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Add the ExprList.nAlloc column and use it to make the sqlite3ExprListAppend()

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routine much faster.

FossilOrigin-Name: 1d3c4662c2f522ac695d97441324069f3fc65f3fa0b87194c7094dfb8cd549f2
This commit is contained in:
drh
2021-03-23 14:27:35 +00:00
parent a7fc252b0a
commit 50e43c5094
4 changed files with 57 additions and 33 deletions
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72
src/expr.c
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@@ -1478,6 +1478,7 @@ ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p, int flags){
pNew = sqlite3DbMallocRawNN(db, sqlite3DbMallocSize(db, p));
if( pNew==0 ) return 0;
pNew->nExpr = p->nExpr;
pNew->nAlloc = p->nAlloc;
pItem = pNew->a;
pOldItem = p->a;
for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){
@@ -1650,41 +1651,64 @@ Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
** NULL is returned. If non-NULL is returned, then it is guaranteed
** that the new entry was successfully appended.
*/
static const struct ExprList_item zeroItem;
SQLITE_NOINLINE ExprList *sqlite3ExprListAppendNew(
sqlite3 *db, /* Database handle. Used for memory allocation */
Expr *pExpr /* Expression to be appended. Might be NULL */
){
struct ExprList_item *pItem;
ExprList *pList;
pList = sqlite3DbMallocRawNN(db, sizeof(ExprList)+sizeof(pList->a[0])*4 );
if( pList==0 ){
sqlite3ExprDelete(db, pExpr);
return 0;
}
pList->nAlloc = 4;
pList->nExpr = 1;
pItem = &pList->a[0];
*pItem = zeroItem;
pItem->pExpr = pExpr;
return pList;
}
SQLITE_NOINLINE ExprList *sqlite3ExprListAppendGrow(
sqlite3 *db, /* Database handle. Used for memory allocation */
ExprList *pList, /* List to which to append. Might be NULL */
Expr *pExpr /* Expression to be appended. Might be NULL */
){
struct ExprList_item *pItem;
ExprList *pNew;
pList->nAlloc *= 2;
pNew = sqlite3DbRealloc(db, pList,
sizeof(*pList)+(pList->nAlloc-1)*sizeof(pList->a[0]));
if( pNew==0 ){
sqlite3ExprListDelete(db, pList);
sqlite3ExprDelete(db, pExpr);
return 0;
}else{
pList = pNew;
}
pItem = &pList->a[pList->nExpr++];
*pItem = zeroItem;
pItem->pExpr = pExpr;
return pList;
}
ExprList *sqlite3ExprListAppend(
Parse *pParse, /* Parsing context */
ExprList *pList, /* List to which to append. Might be NULL */
Expr *pExpr /* Expression to be appended. Might be NULL */
){
struct ExprList_item *pItem;
sqlite3 *db = pParse->db;
assert( db!=0 );
if( pList==0 ){
pList = sqlite3DbMallocRawNN(db, sizeof(ExprList) );
if( pList==0 ){
goto no_mem;
}
pList->nExpr = 0;
}else if( (pList->nExpr & (pList->nExpr-1))==0 ){
ExprList *pNew;
pNew = sqlite3DbRealloc(db, pList,
sizeof(*pList)+(2*(sqlite3_int64)pList->nExpr-1)*sizeof(pList->a[0]));
if( pNew==0 ){
goto no_mem;
}
pList = pNew;
return sqlite3ExprListAppendNew(pParse->db,pExpr);
}
if( pList->nAlloc<pList->nExpr+1 ){
return sqlite3ExprListAppendGrow(pParse->db,pList,pExpr);
}
pItem = &pList->a[pList->nExpr++];
assert( offsetof(struct ExprList_item,zEName)==sizeof(pItem->pExpr) );
assert( offsetof(struct ExprList_item,pExpr)==0 );
memset(&pItem->zEName,0,sizeof(*pItem)-offsetof(struct ExprList_item,zEName));
*pItem = zeroItem;
pItem->pExpr = pExpr;
return pList;
no_mem:
/* Avoid leaking memory if malloc has failed. */
sqlite3ExprDelete(db, pExpr);
sqlite3ExprListDelete(db, pList);
return 0;
}
/*