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nack_requester.h (5186B)

      1 /*
      2 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
      3 *
      4 *  Use of this source code is governed by a BSD-style license
      5 *  that can be found in the LICENSE file in the root of the source
      6 *  tree. An additional intellectual property rights grant can be found
      7 *  in the file PATENTS.  All contributing project authors may
      8 *  be found in the AUTHORS file in the root of the source tree.
      9 */
     10 
     11 #ifndef MODULES_VIDEO_CODING_NACK_REQUESTER_H_
     12 #define MODULES_VIDEO_CODING_NACK_REQUESTER_H_
     13 
     14 #include <stdint.h>
     15 
     16 #include <map>
     17 #include <set>
     18 #include <vector>
     19 
     20 #include "api/field_trials_view.h"
     21 #include "api/sequence_checker.h"
     22 #include "api/task_queue/pending_task_safety_flag.h"
     23 #include "api/task_queue/task_queue_base.h"
     24 #include "api/units/time_delta.h"
     25 #include "api/units/timestamp.h"
     26 #include "modules/include/module_common_types.h"
     27 #include "modules/video_coding/histogram.h"
     28 #include "rtc_base/numerics/sequence_number_util.h"
     29 #include "rtc_base/system/no_unique_address.h"
     30 #include "rtc_base/task_utils/repeating_task.h"
     31 #include "rtc_base/thread_annotations.h"
     32 #include "system_wrappers/include/clock.h"
     33 
     34 namespace webrtc {
     35 
     36 class NackRequesterBase {
     37 public:
     38  virtual ~NackRequesterBase() = default;
     39  virtual void ProcessNacks() = 0;
     40 };
     41 
     42 class NackPeriodicProcessor {
     43 public:
     44  static constexpr TimeDelta kUpdateInterval = TimeDelta::Millis(20);
     45  explicit NackPeriodicProcessor(TimeDelta update_interval = kUpdateInterval);
     46  ~NackPeriodicProcessor();
     47  void RegisterNackModule(NackRequesterBase* module);
     48  void UnregisterNackModule(NackRequesterBase* module);
     49 
     50 private:
     51  void ProcessNackModules() RTC_RUN_ON(sequence_);
     52 
     53  const TimeDelta update_interval_;
     54  RepeatingTaskHandle repeating_task_ RTC_GUARDED_BY(sequence_);
     55  std::vector<NackRequesterBase*> modules_ RTC_GUARDED_BY(sequence_);
     56  RTC_NO_UNIQUE_ADDRESS SequenceChecker sequence_;
     57 };
     58 
     59 class ScopedNackPeriodicProcessorRegistration {
     60 public:
     61  ScopedNackPeriodicProcessorRegistration(NackRequesterBase* module,
     62                                          NackPeriodicProcessor* processor);
     63  ~ScopedNackPeriodicProcessorRegistration();
     64 
     65 private:
     66  NackRequesterBase* const module_;
     67  NackPeriodicProcessor* const processor_;
     68 };
     69 
     70 class NackRequester final : public NackRequesterBase {
     71 public:
     72  NackRequester(TaskQueueBase* current_queue,
     73                NackPeriodicProcessor* periodic_processor,
     74                Clock* clock,
     75                NackSender* nack_sender,
     76                KeyFrameRequestSender* keyframe_request_sender,
     77                const FieldTrialsView& field_trials);
     78  ~NackRequester();
     79 
     80  void ProcessNacks() override;
     81 
     82  int OnReceivedPacket(uint16_t seq_num);
     83  int OnReceivedPacket(uint16_t seq_num, bool is_recovered);
     84 
     85  void ClearUpTo(uint16_t seq_num);
     86  void UpdateRtt(int64_t rtt_ms);
     87 
     88 private:
     89  // Which fields to consider when deciding which packet to nack in
     90  // GetNackBatch.
     91  enum NackFilterOptions { kSeqNumOnly, kTimeOnly };
     92 
     93  // This class holds the sequence number of the packet that is in the nack list
     94  // as well as the meta data about when it should be nacked and how many times
     95  // we have tried to nack this packet.
     96  struct NackInfo {
     97    NackInfo();
     98    NackInfo(uint16_t seq_num,
     99             uint16_t send_at_seq_num,
    100             Timestamp created_at_time);
    101 
    102    uint16_t seq_num;
    103    uint16_t send_at_seq_num;
    104    Timestamp created_at_time;
    105    Timestamp sent_at_time;
    106    int retries;
    107  };
    108 
    109  void AddPacketsToNack(uint16_t seq_num_start, uint16_t seq_num_end)
    110      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
    111 
    112  std::vector<uint16_t> GetNackBatch(NackFilterOptions options)
    113      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
    114 
    115  // Update the reordering distribution.
    116  void UpdateReorderingStatistics(uint16_t seq_num)
    117      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
    118 
    119  // Returns how many packets we have to wait in order to receive the packet
    120  // with probability `probabilty` or higher.
    121  int WaitNumberOfPackets(float probability) const
    122      RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
    123 
    124  TaskQueueBase* const worker_thread_;
    125  Clock* const clock_;
    126  NackSender* const nack_sender_;
    127  KeyFrameRequestSender* const keyframe_request_sender_;
    128 
    129  // TODO(philipel): Some of the variables below are consistently used on a
    130  // known thread (e.g. see `initialized_`). Those probably do not need
    131  // synchronized access.
    132  std::map<uint16_t, NackInfo, DescendingSeqNumComp<uint16_t>> nack_list_
    133      RTC_GUARDED_BY(worker_thread_);
    134  std::set<uint16_t, DescendingSeqNumComp<uint16_t>> recovered_list_
    135      RTC_GUARDED_BY(worker_thread_);
    136  video_coding::Histogram reordering_histogram_ RTC_GUARDED_BY(worker_thread_);
    137  bool initialized_ RTC_GUARDED_BY(worker_thread_);
    138  TimeDelta rtt_ RTC_GUARDED_BY(worker_thread_);
    139  uint16_t newest_seq_num_ RTC_GUARDED_BY(worker_thread_);
    140 
    141  // Adds a delay before send nack on packet received.
    142  const TimeDelta send_nack_delay_;
    143 
    144  ScopedNackPeriodicProcessorRegistration processor_registration_;
    145 
    146  // Used to signal destruction to potentially pending tasks.
    147  ScopedTaskSafety task_safety_;
    148 };
    149 
    150 }  // namespace webrtc
    151 
    152 #endif  // MODULES_VIDEO_CODING_NACK_REQUESTER_H_