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/*
* 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, bool is_keyframe);
int OnReceivedPacket(uint16_t seq_num, bool is_keyframe, 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_);
// Removes packets from the nack list until the next keyframe. Returns true
// if packets were removed.
bool RemovePacketsUntilKeyFrame()
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>> keyframe_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_
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