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Extract most of PacedSender into PacedSendingController.

Browse Source 
The Pacer now just handles interaction with Module/ProcessThread and
forwarding packets to PacketRouter.
All other logic is moved to PacedSendingController, including tests.
PacedSender unittest are now just some basic sanity tests.

Bug: webrtc:10809
Change-Id: I69223cd9d8300997375b03706d2e99c88e46241c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/149041
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28886}
This commit is contained in:
Erik Språng
2019-08-14 10:43:47 +02:00
committed by Commit Bot
parent 9755f97e7f
commit d05edecf4c
6 changed files with 2363 additions and 516 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
modules/pacing/BUILD.gn
View File

@ -19,6 +19,8 @@ rtc_static_library("pacing") {
"bitrate_prober.h",
"paced_sender.cc",
"paced_sender.h",
"pacing_controller.cc",
"pacing_controller.h",
"packet_router.cc",
"packet_router.h",
"round_robin_packet_queue.cc",
@ -75,11 +77,13 @@ if (rtc_include_tests) {
"bitrate_prober_unittest.cc",
"interval_budget_unittest.cc",
"paced_sender_unittest.cc",
"pacing_controller_unittest.cc",
"packet_router_unittest.cc",
]
deps = [
":interval_budget",
":pacing",
"../../api/units:data_rate",
"../../api/units:time_delta",
"../../rtc_base:checks",
"../../rtc_base:rtc_base_approved",

523
modules/pacing/paced_sender.cc
View File

@ -16,8 +16,6 @@
#include "absl/memory/memory.h"
#include "api/rtc_event_log/rtc_event_log.h"
#include "modules/pacing/bitrate_prober.h"
#include "modules/pacing/interval_budget.h"
#include "modules/utility/include/process_thread.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
@ -25,50 +23,6 @@
#include "system_wrappers/include/clock.h"
namespace webrtc {
namespace {
// Time limit in milliseconds between packet bursts.
constexpr TimeDelta kDefaultMinPacketLimit = TimeDelta::Millis<5>();
constexpr TimeDelta kCongestedPacketInterval = TimeDelta::Millis<500>();
constexpr TimeDelta kPausedProcessInterval = kCongestedPacketInterval;
constexpr TimeDelta kMaxElapsedTime = TimeDelta::Seconds<2>();
// Upper cap on process interval, in case process has not been called in a long
// time.
constexpr TimeDelta kMaxProcessingInterval = TimeDelta::Millis<30>();
bool IsDisabled(const WebRtcKeyValueConfig& field_trials,
absl::string_view key) {
return field_trials.Lookup(key).find("Disabled") == 0;
}
bool IsEnabled(const WebRtcKeyValueConfig& field_trials,
absl::string_view key) {
return field_trials.Lookup(key).find("Enabled") == 0;
}
int GetPriorityForType(RtpPacketToSend::Type type) {
switch (type) {
case RtpPacketToSend::Type::kAudio:
// Audio is always prioritized over other packet types.
return 0;
case RtpPacketToSend::Type::kRetransmission:
// Send retransmissions before new media.
return 1;
case RtpPacketToSend::Type::kVideo:
// Video has "normal" priority, in the old speak.
return 2;
case RtpPacketToSend::Type::kForwardErrorCorrection:
// Send redundancy concurrently to video. If it is delayed it might have a
// lower chance of being useful.
return 2;
case RtpPacketToSend::Type::kPadding:
// Packets that are in themselves likely useless, only sent to keep the
// BWE high.
return 3;
}
}
} // namespace
const int64_t PacedSender::kMaxQueueLengthMs = 2000;
const float PacedSender::kDefaultPaceMultiplier = 2.5f;
@ -76,60 +30,24 @@ PacedSender::PacedSender(Clock* clock,
PacketRouter* packet_router,
RtcEventLog* event_log,
const WebRtcKeyValueConfig* field_trials)
: clock_(clock),
: pacing_controller_(clock,
static_cast<PacingController::PacketSender*>(this),
event_log,
field_trials),
packet_router_(packet_router),
fallback_field_trials_(
!field_trials ? absl::make_unique<FieldTrialBasedConfig>() : nullptr),
field_trials_(field_trials ? field_trials : fallback_field_trials_.get()),
drain_large_queues_(
!IsDisabled(*field_trials_, "WebRTC-Pacer-DrainQueue")),
send_padding_if_silent_(
IsEnabled(*field_trials_, "WebRTC-Pacer-PadInSilence")),
pace_audio_(!IsDisabled(*field_trials_, "WebRTC-Pacer-BlockAudio")),
min_packet_limit_(kDefaultMinPacketLimit),
last_timestamp_(clock_->CurrentTime()),
paused_(false),
media_budget_(0),
padding_budget_(0),
prober_(*field_trials_),
probing_send_failure_(false),
pacing_bitrate_(DataRate::Zero()),
time_last_process_(clock->CurrentTime()),
last_send_time_(time_last_process_),
packets_(time_last_process_, field_trials),
packet_counter_(0),
congestion_window_size_(DataSize::PlusInfinity()),
outstanding_data_(DataSize::Zero()),
process_thread_(nullptr),
queue_time_limit(TimeDelta::ms(kMaxQueueLengthMs)),
account_for_audio_(false),
legacy_packet_referencing_(
IsEnabled(*field_trials_, "WebRTC-Pacer-LegacyPacketReferencing")) {
if (!drain_large_queues_) {
RTC_LOG(LS_WARNING) << "Pacer queues will not be drained,"
"pushback experiment must be enabled.";
}
FieldTrialParameter<int> min_packet_limit_ms("", min_packet_limit_.ms());
ParseFieldTrial({&min_packet_limit_ms},
field_trials_->Lookup("WebRTC-Pacer-MinPacketLimitMs"));
min_packet_limit_ = TimeDelta::ms(min_packet_limit_ms.Get());
UpdateBudgetWithElapsedTime(min_packet_limit_);
}
process_thread_(nullptr) {}
PacedSender::~PacedSender() {}
PacedSender::~PacedSender() = default;
void PacedSender::CreateProbeCluster(DataRate bitrate, int cluster_id) {
rtc::CritScope cs(&critsect_);
prober_.CreateProbeCluster(bitrate.bps(), CurrentTime().ms(), cluster_id);
return pacing_controller_.CreateProbeCluster(bitrate, cluster_id);
}
void PacedSender::Pause() {
{
rtc::CritScope cs(&critsect_);
if (!paused_)
RTC_LOG(LS_INFO) << "PacedSender paused.";
paused_ = true;
packets_.SetPauseState(true, CurrentTime());
pacing_controller_.Pause();
}
rtc::CritScope cs(&process_thread_lock_);
// Tell the process thread to call our TimeUntilNextProcess() method to get
@ -141,10 +59,7 @@ void PacedSender::Pause() {
void PacedSender::Resume() {
{
rtc::CritScope cs(&critsect_);
if (paused_)
RTC_LOG(LS_INFO) << "PacedSender resumed.";
paused_ = false;
packets_.SetPauseState(false, CurrentTime());
pacing_controller_.Resume();
}
rtc::CritScope cs(&process_thread_lock_);
// Tell the process thread to call our TimeUntilNextProcess() method to
@ -155,49 +70,22 @@ void PacedSender::Resume() {
void PacedSender::SetCongestionWindow(DataSize congestion_window_size) {
rtc::CritScope cs(&critsect_);
congestion_window_size_ = congestion_window_size;
pacing_controller_.SetCongestionWindow(congestion_window_size);
}
void PacedSender::UpdateOutstandingData(DataSize outstanding_data) {
rtc::CritScope cs(&critsect_);
outstanding_data_ = outstanding_data;
}
bool PacedSender::Congested() const {
if (congestion_window_size_.IsFinite()) {
return outstanding_data_ >= congestion_window_size_;
}
return false;
}
Timestamp PacedSender::CurrentTime() const {
Timestamp time = clock_->CurrentTime();
if (time < last_timestamp_) {
RTC_LOG(LS_WARNING)
<< "Non-monotonic clock behavior observed. Previous timestamp: "
<< last_timestamp_.ms() << ", new timestamp: " << time.ms();
RTC_DCHECK_GE(time, last_timestamp_);
time = last_timestamp_;
}
last_timestamp_ = time;
return time;
pacing_controller_.UpdateOutstandingData(outstanding_data);
}
void PacedSender::SetProbingEnabled(bool enabled) {
rtc::CritScope cs(&critsect_);
RTC_CHECK_EQ(0, packet_counter_);
prober_.SetEnabled(enabled);
pacing_controller_.SetProbingEnabled(enabled);
}
void PacedSender::SetPacingRates(DataRate pacing_rate, DataRate padding_rate) {
rtc::CritScope cs(&critsect_);
RTC_DCHECK_GT(pacing_rate, DataRate::Zero());
pacing_bitrate_ = pacing_rate;
padding_budget_.set_target_rate_kbps(padding_rate.kbps());
RTC_LOG(LS_VERBOSE) << "bwe:pacer_updated pacing_kbps="
<< pacing_bitrate_.kbps()
<< " padding_budget_kbps=" << padding_rate.kbps();
pacing_controller_.SetPacingRates(pacing_rate, padding_rate);
}
void PacedSender::InsertPacket(RtpPacketSender::Priority priority,
@ -207,288 +95,69 @@ void PacedSender::InsertPacket(RtpPacketSender::Priority priority,
size_t bytes,
bool retransmission) {
rtc::CritScope cs(&critsect_);
RTC_DCHECK(pacing_bitrate_ > DataRate::Zero())
<< "SetPacingRate must be called before InsertPacket.";
Timestamp now = CurrentTime();
prober_.OnIncomingPacket(bytes);
if (capture_time_ms < 0)
capture_time_ms = now.ms();
RtpPacketToSend::Type type;
switch (priority) {
case RtpPacketSender::kHighPriority:
type = RtpPacketToSend::Type::kAudio;
break;
case RtpPacketSender::kNormalPriority:
type = RtpPacketToSend::Type::kRetransmission;
break;
default:
type = RtpPacketToSend::Type::kVideo;
}
packets_.Push(GetPriorityForType(type), type, ssrc, sequence_number,
capture_time_ms, now, DataSize::bytes(bytes), retransmission,
packet_counter_++);
pacing_controller_.InsertPacket(priority, ssrc, sequence_number,
capture_time_ms, bytes, retransmission);
}
void PacedSender::EnqueuePacket(std::unique_ptr<RtpPacketToSend> packet) {
rtc::CritScope cs(&critsect_);
RTC_DCHECK(pacing_bitrate_ > DataRate::Zero())
<< "SetPacingRate must be called before InsertPacket.";
Timestamp now = CurrentTime();
prober_.OnIncomingPacket(packet->payload_size());
if (packet->capture_time_ms() < 0) {
packet->set_capture_time_ms(now.ms());
}
RTC_CHECK(packet->packet_type());
int priority = GetPriorityForType(*packet->packet_type());
packets_.Push(priority, now, packet_counter_++, std::move(packet));
pacing_controller_.EnqueuePacket(std::move(packet));
}
void PacedSender::SetAccountForAudioPackets(bool account_for_audio) {
rtc::CritScope cs(&critsect_);
account_for_audio_ = account_for_audio;
pacing_controller_.SetAccountForAudioPackets(account_for_audio);
}
TimeDelta PacedSender::ExpectedQueueTime() const {
rtc::CritScope cs(&critsect_);
RTC_DCHECK_GT(pacing_bitrate_, DataRate::Zero());
return TimeDelta::ms(
(QueueSizeData().bytes() * 8 * rtc::kNumMillisecsPerSec) /
pacing_bitrate_.bps());
return pacing_controller_.ExpectedQueueTime();
}
size_t PacedSender::QueueSizePackets() const {
rtc::CritScope cs(&critsect_);
return packets_.SizeInPackets();
return pacing_controller_.QueueSizePackets();
}
DataSize PacedSender::QueueSizeData() const {
rtc::CritScope cs(&critsect_);
return packets_.Size();
return pacing_controller_.QueueSizeData();
}
absl::optional<Timestamp> PacedSender::FirstSentPacketTime() const {
rtc::CritScope cs(&critsect_);
return first_sent_packet_time_;
return pacing_controller_.FirstSentPacketTime();
}
TimeDelta PacedSender::OldestPacketWaitTime() const {
rtc::CritScope cs(&critsect_);
Timestamp oldest_packet = packets_.OldestEnqueueTime();
if (oldest_packet.IsInfinite()) {
return TimeDelta::Zero();
}
return CurrentTime() - oldest_packet;
return pacing_controller_.OldestPacketWaitTime();
}
int64_t PacedSender::TimeUntilNextProcess() {
rtc::CritScope cs(&critsect_);
TimeDelta elapsed_time = CurrentTime() - time_last_process_;
// When paused we wake up every 500 ms to send a padding packet to ensure
// we won't get stuck in the paused state due to no feedback being received.
if (paused_) {
return std::max(kPausedProcessInterval - elapsed_time, TimeDelta::Zero())
TimeDelta elapsed_time = pacing_controller_.TimeElapsedSinceLastProcess();
if (pacing_controller_.IsPaused()) {
return std::max(PacingController::kPausedProcessInterval - elapsed_time,
TimeDelta::Zero())
.ms();
}
if (prober_.IsProbing()) {
int64_t ret = prober_.TimeUntilNextProbe(CurrentTime().ms());
if (ret > 0 || (ret == 0 && !probing_send_failure_))
return ret;
}
return std::max(min_packet_limit_ - elapsed_time, TimeDelta::Zero()).ms();
auto next_probe = pacing_controller_.TimeUntilNextProbe();
if (next_probe) {
return next_probe->ms();
}
TimeDelta PacedSender::UpdateTimeAndGetElapsed(Timestamp now) {
TimeDelta elapsed_time = now - time_last_process_;
time_last_process_ = now;
if (elapsed_time > kMaxElapsedTime) {
RTC_LOG(LS_WARNING) << "Elapsed time (" << elapsed_time.ms()
<< " ms) longer than expected, limiting to "
<< kMaxElapsedTime.ms();
elapsed_time = kMaxElapsedTime;
}
return elapsed_time;
}
bool PacedSender::ShouldSendKeepalive(Timestamp now) const {
if (send_padding_if_silent_ || paused_ || Congested()) {
// We send a padding packet every 500 ms to ensure we won't get stuck in
// congested state due to no feedback being received.
TimeDelta elapsed_since_last_send = now - last_send_time_;
if (elapsed_since_last_send >= kCongestedPacketInterval) {
// We can not send padding unless a normal packet has first been sent. If
// we do, timestamps get messed up.
if (packet_counter_ > 0) {
return true;
}
}
}
return false;
const TimeDelta min_packet_limit = TimeDelta::ms(5);
return std::max(min_packet_limit - elapsed_time, TimeDelta::Zero()).ms();
}
void PacedSender::Process() {
rtc::CritScope cs(&critsect_);
Timestamp now = CurrentTime();
TimeDelta elapsed_time = UpdateTimeAndGetElapsed(now);
if (ShouldSendKeepalive(now)) {
if (legacy_packet_referencing_) {
critsect_.Leave();
size_t bytes_sent =
packet_router_->TimeToSendPadding(1, PacedPacketInfo());
critsect_.Enter();
OnPaddingSent(DataSize::bytes(bytes_sent));
} else {
DataSize keepalive_data_sent = DataSize::Zero();
critsect_.Leave();
std::vector<std::unique_ptr<RtpPacketToSend>> keepalive_packets =
packet_router_->GeneratePadding(1);
for (auto& packet : keepalive_packets) {
keepalive_data_sent +=
DataSize::bytes(packet->payload_size() + packet->padding_size());
packet_router_->SendPacket(std::move(packet), PacedPacketInfo());
}
critsect_.Enter();
OnPaddingSent(keepalive_data_sent);
}
}
if (paused_)
return;
if (elapsed_time > TimeDelta::Zero()) {
DataRate target_rate = pacing_bitrate_;
DataSize queue_size_data = packets_.Size();
if (queue_size_data > DataSize::Zero()) {
// Assuming equal size packets and input/output rate, the average packet
// has avg_time_left_ms left to get queue_size_bytes out of the queue, if
// time constraint shall be met. Determine bitrate needed for that.
packets_.UpdateQueueTime(CurrentTime());
if (drain_large_queues_) {
TimeDelta avg_time_left = std::max(
TimeDelta::ms(1), queue_time_limit - packets_.AverageQueueTime());
DataRate min_rate_needed = queue_size_data / avg_time_left;
if (min_rate_needed > target_rate) {
target_rate = min_rate_needed;
RTC_LOG(LS_VERBOSE) << "bwe:large_pacing_queue pacing_rate_kbps="
<< target_rate.kbps();
}
}
}
media_budget_.set_target_rate_kbps(target_rate.kbps());
UpdateBudgetWithElapsedTime(elapsed_time);
}
bool is_probing = prober_.IsProbing();
PacedPacketInfo pacing_info;
absl::optional<DataSize> recommended_probe_size;
if (is_probing) {
pacing_info = prober_.CurrentCluster();
recommended_probe_size = DataSize::bytes(prober_.RecommendedMinProbeSize());
}
DataSize data_sent = DataSize::Zero();
// The paused state is checked in the loop since it leaves the critical
// section allowing the paused state to be changed from other code.
while (!paused_) {
auto* packet = GetPendingPacket(pacing_info);
if (packet == nullptr) {
// No packet available to send, check if we should send padding.
if (!legacy_packet_referencing_) {
DataSize padding_to_add =
PaddingToAdd(recommended_probe_size, data_sent);
if (padding_to_add > DataSize::Zero()) {
critsect_.Leave();
std::vector<std::unique_ptr<RtpPacketToSend>> padding_packets =
packet_router_->GeneratePadding(padding_to_add.bytes());
critsect_.Enter();
if (padding_packets.empty()) {
// No padding packets were generated, quite send loop.
break;
}
for (auto& packet : padding_packets) {
EnqueuePacket(std::move(packet));
}
// Continue loop to send the padding that was just added.
continue;
}
}
// Can't fetch new packet and no padding to send, exit send loop.
break;
}
std::unique_ptr<RtpPacketToSend> rtp_packet = packet->ReleasePacket();
const bool owned_rtp_packet = rtp_packet != nullptr;
RtpPacketSendResult success;
if (rtp_packet != nullptr) {
critsect_.Leave();
packet_router_->SendPacket(std::move(rtp_packet), pacing_info);
critsect_.Enter();
success = RtpPacketSendResult::kSuccess;
} else {
critsect_.Leave();
success = packet_router_->TimeToSendPacket(
packet->ssrc(), packet->sequence_number(), packet->capture_time_ms(),
packet->is_retransmission(), pacing_info);
critsect_.Enter();
}
if (success == RtpPacketSendResult::kSuccess ||
success == RtpPacketSendResult::kPacketNotFound) {
// Packet sent or invalid packet, remove it from queue.
// TODO(webrtc:8052): Don't consume media budget on kInvalid.
data_sent += packet->size();
// Send succeeded, remove it from the queue.
OnPacketSent(packet);
if (recommended_probe_size && data_sent > *recommended_probe_size)
break;
} else if (owned_rtp_packet) {
// Send failed, but we can't put it back in the queue, remove it without
// consuming budget.
packets_.FinalizePop();
break;
} else {
// Send failed, put it back into the queue.
packets_.CancelPop();
break;
}
}
if (legacy_packet_referencing_ && packets_.Empty() && !Congested()) {
// We can not send padding unless a normal packet has first been sent. If we
// do, timestamps get messed up.
if (packet_counter_ > 0) {
DataSize padding_needed =
(recommended_probe_size && *recommended_probe_size > data_sent)
? (*recommended_probe_size - data_sent)
: DataSize::bytes(padding_budget_.bytes_remaining());
if (padding_needed > DataSize::Zero()) {
DataSize padding_sent = DataSize::Zero();
critsect_.Leave();
padding_sent = DataSize::bytes(packet_router_->TimeToSendPadding(
padding_needed.bytes(), pacing_info));
critsect_.Enter();
data_sent += padding_sent;
OnPaddingSent(padding_sent);
}
}
}
if (is_probing) {
probing_send_failure_ = data_sent == DataSize::Zero();
if (!probing_send_failure_) {
prober_.ProbeSent(CurrentTime().ms(), data_sent.bytes());
}
}
pacing_controller_.ProcessPackets();
}
void PacedSender::ProcessThreadAttached(ProcessThread* process_thread) {
@ -497,93 +166,49 @@ void PacedSender::ProcessThreadAttached(ProcessThread* process_thread) {
process_thread_ = process_thread;
}
DataSize PacedSender::PaddingToAdd(
absl::optional<DataSize> recommended_probe_size,
DataSize data_sent) {
if (!packets_.Empty()) {
// Actual payload available, no need to add padding.
return DataSize::Zero();
}
if (Congested()) {
// Don't add padding if congested, even if requested for probing.
return DataSize::Zero();
}
if (packet_counter_ == 0) {
// We can not send padding unless a normal packet has first been sent. If we
// do, timestamps get messed up.
return DataSize::Zero();
}
if (recommended_probe_size) {
if (*recommended_probe_size > data_sent) {
return *recommended_probe_size - data_sent;
}
return DataSize::Zero();
}
return DataSize::bytes(padding_budget_.bytes_remaining());
}
RoundRobinPacketQueue::QueuedPacket* PacedSender::GetPendingPacket(
const PacedPacketInfo& pacing_info) {
if (packets_.Empty()) {
return nullptr;
}
// Since we need to release the lock in order to send, we first pop the
// element from the priority queue but keep it in storage, so that we can
// reinsert it if send fails.
RoundRobinPacketQueue::QueuedPacket* packet = packets_.BeginPop();
bool audio_packet = packet->type() == RtpPacketToSend::Type::kAudio;
bool apply_pacing = !audio_packet || pace_audio_;
if (apply_pacing && (Congested() || (media_budget_.bytes_remaining() == 0 &&
pacing_info.probe_cluster_id ==
PacedPacketInfo::kNotAProbe))) {
packets_.CancelPop();
return nullptr;
}
return packet;
}
void PacedSender::OnPacketSent(RoundRobinPacketQueue::QueuedPacket* packet) {
Timestamp now = CurrentTime();
if (!first_sent_packet_time_) {
first_sent_packet_time_ = now;
}
bool audio_packet = packet->type() == RtpPacketToSend::Type::kAudio;
if (!audio_packet || account_for_audio_) {
// Update media bytes sent.
UpdateBudgetWithSentData(packet->size());
last_send_time_ = now;
}
// Send succeeded, remove it from the queue.
packets_.FinalizePop();
}
void PacedSender::OnPaddingSent(DataSize data_sent) {
if (data_sent > DataSize::Zero()) {
UpdateBudgetWithSentData(data_sent);
}
last_send_time_ = CurrentTime();
}
void PacedSender::UpdateBudgetWithElapsedTime(TimeDelta delta) {
delta = std::min(kMaxProcessingInterval, delta);
media_budget_.IncreaseBudget(delta.ms());
padding_budget_.IncreaseBudget(delta.ms());
}
void PacedSender::UpdateBudgetWithSentData(DataSize size) {
outstanding_data_ += size;
media_budget_.UseBudget(size.bytes());
padding_budget_.UseBudget(size.bytes());
}
void PacedSender::SetQueueTimeLimit(TimeDelta limit) {
rtc::CritScope cs(&critsect_);
queue_time_limit = limit;
pacing_controller_.SetQueueTimeLimit(limit);
}
void PacedSender::SendRtpPacket(std::unique_ptr<RtpPacketToSend> packet,
const PacedPacketInfo& cluster_info) {
critsect_.Leave();
packet_router_->SendPacket(std::move(packet), cluster_info);
critsect_.Enter();
}
std::vector<std::unique_ptr<RtpPacketToSend>> PacedSender::GeneratePadding(
DataSize size) {
std::vector<std::unique_ptr<RtpPacketToSend>> padding_packets;
critsect_.Leave();
padding_packets = packet_router_->GeneratePadding(size.bytes());
critsect_.Enter();
return padding_packets;
}
RtpPacketSendResult PacedSender::TimeToSendPacket(
uint32_t ssrc,
uint16_t sequence_number,
int64_t capture_timestamp,
bool retransmission,
const PacedPacketInfo& packet_info) {
RtpPacketSendResult result;
critsect_.Leave();
result = packet_router_->TimeToSendPacket(
ssrc, sequence_number, capture_timestamp, retransmission, packet_info);
critsect_.Enter();
return result;
}
DataSize PacedSender::TimeToSendPadding(DataSize size,
const PacedPacketInfo& pacing_info) {
size_t padding_bytes_sent;
critsect_.Leave();
padding_bytes_sent =
packet_router_->TimeToSendPadding(size.bytes(), pacing_info);
critsect_.Enter();
return DataSize::bytes(padding_bytes_sent);
}
} // namespace webrtc

89
modules/pacing/paced_sender.h
View File

@ -16,6 +16,7 @@
#include <atomic>
#include <memory>
#include <vector>
#include "absl/types/optional.h"
#include "api/function_view.h"
@ -25,14 +26,13 @@
#include "modules/include/module.h"
#include "modules/pacing/bitrate_prober.h"
#include "modules/pacing/interval_budget.h"
#include "modules/pacing/pacing_controller.h"
#include "modules/pacing/packet_router.h"
#include "modules/pacing/round_robin_packet_queue.h"
#include "modules/pacing/rtp_packet_pacer.h"
#include "modules/rtp_rtcp/include/rtp_packet_sender.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "modules/utility/include/process_thread.h"
#include "rtc_base/critical_section.h"
#include "rtc_base/experiments/field_trial_parser.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
@ -41,7 +41,8 @@ class RtcEventLog;
class PacedSender : public Module,
public RtpPacketPacer,
public RtpPacketSender {
public RtpPacketSender,
private PacingController::PacketSender {
public:
// Expected max pacer delay in ms. If ExpectedQueueTime() is higher than
// this value, the packet producers should wait (eg drop frames rather than
@ -116,6 +117,7 @@ class PacedSender : public Module,
// Below are methods specific to this implementation, such as things related
// to module processing thread specifics or methods exposed for test.
// TODO(bugs.webrtc.org/10809): Remove when cleanup up unit tests.
// Enable bitrate probing. Enabled by default, mostly here to simplify
// testing. Must be called before any packets are being sent to have an
// effect.
@ -134,69 +136,30 @@ class PacedSender : public Module,
void ProcessThreadAttached(ProcessThread* process_thread) override;
private:
TimeDelta UpdateTimeAndGetElapsed(Timestamp now)
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
bool ShouldSendKeepalive(Timestamp now) const
// Methods implementing PacedSenderController:PacketSender.
void SendRtpPacket(std::unique_ptr<RtpPacketToSend> packet,
const PacedPacketInfo& cluster_info) override
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
// Updates the number of bytes that can be sent for the next time interval.
void UpdateBudgetWithElapsedTime(TimeDelta delta)
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
void UpdateBudgetWithSentData(DataSize size)
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
std::vector<std::unique_ptr<RtpPacketToSend>> GeneratePadding(
DataSize size) override RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
DataSize PaddingToAdd(absl::optional<DataSize> recommended_probe_size,
DataSize data_sent)
// TODO(bugs.webrtc.org/10633): Remove these when old code path is gone.
RtpPacketSendResult TimeToSendPacket(uint32_t ssrc,
uint16_t sequence_number,
int64_t capture_timestamp,
bool retransmission,
const PacedPacketInfo& packet_info)
override RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
DataSize TimeToSendPadding(DataSize size,
const PacedPacketInfo& pacing_info) override
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
RoundRobinPacketQueue::QueuedPacket* GetPendingPacket(
const PacedPacketInfo& pacing_info)
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
void OnPacketSent(RoundRobinPacketQueue::QueuedPacket* packet)
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
void OnPaddingSent(DataSize padding_sent)
RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
bool Congested() const RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
Timestamp CurrentTime() const RTC_EXCLUSIVE_LOCKS_REQUIRED(critsect_);
Clock* const clock_;
PacketRouter* const packet_router_;
const std::unique_ptr<FieldTrialBasedConfig> fallback_field_trials_;
const WebRtcKeyValueConfig* field_trials_;
const bool drain_large_queues_;
const bool send_padding_if_silent_;
const bool pace_audio_;
TimeDelta min_packet_limit_;
rtc::CriticalSection critsect_;
// TODO(webrtc:9716): Remove this when we are certain clocks are monotonic.
// The last millisecond timestamp returned by |clock_|.
mutable Timestamp last_timestamp_ RTC_GUARDED_BY(critsect_);
bool paused_ RTC_GUARDED_BY(critsect_);
// This is the media budget, keeping track of how many bits of media
// we can pace out during the current interval.
IntervalBudget media_budget_ RTC_GUARDED_BY(critsect_);
// This is the padding budget, keeping track of how many bits of padding we're
// allowed to send out during the current interval. This budget will be
// utilized when there's no media to send.
IntervalBudget padding_budget_ RTC_GUARDED_BY(critsect_);
PacingController pacing_controller_ RTC_GUARDED_BY(critsect_);
BitrateProber prober_ RTC_GUARDED_BY(critsect_);
bool probing_send_failure_ RTC_GUARDED_BY(critsect_);
DataRate pacing_bitrate_ RTC_GUARDED_BY(critsect_);
Timestamp time_last_process_ RTC_GUARDED_BY(critsect_);
Timestamp last_send_time_ RTC_GUARDED_BY(critsect_);
absl::optional<Timestamp> first_sent_packet_time_ RTC_GUARDED_BY(critsect_);
RoundRobinPacketQueue packets_ RTC_GUARDED_BY(critsect_);
uint64_t packet_counter_ RTC_GUARDED_BY(critsect_);
DataSize congestion_window_size_ RTC_GUARDED_BY(critsect_);
DataSize outstanding_data_ RTC_GUARDED_BY(critsect_);
PacketRouter* const packet_router_;
// Lock to avoid race when attaching process thread. This can happen due to
// the Call class setting network state on RtpTransportControllerSend, which
@ -205,14 +168,6 @@ class PacedSender : public Module,
// queue separate from the thread used by Call, this causes a race.
rtc::CriticalSection process_thread_lock_;
ProcessThread* process_thread_ RTC_GUARDED_BY(process_thread_lock_);
TimeDelta queue_time_limit RTC_GUARDED_BY(critsect_);
bool account_for_audio_ RTC_GUARDED_BY(critsect_);
// If true, PacedSender should only reference packets as in legacy mode.
// If false, PacedSender may have direct ownership of RtpPacketToSend objects.
// Defaults to true, will be changed to default false soon.
const bool legacy_packet_referencing_;
};
} // namespace webrtc
#endif // MODULES_PACING_PACED_SENDER_H_

552
modules/pacing/pacing_controller.cc Normal file
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@ -0,0 +1,552 @@
/*
* 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/pacing_controller.h"
#include <algorithm>
#include <utility>
#include <vector>
#include "absl/memory/memory.h"
#include "modules/pacing/bitrate_prober.h"
#include "modules/pacing/interval_budget.h"
#include "modules/utility/include/process_thread.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/time_utils.h"
#include "system_wrappers/include/clock.h"
namespace webrtc {
namespace {
// Time limit in milliseconds between packet bursts.
constexpr TimeDelta kDefaultMinPacketLimit = TimeDelta::Millis<5>();
constexpr TimeDelta kCongestedPacketInterval = TimeDelta::Millis<500>();
constexpr TimeDelta kMaxElapsedTime = TimeDelta::Seconds<2>();
// Upper cap on process interval, in case process has not been called in a long
// time.
constexpr TimeDelta kMaxProcessingInterval = TimeDelta::Millis<30>();
bool IsDisabled(const WebRtcKeyValueConfig& field_trials,
absl::string_view key) {
return field_trials.Lookup(key).find("Disabled") == 0;
}
bool IsEnabled(const WebRtcKeyValueConfig& field_trials,
absl::string_view key) {
return field_trials.Lookup(key).find("Enabled") == 0;
}
int GetPriorityForType(RtpPacketToSend::Type type) {
switch (type) {
case RtpPacketToSend::Type::kAudio:
// Audio is always prioritized over other packet types.
return 0;
case RtpPacketToSend::Type::kRetransmission:
// Send retransmissions before new media.
return 1;
case RtpPacketToSend::Type::kVideo:
// Video has "normal" priority, in the old speak.
return 2;
case RtpPacketToSend::Type::kForwardErrorCorrection:
// Send redundancy concurrently to video. If it is delayed it might have a
// lower chance of being useful.
return 2;
case RtpPacketToSend::Type::kPadding:
// Packets that are in themselves likely useless, only sent to keep the
// BWE high.
return 3;
}
}
} // namespace
const TimeDelta PacingController::kMaxExpectedQueueLength =
TimeDelta::Millis<2000>();
const float PacingController::kDefaultPaceMultiplier = 2.5f;
const TimeDelta PacingController::kPausedProcessInterval =
kCongestedPacketInterval;
PacingController::PacingController(Clock* clock,
PacketSender* packet_sender,
RtcEventLog* event_log,
const WebRtcKeyValueConfig* field_trials)
: clock_(clock),
packet_sender_(packet_sender),
fallback_field_trials_(
!field_trials ? absl::make_unique<FieldTrialBasedConfig>() : nullptr),
field_trials_(field_trials ? field_trials : fallback_field_trials_.get()),
drain_large_queues_(
!IsDisabled(*field_trials_, "WebRTC-Pacer-DrainQueue")),
send_padding_if_silent_(
IsEnabled(*field_trials_, "WebRTC-Pacer-PadInSilence")),
pace_audio_(!IsDisabled(*field_trials_, "WebRTC-Pacer-BlockAudio")),
min_packet_limit_(kDefaultMinPacketLimit),
last_timestamp_(clock_->CurrentTime()),
paused_(false),
media_budget_(0),
padding_budget_(0),
prober_(*field_trials_),
probing_send_failure_(false),
padding_failure_state_(false),
pacing_bitrate_(DataRate::Zero()),
time_last_process_(clock->CurrentTime()),
last_send_time_(time_last_process_),
packet_queue_(time_last_process_, field_trials),
packet_counter_(0),
congestion_window_size_(DataSize::PlusInfinity()),
outstanding_data_(DataSize::Zero()),
queue_time_limit(kMaxExpectedQueueLength),
account_for_audio_(false),
legacy_packet_referencing_(
IsEnabled(*field_trials_, "WebRTC-Pacer-LegacyPacketReferencing")) {
if (!drain_large_queues_) {
RTC_LOG(LS_WARNING) << "Pacer queues will not be drained,"
"pushback experiment must be enabled.";
}
FieldTrialParameter<int> min_packet_limit_ms("", min_packet_limit_.ms());
ParseFieldTrial({&min_packet_limit_ms},
field_trials_->Lookup("WebRTC-Pacer-MinPacketLimitMs"));
min_packet_limit_ = TimeDelta::ms(min_packet_limit_ms.Get());
UpdateBudgetWithElapsedTime(min_packet_limit_);
}
PacingController::~PacingController() = default;
void PacingController::CreateProbeCluster(DataRate bitrate, int cluster_id) {
prober_.CreateProbeCluster(bitrate.bps(), CurrentTime().ms(), cluster_id);
}
void PacingController::Pause() {
if (!paused_)
RTC_LOG(LS_INFO) << "PacedSender paused.";
paused_ = true;
packet_queue_.SetPauseState(true, CurrentTime());
}
void PacingController::Resume() {
if (paused_)
RTC_LOG(LS_INFO) << "PacedSender resumed.";
paused_ = false;
packet_queue_.SetPauseState(false, CurrentTime());
}
bool PacingController::IsPaused() const {
return paused_;
}
void PacingController::SetCongestionWindow(DataSize congestion_window_size) {
congestion_window_size_ = congestion_window_size;
}
void PacingController::UpdateOutstandingData(DataSize outstanding_data) {
outstanding_data_ = outstanding_data;
}
bool PacingController::Congested() const {
if (congestion_window_size_.IsFinite()) {
return outstanding_data_ >= congestion_window_size_;
}
return false;
}
Timestamp PacingController::CurrentTime() const {
Timestamp time = clock_->CurrentTime();
if (time < last_timestamp_) {
RTC_LOG(LS_WARNING)
<< "Non-monotonic clock behavior observed. Previous timestamp: "
<< last_timestamp_.ms() << ", new timestamp: " << time.ms();
RTC_DCHECK_GE(time, last_timestamp_);
time = last_timestamp_;
}
last_timestamp_ = time;
return time;
}
void PacingController::SetProbingEnabled(bool enabled) {
RTC_CHECK_EQ(0, packet_counter_);
prober_.SetEnabled(enabled);
}
void PacingController::SetPacingRates(DataRate pacing_rate,
DataRate padding_rate) {
RTC_DCHECK_GT(pacing_rate, DataRate::Zero());
pacing_bitrate_ = pacing_rate;
padding_budget_.set_target_rate_kbps(padding_rate.kbps());
RTC_LOG(LS_VERBOSE) << "bwe:pacer_updated pacing_kbps="
<< pacing_bitrate_.kbps()
<< " padding_budget_kbps=" << padding_rate.kbps();
}
void PacingController::InsertPacket(RtpPacketSender::Priority priority,
uint32_t ssrc,
uint16_t sequence_number,
int64_t capture_time_ms,
size_t bytes,
bool retransmission) {
RTC_DCHECK(pacing_bitrate_ > DataRate::Zero())
<< "SetPacingRate must be called before InsertPacket.";
Timestamp now = CurrentTime();
prober_.OnIncomingPacket(bytes);
if (capture_time_ms < 0)
capture_time_ms = now.ms();
RtpPacketToSend::Type type;
switch (priority) {
case RtpPacketSender::kHighPriority:
type = RtpPacketToSend::Type::kAudio;
break;
case RtpPacketSender::kNormalPriority:
type = RtpPacketToSend::Type::kRetransmission;
break;
default:
type = RtpPacketToSend::Type::kVideo;
}
packet_queue_.Push(GetPriorityForType(type), type, ssrc, sequence_number,
capture_time_ms, now, DataSize::bytes(bytes),
retransmission, packet_counter_++);
}
void PacingController::EnqueuePacket(std::unique_ptr<RtpPacketToSend> packet) {
RTC_DCHECK(pacing_bitrate_ > DataRate::Zero())
<< "SetPacingRate must be called before InsertPacket.";
Timestamp now = CurrentTime();
prober_.OnIncomingPacket(packet->payload_size());
if (packet->capture_time_ms() < 0) {
packet->set_capture_time_ms(now.ms());
}
RTC_CHECK(packet->packet_type());
int priority = GetPriorityForType(*packet->packet_type());
packet_queue_.Push(priority, now, packet_counter_++, std::move(packet));
}
void PacingController::SetAccountForAudioPackets(bool account_for_audio) {
account_for_audio_ = account_for_audio;
}
TimeDelta PacingController::ExpectedQueueTime() const {
RTC_DCHECK_GT(pacing_bitrate_, DataRate::Zero());
return TimeDelta::ms(
(QueueSizeData().bytes() * 8 * rtc::kNumMillisecsPerSec) /
pacing_bitrate_.bps());
}
size_t PacingController::QueueSizePackets() const {
return packet_queue_.SizeInPackets();
}
DataSize PacingController::QueueSizeData() const {
return packet_queue_.Size();
}
absl::optional<Timestamp> PacingController::FirstSentPacketTime() const {
return first_sent_packet_time_;
}
TimeDelta PacingController::OldestPacketWaitTime() const {
Timestamp oldest_packet = packet_queue_.OldestEnqueueTime();
if (oldest_packet.IsInfinite()) {
return TimeDelta::Zero();
}
return CurrentTime() - oldest_packet;
}
TimeDelta PacingController::UpdateTimeAndGetElapsed(Timestamp now) {
TimeDelta elapsed_time = now - time_last_process_;
time_last_process_ = now;
if (elapsed_time > kMaxElapsedTime) {
RTC_LOG(LS_WARNING) << "Elapsed time (" << elapsed_time.ms()
<< " ms) longer than expected, limiting to "
<< kMaxElapsedTime.ms();
elapsed_time = kMaxElapsedTime;
}
return elapsed_time;
}
bool PacingController::ShouldSendKeepalive(Timestamp now) const {
if (send_padding_if_silent_ || paused_ || Congested()) {
// We send a padding packet every 500 ms to ensure we won't get stuck in
// congested state due to no feedback being received.
TimeDelta elapsed_since_last_send = now - last_send_time_;
if (elapsed_since_last_send >= kCongestedPacketInterval) {
// We can not send padding unless a normal packet has first been sent. If
// we do, timestamps get messed up.
if (packet_counter_ > 0) {
return true;
}
}
}
return false;
}
absl::optional<TimeDelta> PacingController::TimeUntilNextProbe() {
if (!prober_.IsProbing()) {
return absl::nullopt;
}
TimeDelta time_delta =
TimeDelta::ms(prober_.TimeUntilNextProbe(CurrentTime().ms()));
if (time_delta > TimeDelta::Zero() ||
(time_delta == TimeDelta::Zero() && !probing_send_failure_)) {
return time_delta;
}
return absl::nullopt;
}
TimeDelta PacingController::TimeElapsedSinceLastProcess() const {
return CurrentTime() - time_last_process_;
}
void PacingController::ProcessPackets() {
Timestamp now = CurrentTime();
TimeDelta elapsed_time = UpdateTimeAndGetElapsed(now);
if (ShouldSendKeepalive(now)) {
if (legacy_packet_referencing_) {
OnPaddingSent(packet_sender_->TimeToSendPadding(DataSize::bytes(1),
PacedPacketInfo()));
} else {
DataSize keepalive_data_sent = DataSize::Zero();
std::vector<std::unique_ptr<RtpPacketToSend>> keepalive_packets =
packet_sender_->GeneratePadding(DataSize::bytes(1));
for (auto& packet : keepalive_packets) {
keepalive_data_sent +=
DataSize::bytes(packet->payload_size() + packet->padding_size());
packet_sender_->SendRtpPacket(std::move(packet), PacedPacketInfo());
}
OnPaddingSent(keepalive_data_sent);
}
}
if (paused_)
return;
if (elapsed_time > TimeDelta::Zero()) {
DataRate target_rate = pacing_bitrate_;
DataSize queue_size_data = packet_queue_.Size();
if (queue_size_data > DataSize::Zero()) {
// Assuming equal size packets and input/output rate, the average packet
// has avg_time_left_ms left to get queue_size_bytes out of the queue, if
// time constraint shall be met. Determine bitrate needed for that.
packet_queue_.UpdateQueueTime(CurrentTime());
if (drain_large_queues_) {
TimeDelta avg_time_left =
std::max(TimeDelta::ms(1),
queue_time_limit - packet_queue_.AverageQueueTime());
DataRate min_rate_needed = queue_size_data / avg_time_left;
if (min_rate_needed > target_rate) {
target_rate = min_rate_needed;
RTC_LOG(LS_VERBOSE) << "bwe:large_pacing_queue pacing_rate_kbps="
<< target_rate.kbps();
}
}
}
media_budget_.set_target_rate_kbps(target_rate.kbps());
UpdateBudgetWithElapsedTime(elapsed_time);
}
bool is_probing = prober_.IsProbing();
PacedPacketInfo pacing_info;
absl::optional<DataSize> recommended_probe_size;
if (is_probing) {
pacing_info = prober_.CurrentCluster();
recommended_probe_size = DataSize::bytes(prober_.RecommendedMinProbeSize());
}
DataSize data_sent = DataSize::Zero();
// The paused state is checked in the loop since it leaves the critical
// section allowing the paused state to be changed from other code.
while (!paused_) {
auto* packet = GetPendingPacket(pacing_info);
if (packet == nullptr) {
// No packet available to send, check if we should send padding.
if (!legacy_packet_referencing_) {
DataSize padding_to_add =
PaddingToAdd(recommended_probe_size, data_sent);
if (padding_to_add > DataSize::Zero()) {
std::vector<std::unique_ptr<RtpPacketToSend>> padding_packets =
packet_sender_->GeneratePadding(padding_to_add);
if (padding_packets.empty()) {
// No padding packets were generated, quite send loop.
break;
}
for (auto& packet : padding_packets) {
EnqueuePacket(std::move(packet));
}
// Continue loop to send the padding that was just added.
continue;
}
}
// Can't fetch new packet and no padding to send, exit send loop.
break;
}
std::unique_ptr<RtpPacketToSend> rtp_packet = packet->ReleasePacket();
const bool owned_rtp_packet = rtp_packet != nullptr;
RtpPacketSendResult success;
if (rtp_packet != nullptr) {
packet_sender_->SendRtpPacket(std::move(rtp_packet), pacing_info);
success = RtpPacketSendResult::kSuccess;
} else {
success = packet_sender_->TimeToSendPacket(
packet->ssrc(), packet->sequence_number(), packet->capture_time_ms(),
packet->is_retransmission(), pacing_info);
}
if (success == RtpPacketSendResult::kSuccess ||
success == RtpPacketSendResult::kPacketNotFound) {
// Packet sent or invalid packet, remove it from queue.
// TODO(webrtc:8052): Don't consume media budget on kInvalid.
data_sent += packet->size();
// Send succeeded, remove it from the queue.
OnPacketSent(packet);
if (recommended_probe_size && data_sent > *recommended_probe_size)
break;
} else if (owned_rtp_packet) {
// Send failed, but we can't put it back in the queue, remove it without
// consuming budget.
packet_queue_.FinalizePop();
break;
} else {
// Send failed, put it back into the queue.
packet_queue_.CancelPop();
break;
}
}
if (legacy_packet_referencing_ && packet_queue_.Empty() && !Congested()) {
// We can not send padding unless a normal packet has first been sent. If we
// do, timestamps get messed up.
if (packet_counter_ > 0) {
DataSize padding_needed =
(recommended_probe_size && *recommended_probe_size > data_sent)
? (*recommended_probe_size - data_sent)
: DataSize::bytes(padding_budget_.bytes_remaining());
if (padding_needed > DataSize::Zero()) {
DataSize padding_sent = DataSize::Zero();
padding_sent =
packet_sender_->TimeToSendPadding(padding_needed, pacing_info);
data_sent += padding_sent;
OnPaddingSent(padding_sent);
}
}
}
if (is_probing) {
probing_send_failure_ = data_sent == DataSize::Zero();
if (!probing_send_failure_) {
prober_.ProbeSent(CurrentTime().ms(), data_sent.bytes());
}
}
}
DataSize PacingController::PaddingToAdd(
absl::optional<DataSize> recommended_probe_size,
DataSize data_sent) {
if (!packet_queue_.Empty()) {
// Actual payload available, no need to add padding.
return DataSize::Zero();
}
if (Congested()) {
// Don't add padding if congested, even if requested for probing.
return DataSize::Zero();
}
if (packet_counter_ == 0) {
// We can not send padding unless a normal packet has first been sent. If we
// do, timestamps get messed up.
return DataSize::Zero();
}
if (recommended_probe_size) {
if (*recommended_probe_size > data_sent) {
return *recommended_probe_size - data_sent;
}
return DataSize::Zero();
}
return DataSize::bytes(padding_budget_.bytes_remaining());
}
RoundRobinPacketQueue::QueuedPacket* PacingController::GetPendingPacket(
const PacedPacketInfo& pacing_info) {
if (packet_queue_.Empty()) {
return nullptr;
}
// Since we need to release the lock in order to send, we first pop the
// element from the priority queue but keep it in storage, so that we can
// reinsert it if send fails.
RoundRobinPacketQueue::QueuedPacket* packet = packet_queue_.BeginPop();
bool audio_packet = packet->type() == RtpPacketToSend::Type::kAudio;
bool apply_pacing = !audio_packet || pace_audio_;
if (apply_pacing && (Congested() || (media_budget_.bytes_remaining() == 0 &&
pacing_info.probe_cluster_id ==
PacedPacketInfo::kNotAProbe))) {
packet_queue_.CancelPop();
return nullptr;
}
return packet;
}
void PacingController::OnPacketSent(
RoundRobinPacketQueue::QueuedPacket* packet) {
Timestamp now = CurrentTime();
if (!first_sent_packet_time_) {
first_sent_packet_time_ = now;
}
bool audio_packet = packet->type() == RtpPacketToSend::Type::kAudio;
if (!audio_packet || account_for_audio_) {
// Update media bytes sent.
UpdateBudgetWithSentData(packet->size());
last_send_time_ = now;
}
// Send succeeded, remove it from the queue.
packet_queue_.FinalizePop();
padding_failure_state_ = false;
}
void PacingController::OnPaddingSent(DataSize data_sent) {
if (data_sent > DataSize::Zero()) {
UpdateBudgetWithSentData(data_sent);
} else {
padding_failure_state_ = true;
}
last_send_time_ = CurrentTime();
}
void PacingController::UpdateBudgetWithElapsedTime(TimeDelta delta) {
delta = std::min(kMaxProcessingInterval, delta);
media_budget_.IncreaseBudget(delta.ms());
padding_budget_.IncreaseBudget(delta.ms());
}
void PacingController::UpdateBudgetWithSentData(DataSize size) {
outstanding_data_ += size;
media_budget_.UseBudget(size.bytes());
padding_budget_.UseBudget(size.bytes());
}
void PacingController::SetQueueTimeLimit(TimeDelta limit) {
queue_time_limit = limit;
}
} // namespace webrtc

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@ -0,0 +1,221 @@
/*
* 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.
*/
#ifndef MODULES_PACING_PACING_CONTROLLER_H_
#define MODULES_PACING_PACING_CONTROLLER_H_
#include <stddef.h>
#include <stdint.h>
#include <atomic>
#include <memory>
#include <vector>
#include "absl/types/optional.h"
#include "api/function_view.h"
#include "api/rtc_event_log/rtc_event_log.h"
#include "api/transport/field_trial_based_config.h"
#include "api/transport/network_types.h"
#include "api/transport/webrtc_key_value_config.h"
#include "modules/pacing/bitrate_prober.h"
#include "modules/pacing/interval_budget.h"
#include "modules/pacing/round_robin_packet_queue.h"
#include "modules/pacing/rtp_packet_pacer.h"
#include "modules/rtp_rtcp/include/rtp_packet_sender.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "rtc_base/critical_section.h"
#include "rtc_base/experiments/field_trial_parser.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
// This class implements a leaky-buck packet pacing algorithm. It handles the
// logic of determining which packets to send when, but the actual timing of
// the processing is done externally (e.g. PacedSender). Furthermore, the
// forwarding of packets when they are ready to be sent is also handled
// externally, via the PacedSendingController::PacketSender interface.
//
class PacingController {
public:
class PacketSender {
public:
virtual ~PacketSender() = default;
virtual void SendRtpPacket(std::unique_ptr<RtpPacketToSend> packet,
const PacedPacketInfo& cluster_info) = 0;
virtual std::vector<std::unique_ptr<RtpPacketToSend>> GeneratePadding(
DataSize size) = 0;
// TODO(bugs.webrtc.org/10633): Remove these when old code path is gone.
virtual RtpPacketSendResult TimeToSendPacket(
uint32_t ssrc,
uint16_t sequence_number,
int64_t capture_timestamp,
bool retransmission,
const PacedPacketInfo& packet_info) = 0;
virtual DataSize TimeToSendPadding(DataSize size,
const PacedPacketInfo& pacing_info) = 0;
};
// Expected max pacer delay. If ExpectedQueueTime() is higher than
// this value, the packet producers should wait (eg drop frames rather than
// encoding them). Bitrate sent may temporarily exceed target set by
// UpdateBitrate() so that this limit will be upheld.
static const TimeDelta kMaxExpectedQueueLength;
// Pacing-rate relative to our target send rate.
// Multiplicative factor that is applied to the target bitrate to calculate
// the number of bytes that can be transmitted per interval.
// Increasing this factor will result in lower delays in cases of bitrate
// overshoots from the encoder.
static const float kDefaultPaceMultiplier;
// If no media or paused, wake up at least every |kPausedProcessIntervalMs| in
// order to send a keep-alive packet so we don't get stuck in a bad state due
// to lack of feedback.
static const TimeDelta kPausedProcessInterval;
PacingController(Clock* clock,
PacketSender* packet_sender,
RtcEventLog* event_log,
const WebRtcKeyValueConfig* field_trials);
~PacingController();
// Adds the packet information to the queue and calls TimeToSendPacket
// when it's time to send.
void InsertPacket(RtpPacketSender::Priority priority,
uint32_t ssrc,
uint16_t sequence_number,
int64_t capture_time_ms,
size_t bytes,
bool retransmission);
// Adds the packet to the queue and calls PacketRouter::SendPacket() when
// it's time to send.
void EnqueuePacket(std::unique_ptr<RtpPacketToSend> packet);
void CreateProbeCluster(DataRate bitrate, int cluster_id);
void Pause(); // Temporarily pause all sending.
void Resume(); // Resume sending packets.
bool IsPaused() const;
void SetCongestionWindow(DataSize congestion_window_size);
void UpdateOutstandingData(DataSize outstanding_data);
// Sets the pacing rates. Must be called once before packets can be sent.
void SetPacingRates(DataRate pacing_rate, DataRate padding_rate);
// Currently audio traffic is not accounted by pacer and passed through.
// With the introduction of audio BWE audio traffic will be accounted for
// the pacer budget calculation. The audio traffic still will be injected
// at high priority.
void SetAccountForAudioPackets(bool account_for_audio);
// Returns the time since the oldest queued packet was enqueued.
TimeDelta OldestPacketWaitTime() const;
size_t QueueSizePackets() const;
DataSize QueueSizeData() const;
// Returns the time when the first packet was sent;
absl::optional<Timestamp> FirstSentPacketTime() const;
// Returns the number of milliseconds it will take to send the current
// packets in the queue, given the current size and bitrate, ignoring prio.
TimeDelta ExpectedQueueTime() const;
void SetQueueTimeLimit(TimeDelta limit);
// Enable bitrate probing. Enabled by default, mostly here to simplify
// testing. Must be called before any packets are being sent to have an
// effect.
void SetProbingEnabled(bool enabled);
// Time until next probe should be sent. If this value is set, it should be
// respected - i.e. don't call ProcessPackets() before this specified time as
// that can have unintended side effects.
absl::optional<TimeDelta> TimeUntilNextProbe();
// Time since ProcessPackets() was last executed.
TimeDelta TimeElapsedSinceLastProcess() const;
TimeDelta TimeUntilAvailableBudget() const;
// Check queue of pending packets and send them or padding packets, if budget
// is available.
void ProcessPackets();
bool Congested() const;
private:
TimeDelta UpdateTimeAndGetElapsed(Timestamp now);
bool ShouldSendKeepalive(Timestamp now) const;
// Updates the number of bytes that can be sent for the next time interval.
void UpdateBudgetWithElapsedTime(TimeDelta delta);
void UpdateBudgetWithSentData(DataSize size);
DataSize PaddingToAdd(absl::optional<DataSize> recommended_probe_size,
DataSize data_sent);
RoundRobinPacketQueue::QueuedPacket* GetPendingPacket(
const PacedPacketInfo& pacing_info);
void OnPacketSent(RoundRobinPacketQueue::QueuedPacket* packet);
void OnPaddingSent(DataSize padding_sent);
Timestamp CurrentTime() const;
Clock* const clock_;
PacketSender* const packet_sender_;
const std::unique_ptr<FieldTrialBasedConfig> fallback_field_trials_;
const WebRtcKeyValueConfig* field_trials_;
const bool drain_large_queues_;
const bool send_padding_if_silent_;
const bool pace_audio_;
TimeDelta min_packet_limit_;
// TODO(webrtc:9716): Remove this when we are certain clocks are monotonic.
// The last millisecond timestamp returned by |clock_|.
mutable Timestamp last_timestamp_;
bool paused_;
// This is the media budget, keeping track of how many bits of media
// we can pace out during the current interval.
IntervalBudget media_budget_;
// This is the padding budget, keeping track of how many bits of padding we're
// allowed to send out during the current interval. This budget will be
// utilized when there's no media to send.
IntervalBudget padding_budget_;
BitrateProber prober_;
bool probing_send_failure_;
bool padding_failure_state_;
DataRate pacing_bitrate_;
Timestamp time_last_process_;
Timestamp last_send_time_;
absl::optional<Timestamp> first_sent_packet_time_;
RoundRobinPacketQueue packet_queue_;
uint64_t packet_counter_;
DataSize congestion_window_size_;
DataSize outstanding_data_;
TimeDelta queue_time_limit;
bool account_for_audio_;
// If true, PacedSender should only reference packets as in legacy mode.
// If false, PacedSender may have direct ownership of RtpPacketToSend objects.
// Defaults to true, will be changed to default false soon.
const bool legacy_packet_referencing_;
};
} // namespace webrtc
#endif // MODULES_PACING_PACING_CONTROLLER_H_

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