platform: Improve iOS OOM killer

service/oomkiller/service.go

@@ -0,0 +1,138 @@
+//go:build darwin && cgo
+
+package oomkiller
+
+/*
+#include <dispatch/dispatch.h>
+
+static dispatch_source_t memoryPressureSource;
+
+extern void goMemoryPressureCallback(unsigned long status);
+
+static void startMemoryPressureMonitor() {
+	memoryPressureSource = dispatch_source_create(
+		DISPATCH_SOURCE_TYPE_MEMORYPRESSURE,
+		0,
+		DISPATCH_MEMORYPRESSURE_WARN | DISPATCH_MEMORYPRESSURE_CRITICAL,
+		dispatch_get_global_queue(QOS_CLASS_DEFAULT, 0)
+	);
+	dispatch_source_set_event_handler(memoryPressureSource, ^{
+		unsigned long status = dispatch_source_get_data(memoryPressureSource);
+		goMemoryPressureCallback(status);
+	});
+	dispatch_activate(memoryPressureSource);
+}
+
+static void stopMemoryPressureMonitor() {
+	if (memoryPressureSource) {
+		dispatch_source_cancel(memoryPressureSource);
+		memoryPressureSource = NULL;
+	}
+}
+*/
+import "C"
+
+import (
+	"context"
+	runtimeDebug "runtime/debug"
+	"sync"
+
+	"github.com/sagernet/sing-box/adapter"
+	boxService "github.com/sagernet/sing-box/adapter/service"
+	boxConstant "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing/common/memory"
+	"github.com/sagernet/sing/service"
+)
+
+func RegisterService(registry *boxService.Registry) {
+	boxService.Register[option.OOMKillerServiceOptions](registry, boxConstant.TypeOOMKiller, NewService)
+}
+
+var (
+	globalAccess   sync.Mutex
+	globalServices []*Service
+)
+
+type Service struct {
+	boxService.Adapter
+	logger log.ContextLogger
+	router adapter.Router
+}
+
+func NewService(ctx context.Context, logger log.ContextLogger, tag string, options option.OOMKillerServiceOptions) (adapter.Service, error) {
+	return &Service{
+		Adapter: boxService.NewAdapter(boxConstant.TypeOOMKiller, tag),
+		logger:  logger,
+		router:  service.FromContext[adapter.Router](ctx),
+	}, nil
+}
+
+func (s *Service) Start(stage adapter.StartStage) error {
+	if stage != adapter.StartStateStart {
+		return nil
+	}
+	globalAccess.Lock()
+	isFirst := len(globalServices) == 0
+	globalServices = append(globalServices, s)
+	globalAccess.Unlock()
+	if isFirst {
+		C.startMemoryPressureMonitor()
+	}
+	s.logger.Info("started memory pressure monitor")
+	return nil
+}
+
+func (s *Service) Close() error {
+	globalAccess.Lock()
+	for i, service := range globalServices {
+		if service == s {
+			globalServices = append(globalServices[:i], globalServices[i+1:]...)
+			break
+		}
+	}
+	isLast := len(globalServices) == 0
+	globalAccess.Unlock()
+	if isLast {
+		C.stopMemoryPressureMonitor()
+	}
+	return nil
+}
+
+//export goMemoryPressureCallback
+func goMemoryPressureCallback(status C.ulong) {
+	globalAccess.Lock()
+	services := make([]*Service, len(globalServices))
+	copy(services, globalServices)
+	globalAccess.Unlock()
+	if len(services) == 0 {
+		return
+	}
+	criticalFlag := C.ulong(C.DISPATCH_MEMORYPRESSURE_CRITICAL)
+	warnFlag := C.ulong(C.DISPATCH_MEMORYPRESSURE_WARN)
+	isCritical := status&criticalFlag != 0
+	isWarning := status&warnFlag != 0
+	var level string
+	switch {
+	case isCritical:
+		level = "critical"
+	case isWarning:
+		level = "warning"
+	default:
+		level = "normal"
+	}
+	for _, s := range services {
+		if isCritical {
+			s.logger.Error("memory pressure: ", level, ", usage: ", memory.Total()/(1024*1024), " MiB, resetting network")
+			s.router.ResetNetwork()
+		} else if isWarning {
+			s.logger.Warn("memory pressure: ", level, ", usage: ", memory.Total()/(1024*1024), " MiB")
+		} else {
+			s.logger.Debug("memory pressure: ", level, ", usage: ", memory.Total()/(1024*1024), " MiB")
+		}
+	}
+	if isCritical {
+		runtimeDebug.FreeOSMemory()
+	}
+}

service/oomkiller/service_stub.go

@@ -0,0 +1,39 @@
+//go:build !darwin || !cgo
+
+package oomkiller
+
+import (
+	"context"
+
+	"github.com/sagernet/sing-box/adapter"
+	boxService "github.com/sagernet/sing-box/adapter/service"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+func RegisterService(registry *boxService.Registry) {
+	boxService.Register[option.OOMKillerServiceOptions](registry, C.TypeOOMKiller, NewService)
+}
+
+type Service struct {
+	boxService.Adapter
+}
+
+func NewService(ctx context.Context, logger log.ContextLogger, tag string, options option.OOMKillerServiceOptions) (adapter.Service, error) {
+	return &Service{
+		Adapter: boxService.NewAdapter(C.TypeOOMKiller, tag),
+	}, nil
+}
+
+func (s *Service) Start(stage adapter.StartStage) error {
+	if stage != adapter.StartStateStart {
+		return nil
+	}
+	return E.New("memory pressure monitoring is not available on this platform")
+}
+
+func (s *Service) Close() error {
+	return nil
+}