| /* |
| * 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 "modules/congestion_controller/goog_cc/probe_bitrate_estimator.h" |
| |
| #include <algorithm> |
| #include <memory> |
| |
| #include "api/rtc_event_log/rtc_event_log.h" |
| #include "logging/rtc_event_log/events/rtc_event_probe_result_failure.h" |
| #include "logging/rtc_event_log/events/rtc_event_probe_result_success.h" |
| #include "rtc_base/checks.h" |
| #include "rtc_base/logging.h" |
| #include "rtc_base/numerics/safe_conversions.h" |
| |
| namespace webrtc { |
| namespace { |
| // The minumum number of probes we need to receive feedback about in percent |
| // in order to have a valid estimate. |
| constexpr double kMinReceivedProbesRatio = .80; |
| |
| // The minumum number of bytes we need to receive feedback about in percent |
| // in order to have a valid estimate. |
| constexpr double kMinReceivedBytesRatio = .80; |
| |
| // The maximum |receive rate| / |send rate| ratio for a valid estimate. |
| constexpr float kMaxValidRatio = 2.0f; |
| |
| // The minimum |receive rate| / |send rate| ratio assuming that the link is |
| // not saturated, i.e. we assume that we will receive at least |
| // kMinRatioForUnsaturatedLink * |send rate| if |send rate| is less than the |
| // link capacity. |
| constexpr float kMinRatioForUnsaturatedLink = 0.9f; |
| |
| // The target utilization of the link. If we know true link capacity |
| // we'd like to send at 95% of that rate. |
| constexpr float kTargetUtilizationFraction = 0.95f; |
| |
| // The maximum time period over which the cluster history is retained. |
| // This is also the maximum time period beyond which a probing burst is not |
| // expected to last. |
| constexpr TimeDelta kMaxClusterHistory = TimeDelta::Seconds(1); |
| |
| // The maximum time interval between first and the last probe on a cluster |
| // on the sender side as well as the receive side. |
| constexpr TimeDelta kMaxProbeInterval = TimeDelta::Seconds(1); |
| |
| } // namespace |
| |
| ProbeBitrateEstimator::ProbeBitrateEstimator(RtcEventLog* event_log) |
| : event_log_(event_log) {} |
| |
| ProbeBitrateEstimator::~ProbeBitrateEstimator() = default; |
| |
| absl::optional<DataRate> ProbeBitrateEstimator::HandleProbeAndEstimateBitrate( |
| const PacketResult& packet_feedback) { |
| int cluster_id = packet_feedback.sent_packet.pacing_info.probe_cluster_id; |
| RTC_DCHECK_NE(cluster_id, PacedPacketInfo::kNotAProbe); |
| |
| EraseOldClusters(packet_feedback.receive_time); |
| |
| AggregatedCluster* cluster = &clusters_[cluster_id]; |
| |
| if (packet_feedback.sent_packet.send_time < cluster->first_send) { |
| cluster->first_send = packet_feedback.sent_packet.send_time; |
| } |
| if (packet_feedback.sent_packet.send_time > cluster->last_send) { |
| cluster->last_send = packet_feedback.sent_packet.send_time; |
| cluster->size_last_send = packet_feedback.sent_packet.size; |
| } |
| if (packet_feedback.receive_time < cluster->first_receive) { |
| cluster->first_receive = packet_feedback.receive_time; |
| cluster->size_first_receive = packet_feedback.sent_packet.size; |
| } |
| if (packet_feedback.receive_time > cluster->last_receive) { |
| cluster->last_receive = packet_feedback.receive_time; |
| } |
| cluster->size_total += packet_feedback.sent_packet.size; |
| cluster->num_probes += 1; |
| |
| RTC_DCHECK_GT( |
| packet_feedback.sent_packet.pacing_info.probe_cluster_min_probes, 0); |
| RTC_DCHECK_GT(packet_feedback.sent_packet.pacing_info.probe_cluster_min_bytes, |
| 0); |
| |
| int min_probes = |
| packet_feedback.sent_packet.pacing_info.probe_cluster_min_probes * |
| kMinReceivedProbesRatio; |
| DataSize min_size = |
| DataSize::Bytes( |
| packet_feedback.sent_packet.pacing_info.probe_cluster_min_bytes) * |
| kMinReceivedBytesRatio; |
| if (cluster->num_probes < min_probes || cluster->size_total < min_size) |
| return absl::nullopt; |
| |
| TimeDelta send_interval = cluster->last_send - cluster->first_send; |
| TimeDelta receive_interval = cluster->last_receive - cluster->first_receive; |
| |
| if (send_interval <= TimeDelta::Zero() || send_interval > kMaxProbeInterval || |
| receive_interval <= TimeDelta::Zero() || |
| receive_interval > kMaxProbeInterval) { |
| RTC_LOG(LS_INFO) << "Probing unsuccessful, invalid send/receive interval" |
| " [cluster id: " |
| << cluster_id |
| << "] [send interval: " << ToString(send_interval) |
| << "]" |
| " [receive interval: " |
| << ToString(receive_interval) << "]"; |
| if (event_log_) { |
| event_log_->Log(std::make_unique<RtcEventProbeResultFailure>( |
| cluster_id, ProbeFailureReason::kInvalidSendReceiveInterval)); |
| } |
| return absl::nullopt; |
| } |
| // Since the `send_interval` does not include the time it takes to actually |
| // send the last packet the size of the last sent packet should not be |
| // included when calculating the send bitrate. |
| RTC_DCHECK_GT(cluster->size_total, cluster->size_last_send); |
| DataSize send_size = cluster->size_total - cluster->size_last_send; |
| DataRate send_rate = send_size / send_interval; |
| |
| // Since the `receive_interval` does not include the time it takes to |
| // actually receive the first packet the size of the first received packet |
| // should not be included when calculating the receive bitrate. |
| RTC_DCHECK_GT(cluster->size_total, cluster->size_first_receive); |
| DataSize receive_size = cluster->size_total - cluster->size_first_receive; |
| DataRate receive_rate = receive_size / receive_interval; |
| |
| double ratio = receive_rate / send_rate; |
| if (ratio > kMaxValidRatio) { |
| RTC_LOG(LS_INFO) << "Probing unsuccessful, receive/send ratio too high" |
| " [cluster id: " |
| << cluster_id << "] [send: " << ToString(send_size) |
| << " / " << ToString(send_interval) << " = " |
| << ToString(send_rate) |
| << "]" |
| " [receive: " |
| << ToString(receive_size) << " / " |
| << ToString(receive_interval) << " = " |
| << ToString(receive_rate) |
| << " ]" |
| " [ratio: " |
| << ToString(receive_rate) << " / " << ToString(send_rate) |
| << " = " << ratio << " > kMaxValidRatio (" |
| << kMaxValidRatio << ")]"; |
| if (event_log_) { |
| event_log_->Log(std::make_unique<RtcEventProbeResultFailure>( |
| cluster_id, ProbeFailureReason::kInvalidSendReceiveRatio)); |
| } |
| return absl::nullopt; |
| } |
| RTC_LOG(LS_INFO) << "Probing successful" |
| " [cluster id: " |
| << cluster_id << "] [send: " << ToString(send_size) << " / " |
| << ToString(send_interval) << " = " << ToString(send_rate) |
| << " ]" |
| " [receive: " |
| << ToString(receive_size) << " / " |
| << ToString(receive_interval) << " = " |
| << ToString(receive_rate) << "]"; |
| |
| DataRate res = std::min(send_rate, receive_rate); |
| // If we're receiving at significantly lower bitrate than we were sending at, |
| // it suggests that we've found the true capacity of the link. In this case, |
| // set the target bitrate slightly lower to not immediately overuse. |
| if (receive_rate < kMinRatioForUnsaturatedLink * send_rate) { |
| RTC_DCHECK_GT(send_rate, receive_rate); |
| res = kTargetUtilizationFraction * receive_rate; |
| } |
| if (event_log_) { |
| event_log_->Log( |
| std::make_unique<RtcEventProbeResultSuccess>(cluster_id, res.bps())); |
| } |
| estimated_data_rate_ = res; |
| return estimated_data_rate_; |
| } |
| |
| absl::optional<DataRate> |
| ProbeBitrateEstimator::FetchAndResetLastEstimatedBitrate() { |
| absl::optional<DataRate> estimated_data_rate = estimated_data_rate_; |
| estimated_data_rate_.reset(); |
| return estimated_data_rate; |
| } |
| |
| void ProbeBitrateEstimator::EraseOldClusters(Timestamp timestamp) { |
| for (auto it = clusters_.begin(); it != clusters_.end();) { |
| if (it->second.last_receive + kMaxClusterHistory < timestamp) { |
| it = clusters_.erase(it); |
| } else { |
| ++it; |
| } |
| } |
| } |
| } // namespace webrtc |
