[patches] [PATCH 2/3] sql: remove extra key copy from cursor routine

[Nikita Pettik]

SQL cursor holds key which is used to create index iterator.  Iterator
itself doesn't make copy of key, it only saves pointer to it.
moveToUnpacked() allocates memory for the key on region and pass it to
cursor positioning function, which in its turn copies it from region to
malloc.  Other callers of this function pass only static variables as
key arguments.  All points considered, this memory copy in cursor
positioning function turns out to be redundant and can be removed. In
this respect, moveToUnpacked() will allocate memory for key immediately
using malloc.
---
 src/box/sql.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/src/box/sql.c b/src/box/sql.c
index 682f15753..1ed2490c7 100644
--- a/src/box/sql.c
+++ b/src/box/sql.c
@@ -292,15 +292,17 @@ int tarantoolSqlite3MovetoUnpacked(BtCursor *pCur, UnpackedRecord *pIdxKey,
 {
 	int rc, res_success;
 	size_t ks;
-	const char *k, *ke;
+	const char *ke;
 	enum iterator_type iter_type;
+	struct ta_cursor *taCur = pCur->pTaCursor;
 
 	ks = sqlite3VdbeMsgpackRecordLen(pIdxKey->aMem,
 					 pIdxKey->nField);
-	k = region_reserve(&fiber()->gc, ks);
-	if (k == NULL) return SQLITE_NOMEM;
-	ke = k + sqlite3VdbeMsgpackRecordPut((u8 *)k, pIdxKey->aMem,
-					     pIdxKey->nField);
+	taCur = cursor_create(taCur, ks);
+	ke = taCur->key + sqlite3VdbeMsgpackRecordPut((u8 *)taCur->key,
+						      pIdxKey->aMem,
+						      pIdxKey->nField);
+	pCur->pTaCursor = taCur;
 
 	switch (pIdxKey->opcode) {
 	default:
@@ -338,7 +340,7 @@ int tarantoolSqlite3MovetoUnpacked(BtCursor *pCur, UnpackedRecord *pIdxKey,
 		res_success = 0;
 		break;
 	}
-	rc = cursor_seek(pCur, pRes, iter_type, k, ke);
+	rc = cursor_seek(pCur, pRes, iter_type, taCur->key, ke);
 	if (*pRes == 0) {
 		*pRes = res_success;
 		/*
@@ -1184,13 +1186,6 @@ cursor_seek(BtCursor *pCur, int *pRes, enum iterator_type type,
 	}
 	pCur->pTaCursor = c;
 
-	/* Copy key if necessary. */
-	if (key_size != 0) {
-		memcpy(c->key, key, key_end - key);
-		key_end = c->key + (key_end - key);
-		key = c->key;
-	}
-
 	struct space *space;
 	struct index *index;
 	uint32_t space_id = SQLITE_PAGENO_TO_SPACEID(pCur->pgnoRoot);
-- 
2.15.1