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Refactor and simplify the logic used to change journalmode.

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FossilOrigin-Name: 95cc3f6fdec5494560c3cd4439d06870d1c62506
This commit is contained in:
drh
2010-06-11 17:01:24 +00:00
parent 5130c31b0c
commit 0b9b4301b8
8 changed files with 135 additions and 98 deletions
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98
src/pager.c
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@@ -5815,9 +5815,8 @@ int sqlite3PagerLockingMode(Pager *pPager, int eMode){
}
/*
** Get/set the journal-mode for this pager. Parameter eMode must be one of:
** Set the journal-mode for this pager. Parameter eMode must be one of:
**
** PAGER_JOURNALMODE_QUERY
** PAGER_JOURNALMODE_DELETE
** PAGER_JOURNALMODE_TRUNCATE
** PAGER_JOURNALMODE_PERSIST
@@ -5825,55 +5824,94 @@ int sqlite3PagerLockingMode(Pager *pPager, int eMode){
** PAGER_JOURNALMODE_MEMORY
** PAGER_JOURNALMODE_WAL
**
** If the parameter is not _QUERY, then the journal_mode is set to the
** value specified if the change is allowed. The change may be disallowed
** for the following reasons:
** The journalmode is set to the value specified if the change is allowed.
** The change may be disallowed for the following reasons:
**
** * An in-memory database can only have its journal_mode set to _OFF
** or _MEMORY.
**
** * The journal mode may not be changed while a transaction is active.
** * Temporary databases cannot have _WAL journalmode.
**
** The returned indicate the current (possibly updated) journal-mode.
*/
int sqlite3PagerJournalMode(Pager *pPager, int eMode){
assert( eMode==PAGER_JOURNALMODE_QUERY
|| eMode==PAGER_JOURNALMODE_DELETE
int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
u8 eOld = pPager->journalMode; /* Prior journalmode */
/* The eMode parameter is always valid */
assert( eMode==PAGER_JOURNALMODE_DELETE
|| eMode==PAGER_JOURNALMODE_TRUNCATE
|| eMode==PAGER_JOURNALMODE_PERSIST
|| eMode==PAGER_JOURNALMODE_OFF
|| eMode==PAGER_JOURNALMODE_WAL
|| eMode==PAGER_JOURNALMODE_MEMORY );
assert( PAGER_JOURNALMODE_QUERY<0 );
if( eMode==PAGER_JOURNALMODE_WAL
&& pPager->journalMode==PAGER_JOURNALMODE_DELETE
){
pPager->journalMode = PAGER_JOURNALMODE_WAL;
}else if( eMode>=0
&& (pPager->tempFile==0 || eMode!=PAGER_JOURNALMODE_WAL)
&& (!MEMDB || eMode==PAGER_JOURNALMODE_MEMORY||eMode==PAGER_JOURNALMODE_OFF)
&& !pPager->dbModified
&& (!isOpen(pPager->jfd) || 0==pPager->journalOff)
){
if( isOpen(pPager->jfd) ){
/* Do not allow the journalmode of a TEMP database to be changed to WAL
*/
if( pPager->tempFile && eMode==PAGER_JOURNALMODE_WAL ){
assert( eOld!=PAGER_JOURNALMODE_WAL );
eMode = eOld;
}
/* Do allow the journalmode of an in-memory database to be set to
** anything other than MEMORY or OFF
*/
if( MEMDB ){
assert( eOld==PAGER_JOURNALMODE_MEMORY || eOld==PAGER_JOURNALMODE_OFF );
if( eMode!=PAGER_JOURNALMODE_MEMORY && eMode!=PAGER_JOURNALMODE_OFF ){
eMode = eOld;
}
}
if( eMode!=eOld ){
/* When changing between rollback modes, close the journal file prior
** to the change. But when changing from a rollback mode to WAL, keep
** the journal open since there is a rollback-style transaction in play
** used to convert the version numbers in the btree header.
*/
if( isOpen(pPager->jfd) && eMode!=PAGER_JOURNALMODE_WAL ){
sqlite3OsClose(pPager->jfd);
}
assert( (PAGER_JOURNALMODE_TRUNCATE & 1)==1 );
assert( (PAGER_JOURNALMODE_PERSIST & 1)==1 );
assert( (PAGER_JOURNALMODE_DELETE & 1)==0 );
assert( (PAGER_JOURNALMODE_MEMORY & 1)==0 );
assert( (PAGER_JOURNALMODE_OFF & 1)==0 );
if( (pPager->journalMode & 1)==1 && (eMode & 1)==0
&& !pPager->exclusiveMode ){
/* Change the journal mode. */
pPager->journalMode = (u8)eMode;
/* When transistioning from TRUNCATE or PERSIST to any other journal
** mode (and we are not in locking_mode=EXCLUSIVE) then delete the
** journal file.
*/
assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
assert( (PAGER_JOURNALMODE_DELETE & 5)!=1 );
assert( (PAGER_JOURNALMODE_MEMORY & 5)!=1 );
assert( (PAGER_JOURNALMODE_OFF & 5)!=1 );
assert( (PAGER_JOURNALMODE_WAL & 5)!=1 );
if( (eOld & 5)==1 && (eMode & 5)!=1 && !pPager->exclusiveMode ){
sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
}
pPager->journalMode = (u8)eMode;
}
/* Return the new journal mode */
return (int)pPager->journalMode;
}
/*
** Return the current journal mode.
*/
int sqlite3PagerGetJournalMode(Pager *pPager){
return (int)pPager->journalMode;
}
/*
** Return TRUE if the pager is in a state where it is OK to change the
** journalmode. Journalmode changes can only happen when the database
** is unmodified.
*/
int sqlite3PagerOkToChangeJournalMode(Pager *pPager){
if( pPager->dbModified ) return 0;
if( isOpen(pPager->jfd) && pPager->journalOff>0 ) return 0;
return 1;
}
/*
** Get/set the size-limit used for persistent journal files.
**