From dcf785677fbb8d9ada7a63e7d088271236aae697 Mon Sep 17 00:00:00 2001
From: Z <cainiao666999@gmail.com>
Date: Fri, 7 Aug 2020 01:21:09 +0800
Subject: [PATCH] Fix: file-watcher bugs (#1897)
MIME-Version: 1.0
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* 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          |  1 +
 config/source/file/watcher.go       | 42 +++++++++++++++----------
 config/source/file/watcher_linux.go | 49 +++++++++++++++++------------
 3 files changed, 56 insertions(+), 36 deletions(-)

diff --git a/config/source/file/file.go b/config/source/file/file.go
index 17067447..6b42fd19 100644
--- a/config/source/file/file.go
+++ b/config/source/file/file.go
@@ -10,6 +10,7 @@ import (
 
 type file struct {
 	path string
+	data []byte
 	opts source.Options
 }
 
diff --git a/config/source/file/watcher.go b/config/source/file/watcher.go
index 39c20a71..953050b5 100644
--- a/config/source/file/watcher.go
+++ b/config/source/file/watcher.go
@@ -39,26 +39,36 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 	default:
 	}
 
-	// try get the event
-	select {
-	case event, _ := <-w.fw.Events:
-		if event.Op == fsnotify.Rename {
-			// check existence of file, and add watch again
-			_, err := os.Stat(event.Name)
-			if err == nil || os.IsExist(err) {
-				w.fw.Add(event.Name)
+	for {
+		// try get the event
+		select {
+		case event, _ := <-w.fw.Events:
+			if event.Op == fsnotify.Rename {
+				// check existence of file, and add watch again
+				_, err := os.Stat(event.Name)
+				if err == nil || os.IsExist(err) {
+					w.fw.Add(event.Name)
+				}
 			}
-		}
 
-		c, err := w.f.Read()
-		if err != nil {
+			// 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
+			}
+			return c, nil
+		case err := <-w.fw.Errors:
 			return nil, err
+		case <-w.exit:
+			return nil, source.ErrWatcherStopped
 		}
-		return c, nil
-	case err := <-w.fw.Errors:
-		return nil, err
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
 	}
 }
 
diff --git a/config/source/file/watcher_linux.go b/config/source/file/watcher_linux.go
index b8957bf9..4f8be6da 100644
--- a/config/source/file/watcher_linux.go
+++ b/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"
@@ -39,30 +40,38 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 	default:
 	}
 
-	// try get the event
-	select {
-	case event, _ := <-w.fw.Events:
-		if event.Op == fsnotify.Rename {
-			// check existence of file, and add watch again
-			_, err := os.Stat(event.Name)
-			if err == nil || os.IsExist(err) {
-				w.fw.Add(event.Name)
+	for {
+		// try get the event
+		select {
+		case event, _ := <-w.fw.Events:
+			if event.Op == fsnotify.Rename {
+				// check existence of file, and add watch again
+				_, err := os.Stat(event.Name)
+				if err == nil || os.IsExist(err) {
+					w.fw.Add(event.Name)
+				}
 			}
-		}
 
-		c, err := w.f.Read()
-		if err != nil {
+			c, err := w.f.Read()
+			if err != nil {
+				return nil, err
+			}
+
+			// ARCH: Linux centos-7.shared 3.10.0-693.5.2.el7.x86_64
+			// 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:
 			return nil, err
+		case <-w.exit:
+			return nil, source.ErrWatcherStopped
 		}
-
-		// add path again for the event bug of fsnotify
-		w.fw.Add(w.f.path)
-
-		return c, nil
-	case err := <-w.fw.Errors:
-		return nil, err
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
 	}
 }