Docserver: Make ObjectStore set calls return Futures

chrome/common/extensions/docs/server2/persistent_object_store.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from appengine_wrappers import db
 from datastore_models import PersistentObjectStoreItem
 from environment import IsDevServer
-from future import Future
+from future import All, Future
 from object_store import ObjectStore
 
 
 class PersistentObjectStore(ObjectStore):
   '''Stores data persistently using the AppEngine Datastore API.
   '''
   def __init__(self, namespace):
     self._namespace = namespace
 
   def SetMulti(self, mapping):
-    futures = []
-    for key, value in mapping.items():
-      futures.append(db.put_async(
-          PersistentObjectStoreItem.CreateItem(self._namespace, key, value)))
+    rpcs = [db.put_async(
+        PersistentObjectStoreItem.CreateItem(self._namespace, key, value))
+        for key, value in mapping.items()]

[not at google - send to devlin, 2014/10/23 20:00:19]

iteritems

     # If running the dev server, the futures don't complete until the server is
     # *quitting*. This is annoying. Flush now.
     if IsDevServer():
-      [future.wait() for future in futures]
+      [rpc.wait() for rpc in rpcs]
+    futures = [Future(callback=lambda: rpc.get_result()) for rpc in rpcs]
+    return All(futures)

[not at google - send to devlin, 2014/10/23 20:00:19]

this is another case where you should be able to put the generator inside the
All method without constructing an intermediate list.

[Ken Rockot(use gerrit already), 2014/10/23 20:16:18]

Done.

Given my previous comment, note that unlike CacheChainObjectStore we've already
started all the RPCs, so lazy generator evaluation is really OK here.

 
   def GetMulti(self, keys):
     db_futures = dict(
         (k, db.get_async(
             PersistentObjectStoreItem.CreateKey(self._namespace, k)))
         for k in keys)
     def resolve():
       return dict((key, future.get_result().GetValue())
                   for key, future in db_futures.iteritems()
                   if future.get_result() is not None)
     return Future(callback=resolve)
 
   def DelMulti(self, keys):
     futures = []
     for key in keys:
       futures.append(db.delete_async(
         PersistentObjectStoreItem.CreateKey(self._namespace, key)))
     # If running the dev server, the futures don't complete until the server is
     # *quitting*. This is annoying. Flush now.
     if IsDevServer():
       [future.wait() for future in futures]