sync: Finish the SyncScheduler refactor

sync/engine/nudge_tracker.h

Index: sync/engine/nudge_tracker.h
diff --git a/sync/engine/nudge_tracker.h b/sync/engine/nudge_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..1ab962257ebc190dbd1a5a90c8beacac7f6ee362
--- /dev/null
+++ b/sync/engine/nudge_tracker.h
@@ -0,0 +1,49 @@
+// 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.
+
+#ifndef SYNC_ENGINE_NUDGE_TRACKER_H_
+#define SYNC_ENGINE_NUDGE_TRACKER_H_

[tim (not reviewing), 2013/04/15 22:37:49]

nit - A file (or class) comment would be nice.

+
+#include <vector>
+
+#include "sync/base/sync_export.h"
+#include "sync/internal_api/public/sessions/sync_source_info.h"
+
+namespace syncer {
+
+namespace sessions {
+struct SyncSourceInfo;
+}  // namespace sessions

[tim (not reviewing), 2013/04/15 22:37:49]

nit - the comment isn't necessary when the whole namespace fwd declaration is
this short.

Since it looks like you're only really interacting with sessions/ types and the
purpose of this class is mainly as a smart container, it feels as though it
might belong under sessions itself? 

[rlarocque, 2013/04/16 01:30:26]

Maybe?  I never understood why sessions had to be a separate namespace in the
first place.  

I had longer-term dreams of having this class ask the sync DB directly about
which types were unsynced, and having interact with (or replace) the
ThrottledDataTypeTracker.  Would it still be a good idea to put this class in
sessions if it starts to interact with other parts of sync?

[tim (not reviewing), 2013/04/16 20:16:24]

I think so. Sessions can interact with whatever it wants, really.  You're right
that the sessions namespace may not be strictly necessary. But things in the
sync engine should only need to use sessions constructs directly. sessions is an
engine-focused wrapper around syncable that is smart enough to filter enabled /
disabled / relevant / irrelevant types and adds to that whatever transient
engine state (versus data model state) is needed to run a sync session /
SyncShare.

[rlarocque, 2013/04/16 22:20:05]

Done.

+
+class SYNC_EXPORT_PRIVATE NudgeTracker {
+ public:
+  NudgeTracker();
+  ~NudgeTracker();
+
+  // Merges in the information from another nudge.
+  void CoalesceSources(const sessions::SyncSourceInfo& source);
+
+  // Returns true if there are no unserviced nudges.
+  bool IsEmpty();
+
+  // Clear all unserviced nudges.
+  void Reset();
+
+  // Returns the coalesced source info.
+  const sessions::SyncSourceInfo& source_info() const {
+    return source_info_;
+  }
+
+  // Returns the set of locally modified types, according to our tracked source
+  // infos.  The result is often wrong; see implementation comment for details.
+  ModelTypeSet GetLocallyModifiedTypes() const;
+
+ private:
+  // Merged source info for the nudge(s).
+  sessions::SyncSourceInfo source_info_;
+};

[tim (not reviewing), 2013/04/15 22:37:49]

DISALLOW_COPY_AND_ASSIGN

[rlarocque, 2013/04/16 01:30:26]

Done.

+
+}  // namespace syncer
+
+#endif  // SYNC_ENGINE_NUDGE_TRACKER_H_