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Avoid the 1-based indexing on the WalHashLoc.aPgno[] array. Make it 0-indexed

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instead.

FossilOrigin-Name: 28f5f709b4b28ba7f6f56bdd4a9e8c04d0d2df90d13d6df1a589fa4a65163f4d
This commit is contained in:
drh
2021-10-27 20:23:59 +00:00
parent 5f25627a1c
commit 71c3ea7523
3 changed files with 27 additions and 31 deletions
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41
src/wal.c
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@@ -1000,8 +1000,8 @@ struct WalHashLoc {
** slot in the hash table is set to N, it refers to frame number
** (pLoc->iZero+N) in the log.
**
** Finally, set pLoc->aPgno so that pLoc->aPgno[1] is the page number of the
** first frame indexed by the hash table, frame (pLoc->iZero+1).
** Finally, set pLoc->aPgno so that pLoc->aPgno[0] is the page number of the
** first frame indexed by the hash table, frame (pLoc->iZero).
*/
static int walHashGet(
Wal *pWal, /* WAL handle */
@@ -1021,7 +1021,6 @@ static int walHashGet(
}else{
pLoc->iZero = HASHTABLE_NPAGE_ONE + (iHash-1)*HASHTABLE_NPAGE;
}
pLoc->aPgno = &pLoc->aPgno[-1];
}
return rc;
}
@@ -1103,8 +1102,9 @@ static void walCleanupHash(Wal *pWal){
/* Zero the entries in the aPgno array that correspond to frames with
** frame numbers greater than pWal->hdr.mxFrame.
*/
nByte = (int)((char *)sLoc.aHash - (char *)&sLoc.aPgno[iLimit+1]);
memset((void *)&sLoc.aPgno[iLimit+1], 0, nByte);
nByte = (int)((char *)sLoc.aHash - (char *)&sLoc.aPgno[iLimit]);
assert( nByte>=0 );
memset((void *)&sLoc.aPgno[iLimit], 0, nByte);
#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
/* Verify that the every entry in the mapping region is still reachable
@@ -1113,11 +1113,11 @@ static void walCleanupHash(Wal *pWal){
if( iLimit ){
int j; /* Loop counter */
int iKey; /* Hash key */
for(j=1; j<=iLimit; j++){
for(j=0; j<iLimit; j++){
for(iKey=walHash(sLoc.aPgno[j]);sLoc.aHash[iKey];iKey=walNextHash(iKey)){
if( sLoc.aHash[iKey]==j ) break;
if( sLoc.aHash[iKey]==j+1 ) break;
}
assert( sLoc.aHash[iKey]==j );
assert( sLoc.aHash[iKey]==j+1 );
}
}
#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
@@ -1149,9 +1149,9 @@ static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
** entire hash table and aPgno[] array before proceeding.
*/
if( idx==1 ){
int nByte = (int)((u8 *)&sLoc.aHash[HASHTABLE_NSLOT]
- (u8 *)&sLoc.aPgno[1]);
memset((void*)&sLoc.aPgno[1], 0, nByte);
int nByte = (int)((u8*)&sLoc.aHash[HASHTABLE_NSLOT] - (u8*)sLoc.aPgno);
assert( nByte>=0 );
memset((void*)sLoc.aPgno, 0, nByte);
}
/* If the entry in aPgno[] is already set, then the previous writer
@@ -1160,9 +1160,9 @@ static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
** Remove the remnants of that writers uncommitted transaction from
** the hash-table before writing any new entries.
*/
if( sLoc.aPgno[idx] ){
if( sLoc.aPgno[idx-1] ){
walCleanupHash(pWal);
assert( !sLoc.aPgno[idx] );
assert( !sLoc.aPgno[idx-1] );
}
/* Write the aPgno[] array entry and the hash-table slot. */
@@ -1170,7 +1170,7 @@ static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
for(iKey=walHash(iPage); sLoc.aHash[iKey]; iKey=walNextHash(iKey)){
if( (nCollide--)==0 ) return SQLITE_CORRUPT_BKPT;
}
sLoc.aPgno[idx] = iPage;
sLoc.aPgno[idx-1] = iPage;
AtomicStore(&sLoc.aHash[iKey], (ht_slot)idx);
#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
@@ -1191,19 +1191,18 @@ static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
*/
if( (idx&0x3ff)==0 ){
int i; /* Loop counter */
for(i=1; i<=idx; i++){
for(i=0; i<idx; i++){
for(iKey=walHash(sLoc.aPgno[i]);
sLoc.aHash[iKey];
iKey=walNextHash(iKey)){
if( sLoc.aHash[iKey]==i ) break;
if( sLoc.aHash[iKey]==i+1 ) break;
}
assert( sLoc.aHash[iKey]==i );
assert( sLoc.aHash[iKey]==i+1 );
}
}
#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
}
return rc;
}
@@ -1821,7 +1820,6 @@ static int walIteratorInit(Wal *pWal, u32 nBackfill, WalIterator **pp){
int nEntry; /* Number of entries in this segment */
ht_slot *aIndex; /* Sorted index for this segment */
sLoc.aPgno++;
if( (i+1)==nSegment ){
nEntry = (int)(iLast - sLoc.iZero);
}else{
@@ -2960,7 +2958,8 @@ int sqlite3WalSnapshotRecover(Wal *pWal){
rc = walHashGet(pWal, walFramePage(i), &sLoc);
if( rc!=SQLITE_OK ) break;
pgno = sLoc.aPgno[i-sLoc.iZero];
assert( i - sLoc.iZero - 1 >=0 );
pgno = sLoc.aPgno[i-sLoc.iZero-1];
iDbOff = (i64)(pgno-1) * szPage;
if( iDbOff+szPage<=szDb ){
@@ -3193,7 +3192,7 @@ int sqlite3WalFindFrame(
iKey = walHash(pgno);
while( (iH = AtomicLoad(&sLoc.aHash[iKey]))!=0 ){
u32 iFrame = iH + sLoc.iZero;
if( iFrame<=iLast && iFrame>=pWal->minFrame && sLoc.aPgno[iH]==pgno ){
if( iFrame<=iLast && iFrame>=pWal->minFrame && sLoc.aPgno[iH-1]==pgno ){
assert( iFrame>iRead || CORRUPT_DB );
iRead = iFrame;
}