224 lines
8.4 KiB
C++
224 lines
8.4 KiB
C++
/*
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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/pacing/bitrate_prober.h"
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#include <algorithm>
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#include "absl/memory/memory.h"
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#include "api/rtc_event_log/rtc_event.h"
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#include "api/rtc_event_log/rtc_event_log.h"
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#include "logging/rtc_event_log/events/rtc_event_probe_cluster_created.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/logging.h"
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#include "system_wrappers/include/metrics.h"
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namespace webrtc {
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namespace {
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// The min probe packet size is scaled with the bitrate we're probing at.
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// This defines the max min probe packet size, meaning that on high bitrates
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// we have a min probe packet size of 200 bytes.
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constexpr DataSize kMinProbePacketSize = DataSize::Bytes(200);
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constexpr TimeDelta kProbeClusterTimeout = TimeDelta::Seconds(5);
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} // namespace
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BitrateProberConfig::BitrateProberConfig(
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const WebRtcKeyValueConfig* key_value_config)
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: min_probe_packets_sent("min_probe_packets_sent", 5),
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min_probe_delta("min_probe_delta", TimeDelta::Millis(1)),
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min_probe_duration("min_probe_duration", TimeDelta::Millis(15)),
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max_probe_delay("max_probe_delay", TimeDelta::Millis(3)),
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// TODO(bugs.webrtc.org/11780): Change to default true.
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abort_delayed_probes("abort_delayed_probes", false) {
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ParseFieldTrial(
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{&min_probe_packets_sent, &min_probe_delta, &min_probe_duration,
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&max_probe_delay, &abort_delayed_probes},
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key_value_config->Lookup("WebRTC-Bwe-ProbingConfiguration"));
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ParseFieldTrial(
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{&min_probe_packets_sent, &min_probe_delta, &min_probe_duration,
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&max_probe_delay, &abort_delayed_probes},
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key_value_config->Lookup("WebRTC-Bwe-ProbingBehavior"));
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}
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BitrateProber::~BitrateProber() {
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RTC_HISTOGRAM_COUNTS_1000("WebRTC.BWE.Probing.TotalProbeClustersRequested",
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total_probe_count_);
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RTC_HISTOGRAM_COUNTS_1000("WebRTC.BWE.Probing.TotalFailedProbeClusters",
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total_failed_probe_count_);
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}
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BitrateProber::BitrateProber(const WebRtcKeyValueConfig& field_trials)
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: probing_state_(ProbingState::kDisabled),
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next_probe_time_(Timestamp::PlusInfinity()),
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total_probe_count_(0),
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total_failed_probe_count_(0),
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config_(&field_trials) {
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SetEnabled(true);
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}
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void BitrateProber::SetEnabled(bool enable) {
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if (enable) {
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if (probing_state_ == ProbingState::kDisabled) {
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probing_state_ = ProbingState::kInactive;
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RTC_LOG(LS_INFO) << "Bandwidth probing enabled, set to inactive";
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}
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} else {
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probing_state_ = ProbingState::kDisabled;
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RTC_LOG(LS_INFO) << "Bandwidth probing disabled";
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}
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}
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void BitrateProber::OnIncomingPacket(DataSize packet_size) {
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// Don't initialize probing unless we have something large enough to start
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// probing.
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if (probing_state_ == ProbingState::kInactive && !clusters_.empty() &&
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packet_size >= std::min(RecommendedMinProbeSize(), kMinProbePacketSize)) {
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// Send next probe right away.
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next_probe_time_ = Timestamp::MinusInfinity();
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probing_state_ = ProbingState::kActive;
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}
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}
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void BitrateProber::CreateProbeCluster(DataRate bitrate,
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Timestamp now,
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int cluster_id) {
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RTC_DCHECK(probing_state_ != ProbingState::kDisabled);
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RTC_DCHECK_GT(bitrate, DataRate::Zero());
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total_probe_count_++;
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while (!clusters_.empty() &&
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now - clusters_.front().created_at > kProbeClusterTimeout) {
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clusters_.pop();
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total_failed_probe_count_++;
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}
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ProbeCluster cluster;
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cluster.created_at = now;
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cluster.pace_info.probe_cluster_min_probes = config_.min_probe_packets_sent;
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cluster.pace_info.probe_cluster_min_bytes =
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(bitrate * config_.min_probe_duration.Get()).bytes();
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RTC_DCHECK_GE(cluster.pace_info.probe_cluster_min_bytes, 0);
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cluster.pace_info.send_bitrate_bps = bitrate.bps();
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cluster.pace_info.probe_cluster_id = cluster_id;
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clusters_.push(cluster);
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RTC_LOG(LS_INFO) << "Probe cluster (bitrate:min bytes:min packets): ("
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<< cluster.pace_info.send_bitrate_bps << ":"
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<< cluster.pace_info.probe_cluster_min_bytes << ":"
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<< cluster.pace_info.probe_cluster_min_probes << ")";
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// If we are already probing, continue to do so. Otherwise set it to
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// kInactive and wait for OnIncomingPacket to start the probing.
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if (probing_state_ != ProbingState::kActive)
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probing_state_ = ProbingState::kInactive;
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}
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Timestamp BitrateProber::NextProbeTime(Timestamp now) const {
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// Probing is not active or probing is already complete.
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if (probing_state_ != ProbingState::kActive || clusters_.empty()) {
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return Timestamp::PlusInfinity();
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}
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// Legacy behavior, just warn about late probe and return as if not probing.
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if (!config_.abort_delayed_probes && next_probe_time_.IsFinite() &&
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now - next_probe_time_ > config_.max_probe_delay.Get()) {
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RTC_DLOG(LS_WARNING) << "Probe delay too high"
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" (next_ms:"
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<< next_probe_time_.ms() << ", now_ms: " << now.ms()
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<< ")";
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return Timestamp::PlusInfinity();
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}
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return next_probe_time_;
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}
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absl::optional<PacedPacketInfo> BitrateProber::CurrentCluster(Timestamp now) {
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if (clusters_.empty() || probing_state_ != ProbingState::kActive) {
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return absl::nullopt;
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}
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if (config_.abort_delayed_probes && next_probe_time_.IsFinite() &&
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now - next_probe_time_ > config_.max_probe_delay.Get()) {
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RTC_DLOG(LS_WARNING) << "Probe delay too high"
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" (next_ms:"
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<< next_probe_time_.ms() << ", now_ms: " << now.ms()
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<< "), discarding probe cluster.";
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clusters_.pop();
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if (clusters_.empty()) {
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probing_state_ = ProbingState::kSuspended;
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return absl::nullopt;
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}
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}
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PacedPacketInfo info = clusters_.front().pace_info;
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info.probe_cluster_bytes_sent = clusters_.front().sent_bytes;
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return info;
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}
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// Probe size is recommended based on the probe bitrate required. We choose
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// a minimum of twice |kMinProbeDeltaMs| interval to allow scheduling to be
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// feasible.
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DataSize BitrateProber::RecommendedMinProbeSize() const {
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if (clusters_.empty()) {
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return DataSize::Zero();
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}
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DataRate send_rate =
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DataRate::BitsPerSec(clusters_.front().pace_info.send_bitrate_bps);
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return 2 * send_rate * config_.min_probe_delta;
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}
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void BitrateProber::ProbeSent(Timestamp now, DataSize size) {
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RTC_DCHECK(probing_state_ == ProbingState::kActive);
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RTC_DCHECK(!size.IsZero());
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if (!clusters_.empty()) {
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ProbeCluster* cluster = &clusters_.front();
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if (cluster->sent_probes == 0) {
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RTC_DCHECK(cluster->started_at.IsInfinite());
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cluster->started_at = now;
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}
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cluster->sent_bytes += size.bytes<int>();
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cluster->sent_probes += 1;
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next_probe_time_ = CalculateNextProbeTime(*cluster);
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if (cluster->sent_bytes >= cluster->pace_info.probe_cluster_min_bytes &&
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cluster->sent_probes >= cluster->pace_info.probe_cluster_min_probes) {
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RTC_HISTOGRAM_COUNTS_100000("WebRTC.BWE.Probing.ProbeClusterSizeInBytes",
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cluster->sent_bytes);
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RTC_HISTOGRAM_COUNTS_100("WebRTC.BWE.Probing.ProbesPerCluster",
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cluster->sent_probes);
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RTC_HISTOGRAM_COUNTS_10000("WebRTC.BWE.Probing.TimePerProbeCluster",
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(now - cluster->started_at).ms());
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clusters_.pop();
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}
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if (clusters_.empty()) {
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probing_state_ = ProbingState::kSuspended;
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}
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}
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}
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Timestamp BitrateProber::CalculateNextProbeTime(
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const ProbeCluster& cluster) const {
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RTC_CHECK_GT(cluster.pace_info.send_bitrate_bps, 0);
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RTC_CHECK(cluster.started_at.IsFinite());
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// Compute the time delta from the cluster start to ensure probe bitrate stays
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// close to the target bitrate. Result is in milliseconds.
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DataSize sent_bytes = DataSize::Bytes(cluster.sent_bytes);
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DataRate send_bitrate =
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DataRate::BitsPerSec(cluster.pace_info.send_bitrate_bps);
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TimeDelta delta = sent_bytes / send_bitrate;
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return cluster.started_at + delta;
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}
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} // namespace webrtc
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