Fix: file-watcher bugs (#1897)

* Fix: file-watcher bugs

* Update watcher_linux.go

Co-authored-by: 杨铭哲 <yangmz@weipaitang.com>
Co-authored-by: Asim Aslam <asim@aslam.me>

config/source/file/file.go

@@ -10,6 +10,7 @@ import (
 
 type file struct {
 	path string
+	data []byte
 	opts source.Options
 }
 

config/source/file/watcher.go

@@ -39,6 +39,7 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 	default:
 	}
 
+	for {
 		// try get the event
 		select {
 		case event, _ := <-w.fw.Events:
@@ -50,6 +51,14 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 				}
 			}
 
+			// ARCH: Darwin Kernel Version 18.7.0
+			// ioutil.WriteFile truncates it before writing, but the problem is that
+			// you will receive two events(fsnotify.Chmod and fsnotify.Write).
+			// We can solve this problem by ignoring fsnotify.Chmod event.
+			if event.Op&fsnotify.Write != fsnotify.Write {
+				continue
+			}
+
 			c, err := w.f.Read()
 			if err != nil {
 				return nil, err
@@ -60,6 +69,7 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 		case <-w.exit:
 			return nil, source.ErrWatcherStopped
 		}
+	}
 }
 
 func (w *watcher) Stop() error {

config/source/file/watcher_linux.go

@@ -4,6 +4,7 @@ package file
 
 import (
 	"os"
+	"reflect"
 
 	"github.com/fsnotify/fsnotify"
 	"github.com/micro/go-micro/v3/config/source"
@@ -39,6 +40,7 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 	default:
 	}
 
+	for {
 		// try get the event
 		select {
 		case event, _ := <-w.fw.Events:
@@ -55,8 +57,14 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 				return nil, err
 			}
 
-		// add path again for the event bug of fsnotify
+			// ARCH: Linux centos-7.shared 3.10.0-693.5.2.el7.x86_64
-		w.fw.Add(w.f.path)
+			// Sometimes, ioutil.WriteFile triggers multiple fsnotify.Write events, which may be a bug.
+
+			// Detect if the file has changed
+			if reflect.DeepEqual(c.Data, w.f.data) {
+				continue
+			}
+			w.f.data = c.Data
 
 			return c, nil
 		case err := <-w.fw.Errors:
@@ -64,6 +72,7 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 		case <-w.exit:
 			return nil, source.ErrWatcherStopped
 		}
+	}
 }
 
 func (w *watcher) Stop() error {