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Overview
| Comment: | Tweaks to pcache1TruncateUnsafe() to make it slightly smaller and faster and easier to test. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 059f4e2efefb7b9deaf539110c19bcea |
| User & Date: | drh 2016-08-10 15:02:49 |
Context
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2016-08-11
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| 13:03 | Enhance sqlite3PcacheTruncate() to run faster in the common case where the cutoff is just a few pages less than the page number highwater mark. check-in: 03dceaea user: drh tags: branch-3.14 | |
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2016-08-10
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| 18:56 | Performance enhancement in the expression walker. check-in: ebccbd96 user: drh tags: trunk | |
| 15:02 | Tweaks to pcache1TruncateUnsafe() to make it slightly smaller and faster and easier to test. check-in: 059f4e2e user: drh tags: trunk | |
| 14:40 | Rearrange the code inside sqlite3RunParser() routine so that sqlite3Parser() is only called from a single place. This allows sqlite3Parser() to be in-lined, which results in a 0.25% overall performance gain. check-in: 25d1d02b user: drh tags: trunk | |
Changes
Changes to src/pcache1.c.
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unsigned int iLimit /* Drop pages with this pgno or larger */
){
TESTONLY( int nPage = 0; ) /* To assert pCache->nPage is correct */
unsigned int h, iStop;
assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
assert( pCache->iMaxKey >= iLimit );
assert( pCache->nHash > 0 );
if( pCache->iMaxKey - iLimit < pCache->nHash/2 ){
/* If we are just shaving the last few pages off the end of the
** cache, then there is no point in scanning the entire hash table.
** Only scan those hash slots that might contain pages that need to
** be removed. */
iStop = iLimit % pCache->nHash;
h = pCache->iMaxKey % pCache->nHash;
TESTONLY( nPage = -10; ) /* Disable the pCache->nPage validity check */
}else{
/* This is the general case where many pages are being removed.
** It is necessary to scan the entire hash table */
iStop = 0;
h = pCache->nHash - 1;
}
for(;;){
PgHdr1 **pp;
PgHdr1 *pPage;
assert( h<pCache->nHash );
pp = &pCache->apHash[h];
while( (pPage = *pp)!=0 ){
................................................................................
pcache1FreePage(pPage);
}else{
pp = &pPage->pNext;
TESTONLY( if( nPage>=0 ) nPage++; )
}
}
if( h==iStop ) break;
h = h ? h-1 : pCache->nHash - 1;
}
assert( nPage<0 || pCache->nPage==(unsigned)nPage );
}
/******************************************************************************/
/******** sqlite3_pcache Methods **********************************************/
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unsigned int iLimit /* Drop pages with this pgno or larger */
){
TESTONLY( int nPage = 0; ) /* To assert pCache->nPage is correct */
unsigned int h, iStop;
assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
assert( pCache->iMaxKey >= iLimit );
assert( pCache->nHash > 0 );
if( pCache->iMaxKey - iLimit < pCache->nHash ){
/* If we are just shaving the last few pages off the end of the
** cache, then there is no point in scanning the entire hash table.
** Only scan those hash slots that might contain pages that need to
** be removed. */
h = iLimit % pCache->nHash;
iStop = pCache->iMaxKey % pCache->nHash;
TESTONLY( nPage = -10; ) /* Disable the pCache->nPage validity check */
}else{
/* This is the general case where many pages are being removed.
** It is necessary to scan the entire hash table */
h = pCache->nHash/2;
iStop = h - 1;
}
for(;;){
PgHdr1 **pp;
PgHdr1 *pPage;
assert( h<pCache->nHash );
pp = &pCache->apHash[h];
while( (pPage = *pp)!=0 ){
................................................................................
pcache1FreePage(pPage);
}else{
pp = &pPage->pNext;
TESTONLY( if( nPage>=0 ) nPage++; )
}
}
if( h==iStop ) break;
h = (h+1) % pCache->nHash;
}
assert( nPage<0 || pCache->nPage==(unsigned)nPage );
}
/******************************************************************************/
/******** sqlite3_pcache Methods **********************************************/
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