src/cobalt/h5vcc/h5vcc_runtime_event_target.h

/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef COBALT_H5VCC_H5VCC_RUNTIME_EVENT_TARGET_H_
#define COBALT_H5VCC_H5VCC_RUNTIME_EVENT_TARGET_H_

#include <vector>

#include "base/callback.h"
#include "base/message_loop_proxy.h"
#include "base/synchronization/lock.h"
#include "cobalt/script/callback_function.h"
#include "cobalt/script/script_object.h"
#include "cobalt/script/wrappable.h"

namespace cobalt {
namespace h5vcc {

// This class implements the onPause attribute of the h5vcc.runtime protocol,
// modeled after the events in Chrome's runtime extension, e.g.
// https://developer.chrome.com/apps/runtime#event-onSuspend

class H5vccRuntimeEventTarget : public script::Wrappable {
 public:
  // Type for JavaScript event callback.
  typedef script::CallbackFunction<void()> H5vccRuntimeEventCallback;
  typedef script::ScriptObject<H5vccRuntimeEventCallback>
      H5vccRuntimeEventCallbackHolder;

  // Type for listener info.
  // We store the message loop from which the listener was registered,
  // so we can run the callback on the same loop.
  struct ListenerInfo {
    ListenerInfo(H5vccRuntimeEventTarget* const pause_event,
                 const H5vccRuntimeEventCallbackHolder& cb)
        : callback(pause_event, cb),
          message_loop(base::MessageLoopProxy::current()) {}

    H5vccRuntimeEventCallbackHolder::Reference callback;
    scoped_refptr<base::MessageLoopProxy> message_loop;
  };

  H5vccRuntimeEventTarget();
  ~H5vccRuntimeEventTarget();

  // Called from JavaScript to register an event listener callback.
  // May be called from any thread.
  void AddListener(const H5vccRuntimeEventCallbackHolder& callback_holder);

  // Dispatches an event to the registered listeners.
  // May be called from any thread.
  void DispatchEvent();

  DEFINE_WRAPPABLE_TYPE(H5vccRuntimeEventTarget);

 private:
  typedef std::vector<ListenerInfo*> ListenerVector;

  // Notifies a particular listener. Must be called on the same message loop the
  // listener registered its callback from.
  void NotifyListener(const ListenerInfo* listener);

  ListenerVector listeners_;
  base::Lock lock_;

  DISALLOW_COPY_AND_ASSIGN(H5vccRuntimeEventTarget);
};

}  // namespace h5vcc
}  // namespace cobalt

#endif  // COBALT_H5VCC_H5VCC_RUNTIME_EVENT_TARGET_H_