Add the sqlite3VdbeMemClearAndResize() interface to be used in place of

sqlite3VdbeMemGrow().

FossilOrigin-Name: 5b9b8987797abf7c68d2c3154f6657be9b8b1c8f

manifest

@@ -1,5 +1,5 @@
-C Add\sthe\sMem.szMalloc\selement\sto\sthe\sMem\sobject\sand\suse\sit\sto\skeep\strack\sof\nthe\ssize\sof\sthe\sMem.zMalloc\sallocation.
+C Add\sthe\ssqlite3VdbeMemClearAndResize()\sinterface\sto\sbe\sused\sin\splace\sof\nsqlite3VdbeMemGrow().
-D 2014-09-18T21:25:33.845
+D 2014-09-19T00:43:39.899
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in cf57f673d77606ab0f2d9627ca52a9ba1464146a
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -288,14 +288,14 @@ F src/update.c 729f6f18fc27740591d085e1172cebe311144bf0
 F src/utf.c fc6b889ba0779b7722634cdeaa25f1930d93820c
 F src/util.c 4006c01772bd8d8ac4306d523bbcee41d3e392d8
 F src/vacuum.c 59f03f92bcff57faa6a8ca256eb29ccddfb0614a
-F src/vdbe.c fb490f5b1b2ee2f33f60c7dc678c0d0b70f2e0cb
+F src/vdbe.c 7bc115e540282b1bfff9b43205cbf6528e6398a6
 F src/vdbe.h 09f5b4e3719fa454f252322b1cdab5cf1f361327
-F src/vdbeInt.h 1ac536d1fa1260d72f81003ff5b283e8f3c40442
+F src/vdbeInt.h f177bed1ec8d4eb5c7089f012aeb95f374745735
-F src/vdbeapi.c e088ed70b6cc42ed68985ab064397ebd452286d6
+F src/vdbeapi.c e9e33b59834e3edc8790209765e069874c269d9d
-F src/vdbeaux.c b3230032238df611aefee5907ea792786362a55d
+F src/vdbeaux.c ecf0bb835f7c809ba8e22ba7d3a587b7a087ac52
 F src/vdbeblob.c 848238dc73e93e48432991bb5651bf87d865eca4
-F src/vdbemem.c 3aea3831a981378368ca058cd8fc700b1982772d
+F src/vdbemem.c 0678ba6214a810539e51c6d8f263634d405b990f
-F src/vdbesort.c 09efa5e5098d1a159cd21f588eb118e4fe87cfde
+F src/vdbesort.c 75c66c2fc02d450b67b4816873fba8088feaf12c
 F src/vdbetrace.c 4f29b04edb0cec3d5fcd9b566d9f0e75c8984362
 F src/vtab.c 019dbfd0406a7447c990e1f7bd1dfcdb8895697f
 F src/wal.c 10e7de7ce90865a68153f001a61f1d985cd17983
@@ -1198,7 +1198,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 55879932116d373c95a5f32ec44b53a9c3f4db24
+P 9c09ac353df6041808cace41880f4729ee73f5e1
-R 508057a57cef866ce62608d1eb2d9e8e
+R eeadad19cadf3315e345f0babe4222b0
 U drh
-Z 7d8fd1db974daf115bf085d0714b6de9
+Z fd83cfbfc71d89fd149fcf4e06924224

manifest.uuid

@@ -1 +1 @@
-9c09ac353df6041808cace41880f4729ee73f5e1
+5b9b8987797abf7c68d2c3154f6657be9b8b1c8f

src/vdbe.c

@@ -209,7 +209,7 @@ static VdbeCursor *allocateCursor(
     sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
     p->apCsr[iCur] = 0;
   }
-  if( SQLITE_OK==sqlite3VdbeMemGrow(pMem, nByte, 0) ){
+  if( SQLITE_OK==sqlite3VdbeMemClearAndResize(pMem, nByte) ){
     p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
     memset(pCx, 0, sizeof(VdbeCursor));
     pCx->iDb = iDb;
@@ -2633,9 +2633,9 @@ case OP_MakeRecord: {
   /* Make sure the output register has a buffer large enough to store 
   ** the new record. The output register (pOp->p3) is not allowed to
   ** be one of the input registers (because the following call to
-  ** sqlite3VdbeMemGrow() could clobber the value before it is used).
+  ** sqlite3VdbeMemClearAndResize() could clobber the value before it is used).
   */
-  if( sqlite3VdbeMemGrow(pOut, (int)nByte, 0) ){
+  if( sqlite3VdbeMemClearAndResize(pOut, (int)nByte) ){
     goto no_mem;
   }
   zNewRecord = (u8 *)pOut->z;
@@ -4339,7 +4339,7 @@ case OP_RowData: {
       goto too_big;
     }
   }
-  if( sqlite3VdbeMemGrow(pOut, n, 0) ){
+  if( sqlite3VdbeMemClearAndResize(pOut, n) ){
     goto no_mem;
   }
   pOut->n = n;

src/vdbeInt.h

@@ -437,6 +437,7 @@ void sqlite3VdbeMemRelease(Mem *p);
 int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
 const char *sqlite3OpcodeName(int);
 int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
+int sqlite3VdbeMemClearAndResize(Mem *pMem, int n);
 int sqlite3VdbeCloseStatement(Vdbe *, int);
 void sqlite3VdbeFrameDelete(VdbeFrame*);
 int sqlite3VdbeFrameRestore(VdbeFrame *);

src/vdbeapi.c

@@ -665,7 +665,7 @@ static SQLITE_NOINLINE void *createAggContext(sqlite3_context *p, int nByte){
     sqlite3VdbeMemSetNull(pMem);
     pMem->z = 0;
   }else{
-    sqlite3VdbeMemGrow(pMem, nByte, 0);
+    sqlite3VdbeMemClearAndResize(pMem, nByte);
     pMem->flags = MEM_Agg;
     pMem->u.pDef = p->pFunc;
     if( pMem->z ){

src/vdbeaux.c

@@ -1426,7 +1426,7 @@ int sqlite3VdbeList(
     pMem->u.i = pOp->p3;                          /* P3 */
     pMem++;
 
-    if( sqlite3VdbeMemGrow(pMem, 32, 0) ){            /* P4 */
+    if( sqlite3VdbeMemClearAndResize(pMem, 32) ){ /* P4 */
       assert( p->db->mallocFailed );
       return SQLITE_ERROR;
     }
@@ -1442,7 +1442,7 @@ int sqlite3VdbeList(
     pMem++;
 
     if( p->explain==1 ){
-      if( sqlite3VdbeMemGrow(pMem, 4, 0) ){
+      if( sqlite3VdbeMemClearAndResize(pMem, 4) ){
         assert( p->db->mallocFailed );
         return SQLITE_ERROR;
       }
@@ -1453,7 +1453,7 @@ int sqlite3VdbeList(
       pMem++;
   
 #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
-      if( sqlite3VdbeMemGrow(pMem, 500, 0) ){
+      if( sqlite3VdbeMemClearAndResize(pMem, 500) ){
         assert( p->db->mallocFailed );
         return SQLITE_ERROR;
       }

src/vdbemem.c

@@ -107,7 +107,7 @@ int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
 ** blob if bPreserve is true.  If bPreserve is false, any prior content
 ** in pMem->z is discarded.
 */
-int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
+SQLITE_NOINLINE int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
   assert( sqlite3VdbeCheckMemInvariants(pMem) );
   assert( (pMem->flags&MEM_RowSet)==0 );
 
@@ -150,6 +150,33 @@ int sqlite3VdbeMemGrow(Mem *pMem, int n, int bPreserve){
   return SQLITE_OK;
 }
 
+/*
+** Change the pMem->zMalloc allocation to be at least szNew bytes.
+** If pMem->zMalloc already meets or exceeds the requested size, this
+** routine is a no-op.
+**
+** Any prior string or blob content in the pMem object may be discarded.
+** The pMem->xDel destructor is called, if it exists.
+**
+** The value of the pMem after this routine returns might be NULL or
+** it might retain its prior value, depending on circumstances.  The
+** caller should make no assumptions about the state of pMem after this
+** routine returns, except that pMem->zMalloc is at least the requested
+** size and pMem->z==pMem->zMalloc.
+**
+** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
+** if unable to complete the resizing.
+*/
+int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
+  if( pMem->szMalloc<szNew || (pMem->flags & MEM_Dyn)!=0 ){
+    return sqlite3VdbeMemGrow(pMem, szNew, 0);
+  }
+  pMem->z = pMem->zMalloc;
+  pMem->flags &= ~(MEM_Dyn|MEM_Ephem|MEM_Static);
+//  pMem->flags = MEM_Null;
+  return SQLITE_OK;
+}
+
 /*
 ** Make the given Mem object MEM_Dyn.  In other words, make it so
 ** that any TEXT or BLOB content is stored in memory obtained from
@@ -262,7 +289,7 @@ int sqlite3VdbeMemStringify(Mem *pMem, u8 enc, u8 bForce){
   assert( EIGHT_BYTE_ALIGNMENT(pMem) );
 
 
-  if( sqlite3VdbeMemGrow(pMem, nByte, 0) ){
+  if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){
     return SQLITE_NOMEM;
   }
 
@@ -866,7 +893,7 @@ int sqlite3VdbeMemSetStr(
     if( nByte>iLimit ){
       return SQLITE_TOOBIG;
     }
-    if( sqlite3VdbeMemGrow(pMem, nAlloc, 0) ){
+    if( sqlite3VdbeMemClearAndResize(pMem, nAlloc) ){
       return SQLITE_NOMEM;
     }
     memcpy(pMem->z, z, nAlloc);
@@ -944,7 +971,7 @@ int sqlite3VdbeMemFromBtree(
     pMem->n = (int)amt;
   }else{
     pMem->flags = MEM_Null;
-    if( SQLITE_OK==(rc = sqlite3VdbeMemGrow(pMem, amt+2, 0)) ){
+    if( SQLITE_OK==(rc = sqlite3VdbeMemClearAndResize(pMem, amt+2)) ){
       if( key ){
         rc = sqlite3BtreeKey(pCur, offset, amt, pMem->z);
       }else{

src/vdbesort.c

@@ -2461,7 +2461,7 @@ int sqlite3VdbeSorterRowkey(const VdbeCursor *pCsr, Mem *pOut){
   void *pKey; int nKey;           /* Sorter key to copy into pOut */
 
   pKey = vdbeSorterRowkey(pSorter, &nKey);
-  if( sqlite3VdbeMemGrow(pOut, nKey, 0) ){
+  if( sqlite3VdbeMemClearAndResize(pOut, nKey) ){
     return SQLITE_NOMEM;
   }
   pOut->n = nKey;