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-rw-r--r--src/rowset.c103
-rw-r--r--src/sqliteInt.h27
-rw-r--r--src/vdbe.c17
3 files changed, 84 insertions, 63 deletions
diff --git a/src/rowset.c b/src/rowset.c
index c2e73ed72..a70264ed1 100644
--- a/src/rowset.c
+++ b/src/rowset.c
@@ -57,8 +57,9 @@
** of the first SMALLEST is O(NlogN). Second and subsequent SMALLEST
** primitives are constant time. The cost of DESTROY is O(N).
**
-** There is an added cost of O(N) when switching between TEST and
-** SMALLEST primitives.
+** TEST and SMALLEST may not be used by the same RowSet. This used to
+** be possible, but the feature was not used, so it was removed in order
+** to simplify the code.
*/
#include "sqliteInt.h"
@@ -179,7 +180,9 @@ void sqlite3RowSetClear(RowSet *p){
*/
static struct RowSetEntry *rowSetEntryAlloc(RowSet *p){
assert( p!=0 );
- if( p->nFresh==0 ){
+ if( p->nFresh==0 ){ /*OPTIMIZATION-IF-FALSE*/
+ /* We could allocate a fresh RowSetEntry each time one is needed, but it
+ ** is more efficient to pull a preallocated entry from the pool */
struct RowSetChunk *pNew;
pNew = sqlite3DbMallocRawNN(p->db, sizeof(*pNew));
if( pNew==0 ){
@@ -213,7 +216,9 @@ void sqlite3RowSetInsert(RowSet *p, i64 rowid){
pEntry->pRight = 0;
pLast = p->pLast;
if( pLast ){
- if( (p->rsFlags & ROWSET_SORTED)!=0 && rowid<=pLast->v ){
+ if( rowid<=pLast->v ){ /*OPTIMIZATION-IF-FALSE*/
+ /* Avoid unnecessary sorts by preserving the ROWSET_SORTED flags
+ ** where possible */
p->rsFlags &= ~ROWSET_SORTED;
}
pLast->pRight = pEntry;
@@ -335,23 +340,29 @@ static struct RowSetEntry *rowSetNDeepTree(
){
struct RowSetEntry *p; /* Root of the new tree */
struct RowSetEntry *pLeft; /* Left subtree */
- if( *ppList==0 ){
- return 0;
+ if( *ppList==0 ){ /*OPTIMIZATION-IF-TRUE*/
+ /* Prevent unnecessary deep recursion when we run out of entries */
+ return 0;
}
- if( iDepth==1 ){
+ if( iDepth>1 ){ /*OPTIMIZATION-IF-TRUE*/
+ /* This branch causes a *balanced* tree to be generated. A valid tree
+ ** is still generated without this branch, but the tree is wildly
+ ** unbalanced and inefficient. */
+ pLeft = rowSetNDeepTree(ppList, iDepth-1);
+ p = *ppList;
+ if( p==0 ){ /*OPTIMIZATION-IF-FALSE*/
+ /* It is safe to always return here, but the resulting tree
+ ** would be unbalanced */
+ return pLeft;
+ }
+ p->pLeft = pLeft;
+ *ppList = p->pRight;
+ p->pRight = rowSetNDeepTree(ppList, iDepth-1);
+ }else{
p = *ppList;
*ppList = p->pRight;
p->pLeft = p->pRight = 0;
- return p;
}
- pLeft = rowSetNDeepTree(ppList, iDepth-1);
- p = *ppList;
- if( p==0 ){
- return pLeft;
- }
- p->pLeft = pLeft;
- *ppList = p->pRight;
- p->pRight = rowSetNDeepTree(ppList, iDepth-1);
return p;
}
@@ -379,58 +390,36 @@ static struct RowSetEntry *rowSetListToTree(struct RowSetEntry *pList){
}
/*
-** Take all the entries on p->pEntry and on the trees in p->pForest and
-** sort them all together into one big ordered list on p->pEntry.
-**
-** This routine should only be called once in the life of a RowSet.
-*/
-static void rowSetToList(RowSet *p){
-
- /* This routine is called only once */
- assert( p!=0 && (p->rsFlags & ROWSET_NEXT)==0 );
-
- if( (p->rsFlags & ROWSET_SORTED)==0 ){
- p->pEntry = rowSetEntrySort(p->pEntry);
- }
-
- /* While this module could theoretically support it, sqlite3RowSetNext()
- ** is never called after sqlite3RowSetText() for the same RowSet. So
- ** there is never a forest to deal with. Should this change, simply
- ** remove the assert() and the #if 0. */
- assert( p->pForest==0 );
-#if 0
- while( p->pForest ){
- struct RowSetEntry *pTree = p->pForest->pLeft;
- if( pTree ){
- struct RowSetEntry *pHead, *pTail;
- rowSetTreeToList(pTree, &pHead, &pTail);
- p->pEntry = rowSetEntryMerge(p->pEntry, pHead);
- }
- p->pForest = p->pForest->pRight;
- }
-#endif
- p->rsFlags |= ROWSET_NEXT; /* Verify this routine is never called again */
-}
-
-/*
** Extract the smallest element from the RowSet.
** Write the element into *pRowid. Return 1 on success. Return
** 0 if the RowSet is already empty.
**
** After this routine has been called, the sqlite3RowSetInsert()
-** routine may not be called again.
+** routine may not be called again.
+**
+** This routine may not be called after sqlite3RowSetTest() has
+** been used. Older versions of RowSet allowed that, but as the
+** capability was not used by the code generator, it was removed
+** for code economy.
*/
int sqlite3RowSetNext(RowSet *p, i64 *pRowid){
assert( p!=0 );
+ assert( p->pForest==0 ); /* Cannot be used with sqlite3RowSetText() */
/* Merge the forest into a single sorted list on first call */
- if( (p->rsFlags & ROWSET_NEXT)==0 ) rowSetToList(p);
+ if( (p->rsFlags & ROWSET_NEXT)==0 ){ /*OPTIMIZATION-IF-FALSE*/
+ if( (p->rsFlags & ROWSET_SORTED)==0 ){ /*OPTIMIZATION-IF-FALSE*/
+ p->pEntry = rowSetEntrySort(p->pEntry);
+ }
+ p->rsFlags |= ROWSET_SORTED|ROWSET_NEXT;
+ }
/* Return the next entry on the list */
if( p->pEntry ){
*pRowid = p->pEntry->v;
p->pEntry = p->pEntry->pRight;
- if( p->pEntry==0 ){
+ if( p->pEntry==0 ){ /*OPTIMIZATION-IF-TRUE*/
+ /* Free memory immediately, rather than waiting on sqlite3_finalize() */
sqlite3RowSetClear(p);
}
return 1;
@@ -453,13 +442,15 @@ int sqlite3RowSetTest(RowSet *pRowSet, int iBatch, sqlite3_int64 iRowid){
/* This routine is never called after sqlite3RowSetNext() */
assert( pRowSet!=0 && (pRowSet->rsFlags & ROWSET_NEXT)==0 );
- /* Sort entries into the forest on the first test of a new batch
+ /* Sort entries into the forest on the first test of a new batch.
+ ** To save unnecessary work, only do this when the batch number changes.
*/
- if( iBatch!=pRowSet->iBatch ){
+ if( iBatch!=pRowSet->iBatch ){ /*OPTIMIZATION-IF-FALSE*/
p = pRowSet->pEntry;
if( p ){
struct RowSetEntry **ppPrevTree = &pRowSet->pForest;
- if( (pRowSet->rsFlags & ROWSET_SORTED)==0 ){
+ if( (pRowSet->rsFlags & ROWSET_SORTED)==0 ){ /*OPTIMIZATION-IF-FALSE*/
+ /* Only sort the current set of entiries if they need it */
p = rowSetEntrySort(p);
}
for(pTree = pRowSet->pForest; pTree; pTree=pTree->pRight){
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 7bb15d0bf..76bf80962 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -15,6 +15,33 @@
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
+/* Special Comments:
+**
+** Some comments have special meaning to the tools that measure test
+** coverage:
+**
+** NO_TEST - The branches on this line are not
+** measured by branch coverage. This is
+** used on lines of code that actually
+** implement parts of coverage testing.
+**
+** OPTIMIZATION-IF-TRUE - This branch is allowed to alway be false
+** and the correct answer is still obtained,
+** though perhaps more slowly.
+**
+** OPTIMIZATION-IF-FALSE - This branch is allowed to alway be true
+** and the correct answer is still obtained,
+** though perhaps more slowly.
+**
+** PREVENTS-HARMLESS-OVERREAD - This branch prevents a buffer overread
+** that would be harmless and undetectable
+** if it did occur.
+**
+** In all cases, the special comment must be enclosed in the usual
+** slash-asterisk...asterisk-slash comment marks, with no spaces between the
+** asterisks and the comment text.
+*/
+
/*
** Make sure that rand_s() is available on Windows systems with MSVC 2005
** or higher.
diff --git a/src/vdbe.c b/src/vdbe.c
index 244a4ad06..5fba14a5c 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -215,7 +215,7 @@ static VdbeCursor *allocateCursor(
(eCurType==CURTYPE_BTREE?sqlite3BtreeCursorSize():0);
assert( iCur>=0 && iCur<p->nCursor );
- if( p->apCsr[iCur] ){
+ if( p->apCsr[iCur] ){ /*OPTIMIZATION-IF-FALSE*/
sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
p->apCsr[iCur] = 0;
}
@@ -292,7 +292,7 @@ static void applyAffinity(
if( affinity>=SQLITE_AFF_NUMERIC ){
assert( affinity==SQLITE_AFF_INTEGER || affinity==SQLITE_AFF_REAL
|| affinity==SQLITE_AFF_NUMERIC );
- if( (pRec->flags & MEM_Int)==0 ){
+ if( (pRec->flags & MEM_Int)==0 ){ /*OPTIMIZATION-IF-FALSE*/
if( (pRec->flags & MEM_Real)==0 ){
if( pRec->flags & MEM_Str ) applyNumericAffinity(pRec,1);
}else{
@@ -302,10 +302,13 @@ static void applyAffinity(
}else if( affinity==SQLITE_AFF_TEXT ){
/* Only attempt the conversion to TEXT if there is an integer or real
** representation (blob and NULL do not get converted) but no string
- ** representation.
- */
- if( 0==(pRec->flags&MEM_Str) && (pRec->flags&(MEM_Real|MEM_Int)) ){
- sqlite3VdbeMemStringify(pRec, enc, 1);
+ ** representation. It would be harmless to repeat the conversion if
+ ** there is already a string rep, but it is pointless to waste those
+ ** CPU cycles. */
+ if( 0==(pRec->flags&MEM_Str) ){ /*OPTIMIZATION-IF-FALSE*/
+ if( (pRec->flags&(MEM_Real|MEM_Int)) ){
+ sqlite3VdbeMemStringify(pRec, enc, 1);
+ }
}
pRec->flags &= ~(MEM_Real|MEM_Int);
}
@@ -542,7 +545,7 @@ static Mem *out2Prerelease(Vdbe *p, VdbeOp *pOp){
assert( pOp->p2<=(p->nMem+1 - p->nCursor) );
pOut = &p->aMem[pOp->p2];
memAboutToChange(p, pOut);
- if( VdbeMemDynamic(pOut) ){
+ if( VdbeMemDynamic(pOut) ){ /*OPTIMIZATION-IF-FALSE*/
return out2PrereleaseWithClear(pOut);
}else{
pOut->flags = MEM_Int;
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-21 14:10:26 +0000