[GCM] Add heartbeat manager and reconnection logic due to heartbeat failure

google_apis/gcm/engine/heartbeat_manager.h

+// 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 GOOGLE_APIS_GCM_ENGINE_HEARTBEAT_MANAGER_H_
+#define GOOGLE_APIS_GCM_ENGINE_HEARTBEAT_MANAGER_H_
+
+#include "base/callback.h"
+#include "base/logging.h"
+#include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
+#include "google_apis/gcm/base/gcm_export.h"
+
+namespace mcs_proto {
+class HeartbeatConfig;
+}
+
+namespace gcm {
+
+// A heartbeat management class, capable of sending and handling heartbeat
+// receipt/failures and triggering reconnection as necessary.
+class GCM_EXPORT HeartbeatManager {
+ public:
+  HeartbeatManager();
+  ~HeartbeatManager();
+
+  // Start the heartbeat logic.
+  // |send_heartbeat_callback_| is the callback the HeartbeatManager uses to
+  // send new heartbeats. Only one heartbeat can be outstanding at a time.
+  void Start(const base::Closure& send_heartbeat_callback,
+             const base::Closure& trigger_reconnect_callback);
+
+  // Stop the timer. Start(..) must be called again to begin sending heartbeats
+  // afterwards.
+  void Stop();
+
+  // Reset the heartbeat timer. It is valid to call this even if no heartbeat
+  // is associated with the ack (for example if another signal is used to
+  // determine that the connection is alive).
+  void OnHeartbeatAcked();
+
+  // Updates the current heartbeat interval.
+  void UpdateHeartbeatConfig(const mcs_proto::HeartbeatConfig& config);
+
+  // Returns the next scheduled heartbeat time. If non-null and less than
+  // base::Timeticks::Now(), a heartbeat ack is pending. If null, the heartbeat
+  // manager is stopped.

[jianli, 2013/12/20 23:10:03]

What does it mean if the returned value is non-null and not less than
base::Timeticks::Now()?

Also, probably better to say current time, instead of base::Timeticks::Now().

[Nicolas Zea, 2013/12/26 22:55:02]

That's the time that the heartbeat will be sent. Reworded to make it a bit
clearer.

+  base::TimeTicks GetNextHeartbeatTime() const;
+
+ protected:
+  // Helper method to send heartbeat on timer trigger.
+  void OnHeartbeatTriggered();
+
+ private:
+  // Restarts the heartbeat timer.
+  void RestartTimer();
+
+  // Whether the last heartbeat ping sent has been acknowledged or not.
+  bool waiting_for_ack_;
+
+  // The current heartbeat interval.
+  base::TimeDelta heartbeat_interval_;
+  // The most recent server-provided heartbeat interval (0 if none has been
+  // provided).
+  int32 server_interval_ms_;
+
+  // Timer for triggering heartbeats.
+  base::Timer heartbeat_timer_;
+
+  // Callbacks for interacting with the the connection.
+  base::Closure send_heartbeat_callback_;
+  base::Closure trigger_reconnect_callback_;
+
+  base::WeakPtrFactory<HeartbeatManager> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(HeartbeatManager);
+};
+
+}  // namespace gcm
+
+#endif  // GOOGLE_APIS_GCM_ENGINE_HEARTBEAT_MANAGER_H_