to hold the magic header */
- i64 iHdrOff; /* Offset of journal header being read */
-
- assert( isOpen(pPager->jfd) ); /* Journal file must be open. */
+ int rc;
+ unsigned char aMagic[8]; /* A buffer to hold the magic header */
+ i64 jrnlOff;
+ u32 iPageSize;
+ u32 iSectorSize;
- /* Advance Pager.journalOff to the start of the next sector. If the
- ** journal file is too small for there to be a header stored at this
- ** point, return SQLITE_DONE.
- */
- pPager->journalOff = journalHdrOffset(pPager);
+ seekJournalHdr(pPager);
if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
return SQLITE_DONE;
}
- iHdrOff = pPager->journalOff;
+ jrnlOff = pPager->journalOff;
+
+ rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), jrnlOff);
+ if( rc ) return rc;
+ jrnlOff += sizeof(aMagic);
- /* Read in the first 8 bytes of the journal header. If they do not match
- ** the magic string found at the start of each journal header, return
- ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
- ** proceed.
- */
- rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), iHdrOff);
- if( rc ){
- return rc;
- }
if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
return SQLITE_DONE;
}
- /* Read the first three 32-bit fields of the journal header: The nRec
- ** field, the checksum-initializer and the database size at the start
- ** of the transaction. Return an error code if anything goes wrong.
- */
- if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+8, pNRec))
- || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+12, &pPager->cksumInit))
- || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+16, pDbSize))
- ){
- return rc;
- }
+ rc = read32bits(pPager->jfd, jrnlOff, pNRec);
+ if( rc ) return rc;
- if( pPager->journalOff==0 ){
- u32 iPageSize; /* Page-size field of journal header */
- u32 iSectorSize; /* Sector-size field of journal header */
- u16 iPageSize16; /* Copy of iPageSize in 16-bit variable */
+ rc = read32bits(pPager->jfd, jrnlOff+4, &pPager->cksumInit);
+ if( rc ) return rc;
- /* Read the page-size and sector-size journal header fields. */
- if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+20, &iSectorSize))
- || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+24, &iPageSize))
- ){
- return rc;
- }
+ rc = read32bits(pPager->jfd, jrnlOff+8, pDbSize);
+ if( rc ) return rc;
- /* Check that the values read from the page-size and sector-size fields
- ** are within range. To be 'in range', both values need to be a power
- ** of two greater than or equal to 512, and not greater than their
- ** respective compile time maximum limits.
- */
- if( iPageSize<512 || iSectorSize<512
- || iPageSize>SQLITE_MAX_PAGE_SIZE || iSectorSize>MAX_SECTOR_SIZE
- || ((iPageSize-1)&iPageSize)!=0 || ((iSectorSize-1)&iSectorSize)!=0
+ if( pPager->journalOff==0 ){
+ rc = read32bits(pPager->jfd, jrnlOff+16, &iPageSize);
+ if( rc ) return rc;
+
+ if( iPageSize<512
+ || iPageSize>SQLITE_MAX_PAGE_SIZE
+ || ((iPageSize-1)&iPageSize)!=0
){
- /* If the either the page-size or sector-size in the journal-header is
- ** invalid, then the process that wrote the journal-header must have
- ** crashed before the header was synced. In this case stop reading
- ** the journal file here.
+ /* If the page-size in the journal-header is invalid, then the process
+ ** that wrote the journal-header must have crashed before the header
+ ** was synced. In this case stop reading the journal file here.
*/
- return SQLITE_DONE;
+ rc = SQLITE_DONE;
+ }else{
+ u16 pagesize = (u16)iPageSize;
+ rc = sqlite3PagerSetPagesize(pPager, &pagesize);
+ assert( rc!=SQLITE_OK || pagesize==(u16)iPageSize );
}
-
- /* Update the page-size to match the value read from the journal.
- ** Use a testcase() macro to make sure that malloc failure within
- ** PagerSetPagesize() is tested.
- */
- iPageSize16 = (u16)iPageSize;
- rc = sqlite3PagerSetPagesize(pPager, &iPageSize16);
- testcase( rc!=SQLITE_OK );
- assert( rc!=SQLITE_OK || iPageSize16==(u16)iPageSize );
-
+ 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, &iSectorSize);
+ if( rc ) return rc;
+ if( (iSectorSize&(iSectorSize-1))
+ || iSectorSize<512
+ || iSectorSize>MAX_SECTOR_SIZE
+ ){
+ return SQLITE_DONE;
+ }
pPager->sectorSize = iSectorSize;
}
pPager->journalOff += JOURNAL_HDR_SZ(pPager);
- return rc;
+ return SQLITE_OK;
}
** journal file descriptor is advanced to the next sector boundary before
** anything is written. The format is:
**
-** + 4 bytes: PAGER_MJ_PGNO.
-** + N bytes: Master journal filename in utf-8.
-** + 4 bytes: N (length of master journal name in bytes, no nul-terminator).
-** + 4 bytes: Master journal name checksum.
-** + 8 bytes: aJournalMagic[].
+** + 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, where each byte is interpreted as a signed 8-bit integer.
+** 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; /* Return code */
- int nMaster; /* Length of string zMaster */
- i64 iHdrOff; /* Offset of header in journal file */
- i64 jrnlSize; /* Size of journal file on disk */
- u32 cksum = 0; /* Checksum of string zMaster */
-
- assert( isOpen(pPager->jfd) );
- assert( !pPager->setMaster );
-
- if( !zMaster ) return SQLITE_OK;
+ 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;
if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ) return SQLITE_OK;
pPager->setMaster = 1;
- /* Calculate the length in bytes and the checksum of zMaster */
- for(nMaster=0; zMaster[nMaster]; nMaster++){
- cksum += zMaster[nMaster];
+ len = sqlite3Strlen30(zMaster);
+ for(i=0; i<len; i++){
+ cksum += zMaster[i];
}
/* If in full-sync mode, advance to the next disk sector before writing
** the journal has already been synced.
*/
if( pPager->fullSync ){
- pPager->journalOff = journalHdrOffset(pPager);
+ seekJournalHdr(pPager);
}
- iHdrOff = pPager->journalOff;
+ jrnlOff = pPager->journalOff;
+ pPager->journalOff += (len+20);
- /* Write the master journal data to the end of the journal file. If
- ** an error occurs, return the error code to the caller.
- */
- if( (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager)))
- || (rc = sqlite3OsWrite(pPager->jfd, zMaster, nMaster, iHdrOff+4))
- || (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster, nMaster))
- || (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster+4, cksum))
- || (rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, 8, iHdrOff+4+nMaster+8))
- ){
- return rc;
- }
- pPager->journalOff += (nMaster+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
** Easiest thing to do in this scenario is to truncate the journal
** file to the required size.
*/
- if( SQLITE_OK==(rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))
- && jrnlSize>pPager->journalOff
+ if( (rc==SQLITE_OK)
+ && (rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))==SQLITE_OK
+ && jrnlSize>jrnlOff
){
- rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
+ rc = sqlite3OsTruncate(pPager->jfd, jrnlOff);
}
return rc;
}
/*
-** Find a page in the hash table given its page number. Return
-** a pointer to the page or NULL if the requested page is not
-** already in memory.
+** 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; /* Return value */
-
- /* It is not possible for a call to PcacheFetch() with createFlag==0 to
- ** fail, since no attempt to allocate dynamic memory will be made.
- */
- (void)sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &p);
+ PgHdr *p;
+ sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &p);
return p;
}
/*
-** Unless the pager is in error-state, discard all in-memory pages. If
-** the pager is in error-state, then this call is a no-op.
+** 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){
- if( SQLITE_OK==pPager->errCode ){
- sqlite3PcacheClear(pPager->pPCache);
- }
+ if( pPager->errCode ) return;
+ sqlite3PcacheClear(pPager->pPCache);
}
/*
** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
** if it is open and the pager is not in exclusive mode.
*/
-static void releaseAllSavepoints(Pager *pPager){
- int ii; /* Iterator for looping through Pager.aSavepoint */
+static void releaseAllSavepoint(Pager *pPager){
+ int ii;
for(ii=0; ii<pPager->nSavepoint; ii++){
sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
}
sqlite3_free(pPager->aSavepoint);
pPager->aSavepoint = 0;
pPager->nSavepoint = 0;
- pPager->nSubRec = 0;
+ pPager->stmtNRec = 0;
}
/*
-** Set the bit number pgno in the PagerSavepoint.pInSavepoint
-** bitvecs of all open savepoints. Return SQLITE_OK if successful
-** or SQLITE_NOMEM if a malloc failure occurs.
+** Set the bit number pgno in the PagerSavepoint.pInSavepoint bitvecs of
+** all open savepoints.
*/
static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
int ii; /* Loop counter */
PagerSavepoint *p = &pPager->aSavepoint[ii];
if( pgno<=p->nOrig ){
rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
- testcase( rc==SQLITE_NOMEM );
assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
}
}
}
/*
-** Unlock the database file. This function is a no-op if the pager
-** is in exclusive mode.
+** 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
*/
static void pager_unlock(Pager *pPager){
if( !pPager->exclusiveMode ){
- int rc; /* Return code */
+ int rc;
/* 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.
*/
- sqlite3OsClose(pPager->jfd);
- sqlite3BitvecDestroy(pPager->pInJournal);
- pPager->pInJournal = 0;
- releaseAllSavepoints(pPager);
-
- /* If the file is unlocked, somebody else might change it. The
- ** values stored in Pager.dbSize etc. might become invalid if
- ** this happens. TODO: Really, this doesn't need to be cleared
- ** until the change-counter check fails in pagerSharedLock().
- */
- pPager->dbSizeValid = 0;
+ if( pPager->journalOpen ){
+ sqlite3OsClose(pPager->jfd);
+ pPager->journalOpen = 0;
+ sqlite3BitvecDestroy(pPager->pInJournal);
+ pPager->pInJournal = 0;
+ sqlite3BitvecDestroy(pPager->pAlwaysRollback);
+ pPager->pAlwaysRollback = 0;
+ }
rc = osUnlock(pPager->fd, NO_LOCK);
- if( rc ){
- pPager->errCode = rc;
- }
+ if( rc ) pPager->errCode = rc;
+ pPager->dbSizeValid = 0;
IOTRACE(("UNLOCK %p\n", pPager))
/* If Pager.errCode is set, the contents of the pager cache cannot be
** cache can be discarded and the error code safely cleared.
*/
if( pPager->errCode ){
- if( rc==SQLITE_OK ){
- pPager->errCode = SQLITE_OK;
- }
+ if( rc==SQLITE_OK ) pPager->errCode = SQLITE_OK;
pager_reset(pPager);
+ releaseAllSavepoint(pPager);
+ pPager->journalOff = 0;
+ pPager->journalStarted = 0;
+ pPager->dbOrigSize = 0;
}
- pPager->changeCountDone = 0;
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 at this time. Instead, pager_unlock() is called. The
-** call to pager_unlock() will discard all in-memory pages, unlock
-** the database file and clear the error state. If this means that
-** there is a hot-journal left in the file-system, the next connection
-** to obtain a shared lock on the pager (which may be this one) will
-** roll it back.
-**
-** If the pager has not already entered the error state, but an IO or
-** malloc error occurs during a rollback, then this will itself cause
-** the pager to enter the error state. Which will be cleared by the
-** call to pager_unlock(), as described above.
+** database file. If the pager has already entered the error state,
+** do not attempt the rollback.
*/
-static void pagerUnlockAndRollback(Pager *pPager){
- if( pPager->errCode==SQLITE_OK && pPager->state>=PAGER_RESERVED ){
+static void pagerUnlockAndRollback(Pager *p){
+ if( p->errCode==SQLITE_OK && p->state>=PAGER_RESERVED ){
sqlite3BeginBenignMalloc();
- sqlite3PagerRollback(pPager);
+ sqlite3PagerRollback(p);
sqlite3EndBenignMalloc();
}
- pager_unlock(pPager);
+ pager_unlock(p);
}
/*
-** This routine ends a transaction. A transaction is usually ended by
-** either a COMMIT or a ROLLBACK operation. This routine may be called
-** after rollback of a hot-journal, or if an error occurs while opening
-** the journal file or writing the very first journal-header of a
-** database transaction.
-**
-** If the pager is in PAGER_SHARED or PAGER_UNLOCK state when this
-** routine is called, it is a no-op (returns SQLITE_OK).
-**
-** Otherwise, any active savepoints are released.
-**
-** If the journal file is open, then it is "finalized". Once a journal
-** file has been finalized it is not possible to use it to roll back a
-** transaction. Nor will it be considered to be a hot-journal by this
-** or any other database connection. Exactly how a journal is finalized
-** depends on whether or not the pager is running in exclusive mode and
-** the current journal-mode (Pager.journalMode value), as follows:
-**
-** journalMode==MEMORY
-** Journal file descriptor is simply closed. This destroys an
-** in-memory journal.
-**
-** journalMode==TRUNCATE
-** Journal file is truncated to zero bytes in size.
-**
-** journalMode==PERSIST
-** The first 28 bytes of the journal file are zeroed. This invalidates
-** the first journal header in the file, and hence the entire journal
-** file. An invalid journal file cannot be rolled back.
+** This routine ends a transaction. A transaction is ended by either
+** a COMMIT or a ROLLBACK.
**
-** journalMode==DELETE
-** The journal file is closed and deleted using sqlite3OsDelete().
+** 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.
**
-** If the pager is running in exclusive mode, this method of finalizing
-** the journal file is never used. Instead, if the journalMode is
-** DELETE and the pager is in exclusive mode, the method described under
-** journalMode==PERSIST is used instead.
+** The journal file is either deleted or truncated.
**
-** After the journal is finalized, if running in non-exclusive mode, the
-** pager moves to PAGER_SHARED state (and downgrades the lock on the
-** database file accordingly).
-**
-** If the pager is running in exclusive mode and is in PAGER_SYNCED state,
-** it moves to PAGER_EXCLUSIVE. No locks are downgraded when running in
-** exclusive mode.
-**
-** SQLITE_OK is returned if no error occurs. If an error occurs during
-** any of the IO operations to finalize the journal file or unlock the
-** database then the IO error code is returned to the user. If the
-** operation to finalize the journal file fails, then the code still
-** tries to unlock the database file if not in exclusive mode. If the
-** unlock operation fails as well, then the first error code related
-** to the first error encountered (the journal finalization one) is
-** returned.
+** 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){
- int rc = SQLITE_OK; /* Error code from journal finalization operation */
- int rc2 = SQLITE_OK; /* Error code from db file unlock operation */
-
+ int rc = SQLITE_OK;
+ int rc2 = SQLITE_OK;
if( pPager->state<PAGER_RESERVED ){
return SQLITE_OK;
}
- releaseAllSavepoints(pPager);
-
- assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
- if( isOpen(pPager->jfd) ){
-
- /* TODO: There's a problem here if a journal-file was opened in MEMORY
- ** mode and then the journal-mode is changed to TRUNCATE or PERSIST
- ** during the transaction. This code should be changed to assume
- ** that the journal mode has not changed since the transaction was
- ** started. And the sqlite3PagerJournalMode() function should be
- ** changed to make sure that this is the case too.
- */
-
- /* Finalize the journal file. */
+ releaseAllSavepoint(pPager);
+ if( pPager->journalOpen ){
if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
int isMemoryJournal = sqlite3IsMemJournal(pPager->jfd);
sqlite3OsClose(pPager->jfd);
+ pPager->journalOpen = 0;
if( !isMemoryJournal ){
rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
}
}else{
assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE || rc );
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;
+ sqlite3BitvecDestroy(pPager->pAlwaysRollback);
+ pPager->pAlwaysRollback = 0;
#ifdef SQLITE_CHECK_PAGES
sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
#endif
-
sqlite3PcacheCleanAll(pPager->pPCache);
- sqlite3BitvecDestroy(pPager->pInJournal);
- pPager->pInJournal = 0;
+ pPager->dirtyCache = 0;
pPager->nRec = 0;
+ }else{
+ assert( pPager->pInJournal==0 );
}
if( !pPager->exclusiveMode ){
}else if( pPager->state==PAGER_SYNCED ){
pPager->state = PAGER_EXCLUSIVE;
}
+ pPager->dbOrigSize = 0;
pPager->setMaster = 0;
pPager->needSync = 0;
- pPager->dbModified = 0;
-
- /* TODO: Is this optimal? Why is the db size invalidated here
- ** when the database file is not unlocked? */
- pPager->dbOrigSize = 0;
+ /* lruListSetFirstSynced(pPager); */
sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
if( !MEMDB ){
pPager->dbSizeValid = 0;
}
+ pPager->dbModified = 0;
return (rc==SQLITE_OK?rc2:rc);
}
/*
-** Parameter aData must point to a buffer of pPager->pageSize bytes
-** of data. Compute and return a checksum based ont the contents of the
-** page of data and the current value of pPager->cksumInit.
+** 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 (pPager->cksumInit) and every 200th byte
-** of the page data, starting with byte offset (pPager->pageSize%200).
-** Each byte is interpreted as an 8-bit unsigned integer.
+** 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.
**
-** Changing the formula used to compute this checksum results in an
-** incompatible journal file format.
-**
-** 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
+** 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; /* Checksum value to return */
- int i = pPager->pageSize-200; /* Loop counter */
+ u32 cksum = pPager->cksumInit;
+ int i = pPager->pageSize-200;
while( i>0 ){
cksum += aData[i];
i -= 200;
/*
** Read a single page from either the journal file (if isMainJrnl==1) or
** from the sub-journal (if isMainJrnl==0) and playback that page.
-** The page begins at offset *pOffset into the file. The *pOffset
+** The page begins at offset *pOffset into the file. The *pOffset
** value is increased to the start of the next page in the journal.
**
** The isMainJrnl flag is true if this is the main rollback journal and
** false for the statement journal. The main rollback journal uses
** checksums - the statement journal does not.
**
-** If the page number of the page record read from the (sub-)journal file
-** is greater than the current value of Pager.dbSize, then playback is
-** skipped and SQLITE_OK is returned.
-**
** If pDone is not NULL, then it is a record of pages that have already
** been played back. If the page at *pOffset has already been played back
** (if the corresponding pDone bit is set) then skip the playback.
** Make sure the pDone bit corresponding to the *pOffset page is set
** prior to returning.
-**
-** If the page record is successfully read from the (sub-)journal file
-** and played back, then SQLITE_OK is returned. If an IO error occurs
-** while reading the record from the (sub-)journal file or while writing
-** to the database file, then the IO error code is returned. If data
-** is successfully read from the (sub-)journal file but appears to be
-** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
-** two circumstances:
-**
-** * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
-** * If the record is being rolled back from the main journal file
-** and the checksum field does not match the record content.
-**
-** Neither of these two scenarios are possible during a savepoint rollback.
-**
-** If this is a savepoint rollback, then memory may have to be dynamically
-** allocated by this function. If this is the case and an allocation fails,
-** SQLITE_NOMEM is returned.
*/
static int pager_playback_one_page(
Pager *pPager, /* The pager being played back */
aData = (u8*)pPager->pTmpSpace;
assert( aData ); /* Temp storage must have already been allocated */
- /* Read the page number and page data from the journal or sub-journal
- ** file. Return an error code to the caller if an IO error occurs.
- */
jfd = isMainJrnl ? pPager->jfd : pPager->sjfd;
+
rc = read32bits(jfd, *pOffset, &pgno);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3OsRead(jfd, aData, pPager->pageSize, (*pOffset)+4);
** detect this invalid data (with high probability) and ignore it.
*/
if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
- assert( !isSavepnt );
return SQLITE_DONE;
}
if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
return SQLITE_DONE;
}
}
-
if( pDone && (rc = sqlite3BitvecSet(pDone, pgno)) ){
return rc;
}
));
if( (pPager->state>=PAGER_EXCLUSIVE)
&& (pPg==0 || 0==(pPg->flags&PGHDR_NEED_SYNC))
- && isOpen(pPager->fd)
+ && (pPager->fd->pMethods)
){
i64 ofst = (pgno-1)*(i64)pPager->pageSize;
rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize, ofst);
if( pPager->xReiniter ){
pPager->xReiniter(pPg);
}
- if( isMainJrnl && (!isSavepnt || *pOffset<=pPager->journalHdr) ){
+ if( isMainJrnl && (!isSavepnt || pPager->journalOff<=pPager->journalHdr) ){
/* If the contents of this page were just restored from the main
** journal file, then its content must be as they were when the
** transaction was first opened. In this case we can mark the page
** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not
** available for use within this function.
**
-** When a master journal file is created, it is populated with the names
-** of all of its child journals, one after another, formatted as utf-8
-** encoded text. The end of each child journal file is marked with a
-** nul-terminator byte (0x00). i.e. the entire contents of a master journal
-** file for a transaction involving two databases might be:
-**
-** "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
-**
-** A master journal file may only be deleted once all of its child
-** journals have been rolled back.
**
-** This function reads the contents of the master-journal file into
-** memory and loops through each of the child journal names. For
-** each child journal, it checks if:
-**
-** * if the child journal exists, and if so
-** * if the child journal contains a reference to master journal
-** file zMaster
-**
-** If a child journal can be found that matches both of the criteria
-** above, this function returns without doing anything. Otherwise, if
-** no such child journal can be found, file zMaster is deleted from
-** the file-system using sqlite3OsDelete().
-**
-** If an IO error within this function, an error code is returned. This
-** function allocates memory by calling sqlite3Malloc(). If an allocation
-** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors
-** occur, SQLITE_OK is returned.
-**
-** TODO: This function allocates a single block of memory to load
-** the entire contents of the master journal file. This could be
-** a couple of kilobytes or so - potentially larger than the page
-** size.
+** 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; /* Return code */
- sqlite3_file *pMaster; /* Malloc'd master-journal file descriptor */
- sqlite3_file *pJournal; /* Malloc'd child-journal file descriptor */
+ 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 */
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 = pVfs->mxPathname+1;
+ int nMasterPtr = pPager->pVfs->mxPathname+1;
/* Load the entire master journal file into space obtained from
** sqlite3_malloc() and pointed to by zMasterJournal.
if( zMasterJournal ){
sqlite3_free(zMasterJournal);
}
- if( pMaster ){
+ if( master_open ){
sqlite3OsClose(pMaster);
- assert( !isOpen(pJournal) );
}
sqlite3_free(pMaster);
return rc;
/*
-** This function is used to change the actual size of the database
-** file in the file-system. This only happens when committing a transaction,
-** or rolling back a transaction (including rolling back a hot-journal).
-**
-** If the main database file is not open, or an exclusive lock is not
-** held, this function is a no-op. Otherwise, the size of the file is
-** changed to nPage pages (nPage*pPager->pageSize bytes). If the file
-** on disk is currently larger than nPage pages, then use the VFS
-** xTruncate() method to truncate it.
-**
-** Or, it might might be the case that the file on disk is smaller than
-** nPage pages. Some operating system implementations can get confused if
-** you try to truncate a file to some size that is larger than it
-** currently is, so detect this case and write a single zero byte to
-** the end of the new file instead.
-**
-** If successful, return SQLITE_OK. If an IO error occurs while modifying
-** the database file, return the error code to the caller.
+** If the main database file is open and an exclusive lock is held,
+** truncate the main file of the given pager to the specified number
+** of pages.
+**
+** It might might be the case that the file on disk is smaller than nPage.
+** This can happen, for example, if we are in the middle of a transaction
+** which has extended the file size and the new pages are still all held
+** in cache, then an INSERT or UPDATE does a statement rollback. Some
+** operating system implementations can get confused if you try to
+** truncate a file to some size that is larger than it currently is,
+** so detect this case and write a single zero byte to the end of the new
+** file instead.
*/
static int pager_truncate(Pager *pPager, Pgno nPage){
int rc = SQLITE_OK;
- if( pPager->state>=PAGER_EXCLUSIVE && isOpen(pPager->fd) ){
+ if( pPager->state>=PAGER_EXCLUSIVE && pPager->fd->pMethods ){
i64 currentSize, newSize;
- /* TODO: Is it safe to use Pager.dbFileSize here? */
rc = sqlite3OsFileSize(pPager->fd, ¤tSize);
newSize = pPager->pageSize*(i64)nPage;
if( rc==SQLITE_OK && currentSize!=newSize ){
}
/*
-** Set the value of the Pager.sectorSize variable for the given
-** pager based on the value returned by the xSectorSize method
-** of the open database file. The sector size will be used used
-** to determine the size and alignment of journal header and
-** master journal pointers within created journal files.
+** Set the sectorSize for the given pager.
**
-** For temporary files the effective sector size is always 512 bytes.
-**
-** Otherwise, for non-temporary files, the effective sector size is
-** the value returned by the xSectorSize() method rounded up to 512 if
-** it is less than 512, or rounded down to MAX_SECTOR_SIZE if it
-** is greater than MAX_SECTOR_SIZE.
+** 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( isOpen(pPager->fd) || pPager->tempFile );
-
+ 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 which case the OsSectorSize()
+ ** may not have been opened yet, in whcih case the OsSectorSize()
** call will segfault.
*/
pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);
pPager->sectorSize = 512;
}
if( pPager->sectorSize>MAX_SECTOR_SIZE ){
- assert( MAX_SECTOR_SIZE>=512 );
pPager->sectorSize = MAX_SECTOR_SIZE;
}
}
/* Figure out how many records are in the journal. Abort early if
** the journal is empty.
*/
- assert( isOpen(pPager->jfd) );
+ assert( pPager->journalOpen );
rc = sqlite3OsFileSize(pPager->jfd, &szJ);
if( rc!=SQLITE_OK || szJ==0 ){
goto end_playback;
** 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.
- **
- ** TODO: Technically the following is an error because it assumes that
- ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
- ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
- ** mxPathname is 512, which is the same as the minimum allowable value
- ** for pageSize.
*/
zMaster = pPager->pTmpSpace;
rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
}
pPager->journalOff = 0;
- /* This loop terminates either when a readJournalHdr() or
- ** pager_playback_one_page() call returns SQLITE_DONE or an IO error
- ** occurs.
- */
+ /* 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
pPager->dbSize = mxPg;
}
- /* Copy original pages out of the journal and back into the
- ** database file and/or page cache.
+ /* Copy original pages out of the journal and back into the database file.
*/
for(u=0; u<nRec; u++){
rc = pager_playback_one_page(pPager, 1, &pPager->journalOff, 0, 0);
if( rc==SQLITE_OK ){
zMaster = pPager->pTmpSpace;
rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
- testcase( rc!=SQLITE_OK );
}
if( rc==SQLITE_OK ){
rc = pager_end_transaction(pPager, zMaster[0]!='\0');
- testcase( rc!=SQLITE_OK );
}
if( rc==SQLITE_OK && zMaster[0] && res ){
/* 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);
- testcase( rc!=SQLITE_OK );
}
/* The Pager.sectorSize variable may have been updated while rolling
}
/*
-** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
-** the entire master journal file. The case pSavepoint==NULL occurs when
-** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction
-** savepoint.
-**
-** When pSavepoint is not NULL (meaning a non-transaction savepoint is
-** being rolled back), then the rollback consists of up to three stages,
-** performed in the order specified:
-**
-** * Pages are played back from the main journal starting at byte
-** offset PagerSavepoint.iOffset and continuing to
-** PagerSavepoint.iHdrOffset, or to the end of the main journal
-** file if PagerSavepoint.iHdrOffset is zero.
-**
-** * If PagerSavepoint.iHdrOffset is not zero, then pages are played
-** back starting from the journal header immediately following
-** PagerSavepoint.iHdrOffset to the end of the main journal file.
-**
-** * Pages are then played back from the sub-journal file, starting
-** with the PagerSavepoint.iSubRec and continuing to the end of
-** the journal file.
+** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
+** the entire master journal file.
**
-** Throughout the rollback process, each time a page is rolled back, the
-** corresponding bit is set in a bitvec structure (variable pDone in the
-** implementation below). This is used to ensure that a page is only
-** rolled back the first time it is encountered in either journal.
-**
-** If pSavepoint is NULL, then pages are only played back from the main
-** journal file. There is no need for a bitvec in this case.
-**
-** In either case, before playback commences the Pager.dbSize variable
-** is reset to the value that it held at the start of the savepoint
-** (or transaction). No page with a page-number greater than this value
-** is played back. If one is encountered it is simply skipped.
+** The case pSavepoint==NULL occurs when a ROLLBACK TO command is invoked
+** on a SAVEPOINT that is a transaction savepoint.
*/
static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
i64 szJ; /* Effective size of the main journal */
i64 iHdrOff; /* End of first segment of main-journal records */
+ Pgno ii; /* Loop counter */
int rc = SQLITE_OK; /* Return code */
Bitvec *pDone = 0; /* Bitvec to ensure pages played back only once */
- assert( pPager->state>=PAGER_SHARED );
-
/* Allocate a bitvec to use to store the set of pages rolled back */
if( pSavepoint ){
pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
}
}
- /* Set the database size back to the value it was before the savepoint
- ** being reverted was opened.
+ /* Truncate the database back to the size it was before the
+ ** savepoint being reverted was opened.
*/
pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;
+ assert( pPager->state>=PAGER_SHARED );
/* Use pPager->journalOff as the effective size of the main rollback
** journal. The actual file might be larger than this in
pPager->journalOff = pSavepoint->iOffset;
while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
rc = pager_playback_one_page(pPager, 1, &pPager->journalOff, 1, pDone);
+ assert( rc!=SQLITE_DONE );
}
- assert( rc!=SQLITE_DONE );
}else{
pPager->journalOff = 0;
}
** continue adding pages rolled back to pDone.
*/
while( rc==SQLITE_OK && pPager->journalOff<szJ ){
- u32 ii; /* Loop counter */
u32 nJRec = 0; /* Number of Journal Records */
u32 dummy;
rc = readJournalHdr(pPager, szJ, &nJRec, &dummy);
}
for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
rc = pager_playback_one_page(pPager, 1, &pPager->journalOff, 1, pDone);
+ assert( rc!=SQLITE_DONE );
}
- assert( rc!=SQLITE_DONE );
}
assert( rc!=SQLITE_OK || pPager->journalOff==szJ );
** will be skipped. Out-of-range pages are also skipped.
*/
if( pSavepoint ){
- u32 ii; /* Loop counter */
i64 offset = pSavepoint->iSubRec*(4+pPager->pageSize);
- for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
- assert( offset==ii*(4+pPager->pageSize) );
+ for(ii=pSavepoint->iSubRec; rc==SQLITE_OK&&ii<(u32)pPager->stmtNRec; ii++){
+ assert( offset == ii*(4+pPager->pageSize) );
rc = pager_playback_one_page(pPager, 0, &offset, 1, pDone);
+ assert( rc!=SQLITE_DONE );
}
- assert( rc!=SQLITE_DONE );
}
sqlite3BitvecDestroy(pDone);
#endif
/*
-** Open a temporary file.
+** Open a temporary file.
**
-** Write the file descriptor into *pFile. 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.
-**
-** The flags passed to the VFS layer xOpen() call are those specified
-** by parameter vfsFlags ORed with the following:
-**
-** SQLITE_OPEN_READWRITE
-** SQLITE_OPEN_CREATE
-** SQLITE_OPEN_EXCLUSIVE
-** SQLITE_OPEN_DELETEONCLOSE
+** 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 pagerOpentemp(
+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; /* Return code */
+ int rc;
#ifdef SQLITE_TEST
sqlite3_opentemp_count++; /* Used for testing and analysis only */
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 || isOpen(pFile) );
+ assert( rc!=SQLITE_OK || pFile->pMethods );
return rc;
}
static int pagerStress(void *,PgHdr *);
/*
-** Allocate and initialize a new Pager object and put a pointer to it
-** in *ppPager. The pager should eventually be freed by passing it
-** to sqlite3PagerClose().
+** 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().
**
-** The zFilename argument is the path to the database file to open.
** If zFilename is NULL then a randomly-named temporary file is created
-** and used as the file to be cached. Temporary files are be deleted
-** automatically when they are 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.
-**
-** The nExtra parameter specifies the number of bytes of space allocated
-** along with each page reference. This space is available to the user
-** via the sqlite3PagerGetExtra() API.
+** and used as the file to be cached. The file will be deleted
+** automatically when it is closed.
**
-** The flags argument is used to specify properties that affect the
-** operation of the pager. It should be passed some bitwise combination
-** of the PAGER_OMIT_JOURNAL and PAGER_NO_READLOCK flags.
-**
-** The vfsFlags parameter is a bitmask to pass to the flags parameter
-** of the xOpen() method of the supplied VFS when opening files.
-**
-** If the pager object is allocated and the specified file opened
-** successfully, SQLITE_OK is returned and *ppPager set to point to
-** the new pager object. If an error occurs, *ppPager is set to NULL
-** and error code returned. This function may return SQLITE_NOMEM
-** (sqlite3Malloc() is used to allocate memory), SQLITE_CANTOPEN or
-** various SQLITE_IO_XXX errors.
+** 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, /* OUT: Return the Pager structure here */
+ 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; /* Pager object to allocate and return */
- int rc = SQLITE_OK; /* Return code */
- int tempFile = 0; /* True for temp files (incl. in-memory files) */
- int memDb = 0; /* True if this is an in-memory file */
- int readOnly = 0; /* True if this is a read-only file */
- int journalFileSize; /* Bytes to allocate for each journal fd */
- char *zPathname = 0; /* Full path to database file */
- int nPathname = 0; /* Number of bytes in zPathname */
- int useJournal = (flags & PAGER_OMIT_JOURNAL)==0; /* False to omit journal */
- int noReadlock = (flags & PAGER_NO_READLOCK)!=0; /* True to omit read-lock */
- int pcacheSize = sqlite3PcacheSize(); /* Bytes to allocate for PCache */
- u16 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE; /* Default page size */
-
- /* Figure out how much space is required for each journal file-handle
- ** (there are two of them, the main journal and the sub-journal). This
- ** is the maximum space required for an in-memory journal file handle
- ** and a regular journal file-handle. Note that a "regular journal-handle"
- ** may be a wrapper capable of caching the first portion of the journal
- ** file in memory to implement the atomic-write optimization (see
- ** source file journal.c).
- */
+ 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;
+ int pcacheSize = sqlite3PcacheSize();
+ int szPageDflt = SQLITE_DEFAULT_PAGE_SIZE;
+ char *zPathname = 0;
+ int nPathname = 0;
+
if( sqlite3JournalSize(pVfs)>sqlite3MemJournalSize() ){
journalFileSize = sqlite3JournalSize(pVfs);
}else{
journalFileSize = sqlite3MemJournalSize();
}
- /* Set the output variable to NULL in case an error occurs. */
+ /* The default return is a NULL pointer */
*ppPager = 0;
/* Compute and store the full pathname in an allocated buffer pointed
{
rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname);
}
-
- nPathname = sqlite3Strlen30(zPathname);
- if( rc==SQLITE_OK && nPathname+8>pVfs->mxPathname ){
- /* This branch is taken when the journal path required by
- ** the database being opened will be more than pVfs->mxPathname
- ** bytes in length. This means the database cannot be opened,
- ** as it will not be possible to open the journal file or even
- ** check for a hot-journal before reading.
- */
- rc = SQLITE_CANTOPEN;
- }
if( rc!=SQLITE_OK ){
sqlite3_free(zPathname);
return rc;
}
+ nPathname = sqlite3Strlen30(zPathname);
}
- /* Allocate memory for the Pager structure, PCache object, the
- ** three file descriptors, the database file name and the journal
- ** file name. The layout in memory is as follows:
- **
- ** Pager object (sizeof(Pager) bytes)
- ** PCache object (sqlite3PcacheSize() bytes)
- ** Database file handle (pVfs->szOsFile bytes)
- ** Sub-journal file handle (journalFileSize bytes)
- ** Main journal file handle (journalFileSize bytes)
- ** Database file name (nPathname+1 bytes)
- ** Journal file name (nPathname+8+1 bytes)
- */
- pPtr = (u8 *)sqlite3MallocZero(
+ /* Allocate memory for the pager structure */
+ pPager = sqlite3MallocZero(
sizeof(*pPager) + /* Pager structure */
pcacheSize + /* PCache object */
+ journalFileSize + /* The journal file structure */
pVfs->szOsFile + /* The main db file */
journalFileSize * 2 + /* The two journal files */
- nPathname + 1 + /* zFilename */
- nPathname + 8 + 1 /* zJournal */
+ 3*nPathname + 40 /* zFilename, zDirectory, zJournal */
);
- if( !pPtr ){
+ if( !pPager ){
sqlite3_free(zPathname);
return SQLITE_NOMEM;
}
- pPager = (Pager*)(pPtr);
- pPager->pPCache = (PCache*)(pPtr += sizeof(*pPager));
- pPager->fd = (sqlite3_file*)(pPtr += pcacheSize);
- pPager->sjfd = (sqlite3_file*)(pPtr += pVfs->szOsFile);
- pPager->jfd = (sqlite3_file*)(pPtr += journalFileSize);
- pPager->zFilename = (char*)(pPtr += journalFileSize);
-
- /* Fill in the Pager.zFilename and Pager.zJournal buffers, if required. */
+ pPager->pPCache = (PCache *)&pPager[1];
+ pPtr = ((u8 *)&pPager[1]) + pcacheSize;
+ pPager->vfsFlags = vfsFlags;
+ pPager->fd = (sqlite3_file*)&pPtr[pVfs->szOsFile*0];
+ pPager->sjfd = (sqlite3_file*)&pPtr[pVfs->szOsFile];
+ pPager->jfd = (sqlite3_file*)&pPtr[pVfs->szOsFile+journalFileSize];
+ 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 ){
- pPager->zJournal = (char*)(pPtr += nPathname + 1);
- memcpy(pPager->zFilename, zPathname, nPathname);
- memcpy(pPager->zJournal, zPathname, nPathname);
- memcpy(&pPager->zJournal[nPathname], "-journal", 8);
+ memcpy(pPager->zFilename, zPathname, nPathname+1);
sqlite3_free(zPathname);
}
- pPager->pVfs = pVfs;
- pPager->vfsFlags = vfsFlags;
/* Open the pager file.
*/
if( zFilename && zFilename[0] && !memDb ){
- int fout = 0; /* VFS flags returned by xOpen() */
- rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd, 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 ){
- setSectorSize(pPager);
- if( szPageDflt<pPager->sectorSize ){
- szPageDflt = pPager->sectorSize;
- }
+ if( nPathname>(pVfs->mxPathname - (int)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 ){
+ setSectorSize(pPager);
+ if( szPageDflt<pPager->sectorSize ){
+ szPageDflt = pPager->sectorSize;
+ }
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
- {
- int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
- 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;
+ {
+ int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+ 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;
+ if( szPageDflt>SQLITE_MAX_DEFAULT_PAGE_SIZE ){
+ szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
+ }
}
}
}else{
pPager->state = PAGER_EXCLUSIVE;
}
- /* The following call to PagerSetPagesize() serves to set the value of
- ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
- */
- if( rc==SQLITE_OK ){
- assert( pPager->memDb==0 );
- rc = sqlite3PagerSetPagesize(pPager, &szPageDflt);
- testcase( rc!=SQLITE_OK );
+ 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.
+ /* 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( rc!=SQLITE_OK ){
- assert( !pPager->pTmpSpace );
+ if( !pPager || !pPager->pTmpSpace ){
sqlite3OsClose(pPager->fd);
sqlite3_free(pPager);
- return rc;
+ return ((rc==SQLITE_OK)?SQLITE_NOMEM:rc);
}
-
- /* Initialize the PCache object. */
nExtra = FORCE_ALIGNMENT(nExtra);
sqlite3PcacheOpen(szPageDflt, nExtra, !memDb,
!memDb?pagerStress:0, (void *)pPager, pPager->pPCache);
PAGERTRACE(("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=sqlite3Strlen30(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 = (u8)useJournal;
pPager->noReadlock = (noReadlock && readOnly) ?1:0;
/* pPager->stmtOpen = 0; */
/* pPager->stmtInUse = 0; */
/* pPager->nRef = 0; */
pPager->dbSizeValid = (u8)memDb;
+ 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->pLast = 0; */
pPager->nExtra = nExtra;
pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
- assert( isOpen(pPager->fd) || tempFile );
+ assert(pPager->fd->pMethods||tempFile);
setSectorSize(pPager);
if( memDb ){
pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
/*
** Set the busy handler function.
-**
-** The pager invokes the busy-handler if sqlite3OsLock() returns
-** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
-** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE
-** lock. It does *not* invoke the busy handler when upgrading from
-** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
-** (which occurs during hot-journal rollback). Summary:
-**
-** Transition | Invokes xBusyHandler
-** --------------------------------------------------------
-** NO_LOCK -> SHARED_LOCK | Yes
-** SHARED_LOCK -> RESERVED_LOCK | No
-** SHARED_LOCK -> EXCLUSIVE_LOCK | No
-** RESERVED_LOCK -> EXCLUSIVE_LOCK | Yes
-**
-** If the busy-handler callback returns non-zero, the lock is
-** retried. If it returns zero, then the SQLITE_BUSY error is
-** returned to the caller of the pager API function.
*/
void sqlite3PagerSetBusyhandler(
- Pager *pPager, /* Pager object */
- int (*xBusyHandler)(void *), /* Pointer to busy-handler function */
- void *pBusyHandlerArg /* Argument to pass to xBusyHandler */
+ Pager *pPager,
+ int (*xBusyHandler)(void *),
+ void *pBusyHandlerArg
){
pPager->xBusyHandler = xBusyHandler;
pPager->pBusyHandlerArg = pBusyHandlerArg;
}
/*
-** Set the reinitializer for this pager. If not NULL, the reinitializer
-** is called when the content of a page in cache is modified (restored)
-** as part of a transaction or savepoint rollback. The callback gives
-** higher-level code an opportunity to restore the EXTRA section to
-** agree with the restored page data.
+** 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*)){
pPager->xReiniter = xReinit;
}
/*
-** Change the page size used by the Pager object. The new page size
-** is passed in *pPageSize.
-**
-** If the pager is in the error state when this function is called, it
-** is a no-op. The value returned is the error state error code (i.e.
-** one of SQLITE_IOERR, SQLITE_CORRUPT or SQLITE_FULL).
-**
-** Otherwise, if all of the following are true:
-**
-** * the new page size (value of *pPageSize) is valid (a power
-** of two between 512 and SQLITE_MAX_PAGE_SIZE, inclusive), and
-**
-** * there are no outstanding page references, and
-**
-** * the database is either not an in-memory database or it is
-** an in-memory database that currently consists of zero pages.
-**
-** then the pager object page size is set to *pPageSize.
-**
-** If the page size is changed, then this function uses sqlite3PagerMalloc()
-** to obtain a new Pager.pTmpSpace buffer. If this allocation attempt
-** fails, SQLITE_NOMEM is returned and the page size remains unchanged.
-** In all other cases, SQLITE_OK is returned.
-**
-** If the page size is not changed, either because one of the enumerated
-** conditions above is not true, the pager was in error state when this
-** function was called, or because the memory allocation attempt failed,
-** then *pPageSize is set to the old, retained page size before returning.
+** 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 = pPager->errCode;
}else{
pager_reset(pPager);
pPager->pageSize = pageSize;
+ if( !pPager->memDb ) setSectorSize(pPager);
sqlite3PageFree(pPager->pTmpSpace);
pPager->pTmpSpace = pNew;
sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
** Read the first N bytes from the beginning of the file into memory
** that pDest points to.
**
-** If the pager was opened on a transient file (zFilename==""), or
-** opened on a file less than N bytes in size, the output buffer is
-** zeroed and SQLITE_OK returned. The rationale for this is that this
-** function is used to read database headers, and a new transient or
-** zero sized database has a header than consists entirely of zeroes.
-**
-** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
-** the error code is returned to the caller and the contents of the
-** output buffer undefined.
+** 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( isOpen(pPager->fd) || pPager->tempFile );
- if( isOpen(pPager->fd) ){
+ assert(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 ){
}
/*
-** Return the total number of pages in the database file associated
-** with pPager. Normally, this is calculated as (<db file size>/<page-size>).
-** However, if the file is between 1 and <page-size> bytes in size, then
-** this is considered a 1 page file.
+** Return the total number of pages in the disk file associated with
+** pPager.
**
-** If the pager is in error state when this function is called, then the
-** error state error code is returned and *pnPage left unchanged. Or,
-** if the file system has to be queried for the size of the file and
-** the query attempt returns an IO error, the IO error code is returned
-** and *pnPage is left unchanged.
-**
-** Otherwise, if everything is successful, then SQLITE_OK is returned
-** and *pnPage is set to the number of pages in the database.
+** 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){
- Pgno nPage; /* Value to return via *pnPage */
-
- /* If the pager is already in the error state, return the error code. */
+ i64 n = 0;
+ int rc;
+ assert( pPager!=0 );
if( pPager->errCode ){
- return pPager->errCode;
+ rc = pPager->errCode;
+ return rc;
}
-
- /* Determine the number of pages in the file. Store this in nPage. */
if( pPager->dbSizeValid ){
- nPage = pPager->dbSize;
- }else{
- int rc; /* Error returned by OsFileSize() */
- i64 n = 0; /* File size in bytes returned by OsFileSize() */
-
- assert( isOpen(pPager->fd) || pPager->tempFile );
- if( isOpen(pPager->fd) && (rc = sqlite3OsFileSize(pPager->fd, &n)) ){
+ n = pPager->dbSize;
+ } else {
+ assert(pPager->fd->pMethods||pPager->tempFile);
+ if( (pPager->fd->pMethods)
+ && (rc = sqlite3OsFileSize(pPager->fd, &n))!=SQLITE_OK ){
pager_error(pPager, rc);
return rc;
}
if( n>0 && n<pPager->pageSize ){
- nPage = 1;
+ n = 1;
}else{
- nPage = n / pPager->pageSize;
+ n /= pPager->pageSize;
}
if( pPager->state!=PAGER_UNLOCK ){
- pPager->dbSize = (Pgno)nPage;
- pPager->dbFileSize = (Pgno)nPage;
+ pPager->dbSize = (Pgno)n;
+ pPager->dbFileSize = (Pgno)n;
pPager->dbSizeValid = 1;
}
}
-
- /* If the current number of pages in the file is greater than the
- ** configured maximum pager number, increase the allowed limit so
- ** that the file can be read.
- */
- if( nPage>pPager->mxPgno ){
- pPager->mxPgno = (Pgno)nPage;
+ if( n==(PENDING_BYTE/pPager->pageSize) ){
+ n++;
+ }
+ if( n>pPager->mxPgno ){
+ pPager->mxPgno = (Pgno)n;
}
-
- /* Set the output variable and return SQLITE_OK */
if( pnPage ){
- *pnPage = nPage;
+ *pnPage = (int)n;
}
return SQLITE_OK;
}
/*
-** Forward declaration.
+** Forward declaration
*/
static int syncJournal(Pager*);
/*
-** Try to obtain a lock of type locktype on the database file. If
-** a similar or greater lock is already held, this function is a no-op
-** (returning SQLITE_OK immediately).
-**
-** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke
-** the busy callback if the lock is currently not available. Repeat
-** until the busy callback returns false or until the attempt to
-** obtain the lock succeeds.
+** 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. If the lock is obtained successfully, set the Pager.state
-** variable to locktype before returning.
+** the lock.
*/
static int pager_wait_on_lock(Pager *pPager, int locktype){
- int rc; /* Return code */
+ int rc;
/* The OS lock values must be the same as the Pager lock values */
assert( PAGER_SHARED==SHARED_LOCK );
/* If the file is currently unlocked then the size must be unknown */
assert( pPager->state>=PAGER_SHARED || pPager->dbSizeValid==0 );
- /* Check that this is either a no-op (because the requested lock is
- ** already held, or one of the transistions that the busy-handler
- ** may be invoked during, according to the comment above
- ** sqlite3PagerSetBusyhandler().
- */
- assert( (pPager->state>=locktype)
- || (pPager->state==PAGER_UNLOCK && locktype==PAGER_SHARED)
- || (pPager->state==PAGER_RESERVED && locktype==PAGER_EXCLUSIVE)
- );
-
if( pPager->state>=locktype ){
rc = SQLITE_OK;
}else{
void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
assert( pPager->dbSizeValid );
assert( pPager->dbSize>=nPage );
- assert( pPager->state>=PAGER_RESERVED );
pPager->dbSize = nPage;
}
+
+/*
+** Return the current size of the database file image in pages. This
+** function differs from sqlite3PagerPagecount() in two ways:
+**
+** a) It may only be called when at least one reference to a database
+** page is held. This guarantees that the database size is already
+** known and a call to sqlite3OsFileSize() is not required.
+**
+** b) The return value is not adjusted for the locking page.
+*/
+Pgno sqlite3PagerImageSize(Pager *pPager){
+ assert( pPager->dbSizeValid );
+ return pPager->dbSize;
+}
#endif /* ifndef SQLITE_OMIT_AUTOVACUUM */
/*
** to the caller.
*/
int sqlite3PagerClose(Pager *pPager){
+
disable_simulated_io_errors();
sqlite3BeginBenignMalloc();
pPager->errCode = 0;
pPager->exclusiveMode = 0;
pager_reset(pPager);
- if( MEMDB ){
- pager_unlock(pPager);
- }else{
+ if( !MEMDB ){
/* Set Pager.journalHdr to -1 for the benefit of the pager_playback()
** call which may be made from within pagerUnlockAndRollback(). If it
** is not -1, then the unsynced portion of an open journal file may
pPager->journalHdr = -1;
pagerUnlockAndRollback(pPager);
}
- sqlite3EndBenignMalloc();
enable_simulated_io_errors();
+ sqlite3EndBenignMalloc();
PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
IOTRACE(("CLOSE %p\n", pPager))
+ if( pPager->journalOpen ){
+ sqlite3OsClose(pPager->jfd);
+ }
+ sqlite3BitvecDestroy(pPager->pInJournal);
+ sqlite3BitvecDestroy(pPager->pAlwaysRollback);
+ releaseAllSavepoint(pPager);
sqlite3OsClose(pPager->fd);
+ /* Temp files are automatically deleted by the OS
+ ** if( pPager->tempFile ){
+ ** sqlite3OsDelete(pPager->zFilename);
+ ** }
+ */
+
sqlite3PageFree(pPager->pTmpSpace);
sqlite3PcacheClose(pPager->pPCache);
-
- assert( !pPager->aSavepoint && !pPager->pInJournal );
- assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );
-
sqlite3_free(pPager);
return SQLITE_OK;
}
#if !defined(NDEBUG) || defined(SQLITE_TEST)
/*
-** Return the page number for page pPg.
+** Return the page number for the given page data.
*/
-Pgno sqlite3PagerPagenumber(DbPage *pPg){
- return pPg->pgno;
+Pgno sqlite3PagerPagenumber(DbPage *p){
+ return p->pgno;
}
#endif
/*
-** Increment the reference count for page pPg.
+** Increment the reference count for a page. The input pointer is
+** a reference to the page data.
*/
-void sqlite3PagerRef(DbPage *pPg){
+int sqlite3PagerRef(DbPage *pPg){
sqlite3PcacheRef(pPg);
+ return SQLITE_OK;
}
/*
-** Sync the journal. In other words, make sure all the pages that have
+** 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 and can be restored in the event of a hot-journal rollback.
-**
-** If the Pager.needSync flag is not set, then this function is a
-** no-op. Otherwise, the actions required depend on the journal-mode
-** and the device characteristics of the the file-system, as follows:
-**
-** * If the journal file is an in-memory journal file, no action need
-** be taken.
-**
-** * Otherwise, if the device does not support the SAFE_APPEND property,
-** then the nRec field of the most recently written journal header
-** is updated to contain the number of journal records that have
-** been written following it. If the pager is operating in full-sync
-** mode, then the journal file is synced before this field is updated.
-**
-** * If the device does not support the SEQUENTIAL property, then
-** journal file is synced.
-**
-** Or, in pseudo-code:
+** 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.
**
-** if( NOT <in-memory journal> ){
-** if( NOT SAFE_APPEND ){
-** if( <full-sync mode> ) xSync(<journal file>);
-** <update nRec field>
-** }
-** if( NOT SEQUENTIAL ) xSync(<journal file>);
-** }
+** For temporary databases, we do not care if we are able to rollback
+** after a power failure, so no sync occurs.
**
-** The Pager.needSync flag is never be set for temporary files, or any
-** file operating in no-sync mode (Pager.noSync set to non-zero).
+** 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.
**
-** If successful, this routine clears the PGHDR_NEED_SYNC flag of every
-** page currently held in memory before returning SQLITE_OK. If an IO
-** error is encountered, then the IO error code is returned to the caller.
+** This routine clears the needSync field of every page current held in
+** memory.
*/
static int syncJournal(Pager *pPager){
+ 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 ){
assert( !pPager->tempFile );
if( pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
- int rc; /* Return code */
- const int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
- assert( isOpen(pPager->jfd) );
+ int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+ assert( pPager->journalOpen );
if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
- /* Variable iNRecOffset is set to the offset in the journal file
- ** of the nRec field of the most recently written journal header.
- ** This field will be updated following the xSync() operation
- ** on the journal file. */
- i64 iNRecOffset = pPager->journalHdr + sizeof(aJournalMagic);
+ i64 jrnlOff = journalHdrOffset(pPager);
+ u8 zMagic[8];
/* This block deals with an obscure problem. If the last connection
** that wrote to this database was operating in persistent-journal
** To work around this, if the journal file does appear to contain
** a valid header following Pager.journalOff, then write a 0x00
** byte to the start of it to prevent it from being recognized.
- **
- ** Variable iNextHdrOffset is set to the offset at which this
- ** problematic header will occur, if it exists. aMagic is used
- ** as a temporary buffer to inspect the first couple of bytes of
- ** the potential journal header.
*/
- i64 iNextHdrOffset = journalHdrOffset(pPager);
- u8 aMagic[8];
- rc = sqlite3OsRead(pPager->jfd, aMagic, 8, iNextHdrOffset);
- if( rc==SQLITE_OK && 0==memcmp(aMagic, aJournalMagic, 8) ){
+ rc = sqlite3OsRead(pPager->jfd, zMagic, 8, jrnlOff);
+ if( rc==SQLITE_OK && 0==memcmp(zMagic, aJournalMagic, 8) ){
static const u8 zerobyte = 0;
- rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, iNextHdrOffset);
+ rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, jrnlOff);
}
if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
return rc;
PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
IOTRACE(("JSYNC %p\n", pPager))
rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags);
- if( rc!=SQLITE_OK ) return rc;
+ if( rc!=0 ) return rc;
}
- IOTRACE(("JHDR %p %lld %d\n", pPager, iNRecOffset, 4));
- rc = write32bits(pPager->jfd, iNRecOffset, pPager->nRec);
- if( rc!=SQLITE_OK ) 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) ){
PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags|
(pPager->sync_flags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
);
- if( rc!=SQLITE_OK ) return rc;
+ if( rc!=0 ) return rc;
}
+ pPager->journalStarted = 1;
}
+ pPager->needSync = 0;
- /* The journal file was just successfully synced. Set Pager.needSync
- ** to zero and clear the PGHDR_NEED_SYNC flag on all pagess.
+ /* Erase the needSync flag from every page.
*/
- pPager->needSync = 0;
- pPager->journalStarted = 1;
sqlite3PcacheClearSyncFlags(pPager->pPCache);
}
- return SQLITE_OK;
+ return rc;
}
/*
-** The argument is the first in a linked list of dirty pages connected
-** by the PgHdr.pDirty pointer. This function writes each one of the
-** in-memory pages in the list to the database file. The argument may
-** be NULL, representing an empty list. In this case this function is
-** a no-op.
-**
-** The pager must hold at least a RESERVED lock when this function
-** is called. Before writing anything to the database file, this lock
-** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
-** SQLITE_BUSY is returned and no data is written to the database file.
-**
-** If the pager is a temp-file pager and the actual file-system file
-** is not yet open, it is created and opened before any data is
-** written out.
-**
-** Once the lock has been upgraded and, if necessary, the file opened,
-** the pages are written out to the database file in list order. Writing
-** a page is skipped if it meets either of the following criteria:
-**
-** * The page number is greater than Pager.dbSize, or
-** * The PGHDR_DONT_WRITE flag is set on the page.
-**
-** If writing out a page causes the database file to grow, Pager.dbFileSize
-** is updated accordingly. If page 1 is written out, then the value cached
-** in Pager.dbFileVers[] is updated to match the new value stored in
-** the database file.
-**
-** If everything is successful, SQLITE_OK is returned. If an IO error
-** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
-** be obtained, SQLITE_BUSY is returned.
+** Given a list of pages (connected by the PgHdr.pDirty pointer) write
+** every one of those pages out to the database file. No calls are made
+** to the page-cache to mark the pages as clean. It is the responsibility
+** of the caller to use PcacheCleanAll() or PcacheMakeClean() to mark
+** the pages as clean.
*/
static int pager_write_pagelist(PgHdr *pList){
- Pager *pPager; /* Pager object */
- int rc; /* Return code */
+ Pager *pPager;
+ int rc;
if( pList==0 ) return SQLITE_OK;
pPager = pList->pPager;
/* 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
- ** call is a no-op.
+ ** 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
** EXCLUSIVE, it means the database file has been changed and any rollback
** will require a journal playback.
*/
- assert( pPager->state>=PAGER_RESERVED );
rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
-
- /* If the file is a temp-file has not yet been opened, open it now. It
- ** is not possible for rc to be other than SQLITE_OK if this branch
- ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
- */
- if( !isOpen(pPager->fd) ){
- assert( pPager->tempFile && rc==SQLITE_OK );
- rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
+ if( rc!=SQLITE_OK ){
+ return rc;
}
- while( rc==SQLITE_OK && pList ){
- Pgno pgno = pList->pgno;
+ 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 sqlite3PagerTruncateImage() was called to
** make the file smaller (presumably by auto-vacuum code). Do not write
** any such pages to the file.
- **
- ** Also, do not write out any page that has the PGHDR_DONT_WRITE flag
- ** set (set by sqlite3PagerDontWrite()).
*/
- if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
- i64 offset = (pgno-1)*(i64)pPager->pageSize; /* Offset to write */
- char *pData = CODEC2(pPager, pList->pData, pgno, 6); /* Data to write */
+ if( pList->pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
+ i64 offset = (pList->pgno-1)*(i64)pPager->pageSize;
+ char *pData = CODEC2(pPager, pList->pData, pList->pgno, 6);
- /* Write out the page data. */
+ PAGERTRACE(("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);
-
- /* If page 1 was just written, update Pager.dbFileVers to match
- ** the value now stored in the database file. If writing this
- ** page caused the database file to grow, update dbFileSize.
- */
- if( pgno==1 ){
+ PAGER_INCR(sqlite3_pager_writedb_count);
+ PAGER_INCR(pPager->nWrite);
+ if( pList->pgno==1 ){
memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
}
- if( pgno>pPager->dbFileSize ){
- pPager->dbFileSize = pgno;
+ if( pList->pgno>pPager->dbFileSize ){
+ pPager->dbFileSize = pList->pgno;
}
-
- PAGERTRACE(("STORE %d page %d hash(%08x)\n",
- PAGERID(pPager), pgno, pager_pagehash(pList)));
- IOTRACE(("PGOUT %p %d\n", pPager, pgno));
- PAGER_INCR(sqlite3_pager_writedb_count);
- PAGER_INCR(pPager->nWrite);
- }else{
- PAGERTRACE(("NOSTORE %d page %d\n", PAGERID(pPager), pgno));
}
+#ifndef NDEBUG
+ else{
+ PAGERTRACE(("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 rc;
+ return SQLITE_OK;
}
/*
-** Append a record of the current state of page pPg to the sub-journal.
-** It is the callers responsibility to use subjRequiresPage() to check
-** that it is really required before calling this function.
-**
-** If successful, set the bit corresponding to pPg->pgno in the bitvecs
-** for all open savepoints before returning.
-**
-** This function returns SQLITE_OK if everything is successful, an IO
-** error code if the attempt to write to the sub-journal fails, or
-** SQLITE_NOMEM if a malloc fails while setting a bit in a savepoint
-** bitvec.
+** Add the page to the sub-journal. It is the callers responsibility to
+** use subjRequiresPage() to check that it is really required before
+** calling this function.
*/
static int subjournalPage(PgHdr *pPg){
int rc;
void *pData = pPg->pData;
Pager *pPager = pPg->pPager;
- i64 offset = pPager->nSubRec*(4+pPager->pageSize);
+ i64 offset = pPager->stmtNRec*(4+pPager->pageSize);
char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7);
PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
}
if( rc==SQLITE_OK ){
- pPager->nSubRec++;
+ pPager->stmtNRec++;
assert( pPager->nSavepoint>0 );
rc = addToSavepointBitvecs(pPager, pPg->pgno);
- testcase( rc!=SQLITE_OK );
}
return rc;
}
/*
** This function is called by the pcache layer when it has reached some
-** soft memory limit. The first argument is a pointer to a Pager object
-** (cast as a void*). The pager is always 'purgeable' (not an in-memory
-** database). The second argument is a reference to a page that is
-** currently dirty but has no outstanding references. The page
-** is always associated with the Pager object passed as the first
-** argument.
-**
-** The job of this function is to make pPg clean by writing its contents
-** out to the database file, if possible. This may involve syncing the
-** journal file.
-**
-** If successful, sqlite3PcacheMakeClean() is called on the page and
-** SQLITE_OK returned. If an IO error occurs while trying to make the
-** page clean, the IO error code is returned. If the page cannot be
-** made clean for some other reason, but no error occurs, then SQLITE_OK
-** is returned by sqlite3PcacheMakeClean() is not called.
+** soft memory limit. The argument is a pointer to a purgeable Pager
+** object. This function attempts to make a single dirty page that has no
+** outstanding references (if one exists) clean so that it can be recycled
+** by the pcache layer.
*/
static int pagerStress(void *p, PgHdr *pPg){
Pager *pPager = (Pager *)p;
int rc = SQLITE_OK;
- assert( pPg->pPager==pPager );
- assert( pPg->flags&PGHDR_DIRTY );
-
- /* The doNotSync flag is set by the sqlite3PagerWrite() function while it
- ** is journalling a set of two or more database pages that are stored
- ** on the same disk sector. Syncing the journal is not allowed while
- ** this is happening as it is important that all members of such a
- ** set of pages are synced to disk together. So, if the page this function
- ** is trying to make clean will require a journal sync and the doNotSync
- ** flag is set, return without doing anything. The pcache layer will
- ** just have to go ahead and allocate a new page buffer instead of
- ** reusing pPg.
- **
- ** Similarly, if the pager has already entered the error state, do not
- ** try to write the contents of pPg to disk.
- */
- if( pPager->errCode || (pPager->doNotSync && pPg->flags&PGHDR_NEED_SYNC) ){
+ if( pPager->doNotSync ){
return SQLITE_OK;
}
- /* Sync the journal file if required. */
- if( pPg->flags&PGHDR_NEED_SYNC ){
- rc = syncJournal(pPager);
- if( rc==SQLITE_OK && pPager->fullSync &&
- !(pPager->journalMode==PAGER_JOURNALMODE_MEMORY) &&
- !(sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
- ){
- pPager->nRec = 0;
- rc = writeJournalHdr(pPager);
+ assert( pPg->flags&PGHDR_DIRTY );
+ if( pPager->errCode==SQLITE_OK ){
+ if( pPg->flags&PGHDR_NEED_SYNC ){
+ rc = syncJournal(pPager);
+ if( rc==SQLITE_OK && pPager->fullSync &&
+ !(pPager->journalMode==PAGER_JOURNALMODE_MEMORY) &&
+ !(sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
+ ){
+ pPager->nRec = 0;
+ rc = writeJournalHdr(pPager);
+ }
+ }
+ if( rc==SQLITE_OK ){
+ pPg->pDirty = 0;
+ if( pPg->pgno>pPager->dbSize && subjRequiresPage(pPg) ){
+ rc = subjournalPage(pPg);
+ }
+ if( rc==SQLITE_OK ){
+ rc = pager_write_pagelist(pPg);
+ }
+ }
+ if( rc!=SQLITE_OK ){
+ pager_error(pPager, rc);
}
}
- /* If the page number of this page is larger than the current size of
- ** the database image, it may need to be written to the sub-journal.
- ** This is because the call to pager_write_pagelist() below will not
- ** actually write data to the file in this case.
- **
- ** Consider the following sequence of events:
- **
- ** BEGIN;
- ** <journal page X>
- ** <modify page X>
- ** SAVEPOINT sp;
- ** <shrink database file to Y pages>
- ** pagerStress(page X)
- ** ROLLBACK TO sp;
- **
- ** If (X>Y), then when pagerStress is called page X will not be written
- ** out to the database file, but will be dropped from the cache. Then,
- ** following the "ROLLBACK TO sp" statement, reading page X will read
- ** data from the database file. This will be the copy of page X as it
- ** was when the transaction started, not as it was when "SAVEPOINT sp"
- ** was executed.
- **
- ** The solution is to write the current data for page X into the
- ** sub-journal file now (if it is not already there), so that it will
- ** be restored to its current value when the "ROLLBACK TO sp" is
- ** executed.
- */
- if( rc==SQLITE_OK && pPg->pgno>pPager->dbSize && subjRequiresPage(pPg) ){
- rc = subjournalPage(pPg);
- }
-
- /* Write the contents of the page out to the database file. */
- if( rc==SQLITE_OK ){
- pPg->pDirty = 0;
- rc = pager_write_pagelist(pPg);
- }
-
- /* Mark the page as clean. */
if( rc==SQLITE_OK ){
PAGERTRACE(("STRESS %d page %d\n", PAGERID(pPager), pPg->pgno));
sqlite3PcacheMakeClean(pPg);
}
-
- return pager_error(pPager, rc);
+ return rc;
}
/*
-** This function is called after transitioning from PAGER_UNLOCK to
-** PAGER_SHARED state. It tests if there is a hot journal present in
-** the file-system for the given pager. A hot journal is one that
-** needs to be played back. According to this function, a hot-journal
-** file exists if the following three criteria are met:
-**
-** * The journal file exists in the file system, and
-** * No process holds a RESERVED or greater lock on the database file, and
-** * The database file itself is greater than 0 bytes in size.
+** 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. In this case the journal file is
-** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
-** is returned.
+** 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 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.
-**
-** If a hot-journal file is found to exist, *pExists is set to 1 and
-** SQLITE_OK returned. If no hot-journal file is present, *pExists is
-** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
-** to determine whether or not a hot-journal file exists, the IO error
-** code is returned and the value of *pExists is undefined.
*/
static int hasHotJournal(Pager *pPager, int *pExists){
- sqlite3_vfs * const pVfs = pPager->pVfs;
- int rc; /* Return code */
- int exists = 0; /* True if a journal file is present */
- int locked = 0; /* True if some process holds a RESERVED lock */
-
+ sqlite3_vfs *pVfs = pPager->pVfs;
+ int rc = SQLITE_OK;
+ int exists = 0;
+ int locked = 0;
assert( pPager!=0 );
assert( pPager->useJournal );
- assert( isOpen(pPager->fd) );
-
+ assert( pPager->fd->pMethods );
*pExists = 0;
rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
if( rc==SQLITE_OK && exists ){
rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
- if( rc==SQLITE_OK && !locked ){
- int nPage;
- rc = sqlite3PagerPagecount(pPager, &nPage);
- if( rc==SQLITE_OK ){
- if( nPage==0 ){
- sqlite3OsDelete(pVfs, pPager->zJournal, 0);
- }else{
- *pExists = 1;
- }
+ }
+ 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;
}
}
}
}
/*
-** Read the content for page pPg out of the database file and into
-** pPg->pData. A shared lock or greater must be held on the database
-** file before this function is called.
-**
-** If page 1 is read, then the value of Pager.dbFileVers[] is set to
-** the value read from the database file.
-**
-** If an IO error occurs, then the IO error is returned to the caller.
-** Otherwise, SQLITE_OK is returned.
+** Read the content of page pPg out of the database file.
*/
-static int readDbPage(PgHdr *pPg){
- Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
- Pgno pgno = pPg->pgno; /* Page number to read */
- int rc; /* Return code */
- i64 iOffset; /* Byte offset of file to read from */
-
- assert( pPager->state>=PAGER_SHARED && !MEMDB );
-
- if( !isOpen(pPager->fd) ){
- assert( pPager->tempFile );
+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;
}
- iOffset = (pgno-1)*(i64)pPager->pageSize;
- rc = sqlite3OsRead(pPager->fd, pPg->pData, pPager->pageSize, iOffset);
- if( pgno==1 ){
- u8 *dbFileVers = &((u8*)pPg->pData)[24];
- memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
- }
- CODEC1(pPager, pPg->pData, pgno, 3);
-
+ offset = (pgno-1)*(i64)pPager->pageSize;
+ rc = sqlite3OsRead(pPager->fd, pPg->pData, 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*)pPg->pData)[24],
+ sizeof(pPager->dbFileVers));
+ }
+ CODEC1(pPager, pPg->pData, pPg->pgno, 3);
PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
- PAGERID(pPager), pgno, pager_pagehash(pPg)));
-
+ 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
** is performed immediately.
*/
static int pagerSharedLock(Pager *pPager){
- int rc = SQLITE_OK; /* Return code */
- int isErrorReset = 0; /* True if recovering from error state */
+ 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, this is a chance to clear
+ ** 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
&& sqlite3PcacheRefCount(pPager->pPCache)==0 && pPager->errCode
){
- if( isOpen(pPager->jfd) ){
+ if( pPager->journalOpen ){
isErrorReset = 1;
}
pPager->errCode = SQLITE_OK;
}
if( pPager->state==PAGER_UNLOCK || isErrorReset ){
- sqlite3_vfs * const pVfs = pPager->pVfs;
+ sqlite3_vfs *pVfs = pPager->pVfs;
int isHotJournal = 0;
assert( !MEMDB );
assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
** 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 the
- ** hot-journal back.
+ ** database is safe to read while this process is still rolling it
+ ** back.
**
- ** Because the intermediate RESERVED lock is not requested, any
- ** other process attempting to access the database file will get to
- ** this point in the code and fail to obtain its own EXCLUSIVE lock
- ** on the database file.
+ ** 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->state<EXCLUSIVE_LOCK ){
rc = sqlite3OsLock(pPager->fd, EXCLUSIVE_LOCK);
** OsTruncate() call used in exclusive-access mode also requires
** a read/write file handle.
*/
- if( !isOpen(pPager->jfd) ){
+ if( !isErrorReset && pPager->journalOpen==0 ){
int res;
rc = sqlite3OsAccess(pVfs,pPager->zJournal,SQLITE_ACCESS_EXISTS,&res);
if( rc==SQLITE_OK ){
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 || isOpen(pPager->jfd) );
+ assert( rc!=SQLITE_OK || pPager->jfd->pMethods );
if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
rc = SQLITE_CANTOPEN;
sqlite3OsClose(pPager->jfd);
if( rc!=SQLITE_OK ){
goto failed;
}
-
- /* TODO: Why are these cleared here? Is it necessary? */
+ pPager->journalOpen = 1;
pPager->journalStarted = 0;
pPager->journalOff = 0;
pPager->setMaster = 0;
rc = pager_error(pPager, rc);
goto failed;
}
- assert( (pPager->state==PAGER_SHARED)
- || (pPager->exclusiveMode && pPager->state>PAGER_SHARED)
+ assert(pPager->state==PAGER_SHARED ||
+ (pPager->exclusiveMode && pPager->state>PAGER_SHARED)
);
}
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->flags&PGHDR_NEED_READ ){
+ int rc = readDbPage(pPg->pPager, pPg, pPg->pgno);
+ if( rc==SQLITE_OK ){
+ pPg->flags &= ~PGHDR_NEED_READ;
+ }else{
+ return rc;
+ }
+ }
+ return SQLITE_OK;
+}
+
/*
** If the reference count has reached zero, and the pager is not in the
** middle of a write transaction or opened in exclusive mode, unlock it.
**
** 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. This occurs in two seperate scenarios:
-**
-** a) When reading a free-list leaf page from the database, and
-**
-** b) When a savepoint is being rolled back and we need to load
-** a new page into the cache to populate with the data read
-** from the savepoint journal.
-**
-** If noContent is true, then the data returned is zeroed instead of
-** being read from the database. Additionally, the bits corresponding
-** to pgno in Pager.pInJournal (bitvec of pages already written to the
-** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
-** savepoints are set. This means if the page is made writable at any
-** point in the future, using a call to sqlite3PagerWrite(), its contents
-** will not be journaled. This saves IO.
+** 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.
*/
int sqlite3PagerAcquire(
Pager *pPager, /* The pager open on the database file */
}
memset(pPg->pData, 0, pPager->pageSize);
if( noContent ){
- /* Failure to set the bits in the InJournal bit-vectors is benign.
- ** It merely means that we might do some extra work to journal a
- ** page that does not need to be journaled. Nevertheless, be sure
- ** to test the case where a malloc error occurs while trying to set
- ** a bit in a bit vector.
- */
- sqlite3BeginBenignMalloc();
- TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
- testcase( rc==SQLITE_NOMEM );
- TESTONLY( rc = ) addToSavepointBitvecs(pPager, pPg->pgno);
- testcase( rc==SQLITE_NOMEM );
- sqlite3EndBenignMalloc();
+ pPg->flags |= PGHDR_NEED_READ;
}
IOTRACE(("ZERO %p %d\n", pPager, pgno));
}else{
- assert( pPg->pPager==pPager && pPg->pgno==pgno );
- rc = readDbPage(pPg);
+ rc = readDbPage(pPager, pPg, pgno);
if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
+ /* sqlite3PagerUnref(pPg); */
pagerDropPage(pPg);
return rc;
}
#endif
}else{
/* The requested page is in the page cache. */
+ assert(sqlite3PcacheRefCount(pPager->pPCache)>0 || pgno==1);
PAGER_INCR(pPager->nHit);
+ if( !noContent ){
+ rc = pager_get_content(pPg);
+ if( rc ){
+ sqlite3PagerUnref(pPg);
+ return rc;
+ }
+ }
}
*ppPage = pPg;
** are released, a rollback occurs and the lock on the database is
** removed.
*/
-void sqlite3PagerUnref(DbPage *pPg){
+int sqlite3PagerUnref(DbPage *pPg){
if( pPg ){
Pager *pPager = pPg->pPager;
sqlite3PcacheRelease(pPg);
pagerUnlockIfUnused(pPager);
}
+ return SQLITE_OK;
}
/*
*/
static int openSubJournal(Pager *pPager){
int rc = SQLITE_OK;
- if( isOpen(pPager->jfd) && !isOpen(pPager->sjfd) ){
+ if( pPager->journalOpen && !pPager->sjfd->pMethods ){
if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
sqlite3MemJournalOpen(pPager->sjfd);
}else{
- rc = pagerOpentemp(pPager, pPager->sjfd, SQLITE_OPEN_SUBJOURNAL);
+ rc = sqlite3PagerOpentemp(pPager, pPager->sjfd, SQLITE_OPEN_SUBJOURNAL);
}
}
return rc;
goto failed_to_open_journal;
}
- if( !isOpen(pPager->jfd) ){
+ if( pPager->journalOpen==0 ){
if( pPager->tempFile ){
flags |= (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL);
}else{
rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
#endif
}
- assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
+ assert( rc!=SQLITE_OK || pPager->jfd->pMethods );
pPager->journalOff = 0;
pPager->setMaster = 0;
pPager->journalHdr = 0;
goto failed_to_open_journal;
}
}
+ pPager->journalOpen = 1;
pPager->journalStarted = 0;
pPager->needSync = 0;
pPager->nRec = 0;
if( rc!=SQLITE_OK ){
return rc;
}
+ pPager->dirtyCache = 0;
PAGERTRACE(("TRANSACTION %d\n", PAGERID(pPager)));
if( pPager->useJournal && !pPager->tempFile
&& pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
rc = pager_open_journal(pPager);
}
- }else if( isOpen(pPager->jfd) && pPager->journalOff==0 ){
+ }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
rc = writeJournalHdr(pPager);
}
}
- assert( !isOpen(pPager->jfd) || pPager->journalOff>0 || rc!=SQLITE_OK );
+ assert( !pPager->journalOpen || pPager->journalOff>0 || rc!=SQLITE_OK );
return rc;
}
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.
*/
sqlite3PcacheMakeDirty(pPg);
if( pageInJournal(pPg) && !subjRequiresPage(pPg) ){
+ pPager->dirtyCache = 1;
pPager->dbModified = 1;
}else{
return rc;
}
assert( pPager->state>=PAGER_RESERVED );
- if( !isOpen(pPager->jfd) && pPager->useJournal
+ 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( !pageInJournal(pPg) && isOpen(pPager->jfd) ){
+ if( !pageInJournal(pPg) && pPager->journalOpen ){
if( pPg->pgno<=pPager->dbOrigSize ){
u32 cksum;
char *pData2;
** 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 bit corresponding to pDbPage in
+** the Pager.pAlwaysRollback bitvec. 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(PgHdr *pPg){
+int sqlite3PagerDontWrite(DbPage *pDbPage){
+ PgHdr *pPg = pDbPage;
Pager *pPager = pPg->pPager;
- if( (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
- PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
- IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
- pPg->flags |= PGHDR_DONT_WRITE;
+ int rc;
+
+ if( pPg->pgno>pPager->dbOrigSize ){
+ return SQLITE_OK;
+ }
+ if( pPager->pAlwaysRollback==0 ){
+ assert( pPager->pInJournal );
+ pPager->pAlwaysRollback = sqlite3BitvecCreate(pPager->dbOrigSize);
+ if( !pPager->pAlwaysRollback ){
+ return SQLITE_NOMEM;
+ }
+ }
+ rc = sqlite3BitvecSet(pPager->pAlwaysRollback, pPg->pgno);
+
+ if( rc==SQLITE_OK && (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
+ assert( pPager->state>=PAGER_SHARED );
+ if( pPager->dbSize==pPg->pgno && pPager->dbOrigSize<pPager->dbSize ){
+ /* 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{
+ PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
+ IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
+ pPg->flags |= PGHDR_DONT_WRITE;
#ifdef SQLITE_CHECK_PAGES
- pPg->pageHash = pager_pagehash(pPg);
+ pPg->pageHash = pager_pagehash(pPg);
#endif
+ }
}
+ return rc;
+}
+
+/*
+** 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;
+ TESTONLY( int rc; ) /* Return value from sqlite3BitvecSet() */
+
+ assert( pPager->state>=PAGER_RESERVED );
+
+ /* If the journal file is not open, or DontWrite() has been called on
+ ** this page (DontWrite() sets the Pager.pAlwaysRollback bit), then this
+ ** function is a no-op.
+ */
+ if( pPager->journalOpen==0
+ || sqlite3BitvecTest(pPager->pAlwaysRollback, pPg->pgno)
+ || pPg->pgno>pPager->dbOrigSize
+ ){
+ return;
+ }
+
+#ifdef SQLITE_SECURE_DELETE
+ if( sqlite3BitvecTest(pPager->pInJournal, pPg->pgno)!=0
+ || pPg->pgno>pPager->dbOrigSize ){
+ 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->dbOrigSize ); */
+
+ assert( pPager->pInJournal!=0 );
+ pPg->flags &= ~PGHDR_NEED_READ;
+
+ /* Failure to set the bits in the InJournal bit-vectors is benign.
+ ** It merely means that we might do some extra work to journal a page
+ ** that does not need to be journaled. Nevertheless, be sure to test the
+ ** case where a malloc error occurs while trying to set a bit in a
+ ** bit vector.
+ */
+ sqlite3BeginBenignMalloc();
+ TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
+ testcase( rc==SQLITE_NOMEM );
+ TESTONLY( rc = ) addToSavepointBitvecs(pPager, pPg->pgno);
+ testcase( rc==SQLITE_NOMEM );
+ sqlite3EndBenignMalloc();
+
+
+ PAGERTRACE(("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager)));
+ IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno))
}
+
/*
** This routine is called to increment the database file change-counter,
** stored at byte 24 of the pager file.
put32bits(((char*)pPgHdr->pData)+24, change_counter);
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
- if( isDirect && isOpen(pPager->fd) ){
+ if( isDirect && pPager->fd->pMethods ){
const void *zBuf = pPgHdr->pData;
assert( pPager->dbFileSize>0 );
rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
*/
if( pPager->dbModified==0 &&
(pPager->journalMode!=PAGER_JOURNALMODE_DELETE ||
- pPager->exclusiveMode) ){
- assert( pPager->dbModified==0 || !isOpen(pPager->jfd) );
+ pPager->exclusiveMode!=0) ){
+ assert( pPager->dirtyCache==0 || pPager->journalOpen==0 );
return SQLITE_OK;
}
/* 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->dbModified ){
+ if( pPager->state!=PAGER_SYNCED && !MEMDB && pPager->dirtyCache ){
PgHdr *pPg;
#ifdef SQLITE_ENABLE_ATOMIC_WRITE
pPg = sqlite3PcacheDirtyList(pPager->pPCache);
useAtomicWrite = (
!zMaster &&
- isOpen(pPager->jfd) &&
+ pPager->journalOpen &&
pPager->journalOff==jrnlBufferSize(pPager) &&
pPager->dbSize>=pPager->dbFileSize &&
(pPg==0 || pPg->pDirty==0)
);
- assert( isOpen(pPager->jfd) || pPager->journalMode==PAGER_JOURNALMODE_OFF );
+ assert( pPager->journalOpen || pPager->journalMode==PAGER_JOURNALMODE_OFF );
if( useAtomicWrite ){
/* Update the nRec field in the journal file. */
int offset = pPager->journalHdr + sizeof(aJournalMagic);
}
sqlite3PcacheCleanAll(pPager->pPCache);
- if( pPager->dbSize!=pPager->dbFileSize ){
- Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
+ if( pPager->dbSize<pPager->dbFileSize ){
assert( pPager->state>=PAGER_EXCLUSIVE );
- rc = pager_truncate(pPager, nNew);
+ rc = pager_truncate(pPager, pPager->dbSize);
if( rc!=SQLITE_OK ) goto sync_exit;
}
if( pPager->dbModified==0 &&
(pPager->journalMode!=PAGER_JOURNALMODE_DELETE ||
pPager->exclusiveMode!=0) ){
- assert( pPager->dbModified==0 || isOpen(pPager->jfd)==0 );
+ assert( pPager->dirtyCache==0 || pPager->journalOpen==0 );
return SQLITE_OK;
}
PAGERTRACE(("COMMIT %d\n", PAGERID(pPager)));
- assert( pPager->state==PAGER_SYNCED || MEMDB || !pPager->dbModified );
+ assert( pPager->state==PAGER_SYNCED || MEMDB || !pPager->dirtyCache );
rc = pager_end_transaction(pPager, pPager->setMaster);
rc = pager_error(pPager, rc);
return rc;
int sqlite3PagerRollback(Pager *pPager){
int rc = SQLITE_OK;
PAGERTRACE(("ROLLBACK %d\n", PAGERID(pPager)));
- if( !pPager->dbModified || !isOpen(pPager->jfd) ){
+ if( !pPager->dirtyCache || !pPager->journalOpen ){
rc = pager_end_transaction(pPager, pPager->setMaster);
}else if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
if( pPager->state>=PAGER_EXCLUSIVE ){
/* Either there is no active journal or the sub-journal is open or
** the journal is always stored in memory */
- assert( pPager->nSavepoint==0 || isOpen(pPager->sjfd) ||
+ assert( pPager->nSavepoint==0 || pPager->sjfd->pMethods ||
pPager->journalMode==PAGER_JOURNALMODE_MEMORY );
/* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
for(/* no-op */; ii<nSavepoint; ii++){
assert( pPager->dbSizeValid );
aNew[ii].nOrig = pPager->dbSize;
- if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
+ if( pPager->journalOpen && pPager->journalOff>0 ){
aNew[ii].iOffset = pPager->journalOff;
}else{
aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
}
- aNew[ii].iSubRec = pPager->nSubRec;
+ aNew[ii].iSubRec = pPager->stmtNRec;
aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
if( !aNew[ii].pInSavepoint ){
return SQLITE_NOMEM;
}
pPager->nSavepoint = nNew;
- if( op==SAVEPOINT_ROLLBACK && isOpen(pPager->jfd) ){
+ if( op==SAVEPOINT_ROLLBACK && pPager->jfd->pMethods ){
PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
rc = pagerPlaybackSavepoint(pPager, pSavepoint);
assert(rc!=SQLITE_DONE);
/* If this is a release of the outermost savepoint, truncate
** the sub-journal. */
- if( nNew==0 && op==SAVEPOINT_RELEASE && isOpen(pPager->sjfd) ){
+ if( nNew==0 && op==SAVEPOINT_RELEASE && pPager->sjfd->pMethods ){
assert( rc==SQLITE_OK );
rc = sqlite3OsTruncate(pPager->sjfd, 0);
- pPager->nSubRec = 0;
+ pPager->stmtNRec = 0;
}
}
return rc;
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.
*/
PAGERID(pPager), pPg->pgno, (pPg->flags&PGHDR_NEED_SYNC)?1:0, 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.
**
}
sqlite3PcacheMakeDirty(pPg);
+ pPager->dirtyCache = 1;
pPager->dbModified = 1;
if( needSyncPgno ){
** If the parameter is not _QUERY, then the journal-mode is set to the
** value specified.
**
-** The returned indicate the current (possibly updated) journal-mode.
+** The returned indicate the current (possibly updated)
+** journal-mode.
*/
int sqlite3PagerJournalMode(Pager *pPager, int eMode){
if( !MEMDB ){
projects / thirdparty / sqlite.git / commitdiff
