snapshot of https://github.com/livekit/livekit.git @ 08c5433449c106943231037d0b892895f6e92d3b (2026-09-15)

pkg/sfu/ccutils/probe_regulator.go

@@ -0,0 +1,106 @@
+// Copyright 2023 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ccutils
+
+import (
+	"time"
+
+	"github.com/livekit/protocol/logger"
+	"github.com/livekit/protocol/utils/mono"
+)
+
+// ------------------------------------------------
+
+type ProbeRegulatorConfig struct {
+	BaseInterval  time.Duration `yaml:"base_interval,omitempty"`
+	BackoffFactor float64       `yaml:"backoff_factor,omitempty"`
+	MaxInterval   time.Duration `yaml:"max_interval,omitempty"`
+
+	MinDuration            time.Duration `yaml:"min_duration,omitempty"`
+	MaxDuration            time.Duration `yaml:"max_duration,omitempty"`
+	DurationIncreaseFactor float64       `yaml:"duration_increase_factor,omitempty"`
+}
+
+var (
+	DefaultProbeRegulatorConfig = ProbeRegulatorConfig{
+		BaseInterval:  3 * time.Second,
+		BackoffFactor: 1.5,
+		MaxInterval:   2 * time.Minute,
+
+		MinDuration:            200 * time.Millisecond,
+		MaxDuration:            20 * time.Second,
+		DurationIncreaseFactor: 1.5,
+	}
+)
+
+// ---------------------------------------------------------------------------
+
+type ProbeRegulatorParams struct {
+	Config ProbeRegulatorConfig
+	Logger logger.Logger
+}
+
+type ProbeRegulator struct {
+	params ProbeRegulatorParams
+
+	probeInterval       time.Duration
+	probeDuration       time.Duration
+	nextProbeEarliestAt time.Time
+}
+
+func NewProbeRegulator(params ProbeRegulatorParams) *ProbeRegulator {
+	return &ProbeRegulator{
+		params:              params,
+		probeInterval:       params.Config.BaseInterval,
+		probeDuration:       params.Config.MinDuration,
+		nextProbeEarliestAt: mono.Now(),
+	}
+}
+
+func (p *ProbeRegulator) CanProbe() bool {
+	return mono.Now().After(p.nextProbeEarliestAt)
+}
+
+func (p *ProbeRegulator) ProbeDuration() time.Duration {
+	return p.probeDuration
+}
+
+func (p *ProbeRegulator) ProbeSignal(probeSignal ProbeSignal, baseTime time.Time) {
+	if probeSignal == ProbeSignalCongesting {
+		// wait longer till next probe
+		p.probeInterval = time.Duration(p.probeInterval.Seconds()*p.params.Config.BackoffFactor) * time.Second
+		if p.probeInterval > p.params.Config.MaxInterval {
+			p.probeInterval = p.params.Config.MaxInterval
+		}
+
+		// revert back to starting with shortest probe
+		p.probeDuration = p.params.Config.MinDuration
+	} else {
+		// probe can be started again after minimal interval as previous congestion signal indicated congestion clearing
+		p.probeInterval = p.params.Config.BaseInterval
+
+		// can do longer probe after a good probe
+		p.probeDuration = time.Duration(float64(p.probeDuration.Milliseconds())*p.params.Config.DurationIncreaseFactor) * time.Millisecond
+		if p.probeDuration > p.params.Config.MaxDuration {
+			p.probeDuration = p.params.Config.MaxDuration
+		}
+	}
+
+	if baseTime.IsZero() {
+		p.nextProbeEarliestAt = mono.Now().Add(p.probeInterval)
+	} else {
+		p.nextProbeEarliestAt = baseTime.Add(p.probeInterval)
+	}
+}