add config reloader

cmd/config/main.go

@@ -3,6 +3,9 @@ package main
 import (
 	"fmt"
 	"github.com/evanzhang87/evans-tools/pkg/config"
+	"os"
+	"os/signal"
+	"time"
 )
 
 type Config struct {
@@ -18,9 +21,28 @@ func (c *Config) print() {
 
 func main() {
 	var conf Config
-	err := config.LoadConfig(&conf, "config.yaml")
+	reloader := config.NewReloader(&conf)
+	err := reloader.WatchPath("config.yaml")
 	if err != nil {
 		fmt.Println(err.Error())
 	}
-	conf.print()
+	signChan := make(chan os.Signal, 1)
+	signal.Notify(signChan, os.Kill, os.Interrupt)
+	configChan := reloader.SubscribeConfig()
+	reloadTicker := time.NewTicker(time.Second * 10)
+	for {
+		select {
+		case <-signChan:
+			return
+		case configOutlet := <-configChan:
+			if configOutlet != nil {
+				configOutlet.(*Config).print()
+			}
+		case <-reloadTicker.C:
+			confFetch := reloader.FetchConfig()
+			if confFetch != nil {
+				confFetch.(*Config).print()
+			}
+		}
+	}
 }

pkg/config/reloader.go

@@ -0,0 +1,73 @@
+package config
+
+import (
+	"github.com/fsnotify/fsnotify"
+	"sync"
+)
+
+type Reloader struct {
+	configInstance interface{}
+	mutex          *sync.Mutex
+
+	watcher *fsnotify.Watcher
+	opList  []fsnotify.Op
+
+	outlet chan interface{}
+}
+
+func NewReloader(config interface{}) *Reloader {
+	return &Reloader{
+		configInstance: config,
+		mutex:          &sync.Mutex{},
+
+		opList: []fsnotify.Op{fsnotify.Write, fsnotify.Create},
+	}
+}
+
+func (r *Reloader) WithOps(ops ...fsnotify.Op) {
+	r.opList = ops
+}
+
+func (r *Reloader) WatchPath(path string) error {
+	var err error
+	r.watcher, err = fsnotify.NewWatcher()
+	if err != nil {
+		return err
+	}
+	err = r.watcher.Add(path)
+	if err != nil {
+		return err
+	}
+	go func() {
+		for event := range r.watcher.Events {
+			for _, op := range r.opList {
+				if event.Op == op {
+					r.mutex.Lock()
+					_ = LoadConfig(r.configInstance, path)
+					if r.outlet != nil {
+						r.outlet <- r.configInstance
+					}
+					r.mutex.Unlock()
+				}
+			}
+		}
+	}()
+	return err
+}
+
+func (r *Reloader) FetchConfig() interface{} {
+	if r.mutex != nil {
+		r.mutex.Lock()
+		defer r.mutex.Unlock()
+	}
+	return r.configInstance
+}
+
+func (r *Reloader) SubscribeConfig() chan interface{} {
+	r.outlet = make(chan interface{}, 1)
+	return r.outlet
+}
+
+func (r *Reloader) Stop() {
+	_ = r.watcher.Close()
+}