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/*
* Copyright (c) 2019 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 "modules/pacing/task_queue_paced_sender.h"
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <utility>
#include <vector>
#include "absl/cleanup/cleanup.h"
#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/transport/network_types.h"
#include "api/units/data_rate.h"
#include "api/units/data_size.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "modules/pacing/pacing_controller.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "rtc_base/checks.h"
#include "rtc_base/numerics/exp_filter.h"
#include "rtc_base/trace_event.h"
namespace webrtc {
const int TaskQueuePacedSender::kNoPacketHoldback = -1;
TaskQueuePacedSender::TaskQueuePacedSender(
Clock* clock,
PacingController::PacketSender* packet_sender,
const FieldTrialsView& field_trials,
TimeDelta max_hold_back_window,
int max_hold_back_window_in_packets)
: clock_(clock),
max_hold_back_window_(max_hold_back_window),
max_hold_back_window_in_packets_(max_hold_back_window_in_packets),
pacing_controller_(clock, packet_sender, field_trials),
next_process_time_(Timestamp::MinusInfinity()),
is_started_(false),
is_shutdown_(false),
packet_size_(/*alpha=*/0.95),
include_overhead_(false),
task_queue_(TaskQueueBase::Current()) {
RTC_DCHECK_GE(max_hold_back_window_, PacingController::kMinSleepTime);
}
TaskQueuePacedSender::~TaskQueuePacedSender() {
RTC_DCHECK_RUN_ON(task_queue_);
is_shutdown_ = true;
}
void TaskQueuePacedSender::SetSendBurstInterval(TimeDelta burst_interval) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetSendBurstInterval(burst_interval);
}
void TaskQueuePacedSender::SetAllowProbeWithoutMediaPacket(bool allow) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetAllowProbeWithoutMediaPacket(allow);
}
void TaskQueuePacedSender::EnsureStarted() {
RTC_DCHECK_RUN_ON(task_queue_);
is_started_ = true;
MaybeProcessPackets(Timestamp::MinusInfinity());
}
void TaskQueuePacedSender::CreateProbeClusters(
std::vector<ProbeClusterConfig> probe_cluster_configs) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.CreateProbeClusters(probe_cluster_configs);
MaybeScheduleProcessPackets();
}
void TaskQueuePacedSender::Pause() {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.Pause();
}
void TaskQueuePacedSender::Resume() {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.Resume();
MaybeProcessPackets(Timestamp::MinusInfinity());
}
void TaskQueuePacedSender::SetCongested(bool congested) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetCongested(congested);
MaybeScheduleProcessPackets();
}
void TaskQueuePacedSender::SetPacingRates(DataRate pacing_rate,
DataRate padding_rate) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetPacingRates(pacing_rate, padding_rate);
MaybeScheduleProcessPackets();
}
void TaskQueuePacedSender::EnqueuePackets(
std::vector<std::unique_ptr<RtpPacketToSend>> packets) {
task_queue_->PostTask(
SafeTask(safety_.flag(), [this, packets = std::move(packets)]() mutable {
RTC_DCHECK_RUN_ON(task_queue_);
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("webrtc"),
"TaskQueuePacedSender::EnqueuePackets");
for (auto& packet : packets) {
TRACE_EVENT2(TRACE_DISABLED_BY_DEFAULT("webrtc"),
"TaskQueuePacedSender::EnqueuePackets::Loop",
"sequence_number", packet->SequenceNumber(),
"rtp_timestamp", packet->Timestamp());
size_t packet_size = packet->payload_size() + packet->padding_size();
if (include_overhead_) {
packet_size += packet->headers_size();
}
packet_size_.Apply(1, packet_size);
RTC_DCHECK_GE(packet->capture_time(), Timestamp::Zero());
pacing_controller_.EnqueuePacket(std::move(packet));
}
MaybeProcessPackets(Timestamp::MinusInfinity());
}));
}
void TaskQueuePacedSender::RemovePacketsForSsrc(uint32_t ssrc) {
task_queue_->PostTask(SafeTask(safety_.flag(), [this, ssrc] {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.RemovePacketsForSsrc(ssrc);
MaybeProcessPackets(Timestamp::MinusInfinity());
}));
}
void TaskQueuePacedSender::SetAccountForAudioPackets(bool account_for_audio) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetAccountForAudioPackets(account_for_audio);
MaybeProcessPackets(Timestamp::MinusInfinity());
}
void TaskQueuePacedSender::SetIncludeOverhead() {
RTC_DCHECK_RUN_ON(task_queue_);
include_overhead_ = true;
pacing_controller_.SetIncludeOverhead();
MaybeProcessPackets(Timestamp::MinusInfinity());
}
void TaskQueuePacedSender::SetTransportOverhead(DataSize overhead_per_packet) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetTransportOverhead(overhead_per_packet);
MaybeProcessPackets(Timestamp::MinusInfinity());
}
void TaskQueuePacedSender::SetQueueTimeLimit(TimeDelta limit) {
RTC_DCHECK_RUN_ON(task_queue_);
pacing_controller_.SetQueueTimeLimit(limit);
MaybeProcessPackets(Timestamp::MinusInfinity());
}
TimeDelta TaskQueuePacedSender::ExpectedQueueTime() const {
return GetStats().expected_queue_time;
}
DataSize TaskQueuePacedSender::QueueSizeData() const {
return GetStats().queue_size;
}
std::optional<Timestamp> TaskQueuePacedSender::FirstSentPacketTime() const {
return GetStats().first_sent_packet_time;
}
TimeDelta TaskQueuePacedSender::OldestPacketWaitTime() const {
Timestamp oldest_packet = GetStats().oldest_packet_enqueue_time;
if (oldest_packet.IsInfinite()) {
return TimeDelta::Zero();
}
// (webrtc:9716): The clock is not always monotonic.
Timestamp current = clock_->CurrentTime();
if (current < oldest_packet) {
return TimeDelta::Zero();
}
return current - oldest_packet;
}
void TaskQueuePacedSender::OnStatsUpdated(const Stats& stats) {
RTC_DCHECK_RUN_ON(task_queue_);
current_stats_ = stats;
}
// RTC_RUN_ON(task_queue_)
void TaskQueuePacedSender::MaybeScheduleProcessPackets() {
if (!processing_packets_)
MaybeProcessPackets(Timestamp::MinusInfinity());
}
void TaskQueuePacedSender::MaybeProcessPackets(
Timestamp scheduled_process_time) {
RTC_DCHECK_RUN_ON(task_queue_);
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("webrtc"),
"TaskQueuePacedSender::MaybeProcessPackets");
if (is_shutdown_ || !is_started_) {
return;
}
// Protects against re-entry from transport feedback calling into the task
// queue pacer.
RTC_DCHECK(!processing_packets_);
processing_packets_ = true;
absl::Cleanup cleanup = [this] {
RTC_DCHECK_RUN_ON(task_queue_);
processing_packets_ = false;
};
Timestamp next_send_time = pacing_controller_.NextSendTime();
RTC_DCHECK(next_send_time.IsFinite());
const Timestamp now = clock_->CurrentTime();
TimeDelta early_execute_margin =
pacing_controller_.IsProbing()
? PacingController::kMaxEarlyProbeProcessing
: TimeDelta::Zero();
// Process packets and update stats.
while (next_send_time <= now + early_execute_margin) {
pacing_controller_.ProcessPackets();
next_send_time = pacing_controller_.NextSendTime();
RTC_DCHECK(next_send_time.IsFinite());
// Probing state could change. Get margin after process packets.
early_execute_margin = pacing_controller_.IsProbing()
? PacingController::kMaxEarlyProbeProcessing
: TimeDelta::Zero();
}
UpdateStats();
// Ignore retired scheduled task, otherwise reset `next_process_time_`.
if (scheduled_process_time.IsFinite()) {
if (scheduled_process_time != next_process_time_) {
return;
}
next_process_time_ = Timestamp::MinusInfinity();
}
// Do not hold back in probing.
TimeDelta hold_back_window = TimeDelta::Zero();
if (!pacing_controller_.IsProbing()) {
hold_back_window = max_hold_back_window_;
DataRate pacing_rate = pacing_controller_.pacing_rate();
if (max_hold_back_window_in_packets_ != kNoPacketHoldback &&
!pacing_rate.IsZero() &&
packet_size_.filtered() != rtc::ExpFilter::kValueUndefined) {
TimeDelta avg_packet_send_time =
DataSize::Bytes(packet_size_.filtered()) / pacing_rate;
hold_back_window =
std::min(hold_back_window,
avg_packet_send_time * max_hold_back_window_in_packets_);
}
}
// Calculate next process time.
TimeDelta time_to_next_process =
std::max(hold_back_window, next_send_time - now - early_execute_margin);
next_send_time = now + time_to_next_process;
// If no in flight task or in flight task is later than `next_send_time`,
// schedule a new one. Previous in flight task will be retired.
if (next_process_time_.IsMinusInfinity() ||
next_process_time_ > next_send_time) {
// Prefer low precision if allowed and not probing.
task_queue_->PostDelayedHighPrecisionTask(
SafeTask(
safety_.flag(),
[this, next_send_time]() { MaybeProcessPackets(next_send_time); }),
time_to_next_process.RoundUpTo(TimeDelta::Millis(1)));
next_process_time_ = next_send_time;
}
}
void TaskQueuePacedSender::UpdateStats() {
Stats new_stats;
new_stats.expected_queue_time = pacing_controller_.ExpectedQueueTime();
new_stats.first_sent_packet_time = pacing_controller_.FirstSentPacketTime();
new_stats.oldest_packet_enqueue_time =
pacing_controller_.OldestPacketEnqueueTime();
new_stats.queue_size = pacing_controller_.QueueSizeData();
OnStatsUpdated(new_stats);
}
TaskQueuePacedSender::Stats TaskQueuePacedSender::GetStats() const {
RTC_DCHECK_RUN_ON(task_queue_);
return current_stats_;
}
} // namespace webrtc