Copy the (early prototype of) remoting in Chrome into the public tree....

remoting/host/session_manager.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 REMOTING_HOST_RECORD_SESSION_H_
+#define REMOTING_HOST_RECORD_SESSION_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/message_loop.h"
+#include "base/ref_counted.h"
+#include "base/scoped_ptr.h"
+#include "base/time.h"
+#include "remoting/base/protocol/chromotocol.pb.h"
+#include "remoting/host/capturer.h"
+
+namespace media {
+
+class DataBuffer;
+
+}  // namespace media
+
+namespace remoting {
+
+class Encoder;
+class ClientConnection;
+
+// A class for controlling and coordinate Capturer, Encoder
+// and NetworkChannel in a record session.
+//
+// THREADING
+//
+// This class works on three threads, namely capture, encode and network
+// thread. The main function of this class is to coordinate and schedule
+// capture, encode and transmission of data on different threads.
+//
+// The following is an example of timeline for operations scheduled.
+//
+// |       CAPTURE       ENCODE     NETWORK
+// |    .............
+// |    .  Capture  .
+// |    .............
+// |                  ............
+// |                  .          .
+// |    ............. .          .
+// |    .  Capture  . .  Encode  .
+// |    ............. .          .
+// |                  .          .
+// |                  ............
+// |    ............. ............ ..........
+// |    .  Capture  . .          . .  Send  .
+// |    ............. .          . ..........
+// |                  .  Encode  .
+// |                  .          .
+// |                  .          .
+// |                  ............
+// | Time
+// v
+//
+// SessionManager has the following responsibilities:
+// 1. Make sure capture and encode occurs no more frequently than |rate|.
+// 2. Make sure there is at most one outstanding capture not being encoded.
+// 3. Distribute tasks on three threads on a timely fashion to minimize latency.
+class SessionManager : public base::RefCountedThreadSafe<SessionManager> {
+ public:
+
+  // Construct a SessionManager. Message loops and threads are provided.
+  // Ownership of Capturer and Encoder are given to this object.
+  SessionManager(MessageLoop* capture_loop,
+                MessageLoop* encode_loop,
+                MessageLoop* network_loop,
+                Capturer* capturer,
+                Encoder* encoder);
+
+  virtual ~SessionManager();
+
+  // Start recording.
+  void Start();
+
+  // Pause the recording session.
+  void Pause();
+
+  // Set the maximum capture rate. This is denoted by number of updates
+  // in one second. The actual system may run in a slower rate than the maximum
+  // rate due to various factors, e.g. capture speed, encode speed and network
+  // conditions.
+  // This method should be called before Start() is called.
+  void SetMaxRate(double rate);
+
+  // Add a client to this recording session.
+  void AddClient(scoped_refptr<ClientConnection> client);
+
+  // Remove a client from receiving screen updates.
+  void RemoveClient(scoped_refptr<ClientConnection> client);
+
+ private:
+  void DoStart();
+  void DoPause();
+  void DoStartRateControl();
+  void DoPauseRateControl();
+
+  void DoCapture();
+  void DoFinishEncode();
+  void DoEncode();
+  void DoSendUpdate(
+      chromotocol_pb::UpdateStreamPacketHeader* header,
+      scoped_refptr<media::DataBuffer> encoded_data,
+      bool begin_update,
+      bool end_update);
+  void DoSendInit(scoped_refptr<ClientConnection> client,
+                  int width, int height);
+  void DoGetInitInfo(scoped_refptr<ClientConnection> client);
+  void DoSetRate(double rate);
+  void DoSetMaxRate(double max_rate);
+  void DoAddClient(scoped_refptr<ClientConnection> client);
+  void DoRemoveClient(scoped_refptr<ClientConnection> client);
+  void DoRateControl();
+
+  // Hepler method to schedule next capture using the current rate.
+  void ScheduleNextCapture();
+
+  // Helper method to schedule next rate regulation task.
+  void ScheduleNextRateControl();
+
+  void CaptureDoneTask();
+  void EncodeDataAvailableTask();
+
+  // Message loops used by this class.
+  MessageLoop* capture_loop_;
+  MessageLoop* encode_loop_;
+  MessageLoop* network_loop_;
+
+  // Reference to the capturer. This member is always accessed on the capture
+  // thread.
+  scoped_ptr<Capturer> capturer_;
+
+  // Reference to the encoder. This member is always accessed on the encode
+  // thread.
+  scoped_ptr<Encoder> encoder_;
+
+  // A list of clients connected to this hosts.
+  // This member is always accessed on the NETWORK thread.
+  // TODO(hclam): Have to scoped_refptr the clients since they have a shorter
+  // lifetime than this object.
+  typedef std::vector<scoped_refptr<ClientConnection> > ClientConnectionList;
+  ClientConnectionList clients_;
+
+  // The following members are accessed on the capture thread.
+  double rate_;  // Number of captures to perform every second.
+  bool started_;
+  base::Time last_capture_time_; // Saves the time last capture started.
+  int recordings_; // Count the number of recordings
+                   // (i.e. capture or encode) happening.
+
+  // The maximum rate is written on the capture thread and read on the network
+  // thread.
+  double max_rate_;  // Number of captures to perform every second.
+
+  // The following member is accessed on the network thread.
+  bool rate_control_started_;
+
+  // Stores the data and information of the last capture done.
+  // These members are written on capture thread and read on encode thread.
+  // It is guranteed the read happens after the write.
+  DirtyRects capture_dirty_rects_;
+  const uint8* capture_data_[3];
+  int capture_data_strides_[3];
+  int capture_width_;
+  int capture_height_;
+  chromotocol_pb::PixelFormat capture_pixel_format_;
+
+  // The following members are accessed on the encode thread.
+  // Output parameter written by Encoder to carry encoded data.
+  chromotocol_pb::UpdateStreamPacketHeader encoded_data_header_;
+  scoped_refptr<media::DataBuffer> encoded_data_;
+
+  // True if we have started receiving encoded data from the Encoder.
+  bool encode_stream_started_;
+
+  // Output parameter written by Encoder to notify the end of encoded data
+  // stream.
+  bool encode_done_;
+
+  DISALLOW_COPY_AND_ASSIGN(SessionManager);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_RECORD_SESSION_H_