faster RevertableOpStack.apply_packed_undo_ops

hub/db/interface.py

@@ -273,6 +273,7 @@ class BasePrefixDB:
         undo_c_f = self.column_families[DB_PREFIXES.undo.value]
         undo_info = self._db.get((undo_c_f, undo_key))
         self._op_stack.apply_packed_undo_ops(undo_info)
+        self._op_stack.validate_and_apply_stashed_ops()
         try:
             with self._db.write_batch(sync=True) as batch:
                 batch_put = batch.put

hub/db/revertable.py

@@ -324,9 +324,21 @@ class RevertableOpStack:
         """
         Unpack and apply a sequence of undo ops from serialized undo bytes
         """
-        while packed:
-            op, packed = RevertableOp.unpack(packed)
-            self.append_op(op)
+        offset = 0
+        packed_size = len(packed)
+        while offset < packed_size:
+            is_put, key_len, val_len = _OP_STRUCT.unpack(packed[offset:offset + 9])
+            offset += 9
+            key = packed[offset:offset + key_len]
+            offset += key_len
+            value = packed[offset:offset + val_len]
+            offset += val_len
+            if is_put == 1:
+                op = RevertablePut(key, value)
+            else:
+                op = RevertableDelete(key, value)
+            self._stash.append(op)
+            self._stashed_last_op_for_key[op.key] = op
 
     def get_pending_op(self, key: bytes) -> Optional[RevertableOp]:
         if key in self._stashed_last_op_for_key: