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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.
*/
#ifndef MODULES_PACING_BITRATE_PROBER_H_
#define MODULES_PACING_BITRATE_PROBER_H_
#include <stddef.h>
#include <stdint.h>
#include <queue>
#include "api/transport/field_trial_based_config.h"
#include "api/transport/network_types.h"
#include "rtc_base/experiments/field_trial_parser.h"
namespace webrtc {
class RtcEventLog;
struct BitrateProberConfig {
explicit BitrateProberConfig(const FieldTrialsView* key_value_config);
BitrateProberConfig(const BitrateProberConfig&) = default;
BitrateProberConfig& operator=(const BitrateProberConfig&) = default;
~BitrateProberConfig() = default;
// A minimum interval between probes to allow scheduling to be feasible.
FieldTrialParameter<TimeDelta> min_probe_delta;
// Maximum amount of time each probe can be delayed.
FieldTrialParameter<TimeDelta> max_probe_delay;
// This is used to start sending a probe after a large enough packet.
// The min packet size is scaled with the bitrate we're probing at.
// This defines the max min packet size, meaning that on high bitrates
// a packet of at least this size is needed to trigger sending a probe.
FieldTrialParameter<DataSize> min_packet_size;
};
// Note that this class isn't thread-safe by itself and therefore relies
// on being protected by the caller.
class BitrateProber {
public:
explicit BitrateProber(const FieldTrialsView& field_trials);
~BitrateProber() = default;
void SetEnabled(bool enable);
// Returns true if the prober is in a probing session, i.e., it currently
// wants packets to be sent out according to the time returned by
// TimeUntilNextProbe().
bool is_probing() const { return probing_state_ == ProbingState::kActive; }
// Initializes a new probing session if the prober is allowed to probe. Does
// not initialize the prober unless the packet size is large enough to probe
// with.
void OnIncomingPacket(DataSize packet_size);
// Create a cluster used to probe.
void CreateProbeCluster(const ProbeClusterConfig& cluster_config);
// Returns the time at which the next probe should be sent to get accurate
// probing. If probing is not desired at this time, Timestamp::PlusInfinity()
// will be returned.
// TODO(bugs.webrtc.org/11780): Remove `now` argument when old mode is gone.
Timestamp NextProbeTime(Timestamp now) const;
// Information about the current probing cluster.
absl::optional<PacedPacketInfo> CurrentCluster(Timestamp now);
// Returns the minimum number of bytes that the prober recommends for
// the next probe, or zero if not probing. A probe can consist of multiple
// packets that are sent back to back.
DataSize RecommendedMinProbeSize() const;
// Called to report to the prober that a probe has been sent. In case of
// multiple packets per probe, this call would be made at the end of sending
// the last packet in probe. `size` is the total size of all packets in probe.
void ProbeSent(Timestamp now, DataSize size);
private:
enum class ProbingState {
// Probing will not be triggered in this state at all times.
kDisabled,
// Probing is enabled and ready to trigger on the first packet arrival if
// there is a probe cluster.
kInactive,
// Probe cluster is filled with the set of data rates to be probed and
// probes are being sent.
kActive,
};
// A probe cluster consists of a set of probes. Each probe in turn can be
// divided into a number of packets to accommodate the MTU on the network.
struct ProbeCluster {
PacedPacketInfo pace_info;
int sent_probes = 0;
int sent_bytes = 0;
Timestamp requested_at = Timestamp::MinusInfinity();
Timestamp started_at = Timestamp::MinusInfinity();
int retries = 0;
};
Timestamp CalculateNextProbeTime(const ProbeCluster& cluster) const;
bool ReadyToSetActiveState(DataSize packet_size) const;
ProbingState probing_state_;
// Probe bitrate per packet. These are used to compute the delta relative to
// the previous probe packet based on the size and time when that packet was
// sent.
std::queue<ProbeCluster> clusters_;
// Time the next probe should be sent when in kActive state.
Timestamp next_probe_time_;
BitrateProberConfig config_;
};
} // namespace webrtc
#endif // MODULES_PACING_BITRATE_PROBER_H_
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