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-/*
-** 2001 September 15
-**
-** The author disclaims copyright to this source code. In place of
-** a legal notice, here is a blessing:
-**
-** May you do good and not evil.
-** May you find forgiveness for yourself and forgive others.
-** May you share freely, never taking more than you give.
-**
-*************************************************************************
-** This is the implementation of the page cache subsystem or "pager".
-**
-** The pager is used to access a database disk file. It implements
-** atomic commit and rollback through the use of a journal file that
-** is separate from the database file. The pager also implements file
-** locking to prevent two processes from writing the same database
-** file simultaneously, or one process from reading the database while
-** another is writing.
-**
-** @(#) $Id: pager.c,v 1.101 2004/02/25 02:20:41 drh Exp $
-*/
-#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:
-**
-** STQLITE_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.
-**
-** STQLITE_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.
-**
-** STQLITE_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 STQLITE_UNLOCK. The first time a
-** sqlite_page_get() occurs, the state transitions to STQLITE_READLOCK.
-** After all pages have been released using sqlite_page_unref(),
-** the state transitions back to STQLITE_UNLOCK. The first time
-** that sqlite_page_write() is called, the state transitions to
-** STQLITE_WRITELOCK. (Note that sqlite_page_write() can only be
-** called on an outstanding page which means that the pager must
-** be in STQLITE_READLOCK before it transitions to STQLITE_WRITELOCK.)
-** The sqlite_page_rollback() and sqlite_page_commit() functions
-** transition the state from STQLITE_WRITELOCK back to STQLITE_READLOCK.
-*/
-#define STQLITE_UNLOCK 0
-#define STQLITE_READLOCK 1
-#define STQLITE_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 */
- /* STQLITE_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 STQLITE_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]))[STQLITE_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; /* STQLITE_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[STQLITE_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 STQLITE_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 STQLITE_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) \
- (STQLITE_PAGE_SIZE + sizeof(Pgno) + ((X)>=3)*sizeof(u32))
-
-/*
-** Enable reference count tracking here:
-*/
-#ifdef STQLITE_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 STQLITE_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==STQLITE_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 STQLITE_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 = STQLITE_OK;
- if( pPager->errMask & PAGER_ERR_LOCK ) rc = STQLITE_PROTOCOL;
- if( pPager->errMask & PAGER_ERR_DISK ) rc = STQLITE_IOERR;
- if( pPager->errMask & PAGER_ERR_FULL ) rc = STQLITE_FULL;
- if( pPager->errMask & PAGER_ERR_MEM ) rc = STQLITE_NOMEM;
- if( pPager->errMask & PAGER_ERR_CORRUPT ) rc = STQLITE_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>=STQLITE_WRITELOCK ){
- sqlitepager_rollback(pPager);
- }
- sqliteOsUnlock(&pPager->fd);
- pPager->state = STQLITE_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<STQLITE_WRITELOCK ) return STQLITE_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==STQLITE_OK ){
- pPager->state = STQLITE_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 = STQLITE_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!=STQLITE_OK ) return rc;
- rc = sqliteOsRead(jfd, &pgRec.aData, sizeof(pgRec.aData));
- if( rc!=STQLITE_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 STQLITE_DONE;
- }
- if( pgRec.pgno>(unsigned)pPager->dbSize ){
- return STQLITE_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 STQLITE_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)STQLITE_PAGE_SIZE);
- rc = sqliteOsWrite(&pPager->fd, pgRec.aData, STQLITE_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, STQLITE_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.
-** + STQLITE_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 STQLITE_CORRUPT is returned. If it all works, then this routine
-** returns STQLITE_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!=STQLITE_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!=STQLITE_OK ){
- rc = STQLITE_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 = STQLITE_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!=STQLITE_OK ){
- goto end_playback;
- }
- assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg );
- rc = sqliteOsTruncate(&pPager->fd, STQLITE_PAGE_SIZE*(off_t)mxPg);
- if( rc!=STQLITE_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!=STQLITE_OK ){
- if( rc==STQLITE_DONE ){
- rc = STQLITE_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==STQLITE_OK ){
- PgHdr *pPg;
- for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
- char zBuf[STQLITE_PAGE_SIZE];
- if( !pPg->dirty ) continue;
- if( (int)pPg->pgno <= pPager->origDbSize ){
- sqliteOsSeek(&pPager->fd, STQLITE_PAGE_SIZE*(off_t)(pPg->pgno-1));
- rc = sqliteOsRead(&pPager->fd, zBuf, STQLITE_PAGE_SIZE);
- TRACE2("REFETCH %d\n", pPg->pgno);
- CODEC(pPager, zBuf, pPg->pgno, 2);
- if( rc ) break;
- }else{
- memset(zBuf, 0, STQLITE_PAGE_SIZE);
- }
- if( pPg->nRef==0 || memcmp(zBuf, PGHDR_TO_DATA(pPg), STQLITE_PAGE_SIZE) ){
- memcpy(PGHDR_TO_DATA(pPg), zBuf, STQLITE_PAGE_SIZE);
- memset(PGHDR_TO_EXTRA(pPg), 0, pPager->nExtra);
- }
- pPg->needSync = 0;
- pPg->dirty = 0;
- }
- }
-
-end_playback:
- if( rc!=STQLITE_OK ){
- pager_unwritelock(pPager);
- pPager->errMask |= PAGER_ERR_CORRUPT;
- rc = STQLITE_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, STQLITE_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!=STQLITE_DONE );
- if( rc!=STQLITE_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!=STQLITE_OK ){
- goto end_ckpt_playback;
- }
- rc = sqliteOsFileSize(&pPager->jfd, &szJ);
- if( rc!=STQLITE_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!=STQLITE_OK ){
- assert( rc!=STQLITE_DONE );
- goto end_ckpt_playback;
- }
- }
-
-end_ckpt_playback:
- if( rc!=STQLITE_OK ){
- pPager->errMask |= PAGER_ERR_CORRUPT;
- rc = STQLITE_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 STQLITE_TEMPNAME_SIZE bytes long.) Write
-** the file descriptor into *fd. Return STQLITE_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!=STQLITE_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[STQLITE_TEMPNAME_SIZE];
-
- *ppPager = 0;
- if( sqlite_malloc_failed ){
- return STQLITE_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 STQLITE_NOMEM;
- }
- if( rc!=STQLITE_OK ){
- sqliteFree(zFullPathname);
- return STQLITE_CANTOPEN;
- }
- nameLen = strlen(zFullPathname);
- pPager = sqliteMalloc( sizeof(*pPager) + nameLen*3 + 30 );
- if( pPager==0 ){
- sqliteOsClose(&fd);
- sqliteFree(zFullPathname);
- return STQLITE_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 = STQLITE_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 STQLITE_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)!=STQLITE_OK ){
- pPager->errMask |= PAGER_ERR_DISK;
- return 0;
- }
- n /= STQLITE_PAGE_SIZE;
- if( pPager->state!=STQLITE_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 STQLITE_OK;
- }
- syncJournal(pPager);
- rc = sqliteOsTruncate(&pPager->fd, STQLITE_PAGE_SIZE*(off_t)nPage);
- if( rc==STQLITE_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 STQLITE_WRITELOCK: {
- sqlitepager_rollback(pPager);
- sqliteOsUnlock(&pPager->fd);
- assert( pPager->journalOpen==0 );
- break;
- }
- case STQLITE_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 STQLITE_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 STQLITE_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 = STQLITE_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 STQLITE_OK;
- pPager = pList->pPager;
- while( pList ){
- assert( pList->dirty );
- sqliteOsSeek(&pPager->fd, (pList->pgno-1)*(off_t)STQLITE_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), STQLITE_PAGE_SIZE);
- CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 0);
- if( rc ) return rc;
- pList->dirty = 0;
- pList = pList->pDirty;
- }
- return STQLITE_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!=STQLITE_OK ){
- return rc;
- }
- pPager->state = STQLITE_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!=STQLITE_OK ){
- if( sqliteOsUnlock(&pPager->fd)!=STQLITE_OK ){
- /* This should never happen! */
- rc = STQLITE_INTERNAL;
- }
- return rc;
- }
- pPager->state = STQLITE_WRITELOCK;
-
- /* Open the journal for reading only. Return STQLITE_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!=STQLITE_OK ){
- rc = sqliteOsUnlock(&pPager->fd);
- assert( rc==STQLITE_OK );
- return STQLITE_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!=STQLITE_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) + STQLITE_PAGE_SIZE
- + sizeof(u32) + pPager->nExtra );
- if( pPg==0 ){
- pager_unwritelock(pPager);
- pPager->errMask |= PAGER_ERR_MEM;
- return STQLITE_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 STQLITE_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!=STQLITE_OK ){
- sqlitepager_rollback(pPager);
- return STQLITE_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, STQLITE_PAGE_SIZE);
- }else{
- int rc;
- sqliteOsSeek(&pPager->fd, (pgno-1)*(off_t)STQLITE_PAGE_SIZE);
- rc = sqliteOsRead(&pPager->fd, PGHDR_TO_DATA(pPg), STQLITE_PAGE_SIZE);
- TRACE2("FETCH %d\n", pPg->pgno);
- CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
- if( rc!=STQLITE_OK ){
- off_t fileSize;
- if( sqliteOsFileSize(&pPager->fd,&fileSize)!=STQLITE_OK
- || fileSize>=pgno*STQLITE_PAGE_SIZE ){
- sqlitepager_unref(PGHDR_TO_DATA(pPg));
- return rc;
- }else{
- memset(PGHDR_TO_DATA(pPg), 0, STQLITE_PAGE_SIZE);
- }
- }
- }
- }else{
- /* The requested page is in the page cache. */
- pPager->nHit++;
- page_ref(pPg);
- }
- *ppPage = PGHDR_TO_DATA(pPg);
- return STQLITE_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 STQLITE_OK;
-}
-
-/*
-** Create a journal file for pPager. There should already be a write
-** lock on the database file when this routine is called.
-**
-** Return STQLITE_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==STQLITE_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 = STQLITE_READLOCK;
- return STQLITE_NOMEM;
- }
- rc = sqliteOsOpenExclusive(pPager->zJournal, &pPager->jfd,pPager->tempFile);
- if( rc!=STQLITE_OK ){
- sqliteFree(pPager->aInJournal);
- pPager->aInJournal = 0;
- sqliteOsReadLock(&pPager->fd);
- pPager->state = STQLITE_READLOCK;
- return STQLITE_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==STQLITE_OK ){
- rc = write32bits(&pPager->jfd, pPager->noSync ? 0xffffffff : 0);
- }
- if( rc==STQLITE_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==STQLITE_OK ){
- rc = write32bits(&pPager->jfd, pPager->dbSize);
- }
- if( pPager->ckptAutoopen && rc==STQLITE_OK ){
- rc = sqlitepager_ckpt_begin(pPager);
- }
- if( rc!=STQLITE_OK ){
- rc = pager_unwritelock(pPager);
- if( rc==STQLITE_OK ){
- rc = STQLITE_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 = STQLITE_OK;
- assert( pPg->nRef>0 );
- assert( pPager->state!=STQLITE_UNLOCK );
- if( pPager->state==STQLITE_READLOCK ){
- assert( pPager->aInJournal==0 );
- rc = sqliteOsWriteLock(&pPager->fd);
- if( rc!=STQLITE_OK ){
- return rc;
- }
- pPager->state = STQLITE_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 STQLITE_BUSY. The
-** calling routine must check for that return value and be careful not to
-** change any page data until this routine returns STQLITE_OK.
-**
-** If the journal file could not be written because the disk is full,
-** then this routine returns STQLITE_FULL and does an immediate rollback.
-** All subsequent write attempts also return STQLITE_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 = STQLITE_OK;
-
- /* Check for errors
- */
- if( pPager->errMask ){
- return pager_errcode(pPager);
- }
- if( pPager->readOnly ){
- return STQLITE_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 STQLITE_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!=STQLITE_UNLOCK );
- rc = sqlitepager_begin(pData);
- if( rc!=STQLITE_OK ){
- return rc;
- }
- assert( pPager->state==STQLITE_WRITELOCK );
- if( !pPager->journalOpen && pPager->useJournal ){
- rc = pager_open_journal(pPager);
- if( rc!=STQLITE_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, STQLITE_PAGE_SIZE);
- szPg = STQLITE_PAGE_SIZE+8;
- }else{
- szPg = STQLITE_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!=STQLITE_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], STQLITE_PAGE_SIZE+4);
- TRACE2("CKPT-JOURNAL %d\n", pPg->pgno);
- CODEC(pPager, pData, pPg->pgno, 0);
- if( rc!=STQLITE_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==STQLITE_OK ){
- rc = sqlitepager_write(pPage);
- if( rc==STQLITE_OK ){
- memcpy(pPage, pData, STQLITE_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 ){
- 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!=STQLITE_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, STQLITE_OK
-** is returned.
-*/
-int sqlitepager_commit(Pager *pPager){
- int rc;
- PgHdr *pPg;
-
- if( pPager->errMask==PAGER_ERR_FULL ){
- rc = sqlitepager_rollback(pPager);
- if( rc==STQLITE_OK ){
- rc = STQLITE_FULL;
- }
- return rc;
- }
- if( pPager->errMask!=0 ){
- rc = pager_errcode(pPager);
- return rc;
- }
- if( pPager->state!=STQLITE_WRITELOCK ){
- return STQLITE_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!=STQLITE_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)!=STQLITE_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==STQLITE_OK ){
- rc = STQLITE_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 (STQLITE_PROTOCOL) or unless some other
-** process is writing trash into the journal file (STQLITE_CORRUPT) or
-** unless a prior malloc() failed (STQLITE_NOMEM). Appropriate error
-** codes are returned for all these occasions. Otherwise,
-** STQLITE_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>=STQLITE_WRITELOCK ){
- pager_playback(pPager, 1);
- }
- return pager_errcode(pPager);
- }
- if( pPager->state!=STQLITE_WRITELOCK ){
- return STQLITE_OK;
- }
- rc = pager_playback(pPager, 1);
- if( rc!=STQLITE_OK ){
- rc = STQLITE_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[STQLITE_TEMPNAME_SIZE];
- if( !pPager->journalOpen ){
- pPager->ckptAutoopen = 1;
- return STQLITE_OK;
- }
- assert( pPager->journalOpen );
- assert( !pPager->ckptInUse );
- pPager->aInCkpt = sqliteMalloc( pPager->dbSize/8 + 1 );
- if( pPager->aInCkpt==0 ){
- sqliteOsReadLock(&pPager->fd);
- return STQLITE_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 STQLITE_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 STQLITE_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 = STQLITE_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 STQLITE_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