SQLite

Check-in [e6798871ce]
Login

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

Overview
Comment:Detect when a VdbeCursor is still pointing at a valid row but that row has moved, and invalidated the return from prior sqlite3BtreeDataFetch() or sqlite3BtreeKeyFetch() calls.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: e6798871ce94961135762669af418cd78540c121
User & Date: drh 2014-03-25 11:00:21.320
Context
2014-03-25
14:54
Add an ORDER BY test case to speedtest1.c (check-in: 588122641e user: drh tags: trunk)
13:17
Merge all fixes and enhancements from trunk. (check-in: b415dfb6cb user: drh tags: threads)
11:00
Detect when a VdbeCursor is still pointing at a valid row but that row has moved, and invalidated the return from prior sqlite3BtreeDataFetch() or sqlite3BtreeKeyFetch() calls. (check-in: e6798871ce user: drh tags: trunk)
2014-03-24
16:30
Remove unused variables Parse.nColCache and Parse.iColCache. (check-in: 4d7551ce46 user: dan tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/btree.c.
︙︙
742
743
744
745
746
747
748
749








750
751
752
753




754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769


/*
** Determine whether or not a cursor has moved from the position it
** was last placed at.  Cursors can move when the row they are pointing
** at is deleted out from under them.
**
** This routine returns an error code if something goes wrong.  The
** integer *pHasMoved is set to one if the cursor has moved and 0 if not.








*/
int sqlite3BtreeCursorHasMoved(BtCursor *pCur, int *pHasMoved){
  int rc;





  rc = restoreCursorPosition(pCur);
  if( rc ){
    *pHasMoved = 1;
    return rc;
  }
  if( pCur->eState!=CURSOR_VALID || NEVER(pCur->skipNext!=0) ){
    *pHasMoved = 1;
  }else{
    *pHasMoved = 0;
  }
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page








|
>
>
>
>
>
>
>
>




>
>
>
>


|



|

|








742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781


/*
** Determine whether or not a cursor has moved from the position it
** was last placed at.  Cursors can move when the row they are pointing
** at is deleted out from under them.
**
** This routine returns an error code if something goes wrong.  The
** integer *pHasMoved is set as follows:
**
**    0:   The cursor is unchanged
**    1:   The cursor is still pointing at the same row, but the pointers
**         returned by sqlite3BtreeKeyFetch() or sqlite3BtreeDataFetch()
**         might now be invalid because of a balance() or other change to the
**         b-tree.
**    2:   The cursor is no longer pointing to the row.  The row might have
**         been deleted out from under the cursor.
*/
int sqlite3BtreeCursorHasMoved(BtCursor *pCur, int *pHasMoved){
  int rc;

  if( pCur->eState==CURSOR_VALID ){
    *pHasMoved = 0;
    return SQLITE_OK;
  }
  rc = restoreCursorPosition(pCur);
  if( rc ){
    *pHasMoved = 2;
    return rc;
  }
  if( pCur->eState!=CURSOR_VALID || NEVER(pCur->skipNext!=0) ){
    *pHasMoved = 2;
  }else{
    *pHasMoved = 1;
  }
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page
︙︙
4184
4185
4186
4187
4188
4189
4190


4191
4192
4193
4194

4195
4196
4197
4198
4199
4200
4201

  u32 *pAmt            /* Write the number of available bytes here */
){
  assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
  assert( pCur->eState==CURSOR_VALID );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert( cursorHoldsMutex(pCur) );
  assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );


  if( pCur->info.nSize==0 ){
    btreeParseCell(pCur->apPage[pCur->iPage], pCur->aiIdx[pCur->iPage],
                   &pCur->info);
  }

  *pAmt = pCur->info.nLocal;
  return (void*)(pCur->info.pCell + pCur->info.nHeader);
}


/*
** For the entry that cursor pCur is point to, return as








>
>




>








4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216

  u32 *pAmt            /* Write the number of available bytes here */
){
  assert( pCur!=0 && pCur->iPage>=0 && pCur->apPage[pCur->iPage]);
  assert( pCur->eState==CURSOR_VALID );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert( cursorHoldsMutex(pCur) );
  assert( pCur->aiIdx[pCur->iPage]<pCur->apPage[pCur->iPage]->nCell );
  assert( pCur->info.nSize>0 );
#if 0
  if( pCur->info.nSize==0 ){
    btreeParseCell(pCur->apPage[pCur->iPage], pCur->aiIdx[pCur->iPage],
                   &pCur->info);
  }
#endif
  *pAmt = pCur->info.nLocal;
  return (void*)(pCur->info.pCell + pCur->info.nHeader);
}


/*
** For the entry that cursor pCur is point to, return as
︙︙
Changes to src/vdbeaux.c.
︙︙
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745

    p->cacheStatus = CACHE_STALE;
  }else if( p->pCursor ){
    int hasMoved;
    int rc = sqlite3BtreeCursorHasMoved(p->pCursor, &hasMoved);
    if( rc ) return rc;
    if( hasMoved ){
      p->cacheStatus = CACHE_STALE;
      p->nullRow = 1;
    }
  }
  return SQLITE_OK;
}

/*
** The following functions:








|








2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745

    p->cacheStatus = CACHE_STALE;
  }else if( p->pCursor ){
    int hasMoved;
    int rc = sqlite3BtreeCursorHasMoved(p->pCursor, &hasMoved);
    if( rc ) return rc;
    if( hasMoved ){
      p->cacheStatus = CACHE_STALE;
      if( hasMoved==2 ) p->nullRow = 1;
    }
  }
  return SQLITE_OK;
}

/*
** The following functions:
︙︙