diff options
Diffstat (limited to 'ext/sqlite/libsqlite/src/pager.c')
| -rw-r--r-- | ext/sqlite/libsqlite/src/pager.c | 2220 |
1 files changed, 0 insertions, 2220 deletions
diff --git a/ext/sqlite/libsqlite/src/pager.c b/ext/sqlite/libsqlite/src/pager.c deleted file mode 100644 index 278a99f604..0000000000 --- a/ext/sqlite/libsqlite/src/pager.c +++ /dev/null @@ -1,2220 +0,0 @@ -/* -** 2001 September 15 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** May you find forgiveness for yourself and forgive others. -** May you share freely, never taking more than you give. -** -************************************************************************* -** This is the implementation of the page cache subsystem or "pager". -** -** The pager is used to access a database disk file. It implements -** atomic commit and rollback through the use of a journal file that -** is separate from the database file. The pager also implements file -** locking to prevent two processes from writing the same database -** file simultaneously, or one process from reading the database while -** another is writing. -** -** @(#) $Id$ -*/ -#include "os.h" /* Must be first to enable large file support */ -#include "sqliteInt.h" -#include "pager.h" -#include <assert.h> -#include <string.h> - -/* -** Macros for troubleshooting. Normally turned off -*/ -#if 0 -static Pager *mainPager = 0; -#define SET_PAGER(X) if( mainPager==0 ) mainPager = (X) -#define CLR_PAGER(X) if( mainPager==(X) ) mainPager = 0 -#define TRACE1(X) if( pPager==mainPager ) fprintf(stderr,X) -#define TRACE2(X,Y) if( pPager==mainPager ) fprintf(stderr,X,Y) -#define TRACE3(X,Y,Z) if( pPager==mainPager ) fprintf(stderr,X,Y,Z) -#else -#define SET_PAGER(X) -#define CLR_PAGER(X) -#define TRACE1(X) -#define TRACE2(X,Y) -#define TRACE3(X,Y,Z) -#endif - - -/* -** The page cache as a whole is always in one of the following -** states: -** -** SQLITE_UNLOCK The page cache is not currently reading or -** writing the database file. There is no -** data held in memory. This is the initial -** state. -** -** SQLITE_READLOCK The page cache is reading the database. -** Writing is not permitted. There can be -** multiple readers accessing the same database -** file at the same time. -** -** SQLITE_WRITELOCK The page cache is writing the database. -** Access is exclusive. No other processes or -** threads can be reading or writing while one -** process is writing. -** -** The page cache comes up in SQLITE_UNLOCK. The first time a -** sqlite_page_get() occurs, the state transitions to SQLITE_READLOCK. -** After all pages have been released using sqlite_page_unref(), -** the state transitions back to SQLITE_UNLOCK. The first time -** that sqlite_page_write() is called, the state transitions to -** SQLITE_WRITELOCK. (Note that sqlite_page_write() can only be -** called on an outstanding page which means that the pager must -** be in SQLITE_READLOCK before it transitions to SQLITE_WRITELOCK.) -** The sqlite_page_rollback() and sqlite_page_commit() functions -** transition the state from SQLITE_WRITELOCK back to SQLITE_READLOCK. -*/ -#define SQLITE_UNLOCK 0 -#define SQLITE_READLOCK 1 -#define SQLITE_WRITELOCK 2 - - -/* -** Each in-memory image of a page begins with the following header. -** This header is only visible to this pager module. The client -** code that calls pager sees only the data that follows the header. -** -** Client code should call sqlitepager_write() on a page prior to making -** any modifications to that page. The first time sqlitepager_write() -** is called, the original page contents are written into the rollback -** journal and PgHdr.inJournal and PgHdr.needSync are set. Later, once -** the journal page has made it onto the disk surface, PgHdr.needSync -** is cleared. The modified page cannot be written back into the original -** database file until the journal pages has been synced to disk and the -** PgHdr.needSync has been cleared. -** -** The PgHdr.dirty flag is set when sqlitepager_write() is called and -** is cleared again when the page content is written back to the original -** database file. -*/ -typedef struct PgHdr PgHdr; -struct PgHdr { - Pager *pPager; /* The pager to which this page belongs */ - Pgno pgno; /* The page number for this page */ - PgHdr *pNextHash, *pPrevHash; /* Hash collision chain for PgHdr.pgno */ - int nRef; /* Number of users of this page */ - PgHdr *pNextFree, *pPrevFree; /* Freelist of pages where nRef==0 */ - PgHdr *pNextAll, *pPrevAll; /* A list of all pages */ - PgHdr *pNextCkpt, *pPrevCkpt; /* List of pages in the checkpoint journal */ - u8 inJournal; /* TRUE if has been written to journal */ - u8 inCkpt; /* TRUE if written to the checkpoint journal */ - u8 dirty; /* TRUE if we need to write back changes */ - u8 needSync; /* Sync journal before writing this page */ - u8 alwaysRollback; /* Disable dont_rollback() for this page */ - PgHdr *pDirty; /* Dirty pages sorted by PgHdr.pgno */ - /* SQLITE_PAGE_SIZE bytes of page data follow this header */ - /* Pager.nExtra bytes of local data follow the page data */ -}; - - -/* -** A macro used for invoking the codec if there is one -*/ -#ifdef SQLITE_HAS_CODEC -# define CODEC(P,D,N,X) if( P->xCodec ){ P->xCodec(P->pCodecArg,D,N,X); } -#else -# define CODEC(P,D,N,X) -#endif - -/* -** Convert a pointer to a PgHdr into a pointer to its data -** and back again. -*/ -#define PGHDR_TO_DATA(P) ((void*)(&(P)[1])) -#define DATA_TO_PGHDR(D) (&((PgHdr*)(D))[-1]) -#define PGHDR_TO_EXTRA(P) ((void*)&((char*)(&(P)[1]))[SQLITE_PAGE_SIZE]) - -/* -** How big to make the hash table used for locating in-memory pages -** by page number. -*/ -#define N_PG_HASH 2048 - -/* -** Hash a page number -*/ -#define pager_hash(PN) ((PN)&(N_PG_HASH-1)) - -/* -** A open page cache is an instance of the following structure. -*/ -struct Pager { - char *zFilename; /* Name of the database file */ - char *zJournal; /* Name of the journal file */ - char *zDirectory; /* Directory hold database and journal files */ - OsFile fd, jfd; /* File descriptors for database and journal */ - OsFile cpfd; /* File descriptor for the checkpoint journal */ - int dbSize; /* Number of pages in the file */ - int origDbSize; /* dbSize before the current change */ - int ckptSize; /* Size of database (in pages) at ckpt_begin() */ - off_t ckptJSize; /* Size of journal at ckpt_begin() */ - int nRec; /* Number of pages written to the journal */ - u32 cksumInit; /* Quasi-random value added to every checksum */ - int ckptNRec; /* Number of records in the checkpoint journal */ - int nExtra; /* Add this many bytes to each in-memory page */ - void (*xDestructor)(void*); /* Call this routine when freeing pages */ - int nPage; /* Total number of in-memory pages */ - int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */ - int mxPage; /* Maximum number of pages to hold in cache */ - int nHit, nMiss, nOvfl; /* Cache hits, missing, and LRU overflows */ - void (*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */ - void *pCodecArg; /* First argument to xCodec() */ - 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 ckptOpen; /* True if the checkpoint journal is open */ - u8 ckptInUse; /* True we are in a checkpoint */ - u8 ckptAutoopen; /* Open ckpt journal when main journal is opened*/ - u8 noSync; /* Do not sync the journal if true */ - u8 fullSync; /* Do extra syncs of the journal for robustness */ - u8 state; /* SQLITE_UNLOCK, _READLOCK or _WRITELOCK */ - u8 errMask; /* One of several kinds of errors */ - u8 tempFile; /* zFilename is a temporary file */ - u8 readOnly; /* True for a read-only database */ - u8 needSync; /* True if an fsync() is needed on the journal */ - u8 dirtyFile; /* True if database file has changed in any way */ - u8 alwaysRollback; /* Disable dont_rollback() for all pages */ - u8 *aInJournal; /* One bit for each page in the database file */ - u8 *aInCkpt; /* One bit for each page in the database */ - PgHdr *pFirst, *pLast; /* List of free pages */ - PgHdr *pFirstSynced; /* First free page with PgHdr.needSync==0 */ - PgHdr *pAll; /* List of all pages */ - PgHdr *pCkpt; /* List of pages in the checkpoint journal */ - PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number of PgHdr */ -}; - -/* -** These are bits that can be set in Pager.errMask. -*/ -#define PAGER_ERR_FULL 0x01 /* a write() failed */ -#define PAGER_ERR_MEM 0x02 /* malloc() failed */ -#define PAGER_ERR_LOCK 0x04 /* error in the locking protocol */ -#define PAGER_ERR_CORRUPT 0x08 /* database or journal corruption */ -#define PAGER_ERR_DISK 0x10 /* general disk I/O error - bad hard drive? */ - -/* -** The journal file contains page records in the following -** format. -** -** Actually, this structure is the complete page record for pager -** formats less than 3. Beginning with format 3, this record is surrounded -** by two checksums. -*/ -typedef struct PageRecord PageRecord; -struct PageRecord { - Pgno pgno; /* The page number */ - char aData[SQLITE_PAGE_SIZE]; /* Original data for page pgno */ -}; - -/* -** Journal files begin with the following magic string. The data -** was obtained from /dev/random. It is used only as a sanity check. -** -** There are three journal formats (so far). The 1st journal format writes -** 32-bit integers in the byte-order of the host machine. New -** formats writes integers as big-endian. All new journals use the -** new format, but we have to be able to read an older journal in order -** to rollback journals created by older versions of the library. -** -** The 3rd journal format (added for 2.8.0) adds additional sanity -** checking information to the journal. If the power fails while the -** journal is being written, semi-random garbage data might appear in -** the journal file after power is restored. If an attempt is then made -** to roll the journal back, the database could be corrupted. The additional -** sanity checking data is an attempt to discover the garbage in the -** journal and ignore it. -** -** The sanity checking information for the 3rd journal format consists -** of a 32-bit checksum on each page of data. The checksum covers both -** the page number and the SQLITE_PAGE_SIZE bytes of data for the page. -** This cksum is initialized to a 32-bit random value that appears in the -** journal file right after the header. The random initializer is important, -** because garbage data that appears at the end of a journal is likely -** data that was once in other files that have now been deleted. If the -** garbage data came from an obsolete journal file, the checksums might -** be correct. But by initializing the checksum to random value which -** is different for every journal, we minimize that risk. -*/ -static const unsigned char aJournalMagic1[] = { - 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd4, -}; -static const unsigned char aJournalMagic2[] = { - 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd5, -}; -static const unsigned char aJournalMagic3[] = { - 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd6, -}; -#define JOURNAL_FORMAT_1 1 -#define JOURNAL_FORMAT_2 2 -#define JOURNAL_FORMAT_3 3 - -/* -** The following integer determines what format to use when creating -** new primary journal files. By default we always use format 3. -** When testing, we can set this value to older journal formats in order to -** make sure that newer versions of the library are able to rollback older -** journal files. -** -** Note that checkpoint journals always use format 2 and omit the header. -*/ -#ifdef SQLITE_TEST -int journal_format = 3; -#else -# define journal_format 3 -#endif - -/* -** The size of the header and of each page in the journal varies according -** to which journal format is being used. The following macros figure out -** the sizes based on format numbers. -*/ -#define JOURNAL_HDR_SZ(X) \ - (sizeof(aJournalMagic1) + sizeof(Pgno) + ((X)>=3)*2*sizeof(u32)) -#define JOURNAL_PG_SZ(X) \ - (SQLITE_PAGE_SIZE + sizeof(Pgno) + ((X)>=3)*sizeof(u32)) - -/* -** Enable reference count tracking here: -*/ -#ifdef SQLITE_TEST - int pager_refinfo_enable = 0; - static void pager_refinfo(PgHdr *p){ - static int cnt = 0; - if( !pager_refinfo_enable ) return; - printf( - "REFCNT: %4d addr=0x%08x nRef=%d\n", - p->pgno, (int)PGHDR_TO_DATA(p), p->nRef - ); - cnt++; /* Something to set a breakpoint on */ - } -# define REFINFO(X) pager_refinfo(X) -#else -# define REFINFO(X) -#endif - -/* -** Read a 32-bit integer from the given file descriptor. Store the integer -** that is read in *pRes. Return SQLITE_OK if everything worked, or an -** error code is something goes wrong. -** -** If the journal format is 2 or 3, read a big-endian integer. If the -** journal format is 1, read an integer in the native byte-order of the -** host machine. -*/ -static int read32bits(int format, OsFile *fd, u32 *pRes){ - u32 res; - int rc; - rc = sqliteOsRead(fd, &res, sizeof(res)); - if( rc==SQLITE_OK && format>JOURNAL_FORMAT_1 ){ - unsigned char ac[4]; - memcpy(ac, &res, 4); - res = (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3]; - } - *pRes = res; - return rc; -} - -/* -** Write a 32-bit integer into the given file descriptor. Return SQLITE_OK -** on success or an error code is something goes wrong. -** -** If the journal format is 2 or 3, write the integer as 4 big-endian -** bytes. If the journal format is 1, write the integer in the native -** byte order. In normal operation, only formats 2 and 3 are used. -** Journal format 1 is only used for testing. -*/ -static int write32bits(OsFile *fd, u32 val){ - unsigned char ac[4]; - if( journal_format<=1 ){ - return sqliteOsWrite(fd, &val, 4); - } - ac[0] = (val>>24) & 0xff; - ac[1] = (val>>16) & 0xff; - ac[2] = (val>>8) & 0xff; - ac[3] = val & 0xff; - return sqliteOsWrite(fd, ac, 4); -} - -/* -** Write a 32-bit integer into a page header right before the -** page data. This will overwrite the PgHdr.pDirty pointer. -** -** The integer is big-endian for formats 2 and 3 and native byte order -** for journal format 1. -*/ -static void store32bits(u32 val, PgHdr *p, int offset){ - unsigned char *ac; - ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset]; - if( journal_format<=1 ){ - memcpy(ac, &val, 4); - }else{ - ac[0] = (val>>24) & 0xff; - ac[1] = (val>>16) & 0xff; - ac[2] = (val>>8) & 0xff; - ac[3] = val & 0xff; - } -} - - -/* -** Convert the bits in the pPager->errMask into an approprate -** return code. -*/ -static int pager_errcode(Pager *pPager){ - int rc = SQLITE_OK; - if( pPager->errMask & PAGER_ERR_LOCK ) rc = SQLITE_PROTOCOL; - if( pPager->errMask & PAGER_ERR_DISK ) rc = SQLITE_IOERR; - if( pPager->errMask & PAGER_ERR_FULL ) rc = SQLITE_FULL; - if( pPager->errMask & PAGER_ERR_MEM ) rc = SQLITE_NOMEM; - if( pPager->errMask & PAGER_ERR_CORRUPT ) rc = SQLITE_CORRUPT; - return rc; -} - -/* -** Add or remove a page from the list of all pages that are in the -** checkpoint journal. -** -** The Pager keeps a separate list of pages that are currently in -** the checkpoint journal. This helps the sqlitepager_ckpt_commit() -** routine run MUCH faster for the common case where there are many -** pages in memory but only a few are in the checkpoint journal. -*/ -static void page_add_to_ckpt_list(PgHdr *pPg){ - Pager *pPager = pPg->pPager; - if( pPg->inCkpt ) return; - assert( pPg->pPrevCkpt==0 && pPg->pNextCkpt==0 ); - pPg->pPrevCkpt = 0; - if( pPager->pCkpt ){ - pPager->pCkpt->pPrevCkpt = pPg; - } - pPg->pNextCkpt = pPager->pCkpt; - pPager->pCkpt = pPg; - pPg->inCkpt = 1; -} -static void page_remove_from_ckpt_list(PgHdr *pPg){ - if( !pPg->inCkpt ) return; - if( pPg->pPrevCkpt ){ - assert( pPg->pPrevCkpt->pNextCkpt==pPg ); - pPg->pPrevCkpt->pNextCkpt = pPg->pNextCkpt; - }else{ - assert( pPg->pPager->pCkpt==pPg ); - pPg->pPager->pCkpt = pPg->pNextCkpt; - } - if( pPg->pNextCkpt ){ - assert( pPg->pNextCkpt->pPrevCkpt==pPg ); - pPg->pNextCkpt->pPrevCkpt = pPg->pPrevCkpt; - } - pPg->pNextCkpt = 0; - pPg->pPrevCkpt = 0; - pPg->inCkpt = 0; -} - -/* -** 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 = pPager->aHash[pager_hash(pgno)]; - while( p && p->pgno!=pgno ){ - p = p->pNextHash; - } - return p; -} - -/* -** Unlock the database and clear the in-memory cache. This routine -** sets the state of the pager back to what it was when it was first -** opened. Any outstanding pages are invalidated and subsequent attempts -** to access those pages will likely result in a coredump. -*/ -static void pager_reset(Pager *pPager){ - PgHdr *pPg, *pNext; - for(pPg=pPager->pAll; pPg; pPg=pNext){ - pNext = pPg->pNextAll; - sqliteFree(pPg); - } - pPager->pFirst = 0; - pPager->pFirstSynced = 0; - pPager->pLast = 0; - pPager->pAll = 0; - memset(pPager->aHash, 0, sizeof(pPager->aHash)); - pPager->nPage = 0; - if( pPager->state>=SQLITE_WRITELOCK ){ - sqlitepager_rollback(pPager); - } - sqliteOsUnlock(&pPager->fd); - pPager->state = SQLITE_UNLOCK; - pPager->dbSize = -1; - pPager->nRef = 0; - assert( pPager->journalOpen==0 ); -} - -/* -** When this routine is called, the pager has the journal file open and -** a write lock on the database. This routine releases the database -** write lock and acquires a read lock in its place. The journal file -** is deleted and closed. -** -** 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_unwritelock(Pager *pPager){ - int rc; - PgHdr *pPg; - if( pPager->state<SQLITE_WRITELOCK ) return SQLITE_OK; - sqlitepager_ckpt_commit(pPager); - if( pPager->ckptOpen ){ - sqliteOsClose(&pPager->cpfd); - pPager->ckptOpen = 0; - } - if( pPager->journalOpen ){ - sqliteOsClose(&pPager->jfd); - pPager->journalOpen = 0; - sqliteOsDelete(pPager->zJournal); - sqliteFree( pPager->aInJournal ); - pPager->aInJournal = 0; - for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ - pPg->inJournal = 0; - pPg->dirty = 0; - pPg->needSync = 0; - } - }else{ - assert( pPager->dirtyFile==0 || pPager->useJournal==0 ); - } - rc = sqliteOsReadLock(&pPager->fd); - if( rc==SQLITE_OK ){ - pPager->state = SQLITE_READLOCK; - }else{ - /* This can only happen if a process does a BEGIN, then forks and the - ** child process does the COMMIT. Because of the semantics of unix - ** file locking, the unlock will fail. - */ - pPager->state = SQLITE_UNLOCK; - } - return rc; -} - -/* -** Compute and return a checksum for the page of data. -** -** This is not a real checksum. It is really just the sum of the -** random initial value and the page number. We considered do a checksum -** of the database, but that was found to be too slow. -*/ -static u32 pager_cksum(Pager *pPager, Pgno pgno, const char *aData){ - u32 cksum = pPager->cksumInit + pgno; - return cksum; -} - -/* -** Read a single page from the journal file opened on file descriptor -** jfd. Playback this one page. -** -** There are three different journal formats. The format parameter determines -** which format is used by the journal that is played back. -*/ -static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int format){ - int rc; - PgHdr *pPg; /* An existing page in the cache */ - PageRecord pgRec; - u32 cksum; - - rc = read32bits(format, jfd, &pgRec.pgno); - if( rc!=SQLITE_OK ) return rc; - rc = sqliteOsRead(jfd, &pgRec.aData, sizeof(pgRec.aData)); - if( rc!=SQLITE_OK ) return rc; - - /* Sanity checking on the page. This is more important that I originally - ** thought. If a power failure occurs while the journal is being written, - ** it could cause invalid data to be written into the journal. We need to - ** detect this invalid data (with high probability) and ignore it. - */ - if( pgRec.pgno==0 ){ - return SQLITE_DONE; - } - if( pgRec.pgno>(unsigned)pPager->dbSize ){ - return SQLITE_OK; - } - if( format>=JOURNAL_FORMAT_3 ){ - rc = read32bits(format, jfd, &cksum); - if( rc ) return rc; - if( pager_cksum(pPager, pgRec.pgno, pgRec.aData)!=cksum ){ - return SQLITE_DONE; - } - } - - /* Playback the page. Update the in-memory copy of the page - ** at the same time, if there is one. - */ - pPg = pager_lookup(pPager, pgRec.pgno); - TRACE2("PLAYBACK %d\n", pgRec.pgno); - sqliteOsSeek(&pPager->fd, (pgRec.pgno-1)*(off_t)SQLITE_PAGE_SIZE); - rc = sqliteOsWrite(&pPager->fd, pgRec.aData, SQLITE_PAGE_SIZE); - if( pPg ){ - /* No page should ever be rolled back that is in use, except for page - ** 1 which is held in use in order to keep the lock on the database - ** active. - */ - assert( pPg->nRef==0 || pPg->pgno==1 ); - memcpy(PGHDR_TO_DATA(pPg), pgRec.aData, SQLITE_PAGE_SIZE); - memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra); - pPg->dirty = 0; - pPg->needSync = 0; - CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3); - } - return rc; -} - -/* -** Playback the journal and thus restore the database file to -** the state it was in before we started making changes. -** -** The journal file format is as follows: -** -** * 8 byte prefix. One of the aJournalMagic123 vectors defined -** above. The format of the journal file is determined by which -** of the three prefix vectors is seen. -** * 4 byte big-endian integer which is the number of valid page records -** in the journal. If this value is 0xffffffff, then compute the -** number of page records from the journal size. This field appears -** in format 3 only. -** * 4 byte big-endian integer which is the initial value for the -** sanity checksum. This field appears in format 3 only. -** * 4 byte integer which is the number of pages to truncate the -** database to during a rollback. -** * Zero or more pages instances, each as follows: -** + 4 byte page number. -** + SQLITE_PAGE_SIZE bytes of data. -** + 4 byte checksum (format 3 only) -** -** When we speak of the journal header, we mean the first 4 bullets above. -** Each entry in the journal is an instance of the 5th bullet. Note that -** bullets 2 and 3 only appear in format-3 journals. -** -** Call the value from the second bullet "nRec". nRec is the number of -** valid page entries in the journal. In most cases, you can compute the -** value of nRec from the size of the journal file. But if a power -** failure occurred while the journal was being written, it could be the -** case that the size of the journal file had already been increased but -** the extra entries had not yet made it safely to disk. In such a case, -** the value of nRec computed from the file size would be too large. For -** that reason, we always use the nRec value in the header. -** -** If the nRec value is 0xffffffff it means that nRec should be computed -** from the file size. This value is used when the user selects the -** no-sync option for the journal. A power failure could lead to corruption -** in this case. But for things like temporary table (which will be -** deleted when the power is restored) we don't care. -** -** Journal formats 1 and 2 do not have an nRec value in the header so we -** have to compute nRec from the file size. This has risks (as described -** above) which is why all persistent tables have been changed to use -** format 3. -** -** If the file opened as the journal file is not a well-formed -** journal file then the database will likely already be -** corrupted, so the PAGER_ERR_CORRUPT bit is set in pPager->errMask -** and SQLITE_CORRUPT is returned. If it all works, then this routine -** returns SQLITE_OK. -*/ -static int pager_playback(Pager *pPager, int useJournalSize){ - off_t szJ; /* Size of the journal file in bytes */ - int nRec; /* Number of Records in the journal */ - int i; /* Loop counter */ - Pgno mxPg = 0; /* Size of the original file in pages */ - int format; /* Format of the journal file. */ - unsigned char aMagic[sizeof(aJournalMagic1)]; - int rc; - - /* Figure out how many records are in the journal. Abort early if - ** the journal is empty. - */ - assert( pPager->journalOpen ); - sqliteOsSeek(&pPager->jfd, 0); - rc = sqliteOsFileSize(&pPager->jfd, &szJ); - if( rc!=SQLITE_OK ){ - goto end_playback; - } - - /* If the journal file is too small to contain a complete header, - ** it must mean that the process that created the journal was just - ** beginning to write the journal file when it died. In that case, - ** the database file should have still been completely unchanged. - ** Nothing needs to be rolled back. We can safely ignore this journal. - */ - if( szJ < sizeof(aMagic)+sizeof(Pgno) ){ - goto end_playback; - } - - /* Read the beginning of the journal and truncate the - ** database file back to its original size. - */ - rc = sqliteOsRead(&pPager->jfd, aMagic, sizeof(aMagic)); - if( rc!=SQLITE_OK ){ - rc = SQLITE_PROTOCOL; - goto end_playback; - } - if( memcmp(aMagic, aJournalMagic3, sizeof(aMagic))==0 ){ - format = JOURNAL_FORMAT_3; - }else if( memcmp(aMagic, aJournalMagic2, sizeof(aMagic))==0 ){ - format = JOURNAL_FORMAT_2; - }else if( memcmp(aMagic, aJournalMagic1, sizeof(aMagic))==0 ){ - format = JOURNAL_FORMAT_1; - }else{ - rc = SQLITE_PROTOCOL; - goto end_playback; - } - if( format>=JOURNAL_FORMAT_3 ){ - if( szJ < sizeof(aMagic) + 3*sizeof(u32) ){ - /* Ignore the journal if it is too small to contain a complete - ** header. We already did this test once above, but at the prior - ** test, we did not know the journal format and so we had to assume - ** the smallest possible header. Now we know the header is bigger - ** than the minimum so we test again. - */ - goto end_playback; - } - rc = read32bits(format, &pPager->jfd, (u32*)&nRec); - if( rc ) goto end_playback; - rc = read32bits(format, &pPager->jfd, &pPager->cksumInit); - if( rc ) goto end_playback; - if( nRec==0xffffffff || useJournalSize ){ - nRec = (szJ - JOURNAL_HDR_SZ(3))/JOURNAL_PG_SZ(3); - } - }else{ - nRec = (szJ - JOURNAL_HDR_SZ(2))/JOURNAL_PG_SZ(2); - assert( nRec*JOURNAL_PG_SZ(2)+JOURNAL_HDR_SZ(2)==szJ ); - } - rc = read32bits(format, &pPager->jfd, &mxPg); - if( rc!=SQLITE_OK ){ - goto end_playback; - } - assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg ); - rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)mxPg); - if( rc!=SQLITE_OK ){ - goto end_playback; - } - pPager->dbSize = mxPg; - - /* Copy original pages out of the journal and back into the database file. - */ - for(i=0; i<nRec; i++){ - rc = pager_playback_one_page(pPager, &pPager->jfd, format); - if( rc!=SQLITE_OK ){ - if( rc==SQLITE_DONE ){ - rc = SQLITE_OK; - } - break; - } - } - - /* Pages that have been written to the journal but never synced - ** where not restored by the loop above. We have to restore those - ** pages by reading them back from the original database. - */ - if( rc==SQLITE_OK ){ - PgHdr *pPg; - for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ - char zBuf[SQLITE_PAGE_SIZE]; - if( !pPg->dirty ) continue; - if( (int)pPg->pgno <= pPager->origDbSize ){ - sqliteOsSeek(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)(pPg->pgno-1)); - rc = sqliteOsRead(&pPager->fd, zBuf, SQLITE_PAGE_SIZE); - TRACE2("REFETCH %d\n", pPg->pgno); - CODEC(pPager, zBuf, pPg->pgno, 2); - if( rc ) break; - }else{ - memset(zBuf, 0, SQLITE_PAGE_SIZE); - } - if( pPg->nRef==0 || memcmp(zBuf, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE) ){ - memcpy(PGHDR_TO_DATA(pPg), zBuf, SQLITE_PAGE_SIZE); - memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra); - } - pPg->needSync = 0; - pPg->dirty = 0; - } - } - -end_playback: - if( rc!=SQLITE_OK ){ - pager_unwritelock(pPager); - pPager->errMask |= PAGER_ERR_CORRUPT; - rc = SQLITE_CORRUPT; - }else{ - rc = pager_unwritelock(pPager); - } - return rc; -} - -/* -** Playback the checkpoint journal. -** -** This is similar to playing back the transaction journal but with -** a few extra twists. -** -** (1) The number of pages in the database file at the start of -** the checkpoint is stored in pPager->ckptSize, not in the -** journal file itself. -** -** (2) In addition to playing back the checkpoint journal, also -** playback all pages of the transaction journal beginning -** at offset pPager->ckptJSize. -*/ -static int pager_ckpt_playback(Pager *pPager){ - off_t szJ; /* Size of the full journal */ - int nRec; /* Number of Records */ - int i; /* Loop counter */ - int rc; - - /* Truncate the database back to its original size. - */ - rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)pPager->ckptSize); - pPager->dbSize = pPager->ckptSize; - - /* Figure out how many records are in the checkpoint journal. - */ - assert( pPager->ckptInUse && pPager->journalOpen ); - sqliteOsSeek(&pPager->cpfd, 0); - nRec = pPager->ckptNRec; - - /* Copy original pages out of the checkpoint journal and back into the - ** database file. Note that the checkpoint journal always uses format - ** 2 instead of format 3 since it does not need to be concerned with - ** power failures corrupting the journal and can thus omit the checksums. - */ - for(i=nRec-1; i>=0; i--){ - rc = pager_playback_one_page(pPager, &pPager->cpfd, 2); - assert( rc!=SQLITE_DONE ); - if( rc!=SQLITE_OK ) goto end_ckpt_playback; - } - - /* Figure out how many pages need to be copied out of the transaction - ** journal. - */ - rc = sqliteOsSeek(&pPager->jfd, pPager->ckptJSize); - if( rc!=SQLITE_OK ){ - goto end_ckpt_playback; - } - rc = sqliteOsFileSize(&pPager->jfd, &szJ); - if( rc!=SQLITE_OK ){ - goto end_ckpt_playback; - } - nRec = (szJ - pPager->ckptJSize)/JOURNAL_PG_SZ(journal_format); - for(i=nRec-1; i>=0; i--){ - rc = pager_playback_one_page(pPager, &pPager->jfd, journal_format); - if( rc!=SQLITE_OK ){ - assert( rc!=SQLITE_DONE ); - goto end_ckpt_playback; - } - } - -end_ckpt_playback: - if( rc!=SQLITE_OK ){ - pPager->errMask |= PAGER_ERR_CORRUPT; - rc = SQLITE_CORRUPT; - } - return rc; -} - -/* -** Change the maximum number of in-memory pages that are allowed. -** -** The maximum number is the absolute value of the mxPage parameter. -** If mxPage is negative, the noSync flag is also set. noSync bypasses -** calls to sqliteOsSync(). The pager runs much faster with noSync on, -** but if the operating system crashes or there is an abrupt power -** failure, the database file might be left in an inconsistent and -** unrepairable state. -*/ -void sqlitepager_set_cachesize(Pager *pPager, int mxPage){ - if( mxPage>=0 ){ - pPager->noSync = pPager->tempFile; - if( pPager->noSync==0 ) pPager->needSync = 0; - }else{ - pPager->noSync = 1; - mxPage = -mxPage; - } - if( mxPage>10 ){ - pPager->mxPage = mxPage; - } -} - -/* -** Adjust the robustness of the database to damage due to OS crashes -** or power failures by changing the number of syncs()s when writing -** the rollback journal. There are three levels: -** -** OFF sqliteOsSync() is never called. This is the default -** for temporary and transient files. -** -** NORMAL The journal is synced once before writes begin on the -** database. This is normally adequate protection, but -** it is theoretically possible, though very unlikely, -** that an inopertune power failure could leave the journal -** in a state which would cause damage to the database -** when it is rolled back. -** -** FULL The journal is synced twice before writes begin on the -** database (with some additional information - the nRec field -** of the journal header - being written in between the two -** syncs). If we assume that writing a -** single disk sector is atomic, then this mode provides -** assurance that the journal will not be corrupted to the -** point of causing damage to the database during rollback. -** -** Numeric values associated with these states are OFF==1, NORMAL=2, -** and FULL=3. -*/ -void sqlitepager_set_safety_level(Pager *pPager, int level){ - pPager->noSync = level==1 || pPager->tempFile; - pPager->fullSync = level==3 && !pPager->tempFile; - if( pPager->noSync==0 ) pPager->needSync = 0; -} - -/* -** Open a temporary file. Write the name of the file into zName -** (zName must be at least SQLITE_TEMPNAME_SIZE bytes long.) 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 sqlitepager_opentemp(char *zFile, OsFile *fd){ - int cnt = 8; - int rc; - do{ - cnt--; - sqliteOsTempFileName(zFile); - rc = sqliteOsOpenExclusive(zFile, fd, 1); - }while( cnt>0 && rc!=SQLITE_OK ); - return rc; -} - -/* -** Create a new page cache and put a pointer to the page cache in *ppPager. -** The file to be cached need not exist. The file is not locked until -** the first call to sqlitepager_get() and is only held open until the -** last page is released using sqlitepager_unref(). -** -** If zFilename is NULL then a randomly-named temporary file is created -** and used as the file to be cached. The file will be deleted -** automatically when it is closed. -*/ -int sqlitepager_open( - Pager **ppPager, /* Return the Pager structure here */ - const char *zFilename, /* Name of the database file to open */ - int mxPage, /* Max number of in-memory cache pages */ - int nExtra, /* Extra bytes append to each in-memory page */ - int useJournal /* TRUE to use a rollback journal on this file */ -){ - Pager *pPager; - char *zFullPathname; - int nameLen; - OsFile fd; - int rc, i; - int tempFile; - int readOnly = 0; - char zTemp[SQLITE_TEMPNAME_SIZE]; - - *ppPager = 0; - if( sqlite_malloc_failed ){ - return SQLITE_NOMEM; - } - if( zFilename && zFilename[0] ){ - zFullPathname = sqliteOsFullPathname(zFilename); - rc = sqliteOsOpenReadWrite(zFullPathname, &fd, &readOnly); - tempFile = 0; - }else{ - rc = sqlitepager_opentemp(zTemp, &fd); - zFilename = zTemp; - zFullPathname = sqliteOsFullPathname(zFilename); - tempFile = 1; - } - if( sqlite_malloc_failed ){ - return SQLITE_NOMEM; - } - if( rc!=SQLITE_OK ){ - sqliteFree(zFullPathname); - return SQLITE_CANTOPEN; - } - nameLen = strlen(zFullPathname); - pPager = sqliteMalloc( sizeof(*pPager) + nameLen*3 + 30 ); - if( pPager==0 ){ - sqliteOsClose(&fd); - sqliteFree(zFullPathname); - return SQLITE_NOMEM; - } - SET_PAGER(pPager); - pPager->zFilename = (char*)&pPager[1]; - pPager->zDirectory = &pPager->zFilename[nameLen+1]; - pPager->zJournal = &pPager->zDirectory[nameLen+1]; - strcpy(pPager->zFilename, zFullPathname); - strcpy(pPager->zDirectory, zFullPathname); - for(i=nameLen; i>0 && pPager->zDirectory[i-1]!='/'; i--){} - if( i>0 ) pPager->zDirectory[i-1] = 0; - strcpy(pPager->zJournal, zFullPathname); - sqliteFree(zFullPathname); - strcpy(&pPager->zJournal[nameLen], "-journal"); - pPager->fd = fd; - pPager->journalOpen = 0; - pPager->useJournal = useJournal; - pPager->ckptOpen = 0; - pPager->ckptInUse = 0; - pPager->nRef = 0; - pPager->dbSize = -1; - pPager->ckptSize = 0; - pPager->ckptJSize = 0; - pPager->nPage = 0; - pPager->mxPage = mxPage>5 ? mxPage : 10; - pPager->state = SQLITE_UNLOCK; - pPager->errMask = 0; - pPager->tempFile = tempFile; - pPager->readOnly = readOnly; - pPager->needSync = 0; - pPager->noSync = pPager->tempFile || !useJournal; - pPager->pFirst = 0; - pPager->pFirstSynced = 0; - pPager->pLast = 0; - pPager->nExtra = nExtra; - memset(pPager->aHash, 0, sizeof(pPager->aHash)); - *ppPager = pPager; - return SQLITE_OK; -} - -/* -** Set the destructor for this pager. If not NULL, the destructor is called -** when the reference count on each page reaches zero. The destructor can -** be used to clean up information in the extra segment appended to each page. -** -** The destructor is not called as a result sqlitepager_close(). -** Destructors are only called by sqlitepager_unref(). -*/ -void sqlitepager_set_destructor(Pager *pPager, void (*xDesc)(void*)){ - pPager->xDestructor = xDesc; -} - -/* -** Return the total number of pages in the disk file associated with -** pPager. -*/ -int sqlitepager_pagecount(Pager *pPager){ - off_t n; - assert( pPager!=0 ); - if( pPager->dbSize>=0 ){ - return pPager->dbSize; - } - if( sqliteOsFileSize(&pPager->fd, &n)!=SQLITE_OK ){ - pPager->errMask |= PAGER_ERR_DISK; - return 0; - } - n /= SQLITE_PAGE_SIZE; - if( pPager->state!=SQLITE_UNLOCK ){ - pPager->dbSize = n; - } - return n; -} - -/* -** Forward declaration -*/ -static int syncJournal(Pager*); - -/* -** Truncate the file to the number of pages specified. -*/ -int sqlitepager_truncate(Pager *pPager, Pgno nPage){ - int rc; - if( pPager->dbSize<0 ){ - sqlitepager_pagecount(pPager); - } - if( pPager->errMask!=0 ){ - rc = pager_errcode(pPager); - return rc; - } - if( nPage>=(unsigned)pPager->dbSize ){ - return SQLITE_OK; - } - syncJournal(pPager); - rc = sqliteOsTruncate(&pPager->fd, SQLITE_PAGE_SIZE*(off_t)nPage); - if( rc==SQLITE_OK ){ - pPager->dbSize = nPage; - } - return rc; -} - -/* -** Shutdown the page cache. Free all memory and close all files. -** -** If a transaction was in progress when this routine is called, that -** transaction is rolled back. All outstanding pages are invalidated -** and their memory is freed. Any attempt to use a page associated -** with this page cache after this function returns will likely -** result in a coredump. -*/ -int sqlitepager_close(Pager *pPager){ - PgHdr *pPg, *pNext; - switch( pPager->state ){ - case SQLITE_WRITELOCK: { - sqlitepager_rollback(pPager); - sqliteOsUnlock(&pPager->fd); - assert( pPager->journalOpen==0 ); - break; - } - case SQLITE_READLOCK: { - sqliteOsUnlock(&pPager->fd); - break; - } - default: { - /* Do nothing */ - break; - } - } - for(pPg=pPager->pAll; pPg; pPg=pNext){ - pNext = pPg->pNextAll; - sqliteFree(pPg); - } - sqliteOsClose(&pPager->fd); - assert( pPager->journalOpen==0 ); - /* Temp files are automatically deleted by the OS - ** if( pPager->tempFile ){ - ** sqliteOsDelete(pPager->zFilename); - ** } - */ - CLR_PAGER(pPager); - if( pPager->zFilename!=(char*)&pPager[1] ){ - assert( 0 ); /* Cannot happen */ - sqliteFree(pPager->zFilename); - sqliteFree(pPager->zJournal); - sqliteFree(pPager->zDirectory); - } - sqliteFree(pPager); - return SQLITE_OK; -} - -/* -** Return the page number for the given page data. -*/ -Pgno sqlitepager_pagenumber(void *pData){ - PgHdr *p = DATA_TO_PGHDR(pData); - return p->pgno; -} - -/* -** Increment the reference count for a page. If the page is -** currently on the freelist (the reference count is zero) then -** remove it from the freelist. -*/ -#define page_ref(P) ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++) -static void _page_ref(PgHdr *pPg){ - if( pPg->nRef==0 ){ - /* The page is currently on the freelist. Remove it. */ - if( pPg==pPg->pPager->pFirstSynced ){ - PgHdr *p = pPg->pNextFree; - while( p && p->needSync ){ p = p->pNextFree; } - pPg->pPager->pFirstSynced = p; - } - if( pPg->pPrevFree ){ - pPg->pPrevFree->pNextFree = pPg->pNextFree; - }else{ - pPg->pPager->pFirst = pPg->pNextFree; - } - if( pPg->pNextFree ){ - pPg->pNextFree->pPrevFree = pPg->pPrevFree; - }else{ - pPg->pPager->pLast = pPg->pPrevFree; - } - pPg->pPager->nRef++; - } - pPg->nRef++; - REFINFO(pPg); -} - -/* -** Increment the reference count for a page. The input pointer is -** a reference to the page data. -*/ -int sqlitepager_ref(void *pData){ - PgHdr *pPg = DATA_TO_PGHDR(pData); - page_ref(pPg); - return SQLITE_OK; -} - -/* -** Sync the journal. In other words, make sure all the pages that have -** been written to the journal have actually reached the surface of the -** disk. It is not safe to modify the original database file until after -** the journal has been synced. If the original database is modified before -** the journal is synced and a power failure occurs, the unsynced journal -** data would be lost and we would be unable to completely rollback the -** database changes. Database corruption would occur. -** -** This routine also updates the nRec field in the header of the journal. -** (See comments on the pager_playback() routine for additional information.) -** If the sync mode is FULL, two syncs will occur. First the whole journal -** is synced, then the nRec field is updated, then a second sync occurs. -** -** For temporary databases, we do not care if we are able to rollback -** after a power failure, so sync occurs. -** -** This routine clears the needSync field of every page current held in -** memory. -*/ -static int syncJournal(Pager *pPager){ - PgHdr *pPg; - int rc = SQLITE_OK; - - /* Sync the journal before modifying the main database - ** (assuming there is a journal and it needs to be synced.) - */ - if( pPager->needSync ){ - if( !pPager->tempFile ){ - assert( pPager->journalOpen ); - /* assert( !pPager->noSync ); // noSync might be set if synchronous - ** was turned off after the transaction was started. Ticket #615 */ -#ifndef NDEBUG - { - /* Make sure the pPager->nRec counter we are keeping agrees - ** with the nRec computed from the size of the journal file. - */ - off_t hdrSz, pgSz, jSz; - hdrSz = JOURNAL_HDR_SZ(journal_format); - pgSz = JOURNAL_PG_SZ(journal_format); - rc = sqliteOsFileSize(&pPager->jfd, &jSz); - if( rc!=0 ) return rc; - assert( pPager->nRec*pgSz+hdrSz==jSz ); - } -#endif - if( journal_format>=3 ){ - /* Write the nRec value into the journal file header */ - off_t szJ; - if( pPager->fullSync ){ - TRACE1("SYNC\n"); - rc = sqliteOsSync(&pPager->jfd); - if( rc!=0 ) return rc; - } - sqliteOsSeek(&pPager->jfd, sizeof(aJournalMagic1)); - rc = write32bits(&pPager->jfd, pPager->nRec); - if( rc ) return rc; - szJ = JOURNAL_HDR_SZ(journal_format) + - pPager->nRec*JOURNAL_PG_SZ(journal_format); - sqliteOsSeek(&pPager->jfd, szJ); - } - TRACE1("SYNC\n"); - rc = sqliteOsSync(&pPager->jfd); - if( rc!=0 ) return rc; - pPager->journalStarted = 1; - } - pPager->needSync = 0; - - /* Erase the needSync flag from every page. - */ - for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ - pPg->needSync = 0; - } - pPager->pFirstSynced = pPager->pFirst; - } - -#ifndef NDEBUG - /* If the Pager.needSync flag is clear then the PgHdr.needSync - ** flag must also be clear for all pages. Verify that this - ** invariant is true. - */ - else{ - for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ - assert( pPg->needSync==0 ); - } - assert( pPager->pFirstSynced==pPager->pFirst ); - } -#endif - - return rc; -} - -/* -** Given a list of pages (connected by the PgHdr.pDirty pointer) write -** every one of those pages out to the database file and mark them all -** as clean. -*/ -static int pager_write_pagelist(PgHdr *pList){ - Pager *pPager; - int rc; - - if( pList==0 ) return SQLITE_OK; - pPager = pList->pPager; - while( pList ){ - assert( pList->dirty ); - sqliteOsSeek(&pPager->fd, (pList->pgno-1)*(off_t)SQLITE_PAGE_SIZE); - CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6); - TRACE2("STORE %d\n", pList->pgno); - rc = sqliteOsWrite(&pPager->fd, PGHDR_TO_DATA(pList), SQLITE_PAGE_SIZE); - CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 0); - if( rc ) return rc; - pList->dirty = 0; - pList = pList->pDirty; - } - return SQLITE_OK; -} - -/* -** Collect every dirty page into a dirty list and -** return a pointer to the head of that list. All pages are -** collected even if they are still in use. -*/ -static PgHdr *pager_get_all_dirty_pages(Pager *pPager){ - PgHdr *p, *pList; - pList = 0; - for(p=pPager->pAll; p; p=p->pNextAll){ - if( p->dirty ){ - p->pDirty = pList; - pList = p; - } - } - return pList; -} - -/* -** Acquire a page. -** -** A read lock on the disk file is obtained when the first page is acquired. -** This read lock is dropped when the last page is released. -** -** A _get works for any page number greater than 0. If the database -** file is smaller than the requested page, then no actual disk -** read occurs and the memory image of the page is initialized to -** all zeros. The extra data appended to a page is always initialized -** to zeros the first time a page is loaded into memory. -** -** The acquisition might fail for several reasons. In all cases, -** an appropriate error code is returned and *ppPage is set to NULL. -** -** See also sqlitepager_lookup(). Both this routine and _lookup() attempt -** to find a page in the in-memory cache first. If the page is not already -** in memory, this routine goes to disk to read it in whereas _lookup() -** just returns 0. This routine acquires a read-lock the first time it -** has to go to disk, and could also playback an old journal if necessary. -** Since _lookup() never goes to disk, it never has to deal with locks -** or journal files. -*/ -int sqlitepager_get(Pager *pPager, Pgno pgno, void **ppPage){ - PgHdr *pPg; - int rc; - - /* Make sure we have not hit any critical errors. - */ - assert( pPager!=0 ); - assert( pgno!=0 ); - *ppPage = 0; - if( pPager->errMask & ~(PAGER_ERR_FULL) ){ - return pager_errcode(pPager); - } - - /* If this is the first page accessed, then get a read lock - ** on the database file. - */ - if( pPager->nRef==0 ){ - rc = sqliteOsReadLock(&pPager->fd); - if( rc!=SQLITE_OK ){ - return rc; - } - pPager->state = SQLITE_READLOCK; - - /* If a journal file exists, try to play it back. - */ - if( pPager->useJournal && sqliteOsFileExists(pPager->zJournal) ){ - int rc; - - /* Get a write lock on the database - */ - rc = sqliteOsWriteLock(&pPager->fd); - if( rc!=SQLITE_OK ){ - if( sqliteOsUnlock(&pPager->fd)!=SQLITE_OK ){ - /* This should never happen! */ - rc = SQLITE_INTERNAL; - } - return rc; - } - pPager->state = SQLITE_WRITELOCK; - - /* Open the journal for reading only. Return SQLITE_BUSY if - ** we are unable to open the journal file. - ** - ** The journal file does not need to be locked itself. The - ** journal file is never open unless the main database file holds - ** a write lock, so there is never any chance of two or more - ** processes opening the journal at the same time. - */ - rc = sqliteOsOpenReadOnly(pPager->zJournal, &pPager->jfd); - if( rc!=SQLITE_OK ){ - rc = sqliteOsUnlock(&pPager->fd); - assert( rc==SQLITE_OK ); - return SQLITE_BUSY; - } - pPager->journalOpen = 1; - pPager->journalStarted = 0; - - /* Playback and delete the journal. Drop the database write - ** lock and reacquire the read lock. - */ - rc = pager_playback(pPager, 0); - if( rc!=SQLITE_OK ){ - return rc; - } - } - pPg = 0; - }else{ - /* Search for page in cache */ - pPg = pager_lookup(pPager, pgno); - } - if( pPg==0 ){ - /* The requested page is not in the page cache. */ - int h; - pPager->nMiss++; - if( pPager->nPage<pPager->mxPage || pPager->pFirst==0 ){ - /* Create a new page */ - pPg = sqliteMallocRaw( sizeof(*pPg) + SQLITE_PAGE_SIZE - + sizeof(u32) + pPager->nExtra ); - if( pPg==0 ){ - pager_unwritelock(pPager); - pPager->errMask |= PAGER_ERR_MEM; - return SQLITE_NOMEM; - } - memset(pPg, 0, sizeof(*pPg)); - pPg->pPager = pPager; - pPg->pNextAll = pPager->pAll; - if( pPager->pAll ){ - pPager->pAll->pPrevAll = pPg; - } - pPg->pPrevAll = 0; - pPager->pAll = pPg; - pPager->nPage++; - }else{ - /* Find a page to recycle. Try to locate a page that does not - ** require us to do an fsync() on the journal. - */ - pPg = pPager->pFirstSynced; - - /* If we could not find a page that does not require an fsync() - ** on the journal file then fsync the journal file. This is a - ** very slow operation, so we work hard to avoid it. But sometimes - ** it can't be helped. - */ - if( pPg==0 ){ - int rc = syncJournal(pPager); - if( rc!=0 ){ - sqlitepager_rollback(pPager); - return SQLITE_IOERR; - } - pPg = pPager->pFirst; - } - assert( pPg->nRef==0 ); - - /* Write the page to the database file if it is dirty. - */ - if( pPg->dirty ){ - assert( pPg->needSync==0 ); - pPg->pDirty = 0; - rc = pager_write_pagelist( pPg ); - if( rc!=SQLITE_OK ){ - sqlitepager_rollback(pPager); - return SQLITE_IOERR; - } - } - assert( pPg->dirty==0 ); - - /* If the page we are recycling is marked as alwaysRollback, then - ** set the global alwaysRollback flag, thus disabling the - ** sqlite_dont_rollback() optimization for the rest of this transaction. - ** It is necessary to do this because the page marked alwaysRollback - ** might be reloaded at a later time but at that point we won't remember - ** that is was marked alwaysRollback. This means that all pages must - ** be marked as alwaysRollback from here on out. - */ - if( pPg->alwaysRollback ){ - pPager->alwaysRollback = 1; - } - - /* Unlink the old page from the free list and the hash table - */ - if( pPg==pPager->pFirstSynced ){ - PgHdr *p = pPg->pNextFree; - while( p && p->needSync ){ p = p->pNextFree; } - pPager->pFirstSynced = p; - } - if( pPg->pPrevFree ){ - pPg->pPrevFree->pNextFree = pPg->pNextFree; - }else{ - assert( pPager->pFirst==pPg ); - pPager->pFirst = pPg->pNextFree; - } - if( pPg->pNextFree ){ - pPg->pNextFree->pPrevFree = pPg->pPrevFree; - }else{ - assert( pPager->pLast==pPg ); - pPager->pLast = pPg->pPrevFree; - } - pPg->pNextFree = pPg->pPrevFree = 0; - if( pPg->pNextHash ){ - pPg->pNextHash->pPrevHash = pPg->pPrevHash; - } - if( pPg->pPrevHash ){ - pPg->pPrevHash->pNextHash = pPg->pNextHash; - }else{ - h = pager_hash(pPg->pgno); - assert( pPager->aHash[h]==pPg ); - pPager->aHash[h] = pPg->pNextHash; - } - pPg->pNextHash = pPg->pPrevHash = 0; - pPager->nOvfl++; - } - pPg->pgno = pgno; - if( pPager->aInJournal && (int)pgno<=pPager->origDbSize ){ - sqliteCheckMemory(pPager->aInJournal, pgno/8); - assert( pPager->journalOpen ); - pPg->inJournal = (pPager->aInJournal[pgno/8] & (1<<(pgno&7)))!=0; - pPg->needSync = 0; - }else{ - pPg->inJournal = 0; - pPg->needSync = 0; - } - if( pPager->aInCkpt && (int)pgno<=pPager->ckptSize - && (pPager->aInCkpt[pgno/8] & (1<<(pgno&7)))!=0 ){ - page_add_to_ckpt_list(pPg); - }else{ - page_remove_from_ckpt_list(pPg); - } - pPg->dirty = 0; - pPg->nRef = 1; - REFINFO(pPg); - pPager->nRef++; - h = pager_hash(pgno); - pPg->pNextHash = pPager->aHash[h]; - pPager->aHash[h] = pPg; - if( pPg->pNextHash ){ - assert( pPg->pNextHash->pPrevHash==0 ); - pPg->pNextHash->pPrevHash = pPg; - } - if( pPager->nExtra>0 ){ - memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra); - } - if( pPager->dbSize<0 ) sqlitepager_pagecount(pPager); - if( pPager->errMask!=0 ){ - sqlitepager_unref(PGHDR_TO_DATA(pPg)); - rc = pager_errcode(pPager); - return rc; - } - if( pPager->dbSize<(int)pgno ){ - memset(PGHDR_TO_DATA(pPg), 0, SQLITE_PAGE_SIZE); - }else{ - int rc; - sqliteOsSeek(&pPager->fd, (pgno-1)*(off_t)SQLITE_PAGE_SIZE); - rc = sqliteOsRead(&pPager->fd, PGHDR_TO_DATA(pPg), SQLITE_PAGE_SIZE); - TRACE2("FETCH %d\n", pPg->pgno); - CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3); - if( rc!=SQLITE_OK ){ - off_t fileSize; - if( sqliteOsFileSize(&pPager->fd,&fileSize)!=SQLITE_OK - || fileSize>=pgno*SQLITE_PAGE_SIZE ){ - sqlitepager_unref(PGHDR_TO_DATA(pPg)); - return rc; - }else{ - memset(PGHDR_TO_DATA(pPg), 0, SQLITE_PAGE_SIZE); - } - } - } - }else{ - /* The requested page is in the page cache. */ - pPager->nHit++; - page_ref(pPg); - } - *ppPage = PGHDR_TO_DATA(pPg); - return SQLITE_OK; -} - -/* -** Acquire a page if it is already in the in-memory cache. Do -** not read the page from disk. Return a pointer to the page, -** or 0 if the page is not in cache. -** -** See also sqlitepager_get(). The difference between this routine -** and sqlitepager_get() is that _get() will go to the disk and read -** in the page if the page is not already in cache. This routine -** returns NULL if the page is not in cache or if a disk I/O error -** has ever happened. -*/ -void *sqlitepager_lookup(Pager *pPager, Pgno pgno){ - PgHdr *pPg; - - assert( pPager!=0 ); - assert( pgno!=0 ); - if( pPager->errMask & ~(PAGER_ERR_FULL) ){ - return 0; - } - /* if( pPager->nRef==0 ){ - ** return 0; - ** } - */ - pPg = pager_lookup(pPager, pgno); - if( pPg==0 ) return 0; - page_ref(pPg); - return PGHDR_TO_DATA(pPg); -} - -/* -** Release a page. -** -** If the number of references to the page drop to zero, then the -** page is added to the LRU list. When all references to all pages -** are released, a rollback occurs and the lock on the database is -** removed. -*/ -int sqlitepager_unref(void *pData){ - PgHdr *pPg; - - /* Decrement the reference count for this page - */ - pPg = DATA_TO_PGHDR(pData); - assert( pPg->nRef>0 ); - pPg->nRef--; - REFINFO(pPg); - - /* When the number of references to a page reach 0, call the - ** destructor and add the page to the freelist. - */ - if( pPg->nRef==0 ){ - Pager *pPager; - pPager = pPg->pPager; - pPg->pNextFree = 0; - pPg->pPrevFree = pPager->pLast; - pPager->pLast = pPg; - if( pPg->pPrevFree ){ - pPg->pPrevFree->pNextFree = pPg; - }else{ - pPager->pFirst = pPg; - } - if( pPg->needSync==0 && pPager->pFirstSynced==0 ){ - pPager->pFirstSynced = pPg; - } - if( pPager->xDestructor ){ - pPager->xDestructor(pData); - } - - /* When all pages reach the freelist, drop the read lock from - ** the database file. - */ - pPager->nRef--; - assert( pPager->nRef>=0 ); - if( pPager->nRef==0 ){ - pager_reset(pPager); - } - } - return SQLITE_OK; -} - -/* -** Create a journal file for pPager. There should already be a write -** lock on the database file when this routine is called. -** -** Return SQLITE_OK if everything. Return an error code and release the -** write lock if anything goes wrong. -*/ -static int pager_open_journal(Pager *pPager){ - int rc; - assert( pPager->state==SQLITE_WRITELOCK ); - assert( pPager->journalOpen==0 ); - assert( pPager->useJournal ); - sqlitepager_pagecount(pPager); - pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 ); - if( pPager->aInJournal==0 ){ - sqliteOsReadLock(&pPager->fd); - pPager->state = SQLITE_READLOCK; - return SQLITE_NOMEM; - } - rc = sqliteOsOpenExclusive(pPager->zJournal, &pPager->jfd,pPager->tempFile); - if( rc!=SQLITE_OK ){ - sqliteFree(pPager->aInJournal); - pPager->aInJournal = 0; - sqliteOsReadLock(&pPager->fd); - pPager->state = SQLITE_READLOCK; - return SQLITE_CANTOPEN; - } - sqliteOsOpenDirectory(pPager->zDirectory, &pPager->jfd); - pPager->journalOpen = 1; - pPager->journalStarted = 0; - pPager->needSync = 0; - pPager->alwaysRollback = 0; - pPager->nRec = 0; - if( pPager->errMask!=0 ){ - rc = pager_errcode(pPager); - return rc; - } - pPager->origDbSize = pPager->dbSize; - if( journal_format==JOURNAL_FORMAT_3 ){ - rc = sqliteOsWrite(&pPager->jfd, aJournalMagic3, sizeof(aJournalMagic3)); - if( rc==SQLITE_OK ){ - rc = write32bits(&pPager->jfd, pPager->noSync ? 0xffffffff : 0); - } - if( rc==SQLITE_OK ){ - sqliteRandomness(sizeof(pPager->cksumInit), &pPager->cksumInit); - rc = write32bits(&pPager->jfd, pPager->cksumInit); - } - }else if( journal_format==JOURNAL_FORMAT_2 ){ - rc = sqliteOsWrite(&pPager->jfd, aJournalMagic2, sizeof(aJournalMagic2)); - }else{ - assert( journal_format==JOURNAL_FORMAT_1 ); - rc = sqliteOsWrite(&pPager->jfd, aJournalMagic1, sizeof(aJournalMagic1)); - } - if( rc==SQLITE_OK ){ - rc = write32bits(&pPager->jfd, pPager->dbSize); - } - if( pPager->ckptAutoopen && rc==SQLITE_OK ){ - rc = sqlitepager_ckpt_begin(pPager); - } - if( rc!=SQLITE_OK ){ - rc = pager_unwritelock(pPager); - if( rc==SQLITE_OK ){ - rc = SQLITE_FULL; - } - } - return rc; -} - -/* -** Acquire a write-lock on the database. The lock is removed when -** the any of the following happen: -** -** * sqlitepager_commit() is called. -** * sqlitepager_rollback() is called. -** * sqlitepager_close() is called. -** * sqlitepager_unref() is called to on every outstanding page. -** -** The parameter to this routine is a pointer to any open page of the -** database file. Nothing changes about the page - it is used merely -** to acquire a pointer to the Pager structure and as proof that there -** is already a read-lock on the database. -** -** A journal file is opened if this is not a temporary file. For -** temporary files, the opening of the journal file is deferred until -** there is an actual need to write to the journal. -** -** If the database is already write-locked, this routine is a no-op. -*/ -int sqlitepager_begin(void *pData){ - PgHdr *pPg = DATA_TO_PGHDR(pData); - Pager *pPager = pPg->pPager; - int rc = SQLITE_OK; - assert( pPg->nRef>0 ); - assert( pPager->state!=SQLITE_UNLOCK ); - if( pPager->state==SQLITE_READLOCK ){ - assert( pPager->aInJournal==0 ); - rc = sqliteOsWriteLock(&pPager->fd); - if( rc!=SQLITE_OK ){ - return rc; - } - pPager->state = SQLITE_WRITELOCK; - pPager->dirtyFile = 0; - TRACE1("TRANSACTION\n"); - if( pPager->useJournal && !pPager->tempFile ){ - rc = pager_open_journal(pPager); - } - } - return rc; -} - -/* -** Mark a data page as writeable. The page is written into the journal -** if it is not there already. This routine must be called before making -** changes to a page. -** -** The first time this routine is called, the pager creates a new -** journal and acquires a write lock on the database. If the write -** lock could not be acquired, this routine returns SQLITE_BUSY. The -** calling routine must check for that return value and be careful not to -** change any page data until this routine returns SQLITE_OK. -** -** If the journal file could not be written because the disk is full, -** then this routine returns SQLITE_FULL and does an immediate rollback. -** All subsequent write attempts also return SQLITE_FULL until there -** is a call to sqlitepager_commit() or sqlitepager_rollback() to -** reset. -*/ -int sqlitepager_write(void *pData){ - PgHdr *pPg = DATA_TO_PGHDR(pData); - Pager *pPager = pPg->pPager; - int rc = SQLITE_OK; - - /* Check for errors - */ - if( pPager->errMask ){ - return pager_errcode(pPager); - } - if( pPager->readOnly ){ - return SQLITE_PERM; - } - - /* Mark the page as dirty. If the page has already been written - ** to the journal then we can return right away. - */ - pPg->dirty = 1; - if( pPg->inJournal && (pPg->inCkpt || pPager->ckptInUse==0) ){ - pPager->dirtyFile = 1; - return SQLITE_OK; - } - - /* If we get this far, it means that the page needs to be - ** written to the transaction journal or the ckeckpoint journal - ** or both. - ** - ** First check to see that the transaction journal exists and - ** create it if it does not. - */ - assert( pPager->state!=SQLITE_UNLOCK ); - rc = sqlitepager_begin(pData); - if( rc!=SQLITE_OK ){ - return rc; - } - assert( pPager->state==SQLITE_WRITELOCK ); - if( !pPager->journalOpen && pPager->useJournal ){ - rc = pager_open_journal(pPager); - if( rc!=SQLITE_OK ) return rc; - } - assert( pPager->journalOpen || !pPager->useJournal ); - pPager->dirtyFile = 1; - - /* The transaction journal now exists and we have a write lock on the - ** main database file. Write the current page to the transaction - ** journal if it is not there already. - */ - if( !pPg->inJournal && pPager->useJournal ){ - if( (int)pPg->pgno <= pPager->origDbSize ){ - int szPg; - u32 saved; - if( journal_format>=JOURNAL_FORMAT_3 ){ - u32 cksum = pager_cksum(pPager, pPg->pgno, pData); - saved = *(u32*)PGHDR_TO_EXTRA(pPg); - store32bits(cksum, pPg, SQLITE_PAGE_SIZE); - szPg = SQLITE_PAGE_SIZE+8; - }else{ - szPg = SQLITE_PAGE_SIZE+4; - } - store32bits(pPg->pgno, pPg, -4); - CODEC(pPager, pData, pPg->pgno, 7); - rc = sqliteOsWrite(&pPager->jfd, &((char*)pData)[-4], szPg); - TRACE3("JOURNAL %d %d\n", pPg->pgno, pPg->needSync); - CODEC(pPager, pData, pPg->pgno, 0); - if( journal_format>=JOURNAL_FORMAT_3 ){ - *(u32*)PGHDR_TO_EXTRA(pPg) = saved; - } - if( rc!=SQLITE_OK ){ - sqlitepager_rollback(pPager); - pPager->errMask |= PAGER_ERR_FULL; - return rc; - } - pPager->nRec++; - assert( pPager->aInJournal!=0 ); - pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7); - pPg->needSync = !pPager->noSync; - pPg->inJournal = 1; - if( pPager->ckptInUse ){ - pPager->aInCkpt[pPg->pgno/8] |= 1<<(pPg->pgno&7); - page_add_to_ckpt_list(pPg); - } - }else{ - pPg->needSync = !pPager->journalStarted && !pPager->noSync; - TRACE3("APPEND %d %d\n", pPg->pgno, pPg->needSync); - } - if( pPg->needSync ){ - pPager->needSync = 1; - } - } - - /* If the checkpoint journal is open and the page is not in it, - ** then write the current page to the checkpoint journal. Note that - ** the checkpoint journal always uses the simplier format 2 that lacks - ** checksums. The header is also omitted from the checkpoint journal. - */ - if( pPager->ckptInUse && !pPg->inCkpt && (int)pPg->pgno<=pPager->ckptSize ){ - assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize ); - store32bits(pPg->pgno, pPg, -4); - CODEC(pPager, pData, pPg->pgno, 7); - rc = sqliteOsWrite(&pPager->cpfd, &((char*)pData)[-4], SQLITE_PAGE_SIZE+4); - TRACE2("CKPT-JOURNAL %d\n", pPg->pgno); - CODEC(pPager, pData, pPg->pgno, 0); - if( rc!=SQLITE_OK ){ - sqlitepager_rollback(pPager); - pPager->errMask |= PAGER_ERR_FULL; - return rc; - } - pPager->ckptNRec++; - assert( pPager->aInCkpt!=0 ); - pPager->aInCkpt[pPg->pgno/8] |= 1<<(pPg->pgno&7); - page_add_to_ckpt_list(pPg); - } - - /* Update the database size and return. - */ - if( pPager->dbSize<(int)pPg->pgno ){ - pPager->dbSize = pPg->pgno; - } - return rc; -} - -/* -** Return TRUE if the page given in the argument was previously passed -** to sqlitepager_write(). In other words, return TRUE if it is ok -** to change the content of the page. -*/ -int sqlitepager_iswriteable(void *pData){ - PgHdr *pPg = DATA_TO_PGHDR(pData); - return pPg->dirty; -} - -/* -** Replace the content of a single page with the information in the third -** argument. -*/ -int sqlitepager_overwrite(Pager *pPager, Pgno pgno, void *pData){ - void *pPage; - int rc; - - rc = sqlitepager_get(pPager, pgno, &pPage); - if( rc==SQLITE_OK ){ - rc = sqlitepager_write(pPage); - if( rc==SQLITE_OK ){ - memcpy(pPage, pData, SQLITE_PAGE_SIZE); - } - sqlitepager_unref(pPage); - } - return rc; -} - -/* -** A call to this routine tells the pager that it is not necessary to -** write the information on page "pgno" back to the disk, even though -** that page might be marked as dirty. -** -** The overlying software layer calls this routine when all of the data -** on the given page is unused. The pager marks the page as clean so -** that it does not get written to disk. -** -** Tests show that this optimization, together with the -** sqlitepager_dont_rollback() below, more than double the speed -** of large INSERT operations and quadruple the speed of large DELETEs. -** -** When this routine is called, set the alwaysRollback flag to true. -** Subsequent calls to sqlitepager_dont_rollback() 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 dont_rollback() routine is called. But because the page contains -** critical data, we still need to be sure it gets rolled back in spite -** of the dont_rollback() call. -*/ -void sqlitepager_dont_write(Pager *pPager, Pgno pgno){ - PgHdr *pPg; - - pPg = pager_lookup(pPager, pgno); - pPg->alwaysRollback = 1; - if( pPg && pPg->dirty && !pPager->ckptInUse ){ - if( pPager->dbSize==(int)pPg->pgno && pPager->origDbSize<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{ - TRACE2("DONT_WRITE %d\n", pgno); - pPg->dirty = 0; - } - } -} - -/* -** 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. -*/ -void sqlitepager_dont_rollback(void *pData){ - PgHdr *pPg = DATA_TO_PGHDR(pData); - Pager *pPager = pPg->pPager; - - if( pPager->state!=SQLITE_WRITELOCK || pPager->journalOpen==0 ) return; - if( pPg->alwaysRollback || pPager->alwaysRollback ) return; - if( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ){ - assert( pPager->aInJournal!=0 ); - pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7); - pPg->inJournal = 1; - if( pPager->ckptInUse ){ - pPager->aInCkpt[pPg->pgno/8] |= 1<<(pPg->pgno&7); - page_add_to_ckpt_list(pPg); - } - TRACE2("DONT_ROLLBACK %d\n", pPg->pgno); - } - if( pPager->ckptInUse && !pPg->inCkpt && (int)pPg->pgno<=pPager->ckptSize ){ - assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize ); - assert( pPager->aInCkpt!=0 ); - pPager->aInCkpt[pPg->pgno/8] |= 1<<(pPg->pgno&7); - page_add_to_ckpt_list(pPg); - } -} - -/* -** Commit all changes to the database and release the write lock. -** -** If the commit fails for any reason, a rollback attempt is made -** and an error code is returned. If the commit worked, SQLITE_OK -** is returned. -*/ -int sqlitepager_commit(Pager *pPager){ - int rc; - PgHdr *pPg; - - if( pPager->errMask==PAGER_ERR_FULL ){ - rc = sqlitepager_rollback(pPager); - if( rc==SQLITE_OK ){ - rc = SQLITE_FULL; - } - return rc; - } - if( pPager->errMask!=0 ){ - rc = pager_errcode(pPager); - return rc; - } - if( pPager->state!=SQLITE_WRITELOCK ){ - return SQLITE_ERROR; - } - TRACE1("COMMIT\n"); - if( pPager->dirtyFile==0 ){ - /* Exit early (without doing the time-consuming sqliteOsSync() calls) - ** if there have been no changes to the database file. */ - assert( pPager->needSync==0 ); - rc = pager_unwritelock(pPager); - pPager->dbSize = -1; - return rc; - } - assert( pPager->journalOpen ); - rc = syncJournal(pPager); - if( rc!=SQLITE_OK ){ - goto commit_abort; - } - pPg = pager_get_all_dirty_pages(pPager); - if( pPg ){ - rc = pager_write_pagelist(pPg); - if( rc || (!pPager->noSync && sqliteOsSync(&pPager->fd)!=SQLITE_OK) ){ - goto commit_abort; - } - } - rc = pager_unwritelock(pPager); - pPager->dbSize = -1; - return rc; - - /* Jump here if anything goes wrong during the commit process. - */ -commit_abort: - rc = sqlitepager_rollback(pPager); - if( rc==SQLITE_OK ){ - rc = SQLITE_FULL; - } - return rc; -} - -/* -** Rollback all changes. The database falls back to read-only mode. -** All in-memory cache pages revert to their original data contents. -** The journal is deleted. -** -** This routine cannot fail unless some other process is not following -** the correct locking protocol (SQLITE_PROTOCOL) or unless some other -** process is writing trash into the journal file (SQLITE_CORRUPT) or -** unless a prior malloc() failed (SQLITE_NOMEM). Appropriate error -** codes are returned for all these occasions. Otherwise, -** SQLITE_OK is returned. -*/ -int sqlitepager_rollback(Pager *pPager){ - int rc; - TRACE1("ROLLBACK\n"); - if( !pPager->dirtyFile || !pPager->journalOpen ){ - rc = pager_unwritelock(pPager); - pPager->dbSize = -1; - return rc; - } - - if( pPager->errMask!=0 && pPager->errMask!=PAGER_ERR_FULL ){ - if( pPager->state>=SQLITE_WRITELOCK ){ - pager_playback(pPager, 1); - } - return pager_errcode(pPager); - } - if( pPager->state!=SQLITE_WRITELOCK ){ - return SQLITE_OK; - } - rc = pager_playback(pPager, 1); - if( rc!=SQLITE_OK ){ - rc = SQLITE_CORRUPT; - pPager->errMask |= PAGER_ERR_CORRUPT; - } - pPager->dbSize = -1; - return rc; -} - -/* -** Return TRUE if the database file is opened read-only. Return FALSE -** if the database is (in theory) writable. -*/ -int sqlitepager_isreadonly(Pager *pPager){ - return pPager->readOnly; -} - -/* -** This routine is used for testing and analysis only. -*/ -int *sqlitepager_stats(Pager *pPager){ - static int a[9]; - a[0] = pPager->nRef; - a[1] = pPager->nPage; - a[2] = pPager->mxPage; - a[3] = pPager->dbSize; - a[4] = pPager->state; - a[5] = pPager->errMask; - a[6] = pPager->nHit; - a[7] = pPager->nMiss; - a[8] = pPager->nOvfl; - return a; -} - -/* -** Set the checkpoint. -** -** This routine should be called with the transaction journal already -** open. A new checkpoint journal is created that can be used to rollback -** changes of a single SQL command within a larger transaction. -*/ -int sqlitepager_ckpt_begin(Pager *pPager){ - int rc; - char zTemp[SQLITE_TEMPNAME_SIZE]; - if( !pPager->journalOpen ){ - pPager->ckptAutoopen = 1; - return SQLITE_OK; - } - assert( pPager->journalOpen ); - assert( !pPager->ckptInUse ); - pPager->aInCkpt = sqliteMalloc( pPager->dbSize/8 + 1 ); - if( pPager->aInCkpt==0 ){ - sqliteOsReadLock(&pPager->fd); - return SQLITE_NOMEM; - } -#ifndef NDEBUG - rc = sqliteOsFileSize(&pPager->jfd, &pPager->ckptJSize); - if( rc ) goto ckpt_begin_failed; - assert( pPager->ckptJSize == - pPager->nRec*JOURNAL_PG_SZ(journal_format)+JOURNAL_HDR_SZ(journal_format) ); -#endif - pPager->ckptJSize = pPager->nRec*JOURNAL_PG_SZ(journal_format) - + JOURNAL_HDR_SZ(journal_format); - pPager->ckptSize = pPager->dbSize; - if( !pPager->ckptOpen ){ - rc = sqlitepager_opentemp(zTemp, &pPager->cpfd); - if( rc ) goto ckpt_begin_failed; - pPager->ckptOpen = 1; - pPager->ckptNRec = 0; - } - pPager->ckptInUse = 1; - return SQLITE_OK; - -ckpt_begin_failed: - if( pPager->aInCkpt ){ - sqliteFree(pPager->aInCkpt); - pPager->aInCkpt = 0; - } - return rc; -} - -/* -** Commit a checkpoint. -*/ -int sqlitepager_ckpt_commit(Pager *pPager){ - if( pPager->ckptInUse ){ - PgHdr *pPg, *pNext; - sqliteOsSeek(&pPager->cpfd, 0); - /* sqliteOsTruncate(&pPager->cpfd, 0); */ - pPager->ckptNRec = 0; - pPager->ckptInUse = 0; - sqliteFree( pPager->aInCkpt ); - pPager->aInCkpt = 0; - for(pPg=pPager->pCkpt; pPg; pPg=pNext){ - pNext = pPg->pNextCkpt; - assert( pPg->inCkpt ); - pPg->inCkpt = 0; - pPg->pPrevCkpt = pPg->pNextCkpt = 0; - } - pPager->pCkpt = 0; - } - pPager->ckptAutoopen = 0; - return SQLITE_OK; -} - -/* -** Rollback a checkpoint. -*/ -int sqlitepager_ckpt_rollback(Pager *pPager){ - int rc; - if( pPager->ckptInUse ){ - rc = pager_ckpt_playback(pPager); - sqlitepager_ckpt_commit(pPager); - }else{ - rc = SQLITE_OK; - } - pPager->ckptAutoopen = 0; - return rc; -} - -/* -** Return the full pathname of the database file. -*/ -const char *sqlitepager_filename(Pager *pPager){ - return pPager->zFilename; -} - -/* -** Set the codec for this pager -*/ -void sqlitepager_set_codec( - Pager *pPager, - void (*xCodec)(void*,void*,Pgno,int), - void *pCodecArg -){ - pPager->xCodec = xCodec; - pPager->pCodecArg = pCodecArg; -} - -#ifdef SQLITE_TEST -/* -** Print a listing of all referenced pages and their ref count. -*/ -void sqlitepager_refdump(Pager *pPager){ - PgHdr *pPg; - for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ - if( pPg->nRef<=0 ) continue; - printf("PAGE %3d addr=0x%08x nRef=%d\n", - pPg->pgno, (int)PGHDR_TO_DATA(pPg), pPg->nRef); - } -} -#endif |