nack_requester.h - mozsearch

Enable keyboard shortcuts

/*

 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef MODULES_VIDEO_CODING_NACK_REQUESTER_H_

#define MODULES_VIDEO_CODING_NACK_REQUESTER_H_

#include <stdint.h>

#include <map>

#include <set>

#include <vector>

#include "api/field_trials_view.h"

#include "api/sequence_checker.h"

#include "api/task_queue/pending_task_safety_flag.h"

#include "api/task_queue/task_queue_base.h"

#include "api/units/time_delta.h"

#include "api/units/timestamp.h"

#include "modules/include/module_common_types.h"

#include "modules/video_coding/histogram.h"

#include "rtc_base/numerics/sequence_number_util.h"

#include "rtc_base/task_utils/repeating_task.h"

#include "rtc_base/thread_annotations.h"

#include "system_wrappers/include/clock.h"

namespace webrtc {

class NackRequesterBase {

 public:

  virtual ~NackRequesterBase() = default;

  virtual void ProcessNacks() = 0;

};

class NackPeriodicProcessor {

 public:

  static constexpr TimeDelta kUpdateInterval = TimeDelta::Millis(20);

  explicit NackPeriodicProcessor(TimeDelta update_interval = kUpdateInterval);

  ~NackPeriodicProcessor();

  void RegisterNackModule(NackRequesterBase* module);

  void UnregisterNackModule(NackRequesterBase* module);

 private:

  void ProcessNackModules() RTC_RUN_ON(sequence_);

  const TimeDelta update_interval_;

  RepeatingTaskHandle repeating_task_ RTC_GUARDED_BY(sequence_);

  std::vector<NackRequesterBase*> modules_ RTC_GUARDED_BY(sequence_);

  RTC_NO_UNIQUE_ADDRESS SequenceChecker sequence_;

};

class ScopedNackPeriodicProcessorRegistration {

 public:

  ScopedNackPeriodicProcessorRegistration(NackRequesterBase* module,

                                          NackPeriodicProcessor* processor);

  ~ScopedNackPeriodicProcessorRegistration();

 private:

  NackRequesterBase* const module_;

  NackPeriodicProcessor* const processor_;

};

class NackRequester final : public NackRequesterBase {

 public:

  NackRequester(TaskQueueBase* current_queue,

                NackPeriodicProcessor* periodic_processor,

                Clock* clock,

                NackSender* nack_sender,

                KeyFrameRequestSender* keyframe_request_sender,

                const FieldTrialsView& field_trials);

  ~NackRequester();

  void ProcessNacks() override;

  int OnReceivedPacket(uint16_t seq_num);

  int OnReceivedPacket(uint16_t seq_num, bool is_recovered);

  void ClearUpTo(uint16_t seq_num);

  void UpdateRtt(int64_t rtt_ms);

 private:

  // Which fields to consider when deciding which packet to nack in

  // GetNackBatch.

  enum NackFilterOptions { kSeqNumOnly, kTimeOnly, kSeqNumAndTime };

  // This class holds the sequence number of the packet that is in the nack list

  // as well as the meta data about when it should be nacked and how many times

  // we have tried to nack this packet.

  struct NackInfo {

    NackInfo();

    NackInfo(uint16_t seq_num,

             uint16_t send_at_seq_num,

             Timestamp created_at_time);

    uint16_t seq_num;

    uint16_t send_at_seq_num;

    Timestamp created_at_time;

    Timestamp sent_at_time;

    int retries;

};

  void AddPacketsToNack(uint16_t seq_num_start, uint16_t seq_num_end)

      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);

  std::vector<uint16_t> GetNackBatch(NackFilterOptions options)

      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);

  // Update the reordering distribution.

  void UpdateReorderingStatistics(uint16_t seq_num)

      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);

  // Returns how many packets we have to wait in order to receive the packet

  // with probability `probabilty` or higher.

  int WaitNumberOfPackets(float probability) const

      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);

  TaskQueueBase* const worker_thread_;

  Clock* const clock_;

  NackSender* const nack_sender_;

  KeyFrameRequestSender* const keyframe_request_sender_;

  // TODO(philipel): Some of the variables below are consistently used on a

  // known thread (e.g. see `initialized_`). Those probably do not need

  // synchronized access.

  std::map<uint16_t, NackInfo, DescendingSeqNumComp<uint16_t>> nack_list_

      RTC_GUARDED_BY(worker_thread_);

  std::set<uint16_t, DescendingSeqNumComp<uint16_t>> recovered_list_

      RTC_GUARDED_BY(worker_thread_);

  video_coding::Histogram reordering_histogram_ RTC_GUARDED_BY(worker_thread_);

  bool initialized_ RTC_GUARDED_BY(worker_thread_);

  TimeDelta rtt_ RTC_GUARDED_BY(worker_thread_);

  uint16_t newest_seq_num_ RTC_GUARDED_BY(worker_thread_);

  // Adds a delay before send nack on packet received.

  const TimeDelta send_nack_delay_;

  ScopedNackPeriodicProcessorRegistration processor_registration_;

  // Used to signal destruction to potentially pending tasks.

  ScopedTaskSafety task_safety_;

};

}  // namespace webrtc

#endif  // MODULES_VIDEO_CODING_NACK_REQUESTER_H_