Refactor: fetcher by generics

adapter/provider/fetcher.go

@@ -16,28 +16,28 @@ var (
 	dirMode  os.FileMode = 0o755
 )
 
-type parser = func([]byte) (any, error)
+type parser[V any] func([]byte) (V, error)
 
-type fetcher struct {
+type fetcher[V any] struct {
 	name      string
 	vehicle   types.Vehicle
 	updatedAt *time.Time
 	ticker    *time.Ticker
 	done      chan struct{}
 	hash      [16]byte
-	parser    parser
+	parser    parser[V]
-	onUpdate  func(any)
+	onUpdate  func(V)
 }
 
-func (f *fetcher) Name() string {
+func (f *fetcher[V]) Name() string {
 	return f.name
 }
 
-func (f *fetcher) VehicleType() types.VehicleType {
+func (f *fetcher[V]) VehicleType() types.VehicleType {
 	return f.vehicle.Type()
 }
 
-func (f *fetcher) Initial() (any, error) {
+func (f *fetcher[V]) Initial() (V, error) {
 	var (
 		buf     []byte
 		err     error
@@ -53,24 +53,24 @@ func (f *fetcher) Initial() (any, error) {
 	}
 
 	if err != nil {
-		return nil, err
+		return getZero[V](), err
 	}
 
 	proxies, err := f.parser(buf)
 	if err != nil {
 		if !isLocal {
-			return nil, err
+			return getZero[V](), err
 		}
 
 		// parse local file error, fallback to remote
 		buf, err = f.vehicle.Read()
 		if err != nil {
-			return nil, err
+			return getZero[V](), err
 		}
 
 		proxies, err = f.parser(buf)
 		if err != nil {
-			return nil, err
+			return getZero[V](), err
 		}
 
 		isLocal = false
@@ -78,7 +78,7 @@ func (f *fetcher) Initial() (any, error) {
 
 	if f.vehicle.Type() != types.File && !isLocal {
 		if err := safeWrite(f.vehicle.Path(), buf); err != nil {
-			return nil, err
+			return getZero[V](), err
 		}
 	}
 
@@ -92,28 +92,28 @@ func (f *fetcher) Initial() (any, error) {
 	return proxies, nil
 }
 
-func (f *fetcher) Update() (any, bool, error) {
+func (f *fetcher[V]) Update() (V, bool, error) {
 	buf, err := f.vehicle.Read()
 	if err != nil {
-		return nil, false, err
+		return getZero[V](), false, err
 	}
 
 	now := time.Now()
 	hash := md5.Sum(buf)
 	if bytes.Equal(f.hash[:], hash[:]) {
 		f.updatedAt = &now
-		os.Chtimes(f.vehicle.Path(), now, now)
+		_ = os.Chtimes(f.vehicle.Path(), now, now)
-		return nil, true, nil
+		return getZero[V](), true, nil
 	}
 
 	proxies, err := f.parser(buf)
 	if err != nil {
-		return nil, false, err
+		return getZero[V](), false, err
 	}
 
 	if f.vehicle.Type() != types.File {
 		if err := safeWrite(f.vehicle.Path(), buf); err != nil {
-			return nil, false, err
+			return getZero[V](), false, err
 		}
 	}
 
@@ -123,14 +123,14 @@ func (f *fetcher) Update() (any, bool, error) {
 	return proxies, false, nil
 }
 
-func (f *fetcher) Destroy() error {
+func (f *fetcher[V]) Destroy() error {
 	if f.ticker != nil {
 		f.done <- struct{}{}
 	}
 	return nil
 }
 
-func (f *fetcher) pullLoop() {
+func (f *fetcher[V]) pullLoop() {
 	for {
 		select {
 		case <-f.ticker.C:
@@ -168,13 +168,13 @@ func safeWrite(path string, buf []byte) error {
 	return os.WriteFile(path, buf, fileMode)
 }
 
-func newFetcher(name string, interval time.Duration, vehicle types.Vehicle, parser parser, onUpdate func(any)) *fetcher {
+func newFetcher[V any](name string, interval time.Duration, vehicle types.Vehicle, parser parser[V], onUpdate func(V)) *fetcher[V] {
 	var ticker *time.Ticker
 	if interval != 0 {
 		ticker = time.NewTicker(interval)
 	}
 
-	return &fetcher{
+	return &fetcher[V]{
 		name:     name,
 		ticker:   ticker,
 		vehicle:  vehicle,
@@ -183,3 +183,8 @@ func newFetcher(name string, interval time.Duration, vehicle types.Vehicle, pars
 		onUpdate: onUpdate,
 	}
 }
+
+func getZero[V any]() V {
+	var result V
+	return result
+}

adapter/provider/provider.go

@@ -23,13 +23,13 @@ type ProxySchema struct {
 	Proxies []map[string]any `yaml:"proxies"`
 }
 
-// for auto gc
+// ProxySetProvider for auto gc
 type ProxySetProvider struct {
 	*proxySetProvider
 }
 
 type proxySetProvider struct {
-	*fetcher
+	*fetcher[[]C.Proxy]
 	proxies     []C.Proxy
 	healthCheck *HealthCheck
 }
@@ -93,7 +93,7 @@ func (pp *proxySetProvider) setProxies(proxies []C.Proxy) {
 
 func stopProxyProvider(pd *ProxySetProvider) {
 	pd.healthCheck.close()
-	pd.fetcher.Destroy()
+	_ = pd.fetcher.Destroy()
 }
 
 func NewProxySetProvider(name string, interval time.Duration, filter string, vehicle types.Vehicle, hc *HealthCheck) (*ProxySetProvider, error) {
@@ -111,45 +111,7 @@ func NewProxySetProvider(name string, interval time.Duration, filter string, veh
 		healthCheck: hc,
 	}
 
-	onUpdate := func(elm any) {
+	fetcher := newFetcher[[]C.Proxy](name, interval, vehicle, proxiesParseAndFilter(filter, filterReg), proxiesOnUpdate(pd))
-		ret := elm.([]C.Proxy)
-		pd.setProxies(ret)
-	}
-
-	proxiesParseAndFilter := func(buf []byte) (any, error) {
-		schema := &ProxySchema{}
-
-		if err := yaml.Unmarshal(buf, schema); err != nil {
-			return nil, err
-		}
-
-		if schema.Proxies == nil {
-			return nil, errors.New("file must have a `proxies` field")
-		}
-
-		proxies := []C.Proxy{}
-		for idx, mapping := range schema.Proxies {
-			if name, ok := mapping["name"]; ok && len(filter) > 0 && !filterReg.MatchString(name.(string)) {
-				continue
-			}
-			proxy, err := adapter.ParseProxy(mapping)
-			if err != nil {
-				return nil, fmt.Errorf("proxy %d error: %w", idx, err)
-			}
-			proxies = append(proxies, proxy)
-		}
-
-		if len(proxies) == 0 {
-			if len(filter) > 0 {
-				return nil, errors.New("doesn't match any proxy, please check your filter")
-			}
-			return nil, errors.New("file doesn't have any proxy")
-		}
-
-		return proxies, nil
-	}
-
-	fetcher := newFetcher(name, interval, vehicle, proxiesParseAndFilter, onUpdate)
 	pd.fetcher = fetcher
 
 	wrapper := &ProxySetProvider{pd}
@@ -157,7 +119,7 @@ func NewProxySetProvider(name string, interval time.Duration, filter string, veh
 	return wrapper, nil
 }
 
-// for auto gc
+// CompatibleProvider for auto gc
 type CompatibleProvider struct {
 	*compatibleProvider
 }
@@ -233,3 +195,44 @@ func NewCompatibleProvider(name string, proxies []C.Proxy, hc *HealthCheck) (*Co
 	runtime.SetFinalizer(wrapper, stopCompatibleProvider)
 	return wrapper, nil
 }
+
+func proxiesOnUpdate(pd *proxySetProvider) func([]C.Proxy) {
+	return func(elm []C.Proxy) {
+		pd.setProxies(elm)
+	}
+}
+
+func proxiesParseAndFilter(filter string, filterReg *regexp.Regexp) parser[[]C.Proxy] {
+	return func(buf []byte) ([]C.Proxy, error) {
+		schema := &ProxySchema{}
+
+		if err := yaml.Unmarshal(buf, schema); err != nil {
+			return nil, err
+		}
+
+		if schema.Proxies == nil {
+			return nil, errors.New("file must have a `proxies` field")
+		}
+
+		proxies := []C.Proxy{}
+		for idx, mapping := range schema.Proxies {
+			if name, ok := mapping["name"]; ok && len(filter) > 0 && !filterReg.MatchString(name.(string)) {
+				continue
+			}
+			proxy, err := adapter.ParseProxy(mapping)
+			if err != nil {
+				return nil, fmt.Errorf("proxy %d error: %w", idx, err)
+			}
+			proxies = append(proxies, proxy)
+		}
+
+		if len(proxies) == 0 {
+			if len(filter) > 0 {
+				return nil, errors.New("doesn't match any proxy, please check your filter")
+			}
+			return nil, errors.New("file doesn't have any proxy")
+		}
+
+		return proxies, nil
+	}
+}