[#1385] metabase: Optimize isTomb check

As tombstone and target must have the same containerID, do not iterate
other containers.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/metabase/inhume.go

@@ -377,11 +377,8 @@ func (db *DB) getInhumeTargetBucketAndValue(garbageBKT, graveyardBKT *bbolt.Buck
 	return targetBucket, value, nil
 }
 
-func (db *DB) markAsGC(graveyardBKT, garbageBKT *bbolt.Bucket, key []byte) (bool, error) {
-	targetIsTomb, err := isTomb(graveyardBKT, key)
-	if err != nil {
-		return false, err
-	}
+func (db *DB) markAsGC(graveyardBKT, garbageBKT *bbolt.Bucket, addressKey []byte) (bool, error) {
+	targetIsTomb := isTomb(graveyardBKT, addressKey)
 
 	// do not add grave if target is a tombstone
 	if targetIsTomb {
@@ -390,7 +387,7 @@ func (db *DB) markAsGC(graveyardBKT, garbageBKT *bbolt.Bucket, key []byte) (bool
 
 	// if tombstone appears object must be
 	// additionally marked with GC
-	return false, garbageBKT.Put(key, zeroValue)
+	return false, garbageBKT.Put(addressKey, zeroValue)
 }
 
 func (db *DB) updateDeleteInfo(tx *bbolt.Tx, garbageBKT, graveyardBKT *bbolt.Bucket, targetKey []byte, cnr cid.ID, obj *objectSDK.Object, res *InhumeRes) error {
@@ -410,25 +407,21 @@ func (db *DB) updateDeleteInfo(tx *bbolt.Tx, garbageBKT, graveyardBKT *bbolt.Buc
 	return nil
 }
 
-func isTomb(graveyardBucket *bbolt.Bucket, key []byte) (bool, error) {
+func isTomb(graveyardBucket *bbolt.Bucket, addressKey []byte) bool {
 	targetIsTomb := false
 
 	// iterate over graveyard and check if target address
 	// is the address of tombstone in graveyard.
-	err := graveyardBucket.ForEach(func(_, v []byte) error {
+	// tombstone must have the same container ID as key.
+	c := graveyardBucket.Cursor()
+	containerPrefix := addressKey[:cidSize]
+	for k, v := c.Seek(containerPrefix); k != nil && bytes.HasPrefix(k, containerPrefix); k, v = c.Next() {
 		// check if graveyard has record with key corresponding
 		// to tombstone address (at least one)
-		targetIsTomb = bytes.Equal(v, key)
-
+		targetIsTomb = bytes.Equal(v, addressKey)
 		if targetIsTomb {
-			// break bucket iterator
-			return errBreakBucketForEach
+			break
 		}
-
-		return nil
-	})
-	if err != nil && !errors.Is(err, errBreakBucketForEach) {
-		return false, err
 	}
-	return targetIsTomb, nil
+	return targetIsTomb
 }