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Add state diagram to comments in experimental version of pager.c. 

FossilOrigin-Name: 16dcf5a6d3ebff9a734705693b5ac740f4ff2cc1
This commit is contained in:
dan 2010-08-03 12:48:45 +00:00
parent 763afe62e1
commit 937ac9da38
3 changed files with 107 additions and 135 deletions
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12
manifest
View File

@ -1,5 +1,5 @@
C Incremental\scheckin\son\spager\sstate\srefactoring.
D 2010-08-03T06:42:40
C Add\sstate\sdiagram\sto\scomments\sin\sexperimental\sversion\sof\spager.c.
D 2010-08-03T12:48:46
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in ec08dc838fd8110fe24c92e5130bcd91cbb1ff2e
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -156,7 +156,7 @@ F src/os_common.h a8f95b81eca8a1ab8593d23e94f8a35f35d4078f
F src/os_os2.c 72d0b2e562952a2464308c4ce5f7913ac10bef3e
F src/os_unix.c ae5ca8a6031380708f3fec7be325233d49944914
F src/os_win.c 51cb62f76262d961ea4249489383d714501315a7
F src/pager.c a22869257641c379545e482d843904702d027db7
F src/pager.c 24f978063ff3f18f1632b05b695717cc9818538a
F src/pager.h 80726162dc3942f59ab27b738fb667b9ba0a89d5
F src/parse.y 12b7ebd61ea54f0e1b1083ff69cc2c8ce9353d58
F src/pcache.c 1e9aa2dbc0845b52e1b51cc39753b6d1e041cb07
@ -841,7 +841,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
P 03a240514aa07a22db787d221641253f23933e88
R 0befc920b01bc332d217d8425323f579
P 0a636798bdb6961a47327091715b254f79add823
R b916884b782901df5d25760d516d1243
U dan
Z 0621f056ce54ddd71f6be378b7d6f549
Z a547af01cff05efb8820775070ecaafe

2
manifest.uuid
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@ -1 +1 @@
0a636798bdb6961a47327091715b254f79add823
16dcf5a6d3ebff9a734705693b5ac740f4ff2cc1

228
src/pager.c
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@ -130,6 +130,7 @@ int sqlite3PagerTrace=1; /* True to enable tracing */
** pager may be in any one of the following six states:
**
** NONE:
**
** The pager starts up in this state. Nothing is guaranteed in this
** state - the file may or may not be locked and the database size is
** unknown. The database may not be read or written.
@ -147,7 +148,8 @@ int sqlite3PagerTrace=1; /* True to enable tracing */
** * A read transaction may be active.
** * A SHARED or greater lock is held on the database file.
** * The dbSize variable may be trusted (even if a user-level read
** transaction is not active).
** transaction is not active). The dbOrigSize and dbFileSize variables
** may not be trusted at this point.
**
** WRITER_INITIAL:
** * A write transaction is active.
@ -178,7 +180,27 @@ int sqlite3PagerTrace=1; /* True to enable tracing */
** commit the transaction. If an error did occur, the caller will need
** to rollback the transaction.
**
** Allowable transitions and the [function] that performs each:
** State diagram:
**
** NONE <-------------+
** | |
** V |
** +---------> READER------------->|
** | | |
** | V |
** |<-------WRITER_INITIAL-----> ERROR
** | | ^
** | V |
** |<------WRITER_CACHEMOD-------->|
** | | |
** | V |
** |<-------WRITER_DBMOD---------->|
** | | |
** | V |
** +<------WRITER_FINISHED-------->+
**
**
** State transitions and the [function] that performs each:
**
** NONE -> READER [PagerSharedLock]
** READER -> WRITER_INITIAL [PagerBegin]
@ -328,7 +350,7 @@ struct PagerSavepoint {
** SQLITE_FULL does not affect the sqlite3PagerGet() and sqlite3PagerLookup()
** APIs, they may still be used successfully.
**
** dbSizeValid, dbSize, dbOrigSize, dbFileSize
** dbSize, dbOrigSize, dbFileSize
**
** Managing the size of the database file in pages is a little complicated.
** The variable Pager.dbSize contains the number of pages that the database
@ -444,15 +466,8 @@ struct Pager {
** other variables in this block are described in the comment directly
** above this class definition.
*/
#if 0
u8 state; /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */
u8 dbModified; /* True if there are any changes to the Db */
u8 journalStarted; /* True if header of journal is synced */
u8 dbSizeValid; /* Set when dbSize is correct */
#endif
u8 eState; /* Pager state (NONE, READER, WRITER_INITIAL..) */
u8 eLock; /* Current lock held on database file */
u8 changeCountDone; /* Set after incrementing the change-counter */
u8 setMaster; /* True if a m-j name has been written to jrnl */
u8 doNotSpill; /* Do not spill the cache when non-zero */
@ -656,6 +671,8 @@ static int assert_pager_state(Pager *p){
if( !pagerUseWal(pPager) ){
assert( p->eLock>=RESERVED_LOCK );
}
assert( pPager->dbSize==pPager->dbOrigSize );
assert( pPager->dbOrigSize==pPager->dbFileSize );
break;
case PAGER_WRITER_CACHEMOD:
@ -671,6 +688,7 @@ static int assert_pager_state(Pager *p){
|| p->journalMode==PAGER_JOURNALMODE_WAL
);
}
assert( pPager->dbOrigSize==pPager->dbFileSize );
break;
case PAGER_WRITER_DBMOD:
@ -702,10 +720,11 @@ static char *print_pager_state(Pager *p){
static char zRet[1024];
sqlite3_snprintf(1024, zRet,
"State: %s\n"
"Lock: %s\n"
"State: %s\n"
"Lock: %s\n"
"Locking mode: locking_mode=%s\n"
"Backing store: tempFile=%d memDb=%d\n"
"Journal mode: journal_mode=%s\n"
"Backing store: tempFile=%d memDb=%d useJournal=%d\n"
, p->eState==PAGER_NONE ? "NONE" :
p->eState==PAGER_READER ? "READER" :
p->eState==PAGER_WRITER_INITIAL ? "WRITER_INITIAL" :
@ -717,7 +736,13 @@ static char *print_pager_state(Pager *p){
p->eLock==EXCLUSIVE_LOCK ? "EXCLUSIVE" :
p->eLock==SHARED_LOCK ? "SHARED" : "?error?"
, p->exclusiveMode ? "exclusive" : "normal"
, (int)p->tempFile, (int)p->memDb
, p->journalMode==PAGER_JOURNALMODE_MEMORY ? "memory" :
p->journalMode==PAGER_JOURNALMODE_OFF ? "off" :
p->journalMode==PAGER_JOURNALMODE_DELETE ? "delete" :
p->journalMode==PAGER_JOURNALMODE_PERSIST ? "persist" :
p->journalMode==PAGER_JOURNALMODE_TRUNCATE ? "truncate" :
p->journalMode==PAGER_JOURNALMODE_WAL ? "wal" : "?error?"
, (int)p->tempFile, (int)p->memDb, (int)p->useJournal
);
return zRet;
@ -2642,6 +2667,15 @@ static int pagerPagecount(Pager *pPager, Pgno *pnPage){
nPage = 1;
}
}
/* If the current number of pages in the file is greater than the
** configured maximum pager number, increase the allowed limit so
** that the file can be read.
*/
if( nPage>pPager->mxPgno ){
pPager->mxPgno = (Pgno)nPage;
}
*pnPage = nPage;
return SQLITE_OK;
}
@ -3045,13 +3079,11 @@ void *sqlite3PagerTempSpace(Pager *pPager){
** Regardless of mxPage, return the current maximum page count.
*/
int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
int nPage;
if( mxPage>0 ){
pPager->mxPgno = mxPage;
}
if( pPager->eState!=PAGER_NONE ){
sqlite3PagerPagecount(pPager, &nPage);
assert( (int)pPager->mxPgno>=nPage );
if( pPager->eState!=PAGER_NONE && pPager->mxPgno<pPager->dbSize ){
pPager->mxPgno = pPager->dbSize;
}
return pPager->mxPgno;
}
@ -3116,67 +3148,16 @@ int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
}
/*
** Return the total number of pages in the database file associated
** with pPager. Normally, this is calculated as (<db file size>/<page-size>).
** This function may only be called when a read-transaction is open on
** the pager. It returns the total number of pages in the database.
**
** However, if the file is between 1 and <page-size> bytes in size, then
** this is considered a 1 page file.
**
** If the pager is in error state when this function is called, then the
** error state error code is returned and *pnPage left unchanged. Or,
** if the file system has to be queried for the size of the file and
** the query attempt returns an IO error, the IO error code is returned
** and *pnPage is left unchanged.
**
** Otherwise, if everything is successful, then SQLITE_OK is returned
** and *pnPage is set to the number of pages in the database.
*/
int sqlite3PagerPagecount(Pager *pPager, int *pnPage){
Pgno nPage = 0; /* Value to return via *pnPage */
assert( pPager->eState>=PAGER_SHARED );
assert( pPager->eState!=PAGER_WRITER_FINISHED );
/* Determine the number of pages in the file. Store this in nPage. */
if( pPager->eState>PAGER_NONE ){
nPage = pPager->dbSize;
}else{
int rc; /* Error returned by OsFileSize() */
i64 n = 0; /* File size in bytes returned by OsFileSize() */
if( pagerUseWal(pPager) && pPager->eState!=PAGER_NONE ){
nPage = sqlite3WalDbsize(pPager->pWal);
}
if( nPage==0 ){
assert( isOpen(pPager->fd) || pPager->tempFile );
if( isOpen(pPager->fd) ){
if( SQLITE_OK!=(rc = sqlite3OsFileSize(pPager->fd, &n)) ){
pager_error(pPager, rc);
return rc;
}
}
if( n>0 && n<pPager->pageSize ){
nPage = 1;
}else{
nPage = (Pgno)(n / pPager->pageSize);
}
}
if( pPager->eState!=PAGER_NONE ){
pPager->dbSize = nPage;
pPager->dbFileSize = nPage;
}
}
/* If the current number of pages in the file is greater than the
** configured maximum pager number, increase the allowed limit so
** that the file can be read.
*/
if( nPage>pPager->mxPgno ){
pPager->mxPgno = (Pgno)nPage;
}
/* Set the output variable and return SQLITE_OK */
*pnPage = nPage;
*pnPage = (int)pPager->dbSize;
return SQLITE_OK;
}
@ -3398,7 +3379,7 @@ void sqlite3PagerRef(DbPage *pPg){
** been written to the journal have actually reached the surface of the
** disk and can be restored in the event of a hot-journal rollback.
**
** If the Pager.noSync flag is set, then this function is a no-op.
** If the Pager.noSync flag is set, then this function is a no-op.
** Otherwise, the actions required depend on the journal-mode and the
** device characteristics of the the file-system, as follows:
**
@ -3428,13 +3409,14 @@ void sqlite3PagerRef(DbPage *pPg){
** page currently held in memory before returning SQLITE_OK. If an IO
** error is encountered, then the IO error code is returned to the caller.
*/
static int syncJournal(Pager *pPager){
static int syncJournal(Pager *pPager, int newHdr){
int rc; /* Return code */
assert( pPager->eState==PAGER_WRITER_CACHEMOD
|| pPager->eState==PAGER_WRITER_DBMOD
);
assert( assert_pager_state(pPager) );
assert( !pagerUseWal(pPager) );
rc = sqlite3PagerExclusiveLock(pPager);
if( rc!=SQLITE_OK ) return rc;
@ -3516,9 +3498,15 @@ static int syncJournal(Pager *pPager){
);
if( rc!=SQLITE_OK ) return rc;
}
}
pPager->journalHdr = pPager->journalOff;
pPager->journalHdr = pPager->journalOff;
if( newHdr && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
pPager->nRec = 0;
rc = writeJournalHdr(pPager);
}
}else{
pPager->journalHdr = pPager->journalOff;
}
}
/* Unless the pager is in noSync mode, the journal file was just
@ -3592,10 +3580,12 @@ static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
** to it in CACHEMOD state.
*/
assert( !pagerUseWal(pPager) );
assert( pPager->eState==PAGER_WRITER_CACHEMOD
|| pPager->eState==PAGER_WRITER_DBMOD
assert( pPager->eState==PAGER_WRITER_DBMOD
|| pPager->eState==PAGER_WRITER_CACHEMOD
);
assert( pPager->eState==PAGER_WRITER_DBMOD
|| (pList->pDirty==0 && pList->pgno<=pPager->dbFileSize)
);
assert( pPager->eState==PAGER_WRITER_DBMOD || pList->pDirty==0 );
rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
@ -3797,15 +3787,7 @@ static int pagerStress(void *p, PgHdr *pPg){
/* Sync the journal file if required. */
if( pPg->flags&PGHDR_NEED_SYNC ){
rc = syncJournal(pPager);
if( rc==SQLITE_OK &&
!pPager->noSync &&
!(pPager->journalMode==PAGER_JOURNALMODE_MEMORY) &&
!(sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
){
pPager->nRec = 0;
rc = writeJournalHdr(pPager);
}
rc = syncJournal(pPager, 1);
}
/* If the page number of this page is larger than the current size of
@ -4624,7 +4606,6 @@ int sqlite3PagerAcquire(
}else{
/* The pager cache has created a new page. Its content needs to
** be initialized. */
int nMax;
PAGER_INCR(pPager->nMiss);
pPg = *ppPage;
@ -4637,12 +4618,7 @@ int sqlite3PagerAcquire(
goto pager_acquire_err;
}
rc = sqlite3PagerPagecount(pPager, &nMax);
if( rc!=SQLITE_OK ){
goto pager_acquire_err;
}
if( MEMDB || nMax<(int)pgno || noContent || !isOpen(pPager->fd) ){
if( MEMDB || pPager->dbSize<(int)pgno || noContent || !isOpen(pPager->fd) ){
if( pgno>pPager->mxPgno ){
rc = SQLITE_FULL;
goto pager_acquire_err;
@ -4753,7 +4729,6 @@ void sqlite3PagerUnref(DbPage *pPg){
*/
static int pager_open_journal(Pager *pPager){
int rc = SQLITE_OK; /* Return code */
int nPage; /* Size of database file */
sqlite3_vfs * const pVfs = pPager->pVfs; /* Local cache of vfs pointer */
assert( pPager->eState==PAGER_WRITER_INITIAL );
@ -4766,9 +4741,7 @@ static int pager_open_journal(Pager *pPager){
if( NEVER(pPager->errCode) ) return pPager->errCode;
if( !pagerUseWal(pPager) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
rc = sqlite3PagerPagecount(pPager, &nPage);
if( rc ) return rc;
pPager->pInJournal = sqlite3BitvecCreate(nPage);
pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
if( pPager->pInJournal==0 ){
return SQLITE_NOMEM;
}
@ -4801,7 +4774,6 @@ static int pager_open_journal(Pager *pPager){
*/
if( rc==SQLITE_OK ){
/* TODO: Check if all of these are really required. */
pPager->dbOrigSize = pPager->dbSize;
pPager->nRec = 0;
pPager->journalOff = 0;
pPager->setMaster = 0;
@ -4814,6 +4786,7 @@ static int pager_open_journal(Pager *pPager){
sqlite3BitvecDestroy(pPager->pInJournal);
pPager->pInJournal = 0;
}else{
assert( pPager->eState==PAGER_WRITER_INITIAL );
pPager->eState = PAGER_WRITER_CACHEMOD;
}
@ -4895,7 +4868,7 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
** WAL mode.
*/
pPager->eState = PAGER_WRITER_INITIAL;
pPager->dbOrigSize = pPager->dbSize;
pPager->dbFileSize = pPager->dbOrigSize = pPager->dbSize;
pPager->journalOff = 0;
}else{
/* Ignore any IO error that occurs within pager_end_transaction(). The
@ -4967,14 +4940,15 @@ static int pager_write(PgHdr *pPg){
if( rc!=SQLITE_OK ) return rc;
}
assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
assert( assert_pager_state(pPager) );
/* The transaction journal now exists and we have a RESERVED or an
** EXCLUSIVE lock on the main database file. Write the current page to
** the transaction journal if it is not there already.
*/
if( !pageInJournal(pPg) && isOpen(pPager->jfd) ){
assert( !pagerUseWal(pPager) );
if( pPg->pgno<=pPager->dbOrigSize ){
if( !pageInJournal(pPg) && !pagerUseWal(pPager) ){
assert( pagerUseWal(pPager)==0 );
if( pPg->pgno<=pPager->dbOrigSize && isOpen(pPager->jfd) ){
u32 cksum;
char *pData2;
@ -5010,9 +4984,7 @@ static int pager_write(PgHdr *pPg){
** in the database file. And if an IO error occurs while doing so,
** then corruption may follow.
*/
if( 1 || !pPager->noSync ){
pPg->flags |= PGHDR_NEED_SYNC;
}
pPg->flags |= PGHDR_NEED_SYNC;
/* An error has occurred writing to the journal file. The
** transaction will be rolled back by the layer above.
@ -5032,7 +5004,7 @@ static int pager_write(PgHdr *pPg){
return rc;
}
}else{
if( pPager->eState!=PAGER_WRITER_DBMOD && (!pPager->noSync || 1)){
if( pPager->eState!=PAGER_WRITER_DBMOD ){
pPg->flags |= PGHDR_NEED_SYNC;
}
PAGERTRACE(("APPEND %d page %d needSync=%d\n",
@ -5080,6 +5052,9 @@ int sqlite3PagerWrite(DbPage *pDbPage){
Pager *pPager = pPg->pPager;
Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);
assert( pPager->eState>=PAGER_WRITER_INITIAL );
assert( assert_pager_state(pPager) );
if( nPagePerSector>1 ){
Pgno nPageCount; /* Total number of pages in database file */
Pgno pg1; /* First page of the sector pPg is located on. */
@ -5101,19 +5076,17 @@ int sqlite3PagerWrite(DbPage *pDbPage){
*/
pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;
rc = sqlite3PagerPagecount(pPager, (int *)&nPageCount);
if( rc==SQLITE_OK ){
if( pPg->pgno>nPageCount ){
nPage = (pPg->pgno - pg1)+1;
}else if( (pg1+nPagePerSector-1)>nPageCount ){
nPage = nPageCount+1-pg1;
}else{
nPage = nPagePerSector;
}
assert(nPage>0);
assert(pg1<=pPg->pgno);
assert((pg1+nPage)>pPg->pgno);
nPageCount = pPager->dbSize;
if( pPg->pgno>nPageCount ){
nPage = (pPg->pgno - pg1)+1;
}else if( (pg1+nPagePerSector-1)>nPageCount ){
nPage = nPageCount+1-pg1;
}else{
nPage = nPagePerSector;
}
assert(nPage>0);
assert(pg1<=pPg->pgno);
assert((pg1+nPage)>pPg->pgno);
for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
Pgno pg = pg1+ii;
@ -5512,7 +5485,7 @@ int sqlite3PagerCommitPhaseOne(
** not the case. In this case it is likely enough that the redundant
** xSync() call will be changed to a no-op by the OS anyhow.
*/
rc = syncJournal(pPager);
rc = syncJournal(pPager, 0);
if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
rc = pager_write_pagelist(pPager,sqlite3PcacheDirtyList(pPager->pPCache));
@ -5773,13 +5746,12 @@ int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
int rc = SQLITE_OK; /* Return code */
int nCurrent = pPager->nSavepoint; /* Current number of savepoints */
assert( pPager->eState>=PAGER_WRITER_INITIAL );
assert( assert_pager_state(pPager) );
if( nSavepoint>nCurrent && pPager->useJournal ){
int ii; /* Iterator variable */
PagerSavepoint *aNew; /* New Pager.aSavepoint array */
int nPage; /* Size of database file */
rc = sqlite3PagerPagecount(pPager, &nPage);
if( rc ) return rc;
/* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
** if the allocation fails. Otherwise, zero the new portion in case a
@ -5796,14 +5768,14 @@ int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
/* Populate the PagerSavepoint structures just allocated. */
for(ii=nCurrent; ii<nSavepoint; ii++){
aNew[ii].nOrig = nPage;
aNew[ii].nOrig = pPager->dbSize;
if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
aNew[ii].iOffset = pPager->journalOff;
}else{
aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
}
aNew[ii].iSubRec = pPager->nSubRec;
aNew[ii].pInSavepoint = sqlite3BitvecCreate(nPage);
aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
if( !aNew[ii].pInSavepoint ){
return SQLITE_NOMEM;
}