Refactor sync-specific parts out of SyncNotifier/SyncNotifierObserver

sync/notifier/sync_notifier_helper.h

Index: sync/notifier/sync_notifier_helper.h
diff --git a/sync/notifier/sync_notifier_helper.h b/sync/notifier/sync_notifier_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..659354f3f98ebb227a9d6fdc93c2330e47ae6e62
--- /dev/null
+++ b/sync/notifier/sync_notifier_helper.h
@@ -0,0 +1,51 @@
+// Copyright (c) 2012 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.
+
+#ifndef SYNC_NOTIFIER_SYNC_NOTIFIER_HELPER_H_
+#define SYNC_NOTIFIER_SYNC_NOTIFIER_HELPER_H_
+
+#include <map>
+
+#include "base/basictypes.h"
+#include "base/observer_list.h"
+#include "sync/notifier/invalidation_util.h"
+#include "sync/notifier/object_id_payload_map.h"
+#include "sync/notifier/sync_notifier_observer.h"
+
+namespace syncer {
+
+class SyncNotifierHelper {

[akalin, 2012/07/19 00:42:07]

class-level comment

[dcheng, 2012/07/19 18:31:05]

Done.

+ public:
+  SyncNotifierHelper();
+  virtual ~SyncNotifierHelper();

[akalin, 2012/07/19 00:42:07]

doesn't need to be virtual

[dcheng, 2012/07/19 18:31:05]

Leftover from an earlier patch. We don't need it at all now.

+
+  // Updates the list of ObjectIds associated with a given |handler|. Passing an
+  // empty ObjectIdSet will unregister |handler|; any other value is an implicit
+  // registration. The return value is an ObjectIdSet containing all currently
+  // registered values.

[akalin, 2012/07/19 00:42:07]

was momentarily confused -- maybe '...values.' -> 'values for all existing
handlers.'

[akalin, 2012/07/19 00:42:07]

Specify that at most one handler can handle a given object ID. (This is true,
right?)

[dcheng, 2012/07/19 18:31:05]

Done.

[dcheng, 2012/07/19 18:31:05]

Done.

+  ObjectIdSet UpdateRegisteredIds(SyncNotifierObserver* handler,
+                                  const ObjectIdSet& ids);
+
+  // Helper that sorts incoming invalidations into a bucket for each handler
+  // and then dispatches the batched invalidations to the corresponding handler.
+  void DispatchInvalidationsToHandlers(const ObjectIdPayloadMap& id_payloads,
+                                       IncomingNotificationSource source);
+
+  // Note that this is non-const because FOR_EACH_OBSERVER() may mutate the

[akalin, 2012/07/19 00:42:07]

Would rather replace this accessor with functions similar to
DispatchInvalidationToHandlers, since we have a small number of observer
methods. (Just applying Law of Demeter)

[dcheng, 2012/07/19 18:31:05]

Done.

+  // original observer list.
+  ObserverList<SyncNotifierObserver>* handlers() { return &handlers_; }
+
+ private:
+  typedef std::map<invalidation::ObjectId,
+                   SyncNotifierObserver*,
+                   ObjectIdLessThan> ObjectIdObserverMap;
+  ObserverList<SyncNotifierObserver> handlers_;
+  ObjectIdObserverMap id_to_handler_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncNotifierHelper);
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_NOTIFIER_SYNC_NOTIFIER_HELPER_H_