From d78ac897f4751a045b76ac19204663071d6c7ac2 Mon Sep 17 00:00:00 2001
From: xgfone <xgfone@126.com>
Date: Thu, 12 Oct 2023 23:08:08 +0800
Subject: [PATCH] use interval poll instead of fsnotify

---
 go.mod         |  3 ---
 go.sum         |  4 ---
 source_file.go | 72 +++++++++++++-------------------------------------
 source_test.go | 45 +++++++++++++++++++++++++++++++
 4 files changed, 63 insertions(+), 61 deletions(-)

diff --git a/go.mod b/go.mod
index 19c41bc..551e49f 100644
--- a/go.mod
+++ b/go.mod
@@ -1,11 +1,8 @@
 module github.com/xgfone/gconf/v6
 
 require (
-	github.com/fsnotify/fsnotify v1.6.0
 	github.com/xgfone/go-cast v0.8.1
 	github.com/xgfone/go-defaults v0.13.0
 )
 
-require golang.org/x/sys v0.0.0-20220908164124-27713097b956 // indirect
-
 go 1.18
diff --git a/go.sum b/go.sum
index 75681f8..efe4f30 100644
--- a/go.sum
+++ b/go.sum
@@ -1,8 +1,4 @@
-github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
-github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
 github.com/xgfone/go-cast v0.8.1 h1:x80Qu+XCUyQoFvCo2j+CFRiKiJydF11jeAJRzRtGY9U=
 github.com/xgfone/go-cast v0.8.1/go.mod h1:aHO9rXhmN4IZ4d1UG35+6WEVbg5yyISynFQJCVltrsk=
 github.com/xgfone/go-defaults v0.13.0 h1:aJX/RJSI8yN6Xxn1b1NlFQyClwION2DM5X1NDz3KQ0U=
 github.com/xgfone/go-defaults v0.13.0/go.mod h1:4qxXP2vvK8n2csVwYmFbhbQAISq5s/2zYZE9CKYj/bw=
-golang.org/x/sys v0.0.0-20220908164124-27713097b956 h1:XeJjHH1KiLpKGb6lvMiksZ9l0fVUh+AmGcm0nOMEBOY=
-golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/source_file.go b/source_file.go
index 0a1da9c..5460664 100644
--- a/source_file.go
+++ b/source_file.go
@@ -21,8 +21,6 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
-
-	"github.com/fsnotify/fsnotify"
 )
 
 // ConfigFileOpt is the default option for the configuration file.
@@ -47,13 +45,14 @@ func NewFileSource(filename string, defaultFormat ...string) Source {
 	}
 
 	id := fmt.Sprintf("file:%s", filename)
-	return fileSource{id: id, filepath: filename, format: format}
+	return fileSource{id: id, filepath: filename, format: format, timeout: time.Second * 10}
 }
 
 type fileSource struct {
 	id       string
 	format   string
 	filepath string
+	timeout  time.Duration
 }
 
 func (f fileSource) String() string { return f.id }
@@ -94,19 +93,9 @@ func (f fileSource) Watch(exit <-chan struct{}, load func(DataSet, error) bool)
 }
 
 func (f fileSource) watch(exit <-chan struct{}, load func(DataSet, error) bool) {
-	fw, err := fsnotify.NewWatcher()
-	if err != nil {
-		load(DataSet{Source: f.id, Format: f.format}, err)
-		return
-	}
-	defer fw.Close()
-
-	var add bool
-	if fw.Add(f.filepath) == nil {
-		add = true
-	}
+	lastsize, lasttime, _ := getfileinfo(f.filepath)
 
-	ticker := time.NewTicker(time.Minute)
+	ticker := time.NewTicker(f.timeout)
 	defer ticker.Stop()
 
 	for {
@@ -115,49 +104,24 @@ func (f fileSource) watch(exit <-chan struct{}, load func(DataSet, error) bool)
 			return
 
 		case <-ticker.C:
-			if _, err := os.Stat(f.filepath); err != nil {
-				if os.IsNotExist(err) {
-					if add {
-						if err := fw.Remove(f.filepath); err != nil {
-							load(DataSet{Source: f.id, Format: f.format}, err)
-						} else {
-							add = false
-						}
-					}
-				} else {
+			if size, time, err := getfileinfo(f.filepath); err != nil {
+				if !os.IsNotExist(err) {
 					load(DataSet{Source: f.id, Format: f.format}, err)
 				}
-				continue
-			}
-
-			if !add {
-				if err := fw.Add(f.filepath); err != nil {
-					load(DataSet{Source: f.id, Format: f.format}, err)
-				} else {
-					add = true
-					load(f.Read())
-				}
-				continue
-			}
-
-		case event, ok := <-fw.Events:
-			if !ok {
-				return
-			}
-
-			// BUG: it will be triggered twice continuously by fsnotify on Windows.
-			if event.Op&fsnotify.Write == fsnotify.Write {
+			} else if size != lastsize || time != lasttime {
 				load(f.Read())
-			} else if event.Op&fsnotify.Remove == fsnotify.Remove {
-				add = false
-			}
-
-		case err, ok := <-fw.Errors:
-			if !ok {
-				return
+				lastsize = size
+				lasttime = time
 			}
-
-			load(DataSet{Source: f.id, Format: f.format}, err)
 		}
 	}
 }
+
+func getfileinfo(filepath string) (size, time int64, err error) {
+	fi, err := os.Stat(filepath)
+	if err == nil {
+		time = fi.ModTime().Unix()
+		size = fi.Size()
+	}
+	return
+}
diff --git a/source_test.go b/source_test.go
index 6acb1ff..32a1e64 100644
--- a/source_test.go
+++ b/source_test.go
@@ -143,6 +143,51 @@ func TestNewFileSource_JSON(t *testing.T) {
 	}
 }
 
+func TestFileSourceWatch(t *testing.T) {
+	// Prepare the json file
+	filename := "_test_file_source_watch_.json"
+	defer os.Remove(filename)
+
+	source := NewFileSource(filename).(fileSource)
+	source.timeout = time.Second * 2
+
+	exit := make(chan struct{})
+	go func() {
+		time.Sleep(time.Second)
+		file, err := os.OpenFile(filename, testfileflag, os.ModePerm)
+		if err != nil {
+			t.Error(err)
+		} else {
+			_, _ = file.Write([]byte(`{"opt": 1}`))
+			file.Close()
+		}
+		time.Sleep(time.Second * 2)
+		close(exit)
+	}()
+
+	var data string
+	start := time.Now()
+	source.Watch(exit, func(ds DataSet, err error) bool {
+		if err != nil {
+			t.Error(err)
+		} else if data == "" {
+			data = string(ds.Data)
+		} else {
+			t.Fail()
+		}
+		return true
+	})
+
+	if cost := time.Since(start); cost < time.Second*3 || cost > time.Second*4 {
+		t.Errorf("not wait for 3~4s")
+	}
+
+	expect := `{"opt": 1}`
+	if data != expect {
+		t.Errorf("expect '%s', but got '%s'", expect, data)
+	}
+}
+
 func TestNewURLSource(t *testing.T) {
 	first := true