Refactor: allow to add an empty proxy provider to proxy group

adapter/provider/healthcheck.go

@@ -25,10 +25,16 @@ type HealthCheck struct {
 	interval  uint
 	lazy      bool
 	lastTouch *atomic.Int64
+	running   *atomic.Bool
 	done      chan struct{}
 }
 
 func (hc *HealthCheck) process() {
+	if hc.running.Load() {
+		return
+	}
+	hc.running.Store(true)
+
 	ticker := time.NewTicker(time.Duration(hc.interval) * time.Second)
 
 	go func() {
@@ -84,6 +90,10 @@ func (hc *HealthCheck) check() {
 }
 
 func (hc *HealthCheck) close() {
+	if !hc.running.Load() {
+		return
+	}
+	hc.running.Store(false)
 	hc.done <- struct{}{}
 }
 
@@ -94,6 +104,7 @@ func NewHealthCheck(proxies []C.Proxy, url string, interval uint, lazy bool) *He
 		interval:  interval,
 		lazy:      lazy,
 		lastTouch: atomic.NewInt64(0),
+		running:   atomic.NewBool(false),
 		done:      make(chan struct{}, 1),
 	}
 }

adapter/provider/provider.go

@@ -234,7 +234,9 @@ func (pf *proxyFilterProvider) HealthCheck() {
 }
 
 func (pf *proxyFilterProvider) Update() error {
-	var proxies []C.Proxy
+	pf.healthCheck.close()
+
+	proxies := []C.Proxy{}
 	if pf.filter != nil {
 		for _, proxy := range pf.psd.Proxies() {
 			if !pf.filter.MatchString(proxy.Name()) {
@@ -248,6 +250,10 @@ func (pf *proxyFilterProvider) Update() error {
 
 	pf.proxies = proxies
 	pf.healthCheck.setProxy(proxies)
+
+	if len(proxies) != 0 && pf.healthCheck.auto() {
+		go pf.healthCheck.process()
+	}
 	return nil
 }
 
@@ -286,10 +292,6 @@ func NewProxyFilterProvider(name string, psd *ProxySetProvider, hc *HealthCheck,
 
 	_ = pd.Update()
 
-	if hc.auto() {
-		go hc.process()
-	}
-
 	wrapper := &ProxyFilterProvider{pd}
 	runtime.SetFinalizer(wrapper, stopProxyFilterProvider)
 	return wrapper