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/*
* Copyright (c) 2014 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/bitrate_prober.h"
#include <algorithm>
#include "logging/rtc_event_log/events/rtc_event_probe_cluster_created.h"
#include "logging/rtc_event_log/rtc_event_log.h"
#include "modules/pacing/paced_sender.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/ptr_util.h"
namespace webrtc {
namespace {
// A minimum interval between probes to allow scheduling to be feasible.
constexpr int kMinProbeDeltaMs = 1;
// The minimum number probing packets used.
constexpr int kMinProbePacketsSent = 5;
// The minimum probing duration in ms.
constexpr int kMinProbeDurationMs = 15;
// Maximum amount of time each probe can be delayed. Probe cluster is reset and
// retried from the start when this limit is reached.
constexpr int kMaxProbeDelayMs = 3;
// Number of times probing is retried before the cluster is dropped.
constexpr int kMaxRetryAttempts = 3;
// The min probe packet size is scaled with the bitrate we're probing at.
// This defines the max min probe packet size, meaning that on high bitrates
// we have a min probe packet size of 200 bytes.
constexpr size_t kMinProbePacketSize = 200;
constexpr int64_t kProbeClusterTimeoutMs = 5000;
} // namespace
BitrateProber::BitrateProber() : BitrateProber(nullptr) {}
BitrateProber::BitrateProber(RtcEventLog* event_log)
: probing_state_(ProbingState::kDisabled),
next_probe_time_ms_(-1),
next_cluster_id_(0),
event_log_(event_log) {
SetEnabled(true);
}
void BitrateProber::SetEnabled(bool enable) {
if (enable) {
if (probing_state_ == ProbingState::kDisabled) {
probing_state_ = ProbingState::kInactive;
RTC_LOG(LS_INFO) << "Bandwidth probing enabled, set to inactive";
}
} else {
probing_state_ = ProbingState::kDisabled;
RTC_LOG(LS_INFO) << "Bandwidth probing disabled";
}
}
bool BitrateProber::IsProbing() const {
return probing_state_ == ProbingState::kActive;
}
void BitrateProber::OnIncomingPacket(size_t packet_size) {
// Don't initialize probing unless we have something large enough to start
// probing.
if (probing_state_ == ProbingState::kInactive && !clusters_.empty() &&
packet_size >=
std::min<size_t>(RecommendedMinProbeSize(), kMinProbePacketSize)) {
// Send next probe right away.
next_probe_time_ms_ = -1;
probing_state_ = ProbingState::kActive;
}
}
void BitrateProber::CreateProbeCluster(int bitrate_bps, int64_t now_ms) {
RTC_DCHECK(probing_state_ != ProbingState::kDisabled);
RTC_DCHECK_GT(bitrate_bps, 0);
while (!clusters_.empty() &&
now_ms - clusters_.front().time_created_ms > kProbeClusterTimeoutMs) {
clusters_.pop();
}
ProbeCluster cluster;
cluster.time_created_ms = now_ms;
cluster.pace_info.probe_cluster_min_probes = kMinProbePacketsSent;
cluster.pace_info.probe_cluster_min_bytes =
bitrate_bps * kMinProbeDurationMs / 8000;
cluster.pace_info.send_bitrate_bps = bitrate_bps;
cluster.pace_info.probe_cluster_id = next_cluster_id_++;
clusters_.push(cluster);
if (event_log_)
event_log_->Log(rtc::MakeUnique<RtcEventProbeClusterCreated>(
cluster.pace_info.probe_cluster_id, cluster.pace_info.send_bitrate_bps,
cluster.pace_info.probe_cluster_min_probes,
cluster.pace_info.probe_cluster_min_bytes));
RTC_LOG(LS_INFO) << "Probe cluster (bitrate:min bytes:min packets): ("
<< cluster.pace_info.send_bitrate_bps << ":"
<< cluster.pace_info.probe_cluster_min_bytes << ":"
<< cluster.pace_info.probe_cluster_min_probes << ")";
// If we are already probing, continue to do so. Otherwise set it to
// kInactive and wait for OnIncomingPacket to start the probing.
if (probing_state_ != ProbingState::kActive)
probing_state_ = ProbingState::kInactive;
}
void BitrateProber::ResetState(int64_t now_ms) {
RTC_DCHECK(probing_state_ == ProbingState::kActive);
// Recreate all probing clusters.
std::queue<ProbeCluster> clusters;
clusters.swap(clusters_);
while (!clusters.empty()) {
if (clusters.front().retries < kMaxRetryAttempts) {
CreateProbeCluster(clusters.front().pace_info.send_bitrate_bps, now_ms);
clusters_.back().retries = clusters.front().retries + 1;
}
clusters.pop();
}
probing_state_ = ProbingState::kInactive;
}
int BitrateProber::TimeUntilNextProbe(int64_t now_ms) {
// Probing is not active or probing is already complete.
if (probing_state_ != ProbingState::kActive || clusters_.empty())
return -1;
int time_until_probe_ms = 0;
if (next_probe_time_ms_ >= 0) {
time_until_probe_ms = next_probe_time_ms_ - now_ms;
if (time_until_probe_ms < -kMaxProbeDelayMs) {
ResetState(now_ms);
return -1;
}
}
return std::max(time_until_probe_ms, 0);
}
PacedPacketInfo BitrateProber::CurrentCluster() const {
RTC_DCHECK(!clusters_.empty());
RTC_DCHECK(probing_state_ == ProbingState::kActive);
return clusters_.front().pace_info;
}
// Probe size is recommended based on the probe bitrate required. We choose
// a minimum of twice |kMinProbeDeltaMs| interval to allow scheduling to be
// feasible.
size_t BitrateProber::RecommendedMinProbeSize() const {
RTC_DCHECK(!clusters_.empty());
return clusters_.front().pace_info.send_bitrate_bps * 2 * kMinProbeDeltaMs /
(8 * 1000);
}
void BitrateProber::ProbeSent(int64_t now_ms, size_t bytes) {
RTC_DCHECK(probing_state_ == ProbingState::kActive);
RTC_DCHECK_GT(bytes, 0);
if (!clusters_.empty()) {
ProbeCluster* cluster = &clusters_.front();
if (cluster->sent_probes == 0) {
RTC_DCHECK_EQ(cluster->time_started_ms, -1);
cluster->time_started_ms = now_ms;
}
cluster->sent_bytes += static_cast<int>(bytes);
cluster->sent_probes += 1;
next_probe_time_ms_ = GetNextProbeTime(*cluster);
if (cluster->sent_bytes >= cluster->pace_info.probe_cluster_min_bytes &&
cluster->sent_probes >= cluster->pace_info.probe_cluster_min_probes) {
clusters_.pop();
}
if (clusters_.empty())
probing_state_ = ProbingState::kSuspended;
}
}
int64_t BitrateProber::GetNextProbeTime(const ProbeCluster& cluster) {
RTC_CHECK_GT(cluster.pace_info.send_bitrate_bps, 0);
RTC_CHECK_GE(cluster.time_started_ms, 0);
// Compute the time delta from the cluster start to ensure probe bitrate stays
// close to the target bitrate. Result is in milliseconds.
int64_t delta_ms =
(8000ll * cluster.sent_bytes + cluster.pace_info.send_bitrate_bps / 2) /
cluster.pace_info.send_bitrate_bps;
return cluster.time_started_ms + delta_ms;
}
} // namespace webrtc
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