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Overview
Comment:Remove a redundant condition from pcache.c. Add an OPTIMIZATION-IF-TRUE comment to another condition that requires it.
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SHA1: 3bfd2621d13b4f842f3af6d35519653f4eb8cad7
User & Date: dan 2016-05-11 20:03:23.145
Context
2016-05-12
09:48
Add a missing OPTIMIZATION-IF-FALSE comment to pcache.c. (check-in: bc202e5b41 user: dan tags: trunk)
2016-05-11
23:54
For in-memory databases, it does not matter if pcache entries are marked "clean" or "writable". (Closed-Leaf check-in: ad601c7962 user: drh tags: pager-dev)
20:03
Remove a redundant condition from pcache.c. Add an OPTIMIZATION-IF-TRUE comment to another condition that requires it. (check-in: 3bfd2621d1 user: dan tags: trunk)
15:41
Remove some a small amount of redundant code related to PCache.pSynced from pcache.c. (check-in: 9cc8cad78f user: dan tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/pcache.c.
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    }else{
      assert( pPage==p->pDirtyTail );
      p->pDirtyTail = pPage->pDirtyPrev;
    }
    if( pPage->pDirtyPrev ){
      pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
    }else{




      assert( pPage==p->pDirty );
      p->pDirty = pPage->pDirtyNext;
      if( p->pDirty==0 && p->bPurgeable ){

        assert( p->eCreate==1 );
        p->eCreate = 2;
      }
    }
    pPage->pDirtyNext = 0;
    pPage->pDirtyPrev = 0;
  }
  if( addRemove & PCACHE_DIRTYLIST_ADD ){








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    }else{
      assert( pPage==p->pDirtyTail );
      p->pDirtyTail = pPage->pDirtyPrev;
    }
    if( pPage->pDirtyPrev ){
      pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
    }else{
      /* If there are now no dirty pages in the cache, set eCreate to 2. 
      ** This is an optimization that allows sqlite3PcacheFetch() to skip
      ** searching for a dirty page to eject from the cache when it might
      ** otherwise have to.  */
      assert( pPage==p->pDirty );
      p->pDirty = pPage->pDirtyNext;
      assert( p->bPurgeable || p->eCreate==2 );
      if( p->pDirty==0 ){         /*OPTIMIZATION-IF-TRUE*/
        assert( p->bPurgeable==0 || p->eCreate==1 );
        p->eCreate = 2;
      }
    }
    pPage->pDirtyNext = 0;
    pPage->pDirtyPrev = 0;
  }
  if( addRemove & PCACHE_DIRTYLIST_ADD ){
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  int eCreate;
  sqlite3_pcache_page *pRes;

  assert( pCache!=0 );
  assert( pCache->pCache!=0 );
  assert( createFlag==3 || createFlag==0 );
  assert( pgno>0 );


  /* eCreate defines what to do if the page does not exist.
  **    0     Do not allocate a new page.  (createFlag==0)
  **    1     Allocate a new page if doing so is inexpensive.
  **          (createFlag==1 AND bPurgeable AND pDirty)
  **    2     Allocate a new page even it doing so is difficult.
  **          (createFlag==1 AND !(bPurgeable AND pDirty)








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  int eCreate;
  sqlite3_pcache_page *pRes;

  assert( pCache!=0 );
  assert( pCache->pCache!=0 );
  assert( createFlag==3 || createFlag==0 );
  assert( pgno>0 );
  assert( pCache->eCreate==((pCache->bPurgeable && pCache->pDirty) ? 1 : 2) );

  /* eCreate defines what to do if the page does not exist.
  **    0     Do not allocate a new page.  (createFlag==0)
  **    1     Allocate a new page if doing so is inexpensive.
  **          (createFlag==1 AND bPurgeable AND pDirty)
  **    2     Allocate a new page even it doing so is difficult.
  **          (createFlag==1 AND !(bPurgeable AND pDirty)
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