Improve: provider can be auto GC

adapters/provider/fetcher.go

@@ -0,0 +1,154 @@
+package provider
+
+import (
+	"bytes"
+	"crypto/md5"
+	"io/ioutil"
+	"os"
+	"time"
+
+	"github.com/Dreamacro/clash/log"
+)
+
+var (
+	fileMode os.FileMode = 0666
+)
+
+type parser = func([]byte) (interface{}, error)
+
+type fetcher struct {
+	name      string
+	vehicle   Vehicle
+	updatedAt *time.Time
+	ticker    *time.Ticker
+	hash      [16]byte
+	parser    parser
+	onUpdate  func(interface{})
+}
+
+func (f *fetcher) Name() string {
+	return f.name
+}
+
+func (f *fetcher) VehicleType() VehicleType {
+	return f.vehicle.Type()
+}
+
+func (f *fetcher) Initial() (interface{}, error) {
+	var buf []byte
+	var err error
+	var isLocal bool
+	if stat, err := os.Stat(f.vehicle.Path()); err == nil {
+		buf, err = ioutil.ReadFile(f.vehicle.Path())
+		modTime := stat.ModTime()
+		f.updatedAt = &modTime
+		isLocal = true
+	} else {
+		buf, err = f.vehicle.Read()
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	proxies, err := f.parser(buf)
+	if err != nil {
+		if !isLocal {
+			return nil, err
+		}
+
+		// parse local file error, fallback to remote
+		buf, err = f.vehicle.Read()
+		if err != nil {
+			return nil, err
+		}
+
+		proxies, err = f.parser(buf)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := ioutil.WriteFile(f.vehicle.Path(), buf, fileMode); err != nil {
+		return nil, err
+	}
+
+	f.hash = md5.Sum(buf)
+
+	// pull proxies automatically
+	if f.ticker != nil {
+		go f.pullLoop()
+	}
+
+	return proxies, nil
+}
+
+func (f *fetcher) Update() (interface{}, bool, error) {
+	buf, err := f.vehicle.Read()
+	if err != nil {
+		return nil, false, err
+	}
+
+	now := time.Now()
+	hash := md5.Sum(buf)
+	if bytes.Equal(f.hash[:], hash[:]) {
+		f.updatedAt = &now
+		return nil, true, nil
+	}
+
+	proxies, err := f.parser(buf)
+	if err != nil {
+		return nil, false, err
+	}
+
+	if err := ioutil.WriteFile(f.vehicle.Path(), buf, fileMode); err != nil {
+		return nil, false, err
+	}
+
+	f.updatedAt = &now
+	f.hash = hash
+
+	return proxies, false, nil
+}
+
+func (f *fetcher) Destroy() error {
+	if f.ticker != nil {
+		f.ticker.Stop()
+	}
+	return nil
+}
+
+func (f *fetcher) pullLoop() {
+	for range f.ticker.C {
+		elm, same, err := f.Update()
+		if err != nil {
+			log.Warnln("[Provider] %s pull error: %s", f.Name(), err.Error())
+			continue
+		}
+
+		if same {
+			log.Debugln("[Provider] %s's proxies doesn't change", f.Name())
+			continue
+		}
+
+		log.Infoln("[Provider] %s's proxies update", f.Name())
+		if f.onUpdate != nil {
+			f.onUpdate(elm)
+		}
+	}
+}
+
+func newFetcher(name string, interval time.Duration, vehicle Vehicle, parser parser, onUpdate func(interface{})) *fetcher {
+	var ticker *time.Ticker
+	if interval != 0 {
+		ticker = time.NewTicker(interval)
+	}
+
+	return &fetcher{
+		name:     name,
+		ticker:   ticker,
+		vehicle:  vehicle,
+		parser:   parser,
+		onUpdate: onUpdate,
+	}
+}