diff options
Diffstat (limited to 'src/pager.c')
| -rw-r--r-- | src/pager.c | 44 |
1 files changed, 27 insertions, 17 deletions
diff --git a/src/pager.c b/src/pager.c index 2e484611b..6ebe39482 100644 --- a/src/pager.c +++ b/src/pager.c @@ -282,11 +282,9 @@ struct PagerSavepoint { ** ** journalStarted ** -** This flag is set whenever the the main journal is opened and -** initialized +** This flag is set during a write-transaction after the first +** journal-header is written and synced to disk. ** -** The point of this flag is that it must be set after the -** first journal header in a journal file has been synced to disk. ** After this has happened, new pages appended to the database ** do not need the PGHDR_NEED_SYNC flag set, as they do not need ** to wait for a journal sync before they can be written out to @@ -294,18 +292,28 @@ struct PagerSavepoint { ** ** setMaster ** -** This variable is used to ensure that the master journal file name -** (if any) is only written into the journal file once. -** -** When committing a transaction, the master journal file name (if any) -** may be written into the journal file while the pager is still in -** PAGER_RESERVED state (see CommitPhaseOne() for the action). It -** then attempts to upgrade to an exclusive lock. If this attempt -** fails, then SQLITE_BUSY may be returned to the user and the user -** may attempt to commit the transaction again later (calling -** CommitPhaseOne() again). This flag is used to ensure that the -** master journal name is only written to the journal file the first -** time CommitPhaseOne() is called. +** When PagerCommitPhaseOne() is called to commit a transaction, it may +** (or may not) specify a master-journal name to be written into the +** journal file before it is synced to disk. +** +** Whether or not a journal file contains a master-journal pointer affects +** the way in which the journal file is finalized after the transaction is +** committed or rolled back when running in "journal_mode=PERSIST" mode. +** If a journal file does not contain a master-journal pointer, it is +** finalized by overwriting the first journal header with zeroes. If, +** on the other hand, it does contain a master-journal pointer, the +** journal file is finalized by truncating it to zero bytes, just as if +** the connection were running in "journal_mode=truncate" mode. +** +** Journal files that contain master journal pointers cannot be finalized +** simply by overwriting the first journal-header with zeroes, as the +** master journal pointer could interfere with hot-journal rollback of any +** subsequently interrupted transaction that reuses the journal file. +** +** The flag is cleared as soon as the journal file is finalized (either +** by PagerCommitPhaseTwo or PagerRollback). If an IO error prevents the +** journal file from being successfully finalized, the setMaster flag +** is cleared anyway. ** ** doNotSpill, doNotSyncSpill ** @@ -1073,7 +1081,9 @@ static int writeMasterJournal(Pager *pPager, const char *zMaster){ i64 jrnlSize; /* Size of journal file on disk */ u32 cksum = 0; /* Checksum of string zMaster */ - if( !zMaster || pPager->setMaster + assert( pPager->setMaster==0 ); + + if( !zMaster || pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->journalMode==PAGER_JOURNALMODE_OFF ){ |