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Avoid reading frames that have already been checkpointed from the wal file.

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FossilOrigin-Name: 5669ac4a40429abc3f44540fc9d2f3b79b404bdf
This commit is contained in:
dan
2015-08-12 19:42:08 +00:00
parent 7899fa78c1
commit 6df003c7a5
4 changed files with 62 additions and 11 deletions
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12
src/wal.c
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@@ -2372,6 +2372,8 @@ int sqlite3WalFindFrame(
u32 iRead = 0; /* If !=0, WAL frame to return data from */
u32 iLast = pWal->hdr.mxFrame; /* Last page in WAL for this reader */
int iHash; /* Used to loop through N hash tables */
u32 iFirst;
int iMinHash;
/* This routine is only be called from within a read transaction. */
assert( pWal->readLock>=0 || pWal->lockError );
@@ -2382,7 +2384,10 @@ int sqlite3WalFindFrame(
** then the WAL is ignored by the reader so return early, as if the
** WAL were empty.
*/
if( iLast==0 || pWal->readLock==0 ){
if( iLast==0
|| pWal->readLock==0
|| iLast==(iFirst = walCkptInfo(pWal)->nBackfill)
){
*piRead = 0;
return SQLITE_OK;
}
@@ -2412,7 +2417,8 @@ int sqlite3WalFindFrame(
** This condition filters out entries that were added to the hash
** table after the current read-transaction had started.
*/
for(iHash=walFramePage(iLast); iHash>=0 && iRead==0; iHash--){
iMinHash = walFramePage(iFirst);
for(iHash=walFramePage(iLast); iHash>=iMinHash && iRead==0; iHash--){
volatile ht_slot *aHash; /* Pointer to hash table */
volatile u32 *aPgno; /* Pointer to array of page numbers */
u32 iZero; /* Frame number corresponding to aPgno[0] */
@@ -2427,7 +2433,7 @@ int sqlite3WalFindFrame(
nCollide = HASHTABLE_NSLOT;
for(iKey=walHash(pgno); aHash[iKey]; iKey=walNextHash(iKey)){
u32 iFrame = aHash[iKey] + iZero;
if( iFrame<=iLast && aPgno[aHash[iKey]]==pgno ){
if( iFrame<=iLast && iFrame>iFirst && aPgno[aHash[iKey]]==pgno ){
assert( iFrame>iRead || CORRUPT_DB );
iRead = iFrame;
}