device/bluetooth: Add I/O watcher for audio data retrieval triggered by state change.

device/bluetooth/bluetooth_audio_sink_chromeos.h

 // Copyright 2015 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 DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_CHROMEOS_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_CHROMEOS_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
 
+#include "base/files/file.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
 #include "base/observer_list.h"
 #include "chromeos/dbus/bluetooth_media_client.h"
 #include "chromeos/dbus/bluetooth_media_endpoint_service_provider.h"
 #include "chromeos/dbus/bluetooth_media_transport_client.h"
 #include "dbus/file_descriptor.h"
 #include "dbus/object_path.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_audio_sink.h"
 #include "device/bluetooth/bluetooth_export.h"
 
 namespace chromeos {
 
 class BluetoothAudioSinkChromeOSTest;
 
 class DEVICE_BLUETOOTH_EXPORT BluetoothAudioSinkChromeOS
     : public device::BluetoothAudioSink,
       public device::BluetoothAdapter::Observer,
       public BluetoothMediaClient::Observer,
       public BluetoothMediaTransportClient::Observer,
-      public BluetoothMediaEndpointServiceProvider::Delegate {
+      public BluetoothMediaEndpointServiceProvider::Delegate,
+      public base::MessageLoopForIO::Watcher {
  public:
   explicit BluetoothAudioSinkChromeOS(
       scoped_refptr<device::BluetoothAdapter> adapter);
 
   // device::BluetoothAudioSink overrides.
   // Unregisters a BluetoothAudioSink. |callback| should handle
   // the clean-up after the audio sink is deleted successfully, otherwise
   // |error_callback| will be called.
   void Unregister(
       const base::Closure& callback,
       const device::BluetoothAudioSink::ErrorCallback& error_callback) override;
   void AddObserver(BluetoothAudioSink::Observer* observer) override;
   void RemoveObserver(BluetoothAudioSink::Observer* observer) override;
   device::BluetoothAudioSink::State GetState() const override;
   uint16_t GetVolume() const override;
 
+  // Registers a BluetoothAudioSink. User applications can use |options| to
+  // configure the audio sink. |callback| will be executed if the audio sink is
+  // successfully registered, otherwise |error_callback| will be called. Called
+  // by BluetoothAdapterChromeOS.
+  void Register(
+      const device::BluetoothAudioSink::Options& options,
+      const base::Closure& callback,
+      const device::BluetoothAudioSink::ErrorCallback& error_callback);
+
+  // Returns a pointer to the media endpoint object. This function should be
+  // used for testing purpose only.
+  BluetoothMediaEndpointServiceProvider* GetEndpointServiceProvider();
+
+ private:
+  ~BluetoothAudioSinkChromeOS() override;
+
   // device::BluetoothAdapter::Observer overrides.
   void AdapterPresentChanged(device::BluetoothAdapter* adapter,
                              bool present) override;
   void AdapterPoweredChanged(device::BluetoothAdapter* adapter,
                              bool powered) override;
 
   // BluetoothMediaClient::Observer overrides.
   void MediaRemoved(const dbus::ObjectPath& object_path) override;
 
   // BluetoothMediaTransportClient::Observer overrides.
   void MediaTransportRemoved(const dbus::ObjectPath& object_path) override;
   void MediaTransportPropertyChanged(const dbus::ObjectPath& object_path,
                                      const std::string& property_name) override;
 
   // BluetoothMediaEndpointServiceProvider::Delegate overrides.
   void SetConfiguration(const dbus::ObjectPath& transport_path,
                         const TransportProperties& properties) override;
   void SelectConfiguration(
       const std::vector<uint8_t>& capabilities,
       const SelectConfigurationCallback& callback) override;
   void ClearConfiguration(const dbus::ObjectPath& transport_path) override;
   void Released() override;
 
-  // Registers a BluetoothAudioSink. User applications can use |options| to
-  // configure the audio sink. |callback| will be executed if the audio sink is
-  // successfully registered, otherwise |error_callback| will be called. Called
-  // by BluetoothAdapterChromeOS.
-  void Register(
-      const device::BluetoothAudioSink::Options& options,
-      const base::Closure& callback,
-      const device::BluetoothAudioSink::ErrorCallback& error_callback);
+  // base::MessageLoopForIO::Watcher overrides.
+  void OnFileCanReadWithoutBlocking(int fd) override;
+  void OnFileCanWriteWithoutBlocking(int fd) override;
 
-  // Returns a pointer to the media endpoint object. This function should be
-  // used for testing purpose only.
-  BluetoothMediaEndpointServiceProvider* GetEndpointServiceProvider();
+  // Acquires file descriptor via current transport object when the state change
+  // is triggered by MediaTransportPropertyChanged.
+  void AcquireFD();
 
- private:
-  ~BluetoothAudioSinkChromeOS() override;
+  // Watches if there is any available data from |fd_|.
+  void WatchFD();
+
+  // Stops watching |fd_| and resets |fd_|.
+  void StopWatchingFD();
+
+  // Reads from the file descriptor acquired via Media Transport object and
+  // notify |observer_| while the audio data is available.
+  void ReadFromFile();
 
   // Called when the state property of BluetoothMediaTransport has been updated.
   void StateChanged(device::BluetoothAudioSink::State state);
 
   // Called when the volume property of BluetoothMediaTransport has been
   // updated.
   void VolumeChanged(uint16_t volume);
 
   // Called when the registration of Media Endpoint has succeeded.
   void OnRegisterSucceeded(const base::Closure& callback);
 
   // Called when the registration of Media Endpoint failed.
   void OnRegisterFailed(
       const device::BluetoothAudioSink::ErrorCallback& error_callback,
       const std::string& error_name,
       const std::string& error_message);
 
   // Called when the unregistration of Media Endpoint has succeeded. The
   // clean-up of media, media transport and media endpoint will be handled here.
   void OnUnregisterSucceeded(const base::Closure& callback);
 
   // Called when the unregistration of Media Endpoint failed.
   void OnUnregisterFailed(
       const device::BluetoothAudioSink::ErrorCallback& error_callback,
       const std::string& error_name,
       const std::string& error_message);
 
-  // Reads from the file descriptor acquired via Media Transport object and
-  // notify |observer_| while the audio data is available.
-  void ReadFromFD();
+  // Called when the file descriptor, read MTU and write MTU are retrieved
+  // successfully using |transport_path_|.
+  void OnAcquireSucceeded(dbus::FileDescriptor* fd,
+                          const uint16_t read_mtu,
+                          const uint16_t write_mtu);
+
+  // Called when acquiring the file descriptor, read MTU and write MTU failed.
+  void OnAcquireFailed(const std::string& error_name,
+                       const std::string& error_message);
+
+  // Called when the file descriptor is released successfully.
+  void OnReleaseFDSucceeded();
+
+  // Called when it failed to release file descriptor.
+  void OnReleaseFDFailed(const std::string& error_name,
+                         const std::string& error_message);
 
   // Helper functions to clean up media, media transport and media endpoint.
   // Called when the |state_| changes to either STATE_INVALID or
   // STATE_DISCONNECTED.
   void ResetMedia();
   void ResetTransport();
   void ResetEndpoint();
 
   // The connection state between the BluetoothAudioSinkChromeOS and the remote
   // device.
   device::BluetoothAudioSink::State state_;
 
   // The volume control by the remote device during the streaming. The valid
   // range of volume is 0-127, and 128 is used to represent invalid volume.
   uint16_t volume_;
 
   // Read MTU of the file descriptor acquired via Media Transport object.
-  scoped_ptr<uint16_t> read_mtu_;
+  uint16_t read_mtu_;
 
   // Write MTU of the file descriptor acquired via Media Transport object.
-  scoped_ptr<uint16_t> write_mtu_;
+  uint16_t write_mtu_;
 
-  // File descriptor acquired via Media Transport object.
-  dbus::FileDescriptor fd_;
+  // Flag for logging the read failure in ReadFromFD.
+  bool read_has_failed_;
+
+  // The file which takes ownership of the file descriptor acquired via Media
+  // Transport object.
+  scoped_ptr<base::File> file_;
+
+  // To avoid reallocation of memory, data will be updated only when |read_mtu_|
+  // changes.
+  scoped_ptr<char[]> data_;
+
+  // File descriptor watcher for the file descriptor acquired via Media
+  // Transport object.
+  base::MessageLoopForIO::FileDescriptorWatcher fd_read_watcher_;
 
   // Object path of the media object being used.
   dbus::ObjectPath media_path_;
 
   // Object path of the transport object being used.
   dbus::ObjectPath transport_path_;
 
   // Object path of the media endpoint object being used.
   dbus::ObjectPath endpoint_path_;
 
@@ skipping 15 matching lines @@
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<BluetoothAudioSinkChromeOS> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BluetoothAudioSinkChromeOS);
 };
 
 }  // namespace chromeos
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_CHROMEOS_H_