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-rw-r--r--src/vdbe.c110
1 files changed, 78 insertions, 32 deletions
diff --git a/src/vdbe.c b/src/vdbe.c
index 5256b655d..e491340fa 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -43,7 +43,7 @@
** in this file for details. If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
-** $Id: vdbe.c,v 1.716 2008/03/25 00:22:21 drh Exp $
+** $Id: vdbe.c,v 1.717 2008/03/25 09:47:35 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -208,15 +208,66 @@ int sqlite3VdbeOpcodeHasProperty(int opcode, int mask){
** Allocate cursor number iCur. Return a pointer to it. Return NULL
** if we run out of memory.
*/
-static Cursor *allocateCursor(Vdbe *p, int iCur, int iDb){
- Cursor *pCx;
+static Cursor *allocateCursor(
+ Vdbe *p,
+ int iCur,
+ Op *pOp,
+ int iDb,
+ int isBtreeCursor
+){
+ /* Find the memory cell that will be used to store the blob of memory
+ ** required for this Cursor structure. It is convenient to use a
+ ** vdbe memory cell to manage the memory allocation required for a
+ ** Cursor structure for the following reasons:
+ **
+ ** * Sometimes cursor numbers are used for a couple of different
+ ** purposes in a vdbe program. The different uses might require
+ ** different sized allocations. Memory cells provide growable
+ ** allocations.
+ **
+ ** * When using ENABLE_MEMORY_MANAGEMENT, memory cell buffers can
+ ** be freed lazily via the sqlite3_release_memory() API. This
+ ** minimizes the number of malloc calls made by the system.
+ **
+ ** Memory cells for cursors are allocated at the top of the address
+ ** space. Memory cell (p->nMem) corresponds to cursor 0. Space for
+ ** cursor 1 is managed by memory cell (p->nMem-1), etc.
+ */
+ Mem *pMem = &p->aMem[p->nMem-iCur];
+
+ Cursor *pCx = 0;
+ /* If the opcode of pOp is OP_SetNumColumns, then pOp->p2 contains
+ ** the number of fields in the records contained in the table or
+ ** index being opened. Use this to reserve space for the
+ ** Cursor.aType[] array.
+ */
+ int nField = 0;
+ if( pOp->opcode==OP_SetNumColumns || pOp->opcode==OP_OpenEphemeral ){
+ nField = pOp->p2;
+ }
+
+
+ int nByte =
+ sizeof(Cursor) +
+ (isBtreeCursor?sqlite3BtreeCursorSize():0) +
+ 2*nField*sizeof(u32);
+
assert( iCur<p->nCursor );
if( p->apCsr[iCur] ){
sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
+ p->apCsr[iCur] = 0;
}
- p->apCsr[iCur] = pCx = sqlite3MallocZero( sizeof(Cursor) );
- if( pCx ){
+ if( SQLITE_OK==sqlite3VdbeMemGrow(pMem, nByte, 0) ){
+ p->apCsr[iCur] = pCx = (Cursor *)pMem->z;
+ memset(pMem->z, 0, nByte);
pCx->iDb = iDb;
+ pCx->nField = nField;
+ if( nField ){
+ pCx->aType = (u32 *)&pMem->z[sizeof(Cursor)];
+ }
+ if( isBtreeCursor ){
+ pCx->pCursor = (BtCursor *)&pMem->z[sizeof(Cursor)+2*nField*sizeof(u32)];
+ }
}
return pCx;
}
@@ -1773,22 +1824,23 @@ case OP_NotNull: { /* same as TK_NOTNULL, jump, in1 */
break;
}
-/* Opcode: SetNumColumns P1 P2 * * *
+/* Opcode: SetNumColumns * P2 * * *
+**
+** This opcode sets the number of columns for the cursor opened by the
+** following instruction to P2.
**
-** Before the OP_Column opcode can be executed on a cursor, this
-** opcode must be called to set the number of fields in the table.
+** An OP_SetNumColumns is only useful if it occurs immediately before
+** one of the following opcodes:
**
-** This opcode sets the number of columns for cursor P1 to P2.
+** OpenRead
+** OpenWrite
+** OpenPseudo
**
-** If OP_KeyAsData is to be applied to cursor P1, it must be executed
-** before this op-code.
+** If the OP_Column opcode is to be executed on a cursor, then
+** this opcode must be present immediately before the opcode that
+** opens the cursor.
*/
case OP_SetNumColumns: {
- Cursor *pC;
- assert( (pOp->p1)<p->nCursor );
- assert( p->apCsr[pOp->p1]!=0 );
- pC = p->apCsr[pOp->p1];
- pC->nField = pOp->p2;
break;
}
@@ -1893,8 +1945,8 @@ case OP_Column: {
/* Read and parse the table header. Store the results of the parse
** into the record header cache fields of the cursor.
*/
+ aType = pC->aType;
if( pC->cacheStatus==p->cacheCtr ){
- aType = pC->aType;
aOffset = pC->aOffset;
}else{
u8 *zIdx; /* Index into header */
@@ -1903,13 +1955,7 @@ case OP_Column: {
int szHdrSz; /* Size of the header size field at start of record */
int avail; /* Number of bytes of available data */
- aType = pC->aType;
- if( aType==0 ){
- pC->aType = aType = sqlite3DbMallocRaw(db, 2*nField*sizeof(aType) );
- }
- if( aType==0 ){
- goto no_mem;
- }
+ assert(aType);
pC->aOffset = aOffset = &aType[nField];
pC->payloadSize = payloadSize;
pC->cacheStatus = p->cacheCtr;
@@ -2515,10 +2561,10 @@ case OP_OpenWrite: {
assert( p2>=2 );
}
assert( i>=0 );
- pCur = allocateCursor(p, i, iDb);
+ pCur = allocateCursor(p, i, &pOp[-1], iDb, 1);
if( pCur==0 ) goto no_mem;
pCur->nullRow = 1;
- rc = sqlite3BtreeCursor(pX, p2, wrFlag, pOp->p4.p, &pCur->pCursor);
+ rc = sqlite3BtreeCursor(pX, p2, wrFlag, pOp->p4.p, pCur->pCursor);
if( pOp->p4type==P4_KEYINFO ){
pCur->pKeyInfo = pOp->p4.pKeyInfo;
pCur->pIncrKey = &pCur->pKeyInfo->incrKey;
@@ -2561,6 +2607,7 @@ case OP_OpenWrite: {
case SQLITE_EMPTY: {
pCur->isTable = pOp->p4type!=P4_KEYINFO;
pCur->isIndex = !pCur->isTable;
+ pCur->pCursor = 0;
rc = SQLITE_OK;
break;
}
@@ -2600,7 +2647,7 @@ case OP_OpenEphemeral: {
SQLITE_OPEN_TRANSIENT_DB;
assert( i>=0 );
- pCx = allocateCursor(p, i, -1);
+ pCx = allocateCursor(p, i, pOp, -1, 1);
if( pCx==0 ) goto no_mem;
pCx->nullRow = 1;
rc = sqlite3BtreeFactory(db, 0, 1, SQLITE_DEFAULT_TEMP_CACHE_SIZE, openFlags,
@@ -2621,19 +2668,18 @@ case OP_OpenEphemeral: {
if( rc==SQLITE_OK ){
assert( pgno==MASTER_ROOT+1 );
rc = sqlite3BtreeCursor(pCx->pBt, pgno, 1,
- (KeyInfo*)pOp->p4.z, &pCx->pCursor);
+ (KeyInfo*)pOp->p4.z, pCx->pCursor);
pCx->pKeyInfo = pOp->p4.pKeyInfo;
pCx->pKeyInfo->enc = ENC(p->db);
pCx->pIncrKey = &pCx->pKeyInfo->incrKey;
}
pCx->isTable = 0;
}else{
- rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, &pCx->pCursor);
+ rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, pCx->pCursor);
pCx->isTable = 1;
pCx->pIncrKey = &pCx->bogusIncrKey;
}
}
- pCx->nField = pOp->p2;
pCx->isIndex = !pCx->isTable;
break;
}
@@ -2654,7 +2700,7 @@ case OP_OpenPseudo: {
int i = pOp->p1;
Cursor *pCx;
assert( i>=0 );
- pCx = allocateCursor(p, i, -1);
+ pCx = allocateCursor(p, i, &pOp[-1], -1, 0);
if( pCx==0 ) goto no_mem;
pCx->nullRow = 1;
pCx->pseudoTable = 1;
@@ -4390,7 +4436,7 @@ case OP_VOpen: {
pVtabCursor->pVtab = pVtab;
/* Initialise vdbe cursor object */
- pCur = allocateCursor(p, pOp->p1, -1);
+ pCur = allocateCursor(p, pOp->p1, &pOp[-1], -1, 0);
if( pCur ){
pCur->pVtabCursor = pVtabCursor;
pCur->pModule = pVtabCursor->pVtab->pModule;
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-19 06:09:00 +0000