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Comment:Minor performance optimizations in pager.c.
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SHA1:ba9eef5f5293633d1479e1d877bf338edb2a9471
User & Date: drh 2013-12-09 19:25:28
Context
2013-12-09
20:43
Simplify the sqlite3BtreeKeyFetch() and sqlite3BtreeDataFetch() interfaces to the storage engine. check-in: bf975985 user: drh tags: trunk
19:25
Minor performance optimizations in pager.c. check-in: ba9eef5f user: drh tags: trunk
19:03
Performance optimizations for sqlite3VXPrintf(). check-in: 9227ad48 user: drh tags: trunk
Changes
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Changes to src/pager.c.

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  ** It is never called in the ERROR state.
  */
  assert( pPager->eState==PAGER_WRITER_LOCKED
       || pPager->eState==PAGER_WRITER_CACHEMOD
       || pPager->eState==PAGER_WRITER_DBMOD
  );
  assert( assert_pager_state(pPager) );

  /* If an error has been previously detected, report the same error
  ** again. This should not happen, but the check provides robustness. */
  if( NEVER(pPager->errCode) )  return pPager->errCode;

  /* Higher-level routines never call this function if database is not
  ** writable.  But check anyway, just for robustness. */
  if( NEVER(pPager->readOnly) ) return SQLITE_PERM;

  CHECK_PAGE(pPg);

  /* The journal file needs to be opened. Higher level routines have already
  ** obtained the necessary locks to begin the write-transaction, but the
  ** rollback journal might not yet be open. Open it now if this is the case.
  **
................................................................................
** as appropriate. Otherwise, SQLITE_OK.
*/
int sqlite3PagerWrite(DbPage *pDbPage){
  int rc = SQLITE_OK;

  PgHdr *pPg = pDbPage;
  Pager *pPager = pPg->pPager;
  Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);

  assert( (pPg->flags & PGHDR_MMAP)==0 );
  assert( pPager->eState>=PAGER_WRITER_LOCKED );
  assert( pPager->eState!=PAGER_ERROR );
  assert( assert_pager_state(pPager) );

  if( nPagePerSector>1 ){
    Pgno nPageCount;          /* Total number of pages in database file */
    Pgno pg1;                 /* First page of the sector pPg is located on. */
    int nPage = 0;            /* Number of pages starting at pg1 to journal */
    int ii;                   /* Loop counter */
    int needSync = 0;         /* True if any page has PGHDR_NEED_SYNC */


    /* Set the doNotSpill NOSYNC bit to 1. This is because we cannot allow
    ** a journal header to be written between the pages journaled by
    ** this function.
    */
    assert( !MEMDB );
    assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)==0 );







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  ** It is never called in the ERROR state.
  */
  assert( pPager->eState==PAGER_WRITER_LOCKED
       || pPager->eState==PAGER_WRITER_CACHEMOD
       || pPager->eState==PAGER_WRITER_DBMOD
  );
  assert( assert_pager_state(pPager) );



  assert( pPager->errCode==0 );



  assert( pPager->readOnly==0 );

  CHECK_PAGE(pPg);

  /* The journal file needs to be opened. Higher level routines have already
  ** obtained the necessary locks to begin the write-transaction, but the
  ** rollback journal might not yet be open. Open it now if this is the case.
  **
................................................................................
** as appropriate. Otherwise, SQLITE_OK.
*/
int sqlite3PagerWrite(DbPage *pDbPage){
  int rc = SQLITE_OK;

  PgHdr *pPg = pDbPage;
  Pager *pPager = pPg->pPager;


  assert( (pPg->flags & PGHDR_MMAP)==0 );
  assert( pPager->eState>=PAGER_WRITER_LOCKED );
  assert( pPager->eState!=PAGER_ERROR );
  assert( assert_pager_state(pPager) );

  if( pPager->sectorSize > pPager->pageSize ){
    Pgno nPageCount;          /* Total number of pages in database file */
    Pgno pg1;                 /* First page of the sector pPg is located on. */
    int nPage = 0;            /* Number of pages starting at pg1 to journal */
    int ii;                   /* Loop counter */
    int needSync = 0;         /* True if any page has PGHDR_NEED_SYNC */
    Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);

    /* Set the doNotSpill NOSYNC bit to 1. This is because we cannot allow
    ** a journal header to be written between the pages journaled by
    ** this function.
    */
    assert( !MEMDB );
    assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)==0 );