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Allow sqlite3_snapshot_open() to be called to change the snapshot after a

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read transaction is already open on database.

FossilOrigin-Name: 051ac0152048ef52723196c26ca5f2629dafb782aec1c66fc30531bf54335043
This commit is contained in:
dan
2018-08-06 17:12:36 +00:00
parent f018fd5284
commit fa3d4c19a9
11 changed files with 343 additions and 36 deletions
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32
src/pager.c
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@@ -7653,6 +7653,38 @@ int sqlite3PagerSnapshotRecover(Pager *pPager){
}
return rc;
}
/*
** The caller currently has a read transaction open on the database.
** If this is not a WAL database, SQLITE_ERROR is returned. Otherwise,
** this function takes a SHARED lock on the CHECKPOINTER slot and then
** checks if the snapshot passed as the second argument is still
** available. If so, SQLITE_OK is returned.
**
** If the snapshot is not available, SQLITE_ERROR is returned. Or, if
** the CHECKPOINTER lock cannot be obtained, SQLITE_BUSY. If any error
** occurs (any value other than SQLITE_OK is returned), the CHECKPOINTER
** lock is released before returning.
*/
int sqlite3PagerSnapshotCheck(Pager *pPager, sqlite3_snapshot *pSnapshot){
int rc;
if( pPager->pWal ){
rc = sqlite3WalSnapshotCheck(pPager->pWal, pSnapshot);
}else{
rc = SQLITE_ERROR;
}
return rc;
}
/*
** Release a lock obtained by an earlier successful call to
** sqlite3PagerSnapshotCheck().
*/
void sqlite3PagerSnapshotUnlock(Pager *pPager){
assert( pPager->pWal );
return sqlite3WalSnapshotUnlock(pPager->pWal);
}
#endif /* SQLITE_ENABLE_SNAPSHOT */
#endif /* !SQLITE_OMIT_WAL */