SQLite: Check-in [059f4e2e]

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

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:	059f4e2efefb7b9deaf539110c19bceaeb10c6ce
User & Date:	drh 2016-08-10 15:02:49

Context

2016-08-11
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)
2016-08-10
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

Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/pcache1.c.

  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 **********************************************/

  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 **********************************************/