1 /* 2 * Copyright (c) 2014 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef MODULES_PACING_BITRATE_PROBER_H_ 12 #define MODULES_PACING_BITRATE_PROBER_H_ 13 14 #include <stddef.h> 15 #include <stdint.h> 16 17 #include <queue> 18 19 #include "api/transport/field_trial_based_config.h" 20 #include "api/transport/network_types.h" 21 #include "rtc_base/experiments/field_trial_parser.h" 22 23 namespace webrtc { 24 class RtcEventLog; 25 26 struct BitrateProberConfig { 27 explicit BitrateProberConfig(const FieldTrialsView* key_value_config); 28 BitrateProberConfig(const BitrateProberConfig&) = default; 29 BitrateProberConfig& operator=(const BitrateProberConfig&) = default; 30 ~BitrateProberConfig() = default; 31 32 // A minimum interval between probes to allow scheduling to be feasible. 33 FieldTrialParameter<TimeDelta> min_probe_delta; 34 // Maximum amount of time each probe can be delayed. 35 FieldTrialParameter<TimeDelta> max_probe_delay; 36 // This is used to start sending a probe after a large enough packet. 37 // The min packet size is scaled with the bitrate we're probing at. 38 // This defines the max min packet size, meaning that on high bitrates 39 // a packet of at least this size is needed to trigger sending a probe. 40 FieldTrialParameter<DataSize> min_packet_size; 41 }; 42 43 // Note that this class isn't thread-safe by itself and therefore relies 44 // on being protected by the caller. 45 class BitrateProber { 46 public: 47 explicit BitrateProber(const FieldTrialsView& field_trials); 48 ~BitrateProber(); 49 50 void SetEnabled(bool enable); 51 52 // Returns true if the prober is in a probing session, i.e., it currently 53 // wants packets to be sent out according to the time returned by 54 // TimeUntilNextProbe(). is_probing()55 bool is_probing() const { return probing_state_ == ProbingState::kActive; } 56 57 // Initializes a new probing session if the prober is allowed to probe. Does 58 // not initialize the prober unless the packet size is large enough to probe 59 // with. 60 void OnIncomingPacket(DataSize packet_size); 61 62 // Create a cluster used to probe. 63 void CreateProbeCluster(const ProbeClusterConfig& cluster_config); 64 // Returns the time at which the next probe should be sent to get accurate 65 // probing. If probing is not desired at this time, Timestamp::PlusInfinity() 66 // will be returned. 67 // TODO(bugs.webrtc.org/11780): Remove `now` argument when old mode is gone. 68 Timestamp NextProbeTime(Timestamp now) const; 69 70 // Information about the current probing cluster. 71 absl::optional<PacedPacketInfo> CurrentCluster(Timestamp now); 72 73 // Returns the minimum number of bytes that the prober recommends for 74 // the next probe, or zero if not probing. A probe can consist of multiple 75 // packets that are sent back to back. 76 DataSize RecommendedMinProbeSize() const; 77 78 // Called to report to the prober that a probe has been sent. In case of 79 // multiple packets per probe, this call would be made at the end of sending 80 // the last packet in probe. `size` is the total size of all packets in probe. 81 void ProbeSent(Timestamp now, DataSize size); 82 83 private: 84 enum class ProbingState { 85 // Probing will not be triggered in this state at all times. 86 kDisabled, 87 // Probing is enabled and ready to trigger on the first packet arrival. 88 kInactive, 89 // Probe cluster is filled with the set of data rates to be probed and 90 // probes are being sent. 91 kActive, 92 // Probing is enabled, but currently suspended until an explicit trigger 93 // to start probing again. 94 kSuspended, 95 }; 96 97 // A probe cluster consists of a set of probes. Each probe in turn can be 98 // divided into a number of packets to accommodate the MTU on the network. 99 struct ProbeCluster { 100 PacedPacketInfo pace_info; 101 102 int sent_probes = 0; 103 int sent_bytes = 0; 104 Timestamp requested_at = Timestamp::MinusInfinity(); 105 Timestamp started_at = Timestamp::MinusInfinity(); 106 int retries = 0; 107 }; 108 109 Timestamp CalculateNextProbeTime(const ProbeCluster& cluster) const; 110 111 ProbingState probing_state_; 112 113 // Probe bitrate per packet. These are used to compute the delta relative to 114 // the previous probe packet based on the size and time when that packet was 115 // sent. 116 std::queue<ProbeCluster> clusters_; 117 118 // Time the next probe should be sent when in kActive state. 119 Timestamp next_probe_time_; 120 121 int total_probe_count_; 122 int total_failed_probe_count_; 123 124 BitrateProberConfig config_; 125 }; 126 127 } // namespace webrtc 128 129 #endif // MODULES_PACING_BITRATE_PROBER_H_ 130