Adding support for pre-sent messages

components/copresence/copresence_manager_impl.h

 // Copyright 2014 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 COMPONENTS_COPRESENCE_COPRESENCE_MANAGER_IMPL_H_
 #define COMPONENTS_COPRESENCE_COPRESENCE_MANAGER_IMPL_H_
 
+#include <map>
 #include <string>
 #include <vector>
 
 #include "base/cancelable_callback.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/copresence/copresence_state_impl.h"
 #include "components/copresence/public/copresence_manager.h"
 
 namespace base {
 class Timer;
 }
 
 namespace net {
 class URLContextGetter;
 }
 
 namespace copresence {
 
 class DirectiveHandler;
 class GCMHandler;
 class ReportRequest;
 class RpcHandler;
+class SubscribedMessage;
 class WhispernetClient;
 
 // The implementation for CopresenceManager. Responsible primarily for
 // client-side initialization. The RpcHandler handles all the details
 // of interacting with the server.
 // TODO(rkc): Add tests for this class.
 class CopresenceManagerImpl : public CopresenceManager {
  public:
   // The delegate is owned by the caller, and must outlive the manager.
   explicit CopresenceManagerImpl(CopresenceDelegate* delegate);
 
   ~CopresenceManagerImpl() override;
 
   // CopresenceManager overrides.
   CopresenceState* state() override;
   void ExecuteReportRequest(const ReportRequest& request,
                             const std::string& app_id,
                             const std::string& auth_token,
                             const StatusCallback& callback) override;
 
  private:
+  // Complete initialization when Whispernet is available.
   void WhispernetInitComplete(bool success);
 
   // Handle tokens decoded by Whispernet.
   // TODO(ckehoe): Replace AudioToken with ReceivedToken.
   void ReceivedTokens(const std::vector<AudioToken>& tokens);
 
-  // This function will be called every kPollTimerIntervalMs milliseconds
+  // Verifies that we can hear the audio we're playing.
+  // This gets called every kAudioCheckIntervalMs milliseconds.
+  void AudioCheck();
+
+  // This gets called every kPollTimerIntervalMs milliseconds
   // to poll the server for new messages.
   void PollForMessages();
 
-  // Verify that we can hear the audio we're playing
-  // every kAudioCheckIntervalMs milliseconds.
-  void AudioCheck();
+  // Send SubscribedMessages to the appropriate clients. Can be called with
+  // a vector or anything that behaves like one, e.g. RepeatedPtrField.
+  template<typename IterableSubscribedMessages>

[rkc, 2015/01/07 21:31:43]

Since we use a std::vector only in our own map, can we instead use a
RepeatedPtrField there too and remove this templatization?

[Charlie, 2015/01/07 22:06:07]

Yes, but that's kind of hacky. This kind of templating is the C++ version of
Java's Iterable interface.

[rkc, 2015/01/07 23:06:10]

Sure but we don't actually need this to be an iterable interface. Templates
introduce compile and run-time costs, which we shouldn't incur unless there is
at least some clear benefit to it.

[Charlie, 2015/01/08 16:47:33]

1. I don't think RepeatedPtrField is really intended to be used anywhere outside
a proto.

2. According to Titus Winters, head of the C++ platform for Google: if you can't
write something in the clearest, simplest way, it's a compiler/libraries bug.
Instead of being "clever", write the code clearly and file a bug. Cleverness is
much more costly in the long run.

That said, RepeatedPtrField is actually easier to deal with than I thought.
After branch maybe I'll ask Titus for his opinion here.

Done.

+  void DispatchMessages(const IterableSubscribedMessages& subscribed_messages);
 
   // Belongs to the caller.
   CopresenceDelegate* const delegate_;
 
   // We use a CancelableCallback here because Whispernet
   // does not provide a way to unregister its init callback.
   base::CancelableCallback<void(bool)> whispernet_init_callback_;
 
   bool init_failed_;
 
   // This order is required because each object
   // makes calls to those listed before it.
   scoped_ptr<CopresenceStateImpl> state_;
   scoped_ptr<RpcHandler> rpc_handler_;
   scoped_ptr<DirectiveHandler> directive_handler_;
   scoped_ptr<GCMHandler> gcm_handler_;
 
   scoped_ptr<base::Timer> poll_timer_;
   scoped_ptr<base::Timer> audio_check_timer_;
 
+  // TODO(ckehoe): Expire queued messages after a certain time
+  //               (e.g. 10 minutes),or limit how many we store.
+  std::map<std::string, std::vector<SubscribedMessage>>

[rkc, 2015/01/07 21:31:43]

Why not use TimedMap?

[Charlie, 2015/01/07 22:06:07]

It doesn't have quite the same functionality. map::operator[] returns a mutable
reference, while TimedMap::GetValue returns a const one. And map::erase has no
equivalent.

But it's a good idea. Updated the TODO.

+  queued_messages_by_token_;
+
   DISALLOW_COPY_AND_ASSIGN(CopresenceManagerImpl);
 };
 
 }  // namespace copresence
 
 #endif  // COMPONENTS_COPRESENCE_COPRESENCE_MANAGER_IMPL_H_