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sqlite-amalgamation.c  view on Meta::CPAN

          }
        }
        while( p ){
          sqlite3_mutex_enter(p->pBt->mutex);
          p->locked++;
          p = p->pNext;
        }
      }
    }
  }
}
SQLITE_PRIVATE void sqlite3BtreeLeaveAll(sqlite3 *db){
  int i;
  Btree *p;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    if( p && p->sharable ){
      assert( p->wantToLock>0 );
      p->wantToLock--;
      if( p->wantToLock==0 ){
        assert( p->locked );
        sqlite3_mutex_leave(p->pBt->mutex);
        p->locked = 0;
      }
    }
  }
}

#ifndef NDEBUG
/*
** Return true if the current thread holds the database connection
** mutex and all required BtShared mutexes.
**
** This routine is used inside assert() statements only.
*/
SQLITE_PRIVATE int sqlite3BtreeHoldsAllMutexes(sqlite3 *db){
  int i;
  if( !sqlite3_mutex_held(db->mutex) ){
    return 0;
  }
  for(i=0; i<db->nDb; i++){
    Btree *p;
    p = db->aDb[i].pBt;
    if( p && p->sharable &&
         (p->wantToLock==0 || !sqlite3_mutex_held(p->pBt->mutex)) ){
      return 0;
    }
  }
  return 1;
}
#endif /* NDEBUG */

/*
** Add a new Btree pointer to a BtreeMutexArray. 
** if the pointer can possibly be shared with
** another database connection.
**
** The pointers are kept in sorted order by pBtree->pBt.  That
** way when we go to enter all the mutexes, we can enter them
** in order without every having to backup and retry and without
** worrying about deadlock.
**
** The number of shared btrees will always be small (usually 0 or 1)
** so an insertion sort is an adequate algorithm here.
*/
SQLITE_PRIVATE void sqlite3BtreeMutexArrayInsert(BtreeMutexArray *pArray, Btree *pBtree){
  int i, j;
  BtShared *pBt;
  if( pBtree==0 || pBtree->sharable==0 ) return;
#ifndef NDEBUG
  {
    for(i=0; i<pArray->nMutex; i++){
      assert( pArray->aBtree[i]!=pBtree );
    }
  }
#endif
  assert( pArray->nMutex>=0 );
  assert( pArray->nMutex<sizeof(pArray->aBtree)/sizeof(pArray->aBtree[0])-1 );
  pBt = pBtree->pBt;
  for(i=0; i<pArray->nMutex; i++){
    assert( pArray->aBtree[i]!=pBtree );
    if( pArray->aBtree[i]->pBt>pBt ){
      for(j=pArray->nMutex; j>i; j--){
        pArray->aBtree[j] = pArray->aBtree[j-1];
      }
      pArray->aBtree[i] = pBtree;
      pArray->nMutex++;
      return;
    }
  }
  pArray->aBtree[pArray->nMutex++] = pBtree;
}

/*
** Enter the mutex of every btree in the array.  This routine is
** called at the beginning of sqlite3VdbeExec().  The mutexes are
** exited at the end of the same function.
*/
SQLITE_PRIVATE void sqlite3BtreeMutexArrayEnter(BtreeMutexArray *pArray){
  int i;
  for(i=0; i<pArray->nMutex; i++){
    Btree *p = pArray->aBtree[i];
    /* Some basic sanity checking */
    assert( i==0 || pArray->aBtree[i-1]->pBt<p->pBt );
    assert( !p->locked || p->wantToLock>0 );

    /* We should already hold a lock on the database connection */
    assert( sqlite3_mutex_held(p->db->mutex) );

    p->wantToLock++;
    if( !p->locked && p->sharable ){
      sqlite3_mutex_enter(p->pBt->mutex);
      p->locked = 1;
    }
  }
}

/*
** Leave the mutex of every btree in the group.
*/

sqlite-amalgamation.c  view on Meta::CPAN

** end.  We use the OP_Sort opcode instead of OP_Rewind to do the
** rewinding so that the global variable will be incremented and
** regression tests can determine whether or not the optimizer is
** correctly optimizing out sorts.
*/
case OP_Sort: {        /* jump */
#ifdef SQLITE_TEST
  sqlite3_sort_count++;
  sqlite3_search_count--;
#endif
  /* Fall through into OP_Rewind */
}
/* Opcode: Rewind P1 P2 * * *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the first entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
*/
case OP_Rewind: {        /* jump */
  int i = pOp->p1;
  Cursor *pC;
  BtCursor *pCrsr;
  int res;

  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  if( (pCrsr = pC->pCursor)!=0 ){
    rc = sqlite3BtreeFirst(pCrsr, &res);
    pC->atFirst = res==0;
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;
  }else{
    res = 1;
  }
  pC->nullRow = res;
  assert( pOp->p2>0 && pOp->p2<p->nOp );
  if( res ){
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: Next P1 P2 * * *
**
** Advance cursor P1 so that it points to the next key/data pair in its
** table or index.  If there are no more key/value pairs then fall through
** to the following instruction.  But if the cursor advance was successful,
** jump immediately to P2.
**
** The P1 cursor must be for a real table, not a pseudo-table.
**
** See also: Prev
*/
/* Opcode: Prev P1 P2 * * *
**
** Back up cursor P1 so that it points to the previous key/data pair in its
** table or index.  If there is no previous key/value pairs then fall through
** to the following instruction.  But if the cursor backup was successful,
** jump immediately to P2.
**
** The P1 cursor must be for a real table, not a pseudo-table.
*/
case OP_Prev:          /* jump */
case OP_Next: {        /* jump */
  Cursor *pC;
  BtCursor *pCrsr;
  int res;

  CHECK_FOR_INTERRUPT;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  if( pC==0 ){
    break;  /* See ticket #2273 */
  }
  pCrsr = pC->pCursor;
  assert( pCrsr );
  res = 1;
  assert( pC->deferredMoveto==0 );
  rc = pOp->opcode==OP_Next ? sqlite3BtreeNext(pCrsr, &res) :
                              sqlite3BtreePrevious(pCrsr, &res);
  pC->nullRow = res;
  pC->cacheStatus = CACHE_STALE;
  if( res==0 ){
    pc = pOp->p2 - 1;
#ifdef SQLITE_TEST
    sqlite3_search_count++;
#endif
  }
  pC->rowidIsValid = 0;
  break;
}

/* Opcode: IdxInsert P1 P2 P3 * *
**
** Register P2 holds a SQL index key made using the
** MakeIdxRec instructions.  This opcode writes that key
** into the index P1.  Data for the entry is nil.
**
** P3 is a flag that provides a hint to the b-tree layer that this
** insert is likely to be an append.
**
** This instruction only works for indices.  The equivalent instruction
** for tables is OP_Insert.
*/
case OP_IdxInsert: {        /* in2 */
  int i = pOp->p1;
  Cursor *pC;
  BtCursor *pCrsr;
  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  assert( pIn2->flags & MEM_Blob );
  if( (pCrsr = (pC = p->apCsr[i])->pCursor)!=0 ){
    assert( pC->isTable==0 );
    rc = ExpandBlob(pIn2);
    if( rc==SQLITE_OK ){
      int nKey = pIn2->n;
      const char *zKey = pIn2->z;
      rc = sqlite3BtreeInsert(pCrsr, zKey, nKey, "", 0, 0, pOp->p3);