diff options
Diffstat (limited to 'kopete/plugins/statistics/sqlite/pager.c')
| -rw-r--r-- | kopete/plugins/statistics/sqlite/pager.c | 3205 |
1 files changed, 3205 insertions, 0 deletions
diff --git a/kopete/plugins/statistics/sqlite/pager.c b/kopete/plugins/statistics/sqlite/pager.c new file mode 100644 index 00000000..a374562b --- /dev/null +++ b/kopete/plugins/statistics/sqlite/pager.c @@ -0,0 +1,3205 @@ +/* +** 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 "sqliteInt.h" +#include "os.h" +#include "pager.h" +#include <assert.h> +#include <string.h> + +/* +** Macros for troubleshooting. Normally turned off +*/ +#if 0 +#define TRACE1(X) sqlite3DebugPrintf(X) +#define TRACE2(X,Y) sqlite3DebugPrintf(X,Y) +#define TRACE3(X,Y,Z) sqlite3DebugPrintf(X,Y,Z) +#define TRACE4(X,Y,Z,W) sqlite3DebugPrintf(X,Y,Z,W) +#else +#define TRACE1(X) +#define TRACE2(X,Y) +#define TRACE3(X,Y,Z) +#define TRACE4(X,Y,Z,W) +#endif + + +/* +** The page cache as a whole is always in one of the following +** states: +** +** PAGER_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. +** +** PAGER_SHARED 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. +** +** PAGER_RESERVED This process has reserved the database for writing +** but has not yet made any changes. Only one process +** at a time can reserve the database. The original +** database file has not been modified so other +** processes may still be reading the on-disk +** database file. +** +** PAGER_EXCLUSIVE 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. +** +** PAGER_SYNCED The pager moves to this state from PAGER_EXCLUSIVE +** after all dirty pages have been written to the +** database file and the file has been synced to +** disk. All that remains to do is to remove the +** journal file and the transaction will be +** committed. +** +** The page cache comes up in PAGER_UNLOCK. The first time a +** sqlite3pager_get() occurs, the state transitions to PAGER_SHARED. +** After all pages have been released using sqlite_page_unref(), +** the state transitions back to PAGER_UNLOCK. The first time +** that sqlite3pager_write() is called, the state transitions to +** PAGER_RESERVED. (Note that sqlite_page_write() can only be +** called on an outstanding page which means that the pager must +** be in PAGER_SHARED before it transitions to PAGER_RESERVED.) +** The transition to PAGER_EXCLUSIVE occurs when before any changes +** are made to the database file. After an sqlite3pager_rollback() +** or sqlite_pager_commit(), the state goes back to PAGER_SHARED. +*/ +#define PAGER_UNLOCK 0 +#define PAGER_SHARED 1 /* same as SHARED_LOCK */ +#define PAGER_RESERVED 2 /* same as RESERVED_LOCK */ +#define PAGER_EXCLUSIVE 4 /* same as EXCLUSIVE_LOCK */ +#define PAGER_SYNCED 5 + +/* +** If the SQLITE_BUSY_RESERVED_LOCK macro is set to true at compile-time, +** then failed attempts to get a reserved lock will invoke the busy callback. +** This is off by default. To see why, consider the following scenario: +** +** Suppose thread A already has a shared lock and wants a reserved lock. +** Thread B already has a reserved lock and wants an exclusive lock. If +** both threads are using their busy callbacks, it might be a long time +** be for one of the threads give up and allows the other to proceed. +** But if the thread trying to get the reserved lock gives up quickly +** (if it never invokes its busy callback) then the contention will be +** resolved quickly. +*/ +#ifndef SQLITE_BUSY_RESERVED_LOCK +# define SQLITE_BUSY_RESERVED_LOCK 0 +#endif + +/* +** 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 sqlite3pager_write() on a page prior to making +** any modifications to that page. The first time sqlite3pager_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 sqlite3pager_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 */ + PgHdr *pNextFree, *pPrevFree; /* Freelist of pages where nRef==0 */ + PgHdr *pNextAll; /* A list of all pages */ + PgHdr *pNextStmt, *pPrevStmt; /* List of pages in the statement journal */ + u8 inJournal; /* TRUE if has been written to journal */ + u8 inStmt; /* TRUE if in the statement subjournal */ + 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 */ + short int nRef; /* Number of users of this page */ + PgHdr *pDirty; /* Dirty pages sorted by PgHdr.pgno */ + /* pPager->pageSize bytes of page data follow this header */ + /* Pager.nExtra bytes of local data follow the page data */ +}; + +/* +** For an in-memory only database, some extra information is recorded about +** each page so that changes can be rolled back. (Journal files are not +** used for in-memory databases.) The following information is added to +** the end of every EXTRA block for in-memory databases. +** +** This information could have been added directly to the PgHdr structure. +** But then it would take up an extra 8 bytes of storage on every PgHdr +** even for disk-based databases. Splitting it out saves 8 bytes. This +** is only a savings of 0.8% but those percentages add up. +*/ +typedef struct PgHistory PgHistory; +struct PgHistory { + u8 *pOrig; /* Original page text. Restore to this on a full rollback */ + u8 *pStmt; /* Text as it was at the beginning of the current statement */ +}; + +/* +** 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(G,P) ((void*)&((char*)(&(G)[1]))[(P)->pageSize]) +#define PGHDR_TO_HIST(P,PGR) \ + ((PgHistory*)&((char*)(&(P)[1]))[(PGR)->pageSize+(PGR)->nExtra]) + +/* +** 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 stfd; /* File descriptor for the statement subjournal*/ + int dbSize; /* Number of pages in the file */ + int origDbSize; /* dbSize before the current change */ + int stmtSize; /* Size of database (in pages) at stmt_begin() */ + i64 stmtJSize; /* Size of journal at stmt_begin() */ + int nRec; /* Number of pages written to the journal */ + u32 cksumInit; /* Quasi-random value added to every checksum */ + int stmtNRec; /* Number of records in stmt subjournal */ + int nExtra; /* Add this many bytes to each in-memory page */ + void (*xDestructor)(void*,int); /* Call this routine when freeing pages */ + void (*xReiniter)(void*,int); /* Call this routine when reloading pages */ + int pageSize; /* Number of bytes in a page */ + 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 stmtOpen; /* True if the statement subjournal is open */ + u8 stmtInUse; /* True we are in a statement subtransaction */ + u8 stmtAutoopen; /* Open stmt 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; /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */ + 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 dirtyCache; /* True if cached pages have changed */ + u8 alwaysRollback; /* Disable dont_rollback() for all pages */ + u8 memDb; /* True to inhibit all file I/O */ + u8 *aInJournal; /* One bit for each page in the database file */ + u8 *aInStmt; /* One bit for each page in the database */ + u8 setMaster; /* True if a m-j name has been written to jrnl */ + BusyHandler *pBusyHandler; /* Pointer to sqlite.busyHandler */ + PgHdr *pFirst, *pLast; /* List of free pages */ + PgHdr *pFirstSynced; /* First free page with PgHdr.needSync==0 */ + PgHdr *pAll; /* List of all pages */ + PgHdr *pStmt; /* List of pages in the statement subjournal */ + i64 journalOff; /* Current byte offset in the journal file */ + i64 journalHdr; /* Byte offset to previous journal header */ + i64 stmtHdrOff; /* First journal header written this statement */ + i64 stmtCksum; /* cksumInit when statement was started */ + int sectorSize; /* Assumed sector size during rollback */ + PgHdr *aHash[N_PG_HASH]; /* Hash table to map page number to 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? */ + +/* +** Journal files begin with the following magic string. The data +** was obtained from /dev/random. It is used only as a sanity check. +** +** Since version 2.8.0, the journal format contains additional sanity +** checking information. If the power fails while the journal is begin +** 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 new journal format consists +** of a 32-bit checksum on each page of data. The checksum covers both +** the page number and the pPager->pageSize 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 aJournalMagic[] = { + 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7, +}; + +/* +** The size of the header and of each page in the journal is determined +** by the following macros. +*/ +#define JOURNAL_PG_SZ(pPager) ((pPager->pageSize) + 8) + +/* +** The journal header size for this pager. In the future, this could be +** set to some value read from the disk controller. The important +** characteristic is that it is the same size as a disk sector. +*/ +#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize) + +#define PAGER_SECTOR_SIZE 512 + +/* +** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is +** reserved for working around a windows/posix incompatibility). It is +** used in the journal to signify that the remainder of the journal file +** is devoted to storing a master journal name - there are no more pages to +** roll back. See comments for function writeMasterJournal() for details. +*/ +#define PAGER_MJ_PGNO(x) (PENDING_BYTE/((x)->pageSize)) + +/* +** Enable reference count tracking (for debugging) here: +*/ +#ifdef SQLITE_TEST + int pager3_refinfo_enable = 0; + static void pager_refinfo(PgHdr *p){ + static int cnt = 0; + if( !pager3_refinfo_enable ) return; + sqlite3DebugPrintf( + "REFCNT: %4d addr=%p nRef=%d\n", + p->pgno, 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. +** +** All values are stored on disk as big-endian. +*/ +static int read32bits(OsFile *fd, u32 *pRes){ + u32 res; + int rc; + rc = sqlite3OsRead(fd, &res, sizeof(res)); + if( rc==SQLITE_OK ){ + 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. +*/ +static int write32bits(OsFile *fd, u32 val){ + unsigned char ac[4]; + ac[0] = (val>>24) & 0xff; + ac[1] = (val>>16) & 0xff; + ac[2] = (val>>8) & 0xff; + ac[3] = val & 0xff; + return sqlite3OsWrite(fd, ac, 4); +} + +/* +** Write the 32-bit integer 'val' into the page identified by page header +** 'p' at offset 'offset'. +*/ +static void store32bits(u32 val, PgHdr *p, int offset){ + unsigned char *ac; + ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset]; + ac[0] = (val>>24) & 0xff; + ac[1] = (val>>16) & 0xff; + ac[2] = (val>>8) & 0xff; + ac[3] = val & 0xff; +} + +/* +** Read a 32-bit integer at offset 'offset' from the page identified by +** page header 'p'. +*/ +static u32 retrieve32bits(PgHdr *p, int offset){ + unsigned char *ac; + ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset]; + return (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3]; +} + + +/* +** 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; +} + +/* +** When this is called the journal file for pager pPager must be open. +** The master journal file name is read from the end of the file and +** written into memory obtained from sqliteMalloc(). *pzMaster is +** set to point at the memory and SQLITE_OK returned. The caller must +** sqliteFree() *pzMaster. +** +** If no master journal file name is present *pzMaster is set to 0 and +** SQLITE_OK returned. +*/ +static int readMasterJournal(OsFile *pJrnl, char **pzMaster){ + int rc; + u32 len; + i64 szJ; + u32 cksum; + int i; + unsigned char aMagic[8]; /* A buffer to hold the magic header */ + + *pzMaster = 0; + + rc = sqlite3OsFileSize(pJrnl, &szJ); + if( rc!=SQLITE_OK || szJ<16 ) return rc; + + rc = sqlite3OsSeek(pJrnl, szJ-16); + if( rc!=SQLITE_OK ) return rc; + + rc = read32bits(pJrnl, &len); + if( rc!=SQLITE_OK ) return rc; + + rc = read32bits(pJrnl, &cksum); + if( rc!=SQLITE_OK ) return rc; + + rc = sqlite3OsRead(pJrnl, aMagic, 8); + if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc; + + rc = sqlite3OsSeek(pJrnl, szJ-16-len); + if( rc!=SQLITE_OK ) return rc; + + *pzMaster = (char *)sqliteMalloc(len+1); + if( !*pzMaster ){ + return SQLITE_NOMEM; + } + rc = sqlite3OsRead(pJrnl, *pzMaster, len); + if( rc!=SQLITE_OK ){ + sqliteFree(*pzMaster); + *pzMaster = 0; + return rc; + } + + /* See if the checksum matches the master journal name */ + for(i=0; i<len; i++){ + cksum -= (*pzMaster)[i]; + } + if( cksum ){ + /* If the checksum doesn't add up, then one or more of the disk sectors + ** containing the master journal filename is corrupted. This means + ** definitely roll back, so just return SQLITE_OK and report a (nul) + ** master-journal filename. + */ + sqliteFree(*pzMaster); + *pzMaster = 0; + } + (*pzMaster)[len] = '\0'; + + return SQLITE_OK; +} + +/* +** Seek the journal file descriptor to the next sector boundary where a +** journal header may be read or written. Pager.journalOff is updated with +** the new seek offset. +** +** i.e for a sector size of 512: +** +** Input Offset Output Offset +** --------------------------------------- +** 0 0 +** 512 512 +** 100 512 +** 2000 2048 +** +*/ +static int seekJournalHdr(Pager *pPager){ + i64 offset = 0; + i64 c = pPager->journalOff; + if( c ){ + offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager); + } + assert( offset%JOURNAL_HDR_SZ(pPager)==0 ); + assert( offset>=c ); + assert( (offset-c)<JOURNAL_HDR_SZ(pPager) ); + pPager->journalOff = offset; + return sqlite3OsSeek(&pPager->jfd, pPager->journalOff); +} + +/* +** The journal file must be open when this routine is called. A journal +** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the +** current location. +** +** The format for the journal header is as follows: +** - 8 bytes: Magic identifying journal format. +** - 4 bytes: Number of records in journal, or -1 no-sync mode is on. +** - 4 bytes: Random number used for page hash. +** - 4 bytes: Initial database page count. +** - 4 bytes: Sector size used by the process that wrote this journal. +** +** Followed by (JOURNAL_HDR_SZ - 24) bytes of unused space. +*/ +static int writeJournalHdr(Pager *pPager){ + + int rc = seekJournalHdr(pPager); + if( rc ) return rc; + + pPager->journalHdr = pPager->journalOff; + if( pPager->stmtHdrOff==0 ){ + pPager->stmtHdrOff = pPager->journalHdr; + } + pPager->journalOff += JOURNAL_HDR_SZ(pPager); + + /* FIX ME: + ** + ** Possibly for a pager not in no-sync mode, the journal magic should not + ** be written until nRec is filled in as part of next syncJournal(). + ** + ** Actually maybe the whole journal header should be delayed until that + ** point. Think about this. + */ + rc = sqlite3OsWrite(&pPager->jfd, aJournalMagic, sizeof(aJournalMagic)); + + if( rc==SQLITE_OK ){ + /* The nRec Field. 0xFFFFFFFF for no-sync journals. */ + rc = write32bits(&pPager->jfd, pPager->noSync ? 0xffffffff : 0); + } + if( rc==SQLITE_OK ){ + /* The random check-hash initialiser */ + sqlite3Randomness(sizeof(pPager->cksumInit), &pPager->cksumInit); + rc = write32bits(&pPager->jfd, pPager->cksumInit); + } + if( rc==SQLITE_OK ){ + /* The initial database size */ + rc = write32bits(&pPager->jfd, pPager->dbSize); + } + if( rc==SQLITE_OK ){ + /* The assumed sector size for this process */ + rc = write32bits(&pPager->jfd, pPager->sectorSize); + } + + /* The journal header has been written successfully. Seek the journal + ** file descriptor to the end of the journal header sector. + */ + if( rc==SQLITE_OK ){ + sqlite3OsSeek(&pPager->jfd, pPager->journalOff-1); + rc = sqlite3OsWrite(&pPager->jfd, "\000", 1); + } + return rc; +} + +/* +** The journal file must be open when this is called. A journal header file +** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal +** file. See comments above function writeJournalHdr() for a description of +** the journal header format. +** +** If the header is read successfully, *nRec is set to the number of +** page records following this header and *dbSize is set to the size of the +** database before the transaction began, in pages. Also, pPager->cksumInit +** is set to the value read from the journal header. SQLITE_OK is returned +** in this case. +** +** If the journal header file appears to be corrupted, SQLITE_DONE is +** returned and *nRec and *dbSize are not set. If JOURNAL_HDR_SZ bytes +** cannot be read from the journal file an error code is returned. +*/ +static int readJournalHdr( + Pager *pPager, + i64 journalSize, + u32 *pNRec, + u32 *pDbSize +){ + int rc; + unsigned char aMagic[8]; /* A buffer to hold the magic header */ + + rc = seekJournalHdr(pPager); + if( rc ) return rc; + + if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){ + return SQLITE_DONE; + } + + rc = sqlite3OsRead(&pPager->jfd, aMagic, sizeof(aMagic)); + if( rc ) return rc; + + if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){ + return SQLITE_DONE; + } + + rc = read32bits(&pPager->jfd, pNRec); + if( rc ) return rc; + + rc = read32bits(&pPager->jfd, &pPager->cksumInit); + if( rc ) return rc; + + rc = read32bits(&pPager->jfd, pDbSize); + if( rc ) return rc; + + /* Update the assumed sector-size to match the value used by + ** the process that created this journal. If this journal was + ** created by a process other than this one, then this routine + ** is being called from within pager_playback(). The local value + ** of Pager.sectorSize is restored at the end of that routine. + */ + rc = read32bits(&pPager->jfd, (u32 *)&pPager->sectorSize); + if( rc ) return rc; + + pPager->journalOff += JOURNAL_HDR_SZ(pPager); + rc = sqlite3OsSeek(&pPager->jfd, pPager->journalOff); + return rc; +} + + +/* +** Write the supplied master journal name into the journal file for pager +** pPager at the current location. The master journal name must be the last +** thing written to a journal file. If the pager is in full-sync mode, the +** journal file descriptor is advanced to the next sector boundary before +** anything is written. The format is: +** +** + 4 bytes: PAGER_MJ_PGNO. +** + N bytes: length of master journal name. +** + 4 bytes: N +** + 4 bytes: Master journal name checksum. +** + 8 bytes: aJournalMagic[]. +** +** The master journal page checksum is the sum of the bytes in the master +** journal name. +*/ +static int writeMasterJournal(Pager *pPager, const char *zMaster){ + int rc; + int len; + int i; + u32 cksum = 0; + + if( !zMaster || pPager->setMaster) return SQLITE_OK; + pPager->setMaster = 1; + + len = strlen(zMaster); + for(i=0; i<len; i++){ + cksum += zMaster[i]; + } + + /* If in full-sync mode, advance to the next disk sector before writing + ** the master journal name. This is in case the previous page written to + ** the journal has already been synced. + */ + if( pPager->fullSync ){ + rc = seekJournalHdr(pPager); + if( rc!=SQLITE_OK ) return rc; + } + pPager->journalOff += (len+20); + + rc = write32bits(&pPager->jfd, PAGER_MJ_PGNO(pPager)); + if( rc!=SQLITE_OK ) return rc; + + rc = sqlite3OsWrite(&pPager->jfd, zMaster, len); + if( rc!=SQLITE_OK ) return rc; + + rc = write32bits(&pPager->jfd, len); + if( rc!=SQLITE_OK ) return rc; + + rc = write32bits(&pPager->jfd, cksum); + if( rc!=SQLITE_OK ) return rc; + + rc = sqlite3OsWrite(&pPager->jfd, aJournalMagic, sizeof(aJournalMagic)); + pPager->needSync = 1; + return rc; +} + +/* +** Add or remove a page from the list of all pages that are in the +** statement journal. +** +** The Pager keeps a separate list of pages that are currently in +** the statement journal. This helps the sqlite3pager_stmt_commit() +** routine run MUCH faster for the common case where there are many +** pages in memory but only a few are in the statement journal. +*/ +static void page_add_to_stmt_list(PgHdr *pPg){ + Pager *pPager = pPg->pPager; + if( pPg->inStmt ) return; + assert( pPg->pPrevStmt==0 && pPg->pNextStmt==0 ); + pPg->pPrevStmt = 0; + if( pPager->pStmt ){ + pPager->pStmt->pPrevStmt = pPg; + } + pPg->pNextStmt = pPager->pStmt; + pPager->pStmt = pPg; + pPg->inStmt = 1; +} +static void page_remove_from_stmt_list(PgHdr *pPg){ + if( !pPg->inStmt ) return; + if( pPg->pPrevStmt ){ + assert( pPg->pPrevStmt->pNextStmt==pPg ); + pPg->pPrevStmt->pNextStmt = pPg->pNextStmt; + }else{ + assert( pPg->pPager->pStmt==pPg ); + pPg->pPager->pStmt = pPg->pNextStmt; + } + if( pPg->pNextStmt ){ + assert( pPg->pNextStmt->pPrevStmt==pPg ); + pPg->pNextStmt->pPrevStmt = pPg->pPrevStmt; + } + pPg->pNextStmt = 0; + pPg->pPrevStmt = 0; + pPg->inStmt = 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>=PAGER_RESERVED ){ + sqlite3pager_rollback(pPager); + } + sqlite3OsUnlock(&pPager->fd, NO_LOCK); + pPager->state = PAGER_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 RESERVED or EXCLUSIVE lock on the database. This routine releases +** the database lock and acquires a SHARED 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){ + PgHdr *pPg; + int rc; + assert( !pPager->memDb ); + if( pPager->state<PAGER_RESERVED ){ + return SQLITE_OK; + } + sqlite3pager_stmt_commit(pPager); + if( pPager->stmtOpen ){ + sqlite3OsClose(&pPager->stfd); + pPager->stmtOpen = 0; + } + if( pPager->journalOpen ){ + sqlite3OsClose(&pPager->jfd); + pPager->journalOpen = 0; + sqlite3OsDelete(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; + } + pPager->dirtyCache = 0; + pPager->nRec = 0; + }else{ + assert( pPager->dirtyCache==0 || pPager->useJournal==0 ); + } + rc = sqlite3OsUnlock(&pPager->fd, SHARED_LOCK); + pPager->state = PAGER_SHARED; + pPager->origDbSize = 0; + pPager->setMaster = 0; + 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 experimented with +** a checksum of the entire data, but that was found to be too slow. +** +** Note that the page number is stored at the beginning of data and +** the checksum is stored at the end. This is important. If journal +** corruption occurs due to a power failure, the most likely scenario +** is that one end or the other of the record will be changed. It is +** much less likely that the two ends of the journal record will be +** correct and the middle be corrupt. Thus, this "checksum" scheme, +** though fast and simple, catches the mostly likely kind of corruption. +** +** FIX ME: Consider adding every 200th (or so) byte of the data to the +** checksum. That way if a single page spans 3 or more disk sectors and +** only the middle sector is corrupt, we will still have a reasonable +** chance of failing the checksum and thus detecting the problem. +*/ +static u32 pager_cksum(Pager *pPager, Pgno pgno, const char *aData){ + u32 cksum = pPager->cksumInit; + int i = pPager->pageSize-200; + while( i>0 ){ + cksum += aData[i]; + i -= 200; + } + return cksum; +} + +/* +** Read a single page from the journal file opened on file descriptor +** jfd. Playback this one page. +** +** If useCksum==0 it means this journal does not use checksums. Checksums +** are not used in statement journals because statement journals do not +** need to survive power failures. +*/ +static int pager_playback_one_page(Pager *pPager, OsFile *jfd, int useCksum){ + int rc; + PgHdr *pPg; /* An existing page in the cache */ + Pgno pgno; /* The page number of a page in journal */ + u32 cksum; /* Checksum used for sanity checking */ + u8 aData[SQLITE_MAX_PAGE_SIZE]; /* Temp storage for a page */ + + rc = read32bits(jfd, &pgno); + if( rc!=SQLITE_OK ) return rc; + rc = sqlite3OsRead(jfd, &aData, pPager->pageSize); + if( rc!=SQLITE_OK ) return rc; + pPager->journalOff += pPager->pageSize + 4; + + /* 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( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){ + return SQLITE_DONE; + } + if( pgno>(unsigned)pPager->dbSize ){ + return SQLITE_OK; + } + if( useCksum ){ + rc = read32bits(jfd, &cksum); + if( rc ) return rc; + pPager->journalOff += 4; + if( pager_cksum(pPager, pgno, aData)!=cksum ){ + return SQLITE_DONE; + } + } + + assert( pPager->state==PAGER_RESERVED || pPager->state>=PAGER_EXCLUSIVE ); + + /* If the pager is in RESERVED state, then there must be a copy of this + ** page in the pager cache. In this case just update the pager cache, + ** not the database file. The page is left marked dirty in this case. + ** + ** If in EXCLUSIVE state, then we update the pager cache if it exists + ** and the main file. The page is then marked not dirty. + */ + pPg = pager_lookup(pPager, pgno); + assert( pPager->state>=PAGER_EXCLUSIVE || pPg ); + TRACE3("PLAYBACK %d page %d\n", pPager->fd.h, pgno); + if( pPager->state>=PAGER_EXCLUSIVE ){ + sqlite3OsSeek(&pPager->fd, (pgno-1)*(i64)pPager->pageSize); + rc = sqlite3OsWrite(&pPager->fd, aData, pPager->pageSize); + } + 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. + */ + void *pData; + assert( pPg->nRef==0 || pPg->pgno==1 ); + pData = PGHDR_TO_DATA(pPg); + memcpy(pData, aData, pPager->pageSize); + if( pPager->xDestructor ){ /*** FIX ME: Should this be xReinit? ***/ + pPager->xDestructor(pData, pPager->pageSize); + } + if( pPager->state>=PAGER_EXCLUSIVE ){ + pPg->dirty = 0; + pPg->needSync = 0; + } + CODEC(pPager, pData, pPg->pgno, 3); + } + return rc; +} + +/* +** Parameter zMaster is the name of a master journal file. A single journal +** file that referred to the master journal file has just been rolled back. +** This routine checks if it is possible to delete the master journal file, +** and does so if it is. +** +** The master journal file contains the names of all child journals. +** To tell if a master journal can be deleted, check to each of the +** children. If all children are either missing or do not refer to +** a different master journal, then this master journal can be deleted. +*/ +static int pager_delmaster(const char *zMaster){ + int rc; + int master_open = 0; + OsFile master; + char *zMasterJournal = 0; /* Contents of master journal file */ + i64 nMasterJournal; /* Size of master journal file */ + + /* Open the master journal file exclusively in case some other process + ** is running this routine also. Not that it makes too much difference. + */ + memset(&master, 0, sizeof(master)); + rc = sqlite3OsOpenReadOnly(zMaster, &master); + if( rc!=SQLITE_OK ) goto delmaster_out; + master_open = 1; + rc = sqlite3OsFileSize(&master, &nMasterJournal); + if( rc!=SQLITE_OK ) goto delmaster_out; + + if( nMasterJournal>0 ){ + char *zJournal; + char *zMasterPtr = 0; + + /* Load the entire master journal file into space obtained from + ** sqliteMalloc() and pointed to by zMasterJournal. + */ + zMasterJournal = (char *)sqliteMalloc(nMasterJournal); + if( !zMasterJournal ){ + rc = SQLITE_NOMEM; + goto delmaster_out; + } + rc = sqlite3OsRead(&master, zMasterJournal, nMasterJournal); + if( rc!=SQLITE_OK ) goto delmaster_out; + + zJournal = zMasterJournal; + while( (zJournal-zMasterJournal)<nMasterJournal ){ + if( sqlite3OsFileExists(zJournal) ){ + /* One of the journals pointed to by the master journal exists. + ** Open it and check if it points at the master journal. If + ** so, return without deleting the master journal file. + */ + OsFile journal; + + memset(&journal, 0, sizeof(journal)); + rc = sqlite3OsOpenReadOnly(zJournal, &journal); + if( rc!=SQLITE_OK ){ + goto delmaster_out; + } + + rc = readMasterJournal(&journal, &zMasterPtr); + sqlite3OsClose(&journal); + if( rc!=SQLITE_OK ){ + goto delmaster_out; + } + + if( zMasterPtr && !strcmp(zMasterPtr, zMaster) ){ + /* We have a match. Do not delete the master journal file. */ + goto delmaster_out; + } + } + zJournal += (strlen(zJournal)+1); + } + } + + sqlite3OsDelete(zMaster); + +delmaster_out: + if( zMasterJournal ){ + sqliteFree(zMasterJournal); + } + if( master_open ){ + sqlite3OsClose(&master); + } + return rc; +} + +/* +** Make every page in the cache agree with what is on disk. In other words, +** reread the disk to reset the state of the cache. +** +** This routine is called after a rollback in which some of the dirty cache +** pages had never been written out to disk. We need to roll back the +** cache content and the easiest way to do that is to reread the old content +** back from the disk. +*/ +static int pager_reload_cache(Pager *pPager){ + PgHdr *pPg; + int rc = SQLITE_OK; + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + char zBuf[SQLITE_MAX_PAGE_SIZE]; + if( !pPg->dirty ) continue; + if( (int)pPg->pgno <= pPager->origDbSize ){ + sqlite3OsSeek(&pPager->fd, pPager->pageSize*(i64)(pPg->pgno-1)); + rc = sqlite3OsRead(&pPager->fd, zBuf, pPager->pageSize); + TRACE3("REFETCH %d page %d\n", pPager->fd.h, pPg->pgno); + if( rc ) break; + CODEC(pPager, zBuf, pPg->pgno, 2); + }else{ + memset(zBuf, 0, pPager->pageSize); + } + if( pPg->nRef==0 || memcmp(zBuf, PGHDR_TO_DATA(pPg), pPager->pageSize) ){ + memcpy(PGHDR_TO_DATA(pPg), zBuf, pPager->pageSize); + if( pPager->xReiniter ){ + pPager->xReiniter(PGHDR_TO_DATA(pPg), pPager->pageSize); + }else{ + memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra); + } + } + pPg->needSync = 0; + pPg->dirty = 0; + } + return rc; +} + +/* +** Truncate the main file of the given pager to the number of pages +** indicated. +*/ +static int pager_truncate(Pager *pPager, int nPage){ + return sqlite3OsTruncate(&pPager->fd, pPager->pageSize*(i64)nPage); +} + +/* +** 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: +** +** (1) 8 byte prefix. A copy of aJournalMagic[]. +** (2) 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. +** (3) 4 byte big-endian integer which is the initial value for the +** sanity checksum. +** (4) 4 byte integer which is the number of pages to truncate the +** database to during a rollback. +** (5) 4 byte integer which is the number of bytes in the master journal +** name. The value may be zero (indicate that there is no master +** journal.) +** (6) N bytes of the master journal name. The name will be nul-terminated +** and might be shorter than the value read from (5). If the first byte +** of the name is \000 then there is no master journal. The master +** journal name is stored in UTF-8. +** (7) Zero or more pages instances, each as follows: +** + 4 byte page number. +** + pPager->pageSize bytes of data. +** + 4 byte checksum +** +** When we speak of the journal header, we mean the first 6 items above. +** Each entry in the journal is an instance of the 7th item. +** +** 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. +** +** If the file opened as the journal file is not a well-formed +** journal file then all pages up to the first corrupted page are rolled +** back (or no pages if the journal header is corrupted). The journal file +** is then deleted and SQLITE_OK returned, just as if no corruption had +** been encountered. +** +** If an I/O or malloc() error occurs, the journal-file is not deleted +** and an error code is returned. +*/ +static int pager_playback(Pager *pPager){ + i64 szJ; /* Size of the journal file in bytes */ + u32 nRec; /* Number of Records in the journal */ + int i; /* Loop counter */ + Pgno mxPg = 0; /* Size of the original file in pages */ + int rc; /* Result code of a subroutine */ + char *zMaster = 0; /* Name of master journal file if any */ + + /* Figure out how many records are in the journal. Abort early if + ** the journal is empty. + */ + assert( pPager->journalOpen ); + rc = sqlite3OsFileSize(&pPager->jfd, &szJ); + if( rc!=SQLITE_OK ){ + goto end_playback; + } + + /* Read the master journal name from the journal, if it is present. + ** If a master journal file name is specified, but the file is not + ** present on disk, then the journal is not hot and does not need to be + ** played back. + */ + rc = readMasterJournal(&pPager->jfd, &zMaster); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK || (zMaster && !sqlite3OsFileExists(zMaster)) ){ + sqliteFree(zMaster); + zMaster = 0; + if( rc==SQLITE_DONE ) rc = SQLITE_OK; + goto end_playback; + } + sqlite3OsSeek(&pPager->jfd, 0); + pPager->journalOff = 0; + + /* This loop terminates either when the readJournalHdr() call returns + ** SQLITE_DONE or an IO error occurs. */ + while( 1 ){ + + /* Read the next journal header from the journal file. If there are + ** not enough bytes left in the journal file for a complete header, or + ** it is corrupted, then a process must of failed while writing it. + ** This indicates nothing more needs to be rolled back. + */ + rc = readJournalHdr(pPager, szJ, &nRec, &mxPg); + if( rc!=SQLITE_OK ){ + if( rc==SQLITE_DONE ){ + rc = SQLITE_OK; + } + goto end_playback; + } + + /* If nRec is 0xffffffff, then this journal was created by a process + ** working in no-sync mode. This means that the rest of the journal + ** file consists of pages, there are no more journal headers. Compute + ** the value of nRec based on this assumption. + */ + if( nRec==0xffffffff ){ + assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ); + nRec = (szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager); + } + + /* If this is the first header read from the journal, truncate the + ** database file back to it's original size. + */ + if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){ + assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg ); + rc = pager_truncate(pPager, mxPg); + if( rc!=SQLITE_OK ){ + goto end_playback; + } + pPager->dbSize = mxPg; + } + + /* rc = sqlite3OsSeek(&pPager->jfd, JOURNAL_HDR_SZ(pPager)); */ + if( rc!=SQLITE_OK ) goto end_playback; + + /* 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, 1); + if( rc!=SQLITE_OK ){ + if( rc==SQLITE_DONE ){ + rc = SQLITE_OK; + pPager->journalOff = szJ; + break; + }else{ + goto end_playback; + } + } + } + } + + /* 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. + */ + assert( rc==SQLITE_OK ); + pager_reload_cache(pPager); + +end_playback: + if( rc==SQLITE_OK ){ + rc = pager_unwritelock(pPager); + } + if( zMaster ){ + /* If there was a master journal and this routine will return true, + ** see if it is possible to delete the master journal. If errors + ** occur during this process, ignore them. + */ + if( rc==SQLITE_OK ){ + pager_delmaster(zMaster); + } + sqliteFree(zMaster); + } + + /* The Pager.sectorSize variable may have been updated while rolling + ** back a journal created by a process with a different PAGER_SECTOR_SIZE + ** value. Reset it to the correct value for this process. + */ + pPager->sectorSize = PAGER_SECTOR_SIZE; + return rc; +} + +/* +** Playback the statement 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 statement is stored in pPager->stmtSize, not in the +** journal file itself. +** +** (2) In addition to playing back the statement journal, also +** playback all pages of the transaction journal beginning +** at offset pPager->stmtJSize. +*/ +static int pager_stmt_playback(Pager *pPager){ + i64 szJ; /* Size of the full journal */ + i64 hdrOff; + int nRec; /* Number of Records */ + int i; /* Loop counter */ + int rc; + + szJ = pPager->journalOff; +#ifndef NDEBUG + { + i64 os_szJ; + rc = sqlite3OsFileSize(&pPager->jfd, &os_szJ); + if( rc!=SQLITE_OK ) return rc; + assert( szJ==os_szJ ); + } +#endif + + /* Set hdrOff to be the offset to the first journal header written + ** this statement transaction, or the end of the file if no journal + ** header was written. + */ + hdrOff = pPager->stmtHdrOff; + assert( pPager->fullSync || !hdrOff ); + if( !hdrOff ){ + hdrOff = szJ; + } + + + /* Truncate the database back to its original size. + */ + rc = pager_truncate(pPager, pPager->stmtSize); + pPager->dbSize = pPager->stmtSize; + + /* Figure out how many records are in the statement journal. + */ + assert( pPager->stmtInUse && pPager->journalOpen ); + sqlite3OsSeek(&pPager->stfd, 0); + nRec = pPager->stmtNRec; + + /* Copy original pages out of the statement journal and back into the + ** database file. Note that the statement journal omits checksums from + ** each record since power-failure recovery is not important to statement + ** journals. + */ + for(i=nRec-1; i>=0; i--){ + rc = pager_playback_one_page(pPager, &pPager->stfd, 0); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK ) goto end_stmt_playback; + } + + /* Now roll some pages back from the transaction journal. Pager.stmtJSize + ** was the size of the journal file when this statement was started, so + ** everything after that needs to be rolled back, either into the + ** database, the memory cache, or both. + ** + ** If it is not zero, then Pager.stmtHdrOff is the offset to the start + ** of the first journal header written during this statement transaction. + */ + rc = sqlite3OsSeek(&pPager->jfd, pPager->stmtJSize); + if( rc!=SQLITE_OK ){ + goto end_stmt_playback; + } + pPager->journalOff = pPager->stmtJSize; + pPager->cksumInit = pPager->stmtCksum; + assert( JOURNAL_HDR_SZ(pPager)<(pPager->pageSize+8) ); + while( pPager->journalOff <= (hdrOff-(pPager->pageSize+8)) ){ + rc = pager_playback_one_page(pPager, &pPager->jfd, 1); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK ) goto end_stmt_playback; + } + + while( pPager->journalOff < szJ ){ + u32 nRec; + u32 dummy; + rc = readJournalHdr(pPager, szJ, &nRec, &dummy); + if( rc!=SQLITE_OK ){ + assert( rc!=SQLITE_DONE ); + goto end_stmt_playback; + } + if( nRec==0 ){ + nRec = (szJ - pPager->journalOff) / (pPager->pageSize+8); + } + for(i=nRec-1; i>=0 && pPager->journalOff < szJ; i--){ + rc = pager_playback_one_page(pPager, &pPager->jfd, 1); + assert( rc!=SQLITE_DONE ); + if( rc!=SQLITE_OK ) goto end_stmt_playback; + } + } + + pPager->journalOff = szJ; + +end_stmt_playback: + if( rc!=SQLITE_OK ){ + pPager->errMask |= PAGER_ERR_CORRUPT; + rc = SQLITE_CORRUPT; /* bkpt-CORRUPT */ + }else{ + pPager->journalOff = szJ; + /* pager_reload_cache(pPager); */ + } + 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 sqlite3OsSync(). 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 sqlite3pager_set_cachesize(Pager *pPager, int mxPage){ + if( mxPage>=0 ){ + pPager->noSync = pPager->tempFile; + if( pPager->noSync ) pPager->needSync = 0; + }else{ + pPager->noSync = 1; + mxPage = -mxPage; + } + if( mxPage>10 ){ + pPager->mxPage = mxPage; + }else{ + pPager->mxPage = 10; + } +} + +/* +** 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 sqlite3OsSync() 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 sqlite3pager_set_safety_level(Pager *pPager, int level){ + pPager->noSync = level==1 || pPager->tempFile; + pPager->fullSync = level==3 && !pPager->tempFile; + if( pPager->noSync ) 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 sqlite3pager_opentemp(char *zFile, OsFile *fd){ + int cnt = 8; + int rc; + do{ + cnt--; + sqlite3OsTempFileName(zFile); + rc = sqlite3OsOpenExclusive(zFile, fd, 1); + }while( cnt>0 && rc!=SQLITE_OK && rc!=SQLITE_NOMEM ); + 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 sqlite3pager_get() and is only held open until the +** last page is released using sqlite3pager_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. +** +** If zFilename is ":memory:" then all information is held in cache. +** It is never written to disk. This can be used to implement an +** in-memory database. +*/ +int sqlite3pager_open( + Pager **ppPager, /* Return the Pager structure here */ + const char *zFilename, /* Name of the database file to open */ + int nExtra, /* Extra bytes append to each in-memory page */ + int useJournal /* TRUE to use a rollback journal on this file */ +){ + Pager *pPager; + char *zFullPathname = 0; + int nameLen; + OsFile fd; + int rc = SQLITE_OK; + int i; + int tempFile = 0; + int memDb = 0; + int readOnly = 0; + char zTemp[SQLITE_TEMPNAME_SIZE]; + + *ppPager = 0; + memset(&fd, 0, sizeof(fd)); + if( sqlite3_malloc_failed ){ + return SQLITE_NOMEM; + } + if( zFilename && zFilename[0] ){ + if( strcmp(zFilename,":memory:")==0 ){ + memDb = 1; + zFullPathname = sqliteStrDup(""); + rc = SQLITE_OK; + }else{ + zFullPathname = sqlite3OsFullPathname(zFilename); + if( zFullPathname ){ + rc = sqlite3OsOpenReadWrite(zFullPathname, &fd, &readOnly); + } + } + }else{ + rc = sqlite3pager_opentemp(zTemp, &fd); + zFilename = zTemp; + zFullPathname = sqlite3OsFullPathname(zFilename); + if( rc==SQLITE_OK ){ + tempFile = 1; + } + } + if( !zFullPathname ){ + sqlite3OsClose(&fd); + return SQLITE_NOMEM; + } + if( rc!=SQLITE_OK ){ + sqlite3OsClose(&fd); + sqliteFree(zFullPathname); + return rc; + } + nameLen = strlen(zFullPathname); + pPager = sqliteMalloc( sizeof(*pPager) + nameLen*3 + 30 ); + if( pPager==0 ){ + sqlite3OsClose(&fd); + sqliteFree(zFullPathname); + return SQLITE_NOMEM; + } + TRACE3("OPEN %d %s\n", fd.h, zFullPathname); + 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; +#if OS_UNIX + pPager->fd.pPager = pPager; +#endif + pPager->journalOpen = 0; + pPager->useJournal = useJournal && !memDb; + pPager->stmtOpen = 0; + pPager->stmtInUse = 0; + pPager->nRef = 0; + pPager->dbSize = memDb-1; + pPager->pageSize = SQLITE_DEFAULT_PAGE_SIZE; + pPager->stmtSize = 0; + pPager->stmtJSize = 0; + pPager->nPage = 0; + pPager->mxPage = 100; + pPager->state = PAGER_UNLOCK; + pPager->errMask = 0; + pPager->tempFile = tempFile; + pPager->memDb = memDb; + pPager->readOnly = readOnly; + pPager->needSync = 0; + pPager->noSync = pPager->tempFile || !useJournal; + pPager->fullSync = (pPager->noSync?0:1); + pPager->pFirst = 0; + pPager->pFirstSynced = 0; + pPager->pLast = 0; + pPager->nExtra = nExtra; + pPager->sectorSize = PAGER_SECTOR_SIZE; + pPager->pBusyHandler = 0; + memset(pPager->aHash, 0, sizeof(pPager->aHash)); + *ppPager = pPager; + return SQLITE_OK; +} + +/* +** Set the busy handler function. +*/ +void sqlite3pager_set_busyhandler(Pager *pPager, BusyHandler *pBusyHandler){ + pPager->pBusyHandler = pBusyHandler; +} + +/* +** 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 sqlite3pager_close(). +** Destructors are only called by sqlite3pager_unref(). +*/ +void sqlite3pager_set_destructor(Pager *pPager, void (*xDesc)(void*,int)){ + pPager->xDestructor = xDesc; +} + +/* +** Set the reinitializer for this pager. If not NULL, the reinitializer +** is called when the content of a page in cache is restored to its original +** value as a result of a rollback. The callback gives higher-level code +** an opportunity to restore the EXTRA section to agree with the restored +** page data. +*/ +void sqlite3pager_set_reiniter(Pager *pPager, void (*xReinit)(void*,int)){ + pPager->xReiniter = xReinit; +} + +/* +** Set the page size. +** +** The page size must only be changed when the cache is empty. +*/ +void sqlite3pager_set_pagesize(Pager *pPager, int pageSize){ + assert( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE ); + pPager->pageSize = pageSize; +} + +/* +** Read the first N bytes from the beginning of the file into memory +** that pDest points to. No error checking is done. +*/ +void sqlite3pager_read_fileheader(Pager *pPager, int N, unsigned char *pDest){ + memset(pDest, 0, N); + if( pPager->memDb==0 ){ + sqlite3OsSeek(&pPager->fd, 0); + sqlite3OsRead(&pPager->fd, pDest, N); + } +} + +/* +** Return the total number of pages in the disk file associated with +** pPager. +*/ +int sqlite3pager_pagecount(Pager *pPager){ + i64 n; + assert( pPager!=0 ); + if( pPager->dbSize>=0 ){ + return pPager->dbSize; + } + if( sqlite3OsFileSize(&pPager->fd, &n)!=SQLITE_OK ){ + pPager->errMask |= PAGER_ERR_DISK; + return 0; + } + n /= pPager->pageSize; + if( !pPager->memDb && n==PENDING_BYTE/pPager->pageSize ){ + n++; + } + if( pPager->state!=PAGER_UNLOCK ){ + pPager->dbSize = n; + } + return n; +} + +/* +** Forward declaration +*/ +static int syncJournal(Pager*); + + +/* +** Unlink a page from the free list (the list of all pages where nRef==0) +** and from its hash collision chain. +*/ +static void unlinkPage(PgHdr *pPg){ + Pager *pPager = pPg->pPager; + + /* Keep the pFirstSynced pointer pointing at the first synchronized page */ + if( pPg==pPager->pFirstSynced ){ + PgHdr *p = pPg->pNextFree; + while( p && p->needSync ){ p = p->pNextFree; } + pPager->pFirstSynced = p; + } + + /* Unlink from the freelist */ + 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; + + /* Unlink from the pgno hash table */ + if( pPg->pNextHash ){ + pPg->pNextHash->pPrevHash = pPg->pPrevHash; + } + if( pPg->pPrevHash ){ + pPg->pPrevHash->pNextHash = pPg->pNextHash; + }else{ + int h = pager_hash(pPg->pgno); + assert( pPager->aHash[h]==pPg ); + pPager->aHash[h] = pPg->pNextHash; + } + pPg->pNextHash = pPg->pPrevHash = 0; +} + +/* +** This routine is used to truncate an in-memory database. Delete +** all pages whose pgno is larger than pPager->dbSize and is unreferenced. +** Referenced pages larger than pPager->dbSize are zeroed. +*/ +static void memoryTruncate(Pager *pPager){ + PgHdr *pPg; + PgHdr **ppPg; + int dbSize = pPager->dbSize; + + ppPg = &pPager->pAll; + while( (pPg = *ppPg)!=0 ){ + if( pPg->pgno<=dbSize ){ + ppPg = &pPg->pNextAll; + }else if( pPg->nRef>0 ){ + memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize); + ppPg = &pPg->pNextAll; + }else{ + *ppPg = pPg->pNextAll; + unlinkPage(pPg); + sqliteFree(pPg); + pPager->nPage--; + } + } +} + +/* +** Truncate the file to the number of pages specified. +*/ +int sqlite3pager_truncate(Pager *pPager, Pgno nPage){ + int rc; + sqlite3pager_pagecount(pPager); + if( pPager->errMask!=0 ){ + rc = pager_errcode(pPager); + return rc; + } + if( nPage>=(unsigned)pPager->dbSize ){ + return SQLITE_OK; + } + if( pPager->memDb ){ + pPager->dbSize = nPage; + memoryTruncate(pPager); + return SQLITE_OK; + } + rc = syncJournal(pPager); + if( rc!=SQLITE_OK ){ + return rc; + } + rc = pager_truncate(pPager, 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 sqlite3pager_close(Pager *pPager){ + PgHdr *pPg, *pNext; + switch( pPager->state ){ + case PAGER_RESERVED: + case PAGER_SYNCED: + case PAGER_EXCLUSIVE: { + sqlite3pager_rollback(pPager); + if( !pPager->memDb ){ + sqlite3OsUnlock(&pPager->fd, NO_LOCK); + } + assert( pPager->journalOpen==0 ); + break; + } + case PAGER_SHARED: { + if( !pPager->memDb ){ + sqlite3OsUnlock(&pPager->fd, NO_LOCK); + } + break; + } + default: { + /* Do nothing */ + break; + } + } + for(pPg=pPager->pAll; pPg; pPg=pNext){ +#ifndef NDEBUG + if( pPager->memDb ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + assert( !pPg->alwaysRollback ); + assert( !pHist->pOrig ); + assert( !pHist->pStmt ); + } +#endif + pNext = pPg->pNextAll; + sqliteFree(pPg); + } + TRACE2("CLOSE %d\n", pPager->fd.h); + sqlite3OsClose(&pPager->fd); + assert( pPager->journalOpen==0 ); + /* Temp files are automatically deleted by the OS + ** if( pPager->tempFile ){ + ** sqlite3OsDelete(pPager->zFilename); + ** } + */ + 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 sqlite3pager_pagenumber(void *pData){ + PgHdr *p = DATA_TO_PGHDR(pData); + return p->pgno; +} + +/* +** The page_ref() function increments 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. +** +** For non-test systems, page_ref() is a macro that calls _page_ref() +** online of the reference count is zero. For test systems, page_ref() +** is a real function so that we can set breakpoints and trace it. +*/ +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); +} +#ifdef SQLITE_TEST + static void page_ref(PgHdr *pPg){ + if( pPg->nRef==0 ){ + _page_ref(pPg); + }else{ + pPg->nRef++; + REFINFO(pPg); + } + } +#else +# define page_ref(P) ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++) +#endif + +/* +** Increment the reference count for a page. The input pointer is +** a reference to the page data. +*/ +int sqlite3pager_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. + */ + i64 jSz; + rc = sqlite3OsFileSize(&pPager->jfd, &jSz); + if( rc!=0 ) return rc; + assert( pPager->journalOff==jSz ); + } +#endif + { + /* Write the nRec value into the journal file header. If in + ** full-synchronous mode, sync the journal first. This ensures that + ** all data has really hit the disk before nRec is updated to mark + ** it as a candidate for rollback. + */ + if( pPager->fullSync ){ + TRACE2("SYNC journal of %d\n", pPager->fd.h); + rc = sqlite3OsSync(&pPager->jfd); + if( rc!=0 ) return rc; + } + sqlite3OsSeek(&pPager->jfd, pPager->journalHdr + sizeof(aJournalMagic)); + rc = write32bits(&pPager->jfd, pPager->nRec); + if( rc ) return rc; + + sqlite3OsSeek(&pPager->jfd, pPager->journalOff); + } + TRACE2("SYNC journal of %d\n", pPager->fd.h); + rc = sqlite3OsSync(&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; +} + +/* +** Try to obtain a lock on a file. Invoke the busy callback if the lock +** is currently not available. Repeate until the busy callback returns +** false or until the lock succeeds. +** +** Return SQLITE_OK on success and an error code if we cannot obtain +** the lock. +*/ +static int pager_wait_on_lock(Pager *pPager, int locktype){ + int rc; + assert( PAGER_SHARED==SHARED_LOCK ); + assert( PAGER_RESERVED==RESERVED_LOCK ); + assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK ); + if( pPager->state>=locktype ){ + rc = SQLITE_OK; + }else{ + int busy = 1; + do { + rc = sqlite3OsLock(&pPager->fd, locktype); + }while( rc==SQLITE_BUSY && + pPager->pBusyHandler && + pPager->pBusyHandler->xFunc && + pPager->pBusyHandler->xFunc(pPager->pBusyHandler->pArg, busy++) + ); + if( rc==SQLITE_OK ){ + pPager->state = locktype; + } + } + 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; + + /* At this point there may be either a RESERVED or EXCLUSIVE lock on the + ** database file. If there is already an EXCLUSIVE lock, the following + ** calls to sqlite3OsLock() are no-ops. + ** + ** Moving the lock from RESERVED to EXCLUSIVE actually involves going + ** through an intermediate state PENDING. A PENDING lock prevents new + ** readers from attaching to the database but is unsufficient for us to + ** write. The idea of a PENDING lock is to prevent new readers from + ** coming in while we wait for existing readers to clear. + ** + ** While the pager is in the RESERVED state, the original database file + ** is unchanged and we can rollback without having to playback the + ** journal into the original database file. Once we transition to + ** EXCLUSIVE, it means the database file has been changed and any rollback + ** will require a journal playback. + */ + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK); + if( rc!=SQLITE_OK ){ + return rc; + } + + while( pList ){ + assert( pList->dirty ); + sqlite3OsSeek(&pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize); + CODEC(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6); + TRACE3("STORE %d page %d\n", pPager->fd.h, pList->pgno); + rc = sqlite3OsWrite(&pPager->fd, PGHDR_TO_DATA(pList), pPager->pageSize); + 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 sqlite3pager_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 sqlite3pager_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 SHARED lock + ** on the database file. + */ + if( pPager->nRef==0 && !pPager->memDb ){ + rc = pager_wait_on_lock(pPager, SHARED_LOCK); + if( rc!=SQLITE_OK ){ + return rc; + } + + /* If a journal file exists, and there is no RESERVED lock on the + ** database file, then it either needs to be played back or deleted. + */ + if( pPager->useJournal && + sqlite3OsFileExists(pPager->zJournal) && + !sqlite3OsCheckReservedLock(&pPager->fd) + ){ + int rc; + + /* Get an EXCLUSIVE lock on the database file. At this point it is + ** important that a RESERVED lock is not obtained on the way to the + ** EXCLUSIVE lock. If it were, another process might open the + ** database file, detect the RESERVED lock, and conclude that the + ** database is safe to read while this process is still rolling it + ** back. + ** + ** Because the intermediate RESERVED lock is not requested, the + ** second process will get to this point in the code and fail to + ** obtain it's own EXCLUSIVE lock on the database file. + */ + rc = sqlite3OsLock(&pPager->fd, EXCLUSIVE_LOCK); + if( rc!=SQLITE_OK ){ + sqlite3OsUnlock(&pPager->fd, NO_LOCK); + pPager->state = PAGER_UNLOCK; + return rc; + } + pPager->state = PAGER_EXCLUSIVE; + + /* 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 = sqlite3OsOpenReadOnly(pPager->zJournal, &pPager->jfd); + if( rc!=SQLITE_OK ){ + sqlite3OsUnlock(&pPager->fd, NO_LOCK); + pPager->state = PAGER_UNLOCK; + return SQLITE_BUSY; + } + pPager->journalOpen = 1; + pPager->journalStarted = 0; + pPager->journalOff = 0; + pPager->setMaster = 0; + pPager->journalHdr = 0; + + /* Playback and delete the journal. Drop the database write + ** lock and reacquire the read lock. + */ + rc = pager_playback(pPager); + if( rc!=SQLITE_OK ){ + return rc; + } + } + pPg = 0; + }else{ + /* Search for page in cache */ + pPg = pager_lookup(pPager, pgno); + if( pPager->memDb && pPager->state==PAGER_UNLOCK ){ + pPager->state = PAGER_SHARED; + } + } + if( pPg==0 ){ + /* The requested page is not in the page cache. */ + int h; + pPager->nMiss++; + if( pPager->nPage<pPager->mxPage || pPager->pFirst==0 || pPager->memDb ){ + /* Create a new page */ + pPg = sqliteMallocRaw( sizeof(*pPg) + pPager->pageSize + + sizeof(u32) + pPager->nExtra + + pPager->memDb*sizeof(PgHistory) ); + if( pPg==0 ){ + if( !pPager->memDb ){ + pager_unwritelock(pPager); + } + pPager->errMask |= PAGER_ERR_MEM; + return SQLITE_NOMEM; + } + memset(pPg, 0, sizeof(*pPg)); + if( pPager->memDb ){ + memset(PGHDR_TO_HIST(pPg, pPager), 0, sizeof(PgHistory)); + } + pPg->pPager = pPager; + pPg->pNextAll = pPager->pAll; + 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 ){ + sqlite3pager_rollback(pPager); + return SQLITE_IOERR; + } + if( pPager->fullSync ){ + /* If in full-sync mode, write a new journal header into the + ** journal file. This is done to avoid ever modifying a journal + ** header that is involved in the rollback of pages that have + ** already been written to the database (in case the header is + ** trashed when the nRec field is updated). + */ + pPager->nRec = 0; + assert( pPager->journalOff > 0 ); + rc = writeJournalHdr(pPager); + if( rc!=0 ){ + sqlite3pager_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 ){ + sqlite3pager_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 + */ + unlinkPage(pPg); + pPager->nOvfl++; + } + pPg->pgno = pgno; + if( pPager->aInJournal && (int)pgno<=pPager->origDbSize ){ + sqlite3CheckMemory(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->aInStmt && (int)pgno<=pPager->stmtSize + && (pPager->aInStmt[pgno/8] & (1<<(pgno&7)))!=0 ){ + page_add_to_stmt_list(pPg); + }else{ + page_remove_from_stmt_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, pPager), 0, pPager->nExtra); + } + sqlite3pager_pagecount(pPager); + if( pPager->errMask!=0 ){ + sqlite3pager_unref(PGHDR_TO_DATA(pPg)); + rc = pager_errcode(pPager); + return rc; + } + if( pPager->dbSize<(int)pgno ){ + memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize); + }else{ + int rc; + assert( pPager->memDb==0 ); + sqlite3OsSeek(&pPager->fd, (pgno-1)*(i64)pPager->pageSize); + rc = sqlite3OsRead(&pPager->fd, PGHDR_TO_DATA(pPg), pPager->pageSize); + TRACE3("FETCH %d page %d\n", pPager->fd.h, pPg->pgno); + CODEC(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3); + if( rc!=SQLITE_OK ){ + i64 fileSize; + if( sqlite3OsFileSize(&pPager->fd,&fileSize)!=SQLITE_OK + || fileSize>=pgno*pPager->pageSize ){ + sqlite3pager_unref(PGHDR_TO_DATA(pPg)); + return rc; + }else{ + memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize); + } + } + } + }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 sqlite3pager_get(). The difference between this routine +** and sqlite3pager_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 *sqlite3pager_lookup(Pager *pPager, Pgno pgno){ + PgHdr *pPg; + + assert( pPager!=0 ); + assert( pgno!=0 ); + if( pPager->errMask & ~(PAGER_ERR_FULL) ){ + 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 sqlite3pager_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, pPager->pageSize); + } + + /* When all pages reach the freelist, drop the read lock from + ** the database file. + */ + pPager->nRef--; + assert( pPager->nRef>=0 ); + if( pPager->nRef==0 && !pPager->memDb ){ + pager_reset(pPager); + } + } + return SQLITE_OK; +} + +/* +** Create a journal file for pPager. There should already be a RESERVED +** or EXCLUSIVE 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->memDb ); + assert( pPager->state>=PAGER_RESERVED ); + assert( pPager->journalOpen==0 ); + assert( pPager->useJournal ); + sqlite3pager_pagecount(pPager); + pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 ); + if( pPager->aInJournal==0 ){ + rc = SQLITE_NOMEM; + goto failed_to_open_journal; + } + rc = sqlite3OsOpenExclusive(pPager->zJournal, &pPager->jfd,pPager->tempFile); + pPager->journalOff = 0; + pPager->setMaster = 0; + pPager->journalHdr = 0; + if( rc!=SQLITE_OK ){ + goto failed_to_open_journal; + } + sqlite3OsOpenDirectory(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; + + rc = writeJournalHdr(pPager); + + if( pPager->stmtAutoopen && rc==SQLITE_OK ){ + rc = sqlite3pager_stmt_begin(pPager); + } + if( rc!=SQLITE_OK ){ + rc = pager_unwritelock(pPager); + if( rc==SQLITE_OK ){ + rc = SQLITE_FULL; + } + } + return rc; + +failed_to_open_journal: + sqliteFree(pPager->aInJournal); + pPager->aInJournal = 0; + sqlite3OsUnlock(&pPager->fd, NO_LOCK); + pPager->state = PAGER_UNLOCK; + return rc; +} + +/* +** Acquire a write-lock on the database. The lock is removed when +** the any of the following happen: +** +** * sqlite3pager_commit() is called. +** * sqlite3pager_rollback() is called. +** * sqlite3pager_close() is called. +** * sqlite3pager_unref() is called to on every outstanding page. +** +** The first 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. +** +** The second parameter indicates how much space in bytes to reserve for a +** master journal file-name at the start of the journal when it is created. +** +** 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 reserved for writing, this routine is a no-op. +** +** If exFlag is true, go ahead and get an EXCLUSIVE lock on the file +** immediately instead of waiting until we try to flush the cache. The +** exFlag is ignored if a transaction is already active. +*/ +int sqlite3pager_begin(void *pData, int exFlag){ + PgHdr *pPg = DATA_TO_PGHDR(pData); + Pager *pPager = pPg->pPager; + int rc = SQLITE_OK; + assert( pPg->nRef>0 ); + assert( pPager->state!=PAGER_UNLOCK ); + if( pPager->state==PAGER_SHARED ){ + assert( pPager->aInJournal==0 ); + if( pPager->memDb ){ + pPager->state = PAGER_EXCLUSIVE; + pPager->origDbSize = pPager->dbSize; + }else{ + if( SQLITE_BUSY_RESERVED_LOCK || exFlag ){ + rc = pager_wait_on_lock(pPager, RESERVED_LOCK); + }else{ + rc = sqlite3OsLock(&pPager->fd, RESERVED_LOCK); + } + if( rc==SQLITE_OK ){ + pPager->state = PAGER_RESERVED; + if( exFlag ){ + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK); + } + } + if( rc!=SQLITE_OK ){ + return rc; + } + pPager->dirtyCache = 0; + TRACE2("TRANSACTION %d\n", pPager->fd.h); + 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 RESERVED lock on the database. If the RESERVED +** 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 sqlite3pager_commit() or sqlite3pager_rollback() to +** reset. +*/ +int sqlite3pager_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; + } + + assert( !pPager->setMaster ); + + /* 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->inStmt || pPager->stmtInUse==0) ){ + pPager->dirtyCache = 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!=PAGER_UNLOCK ); + rc = sqlite3pager_begin(pData, 0); + if( rc!=SQLITE_OK ){ + return rc; + } + assert( pPager->state>=PAGER_RESERVED ); + if( !pPager->journalOpen && pPager->useJournal ){ + rc = pager_open_journal(pPager); + if( rc!=SQLITE_OK ) return rc; + } + assert( pPager->journalOpen || !pPager->useJournal ); + pPager->dirtyCache = 1; + + /* The transaction journal now exists and we have a RESERVED or an + ** EXCLUSIVE lock on the main database file. Write the current page to + ** the transaction journal if it is not there already. + */ + if( !pPg->inJournal && (pPager->useJournal || pPager->memDb) ){ + if( (int)pPg->pgno <= pPager->origDbSize ){ + int szPg; + u32 saved; + if( pPager->memDb ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + TRACE3("JOURNAL %d page %d\n", pPager->fd.h, pPg->pgno); + assert( pHist->pOrig==0 ); + pHist->pOrig = sqliteMallocRaw( pPager->pageSize ); + if( pHist->pOrig ){ + memcpy(pHist->pOrig, PGHDR_TO_DATA(pPg), pPager->pageSize); + } + }else{ + u32 cksum; + CODEC(pPager, pData, pPg->pgno, 7); + cksum = pager_cksum(pPager, pPg->pgno, pData); + saved = *(u32*)PGHDR_TO_EXTRA(pPg, pPager); + store32bits(cksum, pPg, pPager->pageSize); + szPg = pPager->pageSize+8; + store32bits(pPg->pgno, pPg, -4); + rc = sqlite3OsWrite(&pPager->jfd, &((char*)pData)[-4], szPg); + pPager->journalOff += szPg; + TRACE4("JOURNAL %d page %d needSync=%d\n", + pPager->fd.h, pPg->pgno, pPg->needSync); + CODEC(pPager, pData, pPg->pgno, 0); + *(u32*)PGHDR_TO_EXTRA(pPg, pPager) = saved; + if( rc!=SQLITE_OK ){ + sqlite3pager_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; + if( pPager->stmtInUse ){ + pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7); + page_add_to_stmt_list(pPg); + } + } + }else{ + pPg->needSync = !pPager->journalStarted && !pPager->noSync; + TRACE4("APPEND %d page %d needSync=%d\n", + pPager->fd.h, pPg->pgno, pPg->needSync); + } + if( pPg->needSync ){ + pPager->needSync = 1; + } + pPg->inJournal = 1; + } + + /* If the statement journal is open and the page is not in it, + ** then write the current page to the statement journal. Note that + ** the statement journal format differs from the standard journal format + ** in that it omits the checksums and the header. + */ + if( pPager->stmtInUse && !pPg->inStmt && (int)pPg->pgno<=pPager->stmtSize ){ + assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize ); + if( pPager->memDb ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + assert( pHist->pStmt==0 ); + pHist->pStmt = sqliteMallocRaw( pPager->pageSize ); + if( pHist->pStmt ){ + memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize); + } + TRACE3("STMT-JOURNAL %d page %d\n", pPager->fd.h, pPg->pgno); + }else{ + store32bits(pPg->pgno, pPg, -4); + CODEC(pPager, pData, pPg->pgno, 7); + rc = sqlite3OsWrite(&pPager->stfd, ((char*)pData)-4, pPager->pageSize+4); + TRACE3("STMT-JOURNAL %d page %d\n", pPager->fd.h, pPg->pgno); + CODEC(pPager, pData, pPg->pgno, 0); + if( rc!=SQLITE_OK ){ + sqlite3pager_rollback(pPager); + pPager->errMask |= PAGER_ERR_FULL; + return rc; + } + pPager->stmtNRec++; + assert( pPager->aInStmt!=0 ); + pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7); + } + page_add_to_stmt_list(pPg); + } + + /* Update the database size and return. + */ + if( pPager->dbSize<(int)pPg->pgno ){ + pPager->dbSize = pPg->pgno; + if( !pPager->memDb && pPager->dbSize==PENDING_BYTE/pPager->pageSize ){ + pPager->dbSize++; + } + } + return rc; +} + +/* +** Return TRUE if the page given in the argument was previously passed +** to sqlite3pager_write(). In other words, return TRUE if it is ok +** to change the content of the page. +*/ +int sqlite3pager_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 sqlite3pager_overwrite(Pager *pPager, Pgno pgno, void *pData){ + void *pPage; + int rc; + + rc = sqlite3pager_get(pPager, pgno, &pPage); + if( rc==SQLITE_OK ){ + rc = sqlite3pager_write(pPage); + if( rc==SQLITE_OK ){ + memcpy(pPage, pData, pPager->pageSize); + } + sqlite3pager_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 +** sqlite3pager_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 sqlite3pager_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 sqlite3pager_dont_write(Pager *pPager, Pgno pgno){ + PgHdr *pPg; + + if( pPager->memDb ) return; + + 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{ + TRACE3("DONT_WRITE page %d of %d\n", pgno, pPager->fd.h); + 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 sqlite3pager_dont_rollback(void *pData){ + PgHdr *pPg = DATA_TO_PGHDR(pData); + Pager *pPager = pPg->pPager; + + if( pPager->state!=PAGER_EXCLUSIVE || pPager->journalOpen==0 ) return; + if( pPg->alwaysRollback || pPager->alwaysRollback || pPager->memDb ) 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->stmtInUse ){ + pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7); + page_add_to_stmt_list(pPg); + } + TRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, pPager->fd.h); + } + if( pPager->stmtInUse && !pPg->inStmt && (int)pPg->pgno<=pPager->stmtSize ){ + assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize ); + assert( pPager->aInStmt!=0 ); + pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7); + page_add_to_stmt_list(pPg); + } +} + + +/* +** Clear a PgHistory block +*/ +static void clearHistory(PgHistory *pHist){ + sqliteFree(pHist->pOrig); + sqliteFree(pHist->pStmt); + pHist->pOrig = 0; + pHist->pStmt = 0; +} + +/* +** 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 sqlite3pager_commit(Pager *pPager){ + int rc; + PgHdr *pPg; + + if( pPager->errMask==PAGER_ERR_FULL ){ + rc = sqlite3pager_rollback(pPager); + if( rc==SQLITE_OK ){ + rc = SQLITE_FULL; + } + return rc; + } + if( pPager->errMask!=0 ){ + rc = pager_errcode(pPager); + return rc; + } + if( pPager->state<PAGER_RESERVED ){ + return SQLITE_ERROR; + } + TRACE2("COMMIT %d\n", pPager->fd.h); + if( pPager->memDb ){ + pPg = pager_get_all_dirty_pages(pPager); + while( pPg ){ + clearHistory(PGHDR_TO_HIST(pPg, pPager)); + pPg->dirty = 0; + pPg->inJournal = 0; + pPg->inStmt = 0; + pPg->pPrevStmt = pPg->pNextStmt = 0; + pPg = pPg->pDirty; + } +#ifndef NDEBUG + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + assert( !pPg->alwaysRollback ); + assert( !pHist->pOrig ); + assert( !pHist->pStmt ); + } +#endif + pPager->pStmt = 0; + pPager->state = PAGER_SHARED; + return SQLITE_OK; + } + if( pPager->dirtyCache==0 ){ + /* Exit early (without doing the time-consuming sqlite3OsSync() 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 = sqlite3pager_sync(pPager, 0); + if( rc!=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: + sqlite3pager_rollback(pPager); + return rc; +} + +/* +** Rollback all changes. The database falls back to PAGER_SHARED 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 sqlite3pager_rollback(Pager *pPager){ + int rc; + TRACE2("ROLLBACK %d\n", pPager->fd.h); + if( pPager->memDb ){ + PgHdr *p; + for(p=pPager->pAll; p; p=p->pNextAll){ + PgHistory *pHist; + assert( !p->alwaysRollback ); + if( !p->dirty ){ + assert( !((PgHistory *)PGHDR_TO_HIST(p, pPager))->pOrig ); + assert( !((PgHistory *)PGHDR_TO_HIST(p, pPager))->pStmt ); + continue; + } + + pHist = PGHDR_TO_HIST(p, pPager); + if( pHist->pOrig ){ + memcpy(PGHDR_TO_DATA(p), pHist->pOrig, pPager->pageSize); + TRACE3("ROLLBACK-PAGE %d of %d\n", p->pgno, pPager->fd.h); + }else{ + TRACE3("PAGE %d is clean on %d\n", p->pgno, pPager->fd.h); + } + clearHistory(pHist); + p->dirty = 0; + p->inJournal = 0; + p->inStmt = 0; + p->pPrevStmt = p->pNextStmt = 0; + + if( pPager->xReiniter ){ + pPager->xReiniter(PGHDR_TO_DATA(p), pPager->pageSize); + } + + } + pPager->pStmt = 0; + pPager->dbSize = pPager->origDbSize; + memoryTruncate(pPager); + pPager->stmtInUse = 0; + pPager->state = PAGER_SHARED; + return SQLITE_OK; + } + + if( !pPager->dirtyCache || !pPager->journalOpen ){ + rc = pager_unwritelock(pPager); + pPager->dbSize = -1; + return rc; + } + + if( pPager->errMask!=0 && pPager->errMask!=PAGER_ERR_FULL ){ + if( pPager->state>=PAGER_EXCLUSIVE ){ + pager_playback(pPager); + } + return pager_errcode(pPager); + } + if( pPager->state==PAGER_RESERVED ){ + int rc2, rc3; + rc = pager_reload_cache(pPager); + rc2 = pager_truncate(pPager, pPager->origDbSize); + rc3 = pager_unwritelock(pPager); + if( rc==SQLITE_OK ){ + rc = rc2; + if( rc3 ) rc = rc3; + } + }else{ + rc = pager_playback(pPager); + } + if( rc!=SQLITE_OK ){ + rc = SQLITE_CORRUPT; /* bkpt-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 sqlite3pager_isreadonly(Pager *pPager){ + return pPager->readOnly; +} + +/* +** This routine is used for testing and analysis only. +*/ +int *sqlite3pager_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 statement rollback point. +** +** This routine should be called with the transaction journal already +** open. A new statement journal is created that can be used to rollback +** changes of a single SQL command within a larger transaction. +*/ +int sqlite3pager_stmt_begin(Pager *pPager){ + int rc; + char zTemp[SQLITE_TEMPNAME_SIZE]; + assert( !pPager->stmtInUse ); + assert( pPager->dbSize>=0 ); + TRACE2("STMT-BEGIN %d\n", pPager->fd.h); + if( pPager->memDb ){ + pPager->stmtInUse = 1; + pPager->stmtSize = pPager->dbSize; + return SQLITE_OK; + } + if( !pPager->journalOpen ){ + pPager->stmtAutoopen = 1; + return SQLITE_OK; + } + assert( pPager->journalOpen ); + pPager->aInStmt = sqliteMalloc( pPager->dbSize/8 + 1 ); + if( pPager->aInStmt==0 ){ + sqlite3OsLock(&pPager->fd, SHARED_LOCK); + return SQLITE_NOMEM; + } +#ifndef NDEBUG + rc = sqlite3OsFileSize(&pPager->jfd, &pPager->stmtJSize); + if( rc ) goto stmt_begin_failed; + assert( pPager->stmtJSize == pPager->journalOff ); +#endif + pPager->stmtJSize = pPager->journalOff; + pPager->stmtSize = pPager->dbSize; + pPager->stmtHdrOff = 0; + pPager->stmtCksum = pPager->cksumInit; + if( !pPager->stmtOpen ){ + rc = sqlite3pager_opentemp(zTemp, &pPager->stfd); + if( rc ) goto stmt_begin_failed; + pPager->stmtOpen = 1; + pPager->stmtNRec = 0; + } + pPager->stmtInUse = 1; + return SQLITE_OK; + +stmt_begin_failed: + if( pPager->aInStmt ){ + sqliteFree(pPager->aInStmt); + pPager->aInStmt = 0; + } + return rc; +} + +/* +** Commit a statement. +*/ +int sqlite3pager_stmt_commit(Pager *pPager){ + if( pPager->stmtInUse ){ + PgHdr *pPg, *pNext; + TRACE2("STMT-COMMIT %d\n", pPager->fd.h); + if( !pPager->memDb ){ + sqlite3OsSeek(&pPager->stfd, 0); + /* sqlite3OsTruncate(&pPager->stfd, 0); */ + sqliteFree( pPager->aInStmt ); + pPager->aInStmt = 0; + } + for(pPg=pPager->pStmt; pPg; pPg=pNext){ + pNext = pPg->pNextStmt; + assert( pPg->inStmt ); + pPg->inStmt = 0; + pPg->pPrevStmt = pPg->pNextStmt = 0; + if( pPager->memDb ){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + sqliteFree(pHist->pStmt); + pHist->pStmt = 0; + } + } + pPager->stmtNRec = 0; + pPager->stmtInUse = 0; + pPager->pStmt = 0; + } + pPager->stmtAutoopen = 0; + return SQLITE_OK; +} + +/* +** Rollback a statement. +*/ +int sqlite3pager_stmt_rollback(Pager *pPager){ + int rc; + if( pPager->stmtInUse ){ + TRACE2("STMT-ROLLBACK %d\n", pPager->fd.h); + if( pPager->memDb ){ + PgHdr *pPg; + for(pPg=pPager->pStmt; pPg; pPg=pPg->pNextStmt){ + PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager); + if( pHist->pStmt ){ + memcpy(PGHDR_TO_DATA(pPg), pHist->pStmt, pPager->pageSize); + sqliteFree(pHist->pStmt); + pHist->pStmt = 0; + } + } + pPager->dbSize = pPager->stmtSize; + memoryTruncate(pPager); + rc = SQLITE_OK; + }else{ + rc = pager_stmt_playback(pPager); + } + sqlite3pager_stmt_commit(pPager); + }else{ + rc = SQLITE_OK; + } + pPager->stmtAutoopen = 0; + return rc; +} + +/* +** Return the full pathname of the database file. +*/ +const char *sqlite3pager_filename(Pager *pPager){ + return pPager->zFilename; +} + +/* +** Return the directory of the database file. +*/ +const char *sqlite3pager_dirname(Pager *pPager){ + return pPager->zDirectory; +} + +/* +** Return the full pathname of the journal file. +*/ +const char *sqlite3pager_journalname(Pager *pPager){ + return pPager->zJournal; +} + +/* +** Set the codec for this pager +*/ +void sqlite3pager_set_codec( + Pager *pPager, + void (*xCodec)(void*,void*,Pgno,int), + void *pCodecArg +){ + pPager->xCodec = xCodec; + pPager->pCodecArg = pCodecArg; +} + +/* +** This routine is called to increment the database file change-counter, +** stored at byte 24 of the pager file. +*/ +static int pager_incr_changecounter(Pager *pPager){ + void *pPage; + PgHdr *pPgHdr; + u32 change_counter; + int rc; + + /* Open page 1 of the file for writing. */ + rc = sqlite3pager_get(pPager, 1, &pPage); + if( rc!=SQLITE_OK ) return rc; + rc = sqlite3pager_write(pPage); + if( rc!=SQLITE_OK ) return rc; + + /* Read the current value at byte 24. */ + pPgHdr = DATA_TO_PGHDR(pPage); + change_counter = retrieve32bits(pPgHdr, 24); + + /* Increment the value just read and write it back to byte 24. */ + change_counter++; + store32bits(change_counter, pPgHdr, 24); + + /* Release the page reference. */ + sqlite3pager_unref(pPage); + return SQLITE_OK; +} + +/* +** Sync the database file for the pager pPager. zMaster points to the name +** of a master journal file that should be written into the individual +** journal file. zMaster may be NULL, which is interpreted as no master +** journal (a single database transaction). +** +** This routine ensures that the journal is synced, all dirty pages written +** to the database file and the database file synced. The only thing that +** remains to commit the transaction is to delete the journal file (or +** master journal file if specified). +** +** Note that if zMaster==NULL, this does not overwrite a previous value +** passed to an sqlite3pager_sync() call. +*/ +int sqlite3pager_sync(Pager *pPager, const char *zMaster){ + int rc = SQLITE_OK; + + /* If this is an in-memory db, or no pages have been written to, or this + ** function has already been called, it is a no-op. + */ + if( pPager->state!=PAGER_SYNCED && !pPager->memDb && pPager->dirtyCache ){ + PgHdr *pPg; + assert( pPager->journalOpen ); + + /* If a master journal file name has already been written to the + ** journal file, then no sync is required. This happens when it is + ** written, then the process fails to upgrade from a RESERVED to an + ** EXCLUSIVE lock. The next time the process tries to commit the + ** transaction the m-j name will have already been written. + */ + if( !pPager->setMaster ){ + rc = pager_incr_changecounter(pPager); + if( rc!=SQLITE_OK ) goto sync_exit; + rc = writeMasterJournal(pPager, zMaster); + if( rc!=SQLITE_OK ) goto sync_exit; + rc = syncJournal(pPager); + if( rc!=SQLITE_OK ) goto sync_exit; + } + + /* Write all dirty pages to the database file */ + pPg = pager_get_all_dirty_pages(pPager); + rc = pager_write_pagelist(pPg); + if( rc!=SQLITE_OK ) goto sync_exit; + + /* Sync the database file. */ + if( !pPager->noSync ){ + rc = sqlite3OsSync(&pPager->fd); + } + + pPager->state = PAGER_SYNCED; + } + +sync_exit: + return rc; +} + +#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST) +/* +** Return the current state of the file lock for the given pager. +** The return value is one of NO_LOCK, SHARED_LOCK, RESERVED_LOCK, +** PENDING_LOCK, or EXCLUSIVE_LOCK. +*/ +int sqlite3pager_lockstate(Pager *pPager){ +#ifdef OS_TEST + return pPager->fd->fd.locktype; +#else + return pPager->fd.locktype; +#endif +} +#endif + +#ifdef SQLITE_TEST +/* +** Print a listing of all referenced pages and their ref count. +*/ +void sqlite3pager_refdump(Pager *pPager){ + PgHdr *pPg; + for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){ + if( pPg->nRef<=0 ) continue; + sqlite3DebugPrintf("PAGE %3d addr=%p nRef=%d\n", + pPg->pgno, PGHDR_TO_DATA(pPg), pPg->nRef); + } +} +#endif |