blob: f58f88693495247cd0c161baf1ca55243b933764 [file] [log] [blame]
* 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.
#include <stdint.h>
#include <map>
#include <set>
#include <vector>
#include "api/sequence_checker.h"
#include "api/units/time_delta.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_queue.h"
#include "rtc_base/task_utils/pending_task_safety_flag.h"
#include "rtc_base/task_utils/repeating_task.h"
#include "rtc_base/thread_annotations.h"
#include "system_wrappers/include/clock.h"
namespace webrtc {
// TODO( This class no longer implements the Module
// interface and therefore "NackModule" may not be a descriptive name anymore.
// Consider renaming to e.g. NackTracker or NackRequester.
class NackModule2 final {
static constexpr TimeDelta kUpdateInterval = TimeDelta::Millis(20);
NackModule2(TaskQueueBase* current_queue,
Clock* clock,
NackSender* nack_sender,
KeyFrameRequestSender* keyframe_request_sender,
TimeDelta update_interval = kUpdateInterval);
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);
// 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(uint16_t seq_num,
uint16_t send_at_seq_num,
int64_t created_at_time);
uint16_t seq_num;
uint16_t send_at_seq_num;
int64_t created_at_time;
int64_t sent_at_time;
int retries;
struct BackoffSettings {
BackoffSettings(TimeDelta min_retry, TimeDelta max_rtt, double base);
static absl::optional<BackoffSettings> ParseFromFieldTrials();
// Min time between nacks.
const TimeDelta min_retry_interval;
// Upper bound on link-delay considered for exponential backoff.
const TimeDelta max_rtt;
// Base for the exponential backoff.
const double base;
void AddPacketsToNack(uint16_t seq_num_start, uint16_t seq_num_end)
// Removes packets from the nack list until the next keyframe. Returns true
// if packets were removed.
bool RemovePacketsUntilKeyFrame()
std::vector<uint16_t> GetNackBatch(NackFilterOptions options)
// Update the reordering distribution.
void UpdateReorderingStatistics(uint16_t seq_num)
// Returns how many packets we have to wait in order to receive the packet
// with probability |probabilty| or higher.
int WaitNumberOfPackets(float probability) const
TaskQueueBase* const worker_thread_;
// Used to regularly call SendNack if needed.
RepeatingTaskHandle repeating_task_ RTC_GUARDED_BY(worker_thread_);
const TimeDelta update_interval_;
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_
std::set<uint16_t, DescendingSeqNumComp<uint16_t>> keyframe_list_
std::set<uint16_t, DescendingSeqNumComp<uint16_t>> recovered_list_
video_coding::Histogram reordering_histogram_ RTC_GUARDED_BY(worker_thread_);
bool initialized_ RTC_GUARDED_BY(worker_thread_);
int64_t rtt_ms_ 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 int64_t send_nack_delay_ms_;
const absl::optional<BackoffSettings> backoff_settings_;
// Used to signal destruction to potentially pending tasks.
ScopedTaskSafety task_safety_;
} // namespace webrtc