cache api calls and responses on setup (#4565)

* cache api calls and responses on setup

* use PathManager instead of os and json instead of pickle

* fix json.load and file open

* fix typo

Co-authored-by: Martin Corredor <mcorredor@devfair0237.h2.fair>

parlai/tasks/multiwoz_v22/agents.py

@@ -262,10 +262,19 @@ def _get_round(self, dialogue_id, raw_episode, turn_id):
                                     )
                                 if not valid:
                                     continue
+
                             call = maybe_call
-                            resp = self._get_find_api_response(
-                                intent, frame["state"]["slot_values"], sys_dialog_act
-                            )
+                            call_key = str(call)
+                            if call_key not in self.call_response_cache:
+                                resp = self._get_find_api_response(
+                                    intent,
+                                    frame["state"]["slot_values"],
+                                    sys_dialog_act,
+                                )
+                                self.call_response_cache[call_key] = resp
+                            else:
+                                resp = self.call_response_cache[call_key]
+
                 elif "book" in intent:
                     for key in sys_dialog_act:
                         if "Book" in key:  # and "Inform" not in key:
@@ -300,8 +309,17 @@ def setup_episodes(self, fold):
         """
         Parses into TodStructuredEpisode.
         """
-        self.dbs = self.load_dbs()
         self.schemas = self.load_schemas()
+        cache_path = os.path.join(self.dpath, f"{fold}_call_response_cache.json")
+
+        if PathManager.exists(cache_path):
+            with PathManager.open(cache_path, 'r') as f:
+                self.call_response_cache = json.load(f)
+            self.dbs = None
+        else:
+            self.call_response_cache = {}
+            self.dbs = self.load_dbs()
+
         with PathManager.open(os.path.join(self.dpath, "dialog_acts.json")) as f:
             self.dialog_acts = json.load(f)
 
@@ -345,6 +363,10 @@ def setup_episodes(self, fold):
                 rounds=rounds,
             )
             episodes.append(episode)
+
+        with PathManager.open(cache_path, 'w') as f:
+            json.dump(self.call_response_cache, f)
+
         return episodes
 
     def get_id_task_prefix(self):