[GCM] Add RMQ storage and MCS message passing support

google_apis/gcm/engine/rmq_store.h

+// Copyright (c) 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_RMQ_STORE_H_
+#define GOOGLE_APIS_GCM_ENGINE_RMQ_STORE_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/memory/ref_counted.h"
+#include "google_apis/gcm/base/gcm_export.h"
+
+namespace base {
+class FilePath;
+class SequencedTaskRunner;
+}  // namespace base
+
+namespace google {
+namespace protobuf {
+class MessageLite;
+}  // namespace protobuf
+}  // namespace google
+
+namespace gcm {
+
+class MCSMessage;
+
+// A Reliable Message Queue store.
+// Will perform all blocking operations on the blocking task runner, and will
+// post all callbacks to the thread on which the RMQStore is created.
+class GCM_EXPORT RMQStore {
+ public:
+  // Container for Load(..) results.
+  struct LoadResult {
+    LoadResult();
+    ~LoadResult();
+
+    bool success;
+    uint64 device_android_id;
+    uint64 device_security_token;
+    std::vector<std::string> incoming_messages;

[fgorski, 2013/11/01 20:26:10]

Possibly reuse PersistentIdList for the type.

[Nicolas Zea, 2013/11/01 21:18:49]

PersistentIdList is defined below, so I'd have to define it first, then
loadresult, then the loadcallback (which uses LoadResult). This just seemed
cleaner.

+    std::map<std::string, google::protobuf::MessageLite*>
+        outgoing_messages;
+  };
+
+  typedef std::vector<std::string> PersistentIdList;
+  // Note: callee receives ownership of |outgoing_messages|' values.
+  typedef base::Callback<void(const LoadResult& result)> LoadCallback;
+  typedef base::Callback<void(bool success)> UpdateCallback;
+
+  RMQStore(const base::FilePath& path,
+           scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
+  ~RMQStore();
+
+  // Load the directory and pass the initial state back to caller.
+  void Load(const LoadCallback& callback);
+
+  // Clears the RMQ store of all data and destroys any LevelDB files.

[fgorski, 2013/11/01 20:26:10]

these are only the files related to RMQ, and not *any* files, right?

[Nicolas Zea, 2013/11/01 21:18:49]

Right, clarified.

+  // WARNING: this will permanently destroy any pending outgoing messages
+  // and require the device to re-create credentials.
+  void Destroy(const UpdateCallback& callback);
+
+  // Sets this device's messaging credentials.
+  void SetDeviceCredentials(uint64 device_android_id,
+                            uint64 device_security_token,
+                            const UpdateCallback& callback);
+
+  // Unacknowledged incoming message handling.
+  void AddIncomingMessage(const std::string& persistent_id,
+                          const UpdateCallback& callback);
+  void RemoveIncomingMessage(const std::string& persistent_id,
+                             const UpdateCallback& callback);
+  void RemoveIncomingMessages(const PersistentIdList& persistent_ids,
+                              const UpdateCallback& callback);
+
+  // Unacknowledged outgoing messages handling.
+  // TODO(zea): implement per-app limits on the number of outgoing messages.
+  void AddOutgoingMessage(const std::string& persistent_id,
+                          const MCSMessage& message,
+                          const UpdateCallback& callback);
+  void RemoveOutgoingMessage(const std::string& persistent_id,
+                             const UpdateCallback& callback);
+  void RemoveOutgoingMessages(const PersistentIdList& persistent_ids,
+                              const UpdateCallback& callback);
+
+ private:
+  class Backend;
+
+  scoped_refptr<Backend> backend_;
+  scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(RMQStore);
+};
+
+}  // namespace gcm
+
+#endif  // GOOGLE_APIS_GCM_ENGINE_RMQ_STORE_H_