platform: Improve OOM killer for iOS

service/oomkiller/service_timer.go

@@ -0,0 +1,158 @@
+package oomkiller
+
+import (
+	runtimeDebug "runtime/debug"
+	"sync"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing/common/memory"
+)
+
+const (
+	defaultChecksBeforeLimit = 4
+	defaultMinInterval       = 500 * time.Millisecond
+	defaultMaxInterval       = 10 * time.Second
+	defaultSafetyMargin      = 5 * 1024 * 1024
+)
+
+type adaptiveTimer struct {
+	logger            log.ContextLogger
+	router            adapter.Router
+	memoryLimit       uint64
+	safetyMargin      uint64
+	minInterval       time.Duration
+	maxInterval       time.Duration
+	checksBeforeLimit int
+	useAvailable      bool
+
+	access        sync.Mutex
+	timer         *time.Timer
+	previousUsage uint64
+	lastInterval  time.Duration
+}
+
+type timerConfig struct {
+	memoryLimit       uint64
+	safetyMargin      uint64
+	minInterval       time.Duration
+	maxInterval       time.Duration
+	checksBeforeLimit int
+	useAvailable      bool
+}
+
+func newAdaptiveTimer(logger log.ContextLogger, router adapter.Router, config timerConfig) *adaptiveTimer {
+	return &adaptiveTimer{
+		logger:            logger,
+		router:            router,
+		memoryLimit:       config.memoryLimit,
+		safetyMargin:      config.safetyMargin,
+		minInterval:       config.minInterval,
+		maxInterval:       config.maxInterval,
+		checksBeforeLimit: config.checksBeforeLimit,
+		useAvailable:      config.useAvailable,
+	}
+}
+
+func (t *adaptiveTimer) start(_ uint64) {
+	t.access.Lock()
+	defer t.access.Unlock()
+	t.startLocked()
+}
+
+func (t *adaptiveTimer) startNow() {
+	t.access.Lock()
+	t.startLocked()
+	t.access.Unlock()
+	t.poll()
+}
+
+func (t *adaptiveTimer) startLocked() {
+	if t.timer != nil {
+		return
+	}
+	t.previousUsage = memory.Total()
+	t.lastInterval = t.minInterval
+	t.timer = time.AfterFunc(t.minInterval, t.poll)
+}
+
+func (t *adaptiveTimer) stop() {
+	t.access.Lock()
+	defer t.access.Unlock()
+	t.stopLocked()
+}
+
+func (t *adaptiveTimer) stopLocked() {
+	if t.timer != nil {
+		t.timer.Stop()
+		t.timer = nil
+	}
+}
+
+func (t *adaptiveTimer) running() bool {
+	t.access.Lock()
+	defer t.access.Unlock()
+	return t.timer != nil
+}
+
+func (t *adaptiveTimer) poll() {
+	t.access.Lock()
+	defer t.access.Unlock()
+	if t.timer == nil {
+		return
+	}
+
+	usage := memory.Total()
+	delta := int64(usage) - int64(t.previousUsage)
+	t.previousUsage = usage
+
+	var remaining uint64
+	var triggered bool
+
+	if t.memoryLimit > 0 {
+		if usage >= t.memoryLimit {
+			remaining = 0
+			triggered = true
+		} else {
+			remaining = t.memoryLimit - usage
+		}
+	} else if t.useAvailable {
+		available := memory.Available()
+		if available <= t.safetyMargin {
+			remaining = 0
+			triggered = true
+		} else {
+			remaining = available - t.safetyMargin
+		}
+	} else {
+		remaining = 0
+	}
+
+	if triggered {
+		t.logger.Error("memory threshold reached, usage: ", usage/(1024*1024), " MiB, resetting network")
+		t.router.ResetNetwork()
+		runtimeDebug.FreeOSMemory()
+	}
+
+	var interval time.Duration
+	if triggered {
+		interval = t.maxInterval
+	} else if delta <= 0 {
+		interval = t.maxInterval
+	} else if t.checksBeforeLimit <= 0 {
+		interval = t.maxInterval
+	} else {
+		timeToLimit := time.Duration(float64(remaining) / float64(delta) * float64(t.lastInterval))
+		interval = timeToLimit / time.Duration(t.checksBeforeLimit)
+		if interval < t.minInterval {
+			interval = t.minInterval
+		}
+		if interval > t.maxInterval {
+			interval = t.maxInterval
+		}
+	}
+
+	t.lastInterval = interval
+	t.timer.Reset(interval)
+}