media/cast/rtcp/sender_rtcp_event_subscriber.h

// Copyright 2014 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 MEDIA_CAST_RTCP_SENDER_RTCP_EVENT_SUBSCRIBER_H_
#define MEDIA_CAST_RTCP_SENDER_RTCP_EVENT_SUBSCRIBER_H_

#include <map>

#include "base/threading/thread_checker.h"
#include "media/cast/logging/logging_defines.h"
#include "media/cast/logging/raw_event_subscriber.h"
#include "media/cast/rtcp/rtcp_defines.h"

namespace media {
namespace cast {

// The key should really be something more than just a RTP timestamp in order
// to differentiate between video and audio frames, but since the implementation
// only process video frame events, RTP timestamp only as key is fine.
typedef std::map<RtpTimestamp, RtcpEvent> RtcpEventMap;

// A RawEventSubscriber implementation with the following properties:
// - Only processes raw event types that are relevant for sending from cast
//   sender to cast receiver via RTCP.
// - Captures information to be sent over to RTCP from raw event logs into the
//   more compact RtcpEvent struct.
// - Orders events by RTP timestamp with a map.
// - Internally, the map is capped at a maximum size configurable by the caller.
//   The subscriber only keeps the most recent events (determined by RTP
//   timestamp) up to the size limit.
class SenderRtcpEventSubscriber : public RawEventSubscriber {
 public:
  // |max_size_to_retain|: The object will keep up to |max_size_to_retain|
  // events
  // in the map. Once threshold has been reached, an event with the smallest
  // RTP timestamp will be removed.
  SenderRtcpEventSubscriber(const size_t max_size_to_retain);

  virtual ~SenderRtcpEventSubscriber();

  // RawEventSubscriber implementation.
  virtual void OnReceiveFrameEvent(const FrameEvent& frame_event) OVERRIDE;
  virtual void OnReceivePacketEvent(const PacketEvent& packet_event) OVERRIDE;

  // Assigns all collected events since last invocation to |rtcp_events|, and
  // clears |rtcp_events_|.
  void GetRtcpEventsAndReset(RtcpEventMap* rtcp_events);

 private:
  // If |rtcp_events_.size()| exceeds |max_size_to_retain_|, remove an oldest
  // entry
  // (determined by RTP timestamp) so its size no greater than
  // |max_size_to_retain_|.
  void TruncateMapIfNeeded();

  const size_t max_size_to_retain_;
  RtcpEventMap rtcp_events_;

  // Ensures methods are only called on the main thread.
  base::ThreadChecker thread_checker_;

  DISALLOW_COPY_AND_ASSIGN(SenderRtcpEventSubscriber);
};

}  // namespace cast
}  // namespace media

#endif  // MEDIA_CAST_RTCP_SENDER_RTCP_EVENT_SUBSCRIBER_H_