buffered_data_source.h

// Copyright (c) 2010 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 WEBKIT_GLUE_MEDIA_BUFFERED_DATA_SOURCE_H_
#define WEBKIT_GLUE_MEDIA_BUFFERED_DATA_SOURCE_H_

#include <string>

#include "base/callback.h"
#include "base/lock.h"
#include "base/scoped_ptr.h"
#include "base/timer.h"
#include "base/condition_variable.h"
#include "googleurl/src/gurl.h"
#include "media/base/filters.h"
#include "media/base/media_format.h"
#include "media/base/pipeline.h"
#include "media/base/seekable_buffer.h"
#include "net/base/completion_callback.h"
#include "net/base/file_stream.h"
#include "webkit/glue/media/media_resource_loader_bridge_factory.h"
#include "webkit/glue/media/web_data_source.h"
#include "webkit/glue/webmediaplayer_impl.h"

namespace webkit_glue {
/////////////////////////////////////////////////////////////////////////////
// BufferedResourceLoader
// This class works inside demuxer thread and render thread. It contains a
// resource loader bridge and does the actual resource loading. This object
// does buffering internally, it defers the resource loading if buffer is
// full and un-defers the resource loading if it is under buffered.
class BufferedResourceLoader :
    public base::RefCountedThreadSafe<BufferedResourceLoader>,
    public webkit_glue::ResourceLoaderBridge::Peer {
 public:
  typedef Callback0::Type NetworkEventCallback;

  // |bridge_factory| - Factory to create a ResourceLoaderBridge.
  // |url| - URL for the resource to be loaded.
  // |first_byte_position| - First byte to start loading from, -1 for not
  // specified.
  // |last_byte_position| - Last byte to be loaded, -1 for not specified.
  BufferedResourceLoader(
      webkit_glue::MediaResourceLoaderBridgeFactory* bridge_factory,
      const GURL& url,
      int64 first_byte_position,
      int64 last_byte_position);

  // Start the resource loading with the specified URL and range.
  // This method operates in asynchronous mode. Once there's a response from the
  // server, success or fail |callback| is called with the result.
  // |callback| is called with the following values:
  // - net::OK
  //   The request has started successfully.
  // - net::ERR_FAILED
  //   The request has failed because of an error with the network.
  // - net::ERR_INVALID_RESPONSE
  //   An invalid response is received from the server.
  // - (Anything else)
  //   An error code that indicates the request has failed.
  // |event_callback| is called when the response is completed, data is
  // received, the request is suspended or resumed.
  virtual void Start(net::CompletionCallback* callback,
                     NetworkEventCallback* event_callback);

  // Stop this loader, cancels and request and release internal buffer.
  virtual void Stop();

  // Reads the specified |read_size| from |position| into |buffer| and when
  // the operation is done invoke |callback| with number of bytes read or an
  // error code.
  // |callback| is called with the following values:
  // - (Anything greater than or equal 0)
  //   Read was successful with the indicated number of bytes read.
  // - net::ERR_FAILED
  //   The read has failed because of an error with the network.
  // - net::ERR_CACHE_MISS
  //   The read was made too far away from the current buffered position.
  virtual void Read(int64 position, int read_size,
                    uint8* buffer, net::CompletionCallback* callback);

  // Returns the position of the first byte buffered. Returns -1 if such value
  // is not available.
  virtual int64 GetBufferedFirstBytePosition();

  // Returns the position of the last byte buffered. Returns -1 if such value
  // is not available.
  virtual int64 GetBufferedLastBytePosition();

  // Sets whether deferring data is allowed or disallowed.
  virtual void SetAllowDefer(bool is_allowed);

  // Gets the content length in bytes of the instance after this loader has been
  // started. If this value is -1, then content length is unknown.
  virtual int64 content_length() { return content_length_; }

  // Gets the original size of the file requested. If this value is -1, then
  // the size is unknown.
  virtual int64 instance_size() { return instance_size_; }

  // Returns true if the response for this loader is a partial response.
  // It means a 206 response in HTTP/HTTPS protocol.
  virtual bool partial_response() { return partial_response_; }

  // Returns true if network is currently active.
  virtual bool network_activity() { return !completed_ && !deferred_; }

  // Returns resulting URL.
  virtual const GURL& url() { return url_; }

  /////////////////////////////////////////////////////////////////////////////
  // webkit_glue::ResourceLoaderBridge::Peer implementations.
  virtual void OnUploadProgress(uint64 position, uint64 size) {}
  virtual bool OnReceivedRedirect(
      const GURL& new_url,
      const webkit_glue::ResourceResponseInfo& info,
      bool* has_new_first_party_for_cookies,
      GURL* new_first_party_for_cookies);
  virtual void OnReceivedResponse(
      const webkit_glue::ResourceResponseInfo& info,
      bool content_filtered);
  virtual void OnDownloadedData(int len) {}
  virtual void OnReceivedData(const char* data, int len);
  virtual void OnCompletedRequest(
      const URLRequestStatus& status,
      const std::string& security_info,
      const base::Time& completion_time);

 protected:
  friend class base::RefCountedThreadSafe<BufferedResourceLoader>;

  virtual ~BufferedResourceLoader();

 private:
  friend class BufferedResourceLoaderTest;

  // Defer the resource loading if the buffer is full.
  void EnableDeferIfNeeded();

  // Disable defer loading if we are under-buffered.
  void DisableDeferIfNeeded();

  // Returns true if the current read request can be fulfilled by what is in
  // the buffer.
  bool CanFulfillRead();

  // Returns true if the current read request will be fulfilled in the future.
  bool WillFulfillRead();

  // Method that does the actual read and calls the |read_callbac_|, assuming
  // the request range is in |buffer_|.
  void ReadInternal();

  // If we have made a range request, verify the response from the server.
  bool VerifyPartialResponse(const ResourceResponseInfo& info);

  // Done with read. Invokes the read callback and reset parameters for the
  // read request.
  void DoneRead(int error);

  // Done with start. Invokes the start callback and reset it.
  void DoneStart(int error);

  // Calls |event_callback_| in terms of a network event.
  void NotifyNetworkEvent();

  bool HasPendingRead() { return read_callback_.get() != NULL; }

  // A sliding window of buffer.
  scoped_ptr<media::SeekableBuffer> buffer_;

  // True if resource loading was deferred.
  bool deferred_;

  // True if resource loader is allowed to defer, false otherwise.
  bool defer_allowed_;

  // True if resource loading has completed.
  bool completed_;

  // True if a range request was made.
  bool range_requested_;

  // True if response data received is a partial range.
  bool partial_response_;

  webkit_glue::MediaResourceLoaderBridgeFactory* bridge_factory_;
  GURL url_;
  int64 first_byte_position_;
  int64 last_byte_position_;

  // Callback method that listens to network events.
  scoped_ptr<NetworkEventCallback> event_callback_;

  // Members used during request start.
  scoped_ptr<net::CompletionCallback> start_callback_;
  scoped_ptr<webkit_glue::ResourceLoaderBridge> bridge_;
  int64 offset_;
  int64 content_length_;
  int64 instance_size_;

  // Members used during a read operation. They should be reset after each
  // read has completed or failed.
  scoped_ptr<net::CompletionCallback> read_callback_;
  int64 read_position_;
  int read_size_;
  uint8* read_buffer_;

  // Offsets of the requested first byte and last byte in |buffer_|. They are
  // written by VerifyRead().
  int first_offset_;
  int last_offset_;

  DISALLOW_COPY_AND_ASSIGN(BufferedResourceLoader);
};

class BufferedDataSource : public WebDataSource {
 public:
  BufferedDataSource(
      MessageLoop* render_loop,
      webkit_glue::MediaResourceLoaderBridgeFactory* bridge_factory);

  virtual ~BufferedDataSource();

  // media::MediaFilter implementation.
  virtual void Initialize(const std::string& url,
                          media::FilterCallback* callback);
  virtual bool IsUrlSupported(const std::string& url);
  virtual void Stop(media::FilterCallback* callback);
  virtual void SetPlaybackRate(float playback_rate);

  // media::DataSource implementation.
  // Called from demuxer thread.
  virtual void Read(int64 position, size_t size,
                    uint8* data,
                    media::DataSource::ReadCallback* read_callback);
  virtual bool GetSize(int64* size_out);
  virtual bool IsStreaming();

  const media::MediaFormat& media_format() {
    return media_format_;
  }

  // webkit_glue::WebDataSource implementation.
  virtual bool HasSingleOrigin();
  virtual void Abort();

 protected:

  // A factory method to create a BufferedResourceLoader based on the read
  // parameters. We can override this file to object a mock
  // BufferedResourceLoader for testing.
  virtual BufferedResourceLoader* CreateResourceLoader(
      int64 first_byte_position, int64 last_byte_position);

  // Gets the number of milliseconds to declare a request timeout since
  // the request was made. This method is made virtual so as to inject a
  // different number for testing purpose.
  virtual base::TimeDelta GetTimeoutMilliseconds();

 private:
  // Posted to perform initialization on render thread and start resource
  // loading.
  void InitializeTask();

  // Task posted to perform actual reading on the render thread.
  void ReadTask(int64 position, int read_size, uint8* read_buffer,
                media::DataSource::ReadCallback* read_callback);

  // Task posted when Stop() is called. Stops |watch_dog_timer_| and
  // |loader_|, reset Read() variables, and set |stopped_on_render_loop_|
  // to signal any remaining tasks to stop.
  void CleanupTask();

  // Restart resource loading on render thread.
  void RestartLoadingTask();

  // This task monitors the current active read request. If the current read
  // request has timed out, this task will destroy the current loader and
  // creates a new one to accommodate the read request.
  void WatchDogTask();

  // This task uses the current playback rate with the previous playback rate
  // to determine whether we are going from pause to play and play to pause,
  // and signals the buffered resource loader accordingly.
  void SetPlaybackRateTask(float playback_rate);

  // The method that performs actual read. This method can only be executed on
  // the render thread.
  void ReadInternal();

  // Calls |read_callback_| and reset all read parameters.
  void DoneRead_Locked(int error);

  // Calls |initialize_callback_| and reset it.
  void DoneInitialization_Locked();

  // Callback method for |loader_| if URL for the resource requested is using
  // HTTP protocol. This method is called when response for initial request is
  // received.
  void HttpInitialStartCallback(int error);

  // Callback method for |loader_| if URL for the resource requested is using
  // a non-HTTP protocol, e.g. local files. This method is called when response
  // for initial request is received.
  void NonHttpInitialStartCallback(int error);

  // Callback method to be passed to BufferedResourceLoader during range
  // request. Once a resource request has started, this method will be called
  // with the error code. This method will be executed on the thread
  // BufferedResourceLoader lives, i.e. render thread.
  void PartialReadStartCallback(int error);

  // Callback method for making a read request to BufferedResourceLoader.
  // If data arrives or the request has failed, this method is called with
  // the error code or the number of bytes read.
  void ReadCallback(int error);

  // Callback method when a network event is received.
  void NetworkEventCallback();

  media::MediaFormat media_format_;

  // URL of the resource requested.
  GURL url_;

  // Members for total bytes of the requested object. It is written once on
  // render thread but may be read from any thread. However reading of this
  // member is guaranteed to happen after it is first written, so we don't
  // need to protect it.
  int64 total_bytes_;

  // True if this data source is considered loaded.
  bool loaded_;

  // This value will be true if this data source can only support streaming.
  // i.e. range request is not supported.
  bool streaming_;

  // True if the media resource has a single origin.
  bool single_origin_;

  // A factory object to produce ResourceLoaderBridge.
  scoped_ptr<webkit_glue::MediaResourceLoaderBridgeFactory> bridge_factory_;

  // A resource loader for the media resource.
  scoped_refptr<BufferedResourceLoader> loader_;

  // True if network is active.
  bool network_activity_;

  // Callback method from the pipeline for initialization.
  scoped_ptr<media::FilterCallback> initialize_callback_;

  // Read parameters received from the Read() method call.
  scoped_ptr<media::DataSource::ReadCallback> read_callback_;
  int64 read_position_;
  int read_size_;
  uint8* read_buffer_;
  base::Time read_submitted_time_;
  int read_attempts_;

  // This buffer is intermediate, we use it for BufferedResourceLoader to write
  // to. And when read in BufferedResourceLoader is done, we copy data from
  // this buffer to |read_buffer_|. The reason for an additional copy is that
  // we don't own |read_buffer_|. But since the read operation is asynchronous,
  // |read_buffer| can be destroyed at any time, so we only copy into
  // |read_buffer| in the final step when it is safe.
  // Memory is allocated for this member during initialization of this object
  // because we want buffer to be passed into BufferedResourceLoader to be
  // always non-null. And by initializing this member with a default size we can
  // avoid creating zero-sized buffered if the first read has zero size.
  scoped_array<uint8> intermediate_read_buffer_;
  int intermediate_read_buffer_size_;

  // The message loop of the render thread.
  MessageLoop* render_loop_;

  // Protects |stopped_|.
  Lock lock_;

  // Stop signal to suppressing activities. This variable is set on the pipeline
  // thread and read from the render thread.
  bool stop_signal_received_;

  // This variable is set by CleanupTask() that indicates this object is stopped
  // on the render thread.
  bool stopped_on_render_loop_;

  // This variable is true when we are in a paused state and false when we
  // are in a playing state.
  bool media_is_paused_;

  // This timer is to run the WatchDogTask repeatedly. We use a timer instead
  // of doing PostDelayedTask() reduce the extra reference held by the message
  // loop. The RepeatingTimer does PostDelayedTask() internally, by using it
  // the message loop doesn't hold a reference for the watch dog task.
  base::RepeatingTimer<BufferedDataSource> watch_dog_timer_;

  // Keeps track of whether we used a Range header in the initialization
  // request.
  bool using_range_request_;

  DISALLOW_COPY_AND_ASSIGN(BufferedDataSource);
};

}  // namespace webkit_glue

#endif  // WEBKIT_GLUE_MEDIA_BUFFERED_DATA_SOURCE_H_