sync: Report GetUpdate triggers to the server

sync/sessions/sync_session.h

Index: sync/sessions/sync_session.h
diff --git a/sync/sessions/sync_session.h b/sync/sessions/sync_session.h
index 763bd3bc47941101552755b9a3cb0388e8d34219..a8bfb4d61d26c9ce5b340c417c5e77c3081ba2ce 100644
--- a/sync/sessions/sync_session.h
+++ b/sync/sessions/sync_session.h
@@ -36,6 +36,8 @@ class ModelSafeWorker;
 
 namespace sessions {
 
+class NudgeTracker;
+
 class SYNC_EXPORT_PRIVATE SyncSession {
  public:
   // The Delegate services events that occur during the session requiring an
@@ -86,13 +88,27 @@ class SYNC_EXPORT_PRIVATE SyncSession {
     virtual void OnSyncProtocolError(
         const sessions::SyncSessionSnapshot& snapshot) = 0;
 
+    // Called when the server wants to change the number of hints the client
+    // will buffer locally.
+    virtual void OnReceivedClientInvalidationHintBufferSize(int size) = 0;

[tim (not reviewing), 2013/05/07 22:40:34]

You use int here but size_t in NudgeTracker, was there a reason? I didn't see
any input validation that probably wouldn't hurt.

[rlarocque, 2013/05/07 22:56:49]

The protobufs provide us with ints, so I've used ints in the functions that are
meant to transmit data from the protobufs to other parts of the code.  

All The SyncSession::Delegate implementations will treat this as an int, because
that's the format of the message.  

The NudgeTracker deals in size_t, because that's the type of the size of a
vector (or any in-memory list).  The value passed to
NudgeTracker::SetHintBufferSize() will only be used in comparisons against a
size_t, so we'd might as well ask for it and store it in that format.  

What sort of input checking were you looking for?  Should we make sure the int
is non-negative before passing it along to the nudge tracker?  

Should we check that it's within some reasonable bounds?  It seems like that
would defeat the point of making it server-controlled.

[tim (not reviewing), 2013/05/07 23:35:50]

Sanity checking that the value was greater than zero was what I had in mind. I
left it open in case you had any other ideas as well.

+
    protected:
     virtual ~Delegate() {}
   };
 
-  SyncSession(SyncSessionContext* context,
-              Delegate* delegate,
-              const SyncSourceInfo& source);
+  // Build a session with a nudge tracker.  Used for sync cycles with origin of
+  // GU_TRIGGER (ie. notification, local change, and/or refresh request)
+  static SyncSession* BuildForNudge(SyncSessionContext* context,
+                                    Delegate* delegate,
+                                    const SyncSourceInfo& source,
+                                    const NudgeTracker* nudge_tracker);
+
+  // Build a session without a nudge tracker.  Used for poll or configure type
+  // sync cycles.
+  static SyncSession* Build(SyncSessionContext* context,
+                            Delegate* delegate,
+                            const SyncSourceInfo& source);
+
   ~SyncSession();
 
   // Builds a thread-safe and read-only copy of the current session state.
@@ -113,7 +129,14 @@ class SYNC_EXPORT_PRIVATE SyncSession {
 
   const SyncSourceInfo& source() const { return source_; }
 
+  const NudgeTracker* nudge_tracker() const { return nudge_tracker_; }
+
  private:
+  SyncSession(SyncSessionContext* context,
+              Delegate* delegate,
+              const SyncSourceInfo& source,
+              const NudgeTracker* nudge_tracker);
+
   // The context for this session, guaranteed to outlive |this|.
   SyncSessionContext* const context_;
 
@@ -126,6 +149,8 @@ class SYNC_EXPORT_PRIVATE SyncSession {
   // Our controller for various status and error counters.
   scoped_ptr<StatusController> status_controller_;
 
+  const NudgeTracker* nudge_tracker_;
+
   DISALLOW_COPY_AND_ASSIGN(SyncSession);
 };