content/browser/gamepad/gamepad_service.h

// Copyright (c) 2012 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 CONTENT_BROWSER_GAMEPAD_GAMEPAD_SERVICE_H_
#define CONTENT_BROWSER_GAMEPAD_GAMEPAD_SERVICE_H_

#include <memory>
#include <set>

#include "base/callback_forward.h"
#include "base/macros.h"
#include "base/memory/shared_memory.h"
#include "base/memory/singleton.h"
#include "base/threading/thread_checker.h"
#include "content/common/content_export.h"

namespace blink {
class WebGamepad;
}

namespace content {

class GamepadConsumer;
class GamepadDataFetcher;
class GamepadProvider;
class GamepadServiceTestConstructor;
class RenderProcessHost;

// Owns the GamepadProvider (the background polling thread) and keeps track of
// the number of consumers currently using the data (and pausing the provider
// when not in use).
class CONTENT_EXPORT GamepadService {
 public:
  // Returns the GamepadService singleton.
  static GamepadService* GetInstance();

  // Increments the number of users of the provider. The Provider is running
  // when there's > 0 users, and is paused when the count drops to 0.
  // consumer is registered to listen for gamepad connections. If this is the
  // first time it is added to the set of consumers it will be treated
  // specially: it will not be informed about connections before a new user
  // gesture is observed at which point it will be notified for every connected
  // gamepads.
  //
  // Must be called on the I/O thread.
  void ConsumerBecameActive(GamepadConsumer* consumer);

  // Decrements the number of users of the provider. consumer will not be
  // informed about connections until it's added back via ConsumerBecameActive.
  // Must be matched with a ConsumerBecameActive call.
  //
  // Must be called on the I/O thread.
  void ConsumerBecameInactive(GamepadConsumer* consumer);

  // Decrements the number of users of the provider and removes consumer from
  // the set of consumers. Should be matched with a a ConsumerBecameActive
  // call.
  //
  // Must be called on the I/O thread.
  void RemoveConsumer(GamepadConsumer* consumer);

  // Registers the given closure for calling when the user has interacted with
  // the device. This callback will only be issued once. Should only be called
  // while a consumer is active.
  void RegisterForUserGesture(const base::Closure& closure);

  // Returns the shared memory handle of the gamepad data duplicated into the
  // given process.
  base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
      base::ProcessHandle handle);

  // Stop/join with the background thread in GamepadProvider |provider_|.
  void Terminate();

  // Called on IO thread when a gamepad is connected.
  void OnGamepadConnected(int index, const blink::WebGamepad& pad);

  // Called on IO thread when a gamepad is disconnected.
  void OnGamepadDisconnected(int index, const blink::WebGamepad& pad);

 private:
  friend struct base::DefaultSingletonTraits<GamepadService>;
  friend class GamepadServiceTestConstructor;
  friend class GamepadServiceTest;

  GamepadService();

  // Constructor for testing. This specifies the data fetcher to use for a
  // provider, bypassing the default platform one.
  GamepadService(std::unique_ptr<GamepadDataFetcher> fetcher);

  virtual ~GamepadService();

  static void SetInstance(GamepadService*);

  void OnUserGesture();

  struct ConsumerInfo {
    ConsumerInfo(GamepadConsumer* consumer)
        : consumer(consumer),
          did_observe_user_gesture(false) {
    }

    bool operator<(const ConsumerInfo& other) const {
      return consumer < other.consumer;
    }

    GamepadConsumer* consumer;
    mutable bool is_active;
    mutable bool did_observe_user_gesture;
  };

  std::unique_ptr<GamepadProvider> provider_;

  base::ThreadChecker thread_checker_;

  typedef std::set<ConsumerInfo> ConsumerSet;
  ConsumerSet consumers_;

  int num_active_consumers_;

  bool gesture_callback_pending_;

  DISALLOW_COPY_AND_ASSIGN(GamepadService);
};

}  // namespace content

#endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_SERVICE_H_