support Follow=false

CHANGES.md

@@ -5,6 +5,7 @@
 * Fix potential race condition when reopening the file (issue 5)
 * Fix potential blocking of `tail.Stop` (issue 4)
 * Fix uncleaned up ChangeEvents goroutines after calling tail.Stop
+* Support Follow=false
 
 # Feb, 2013
 

tail.go

@@ -58,10 +58,6 @@ func TailFile(filename string, config Config) (*Tail, error) {
 		panic("cannot set ReOpen without Follow.")
 	}
 
-	if !config.Follow {
-		panic("Follow=false is not supported.")
-	}
-
 	t := &Tail{
 		Filename: filename,
 		Lines:    make(chan *Line),
@@ -160,6 +156,9 @@ func (tail *Tail) tailFileSync() {
 				tail.sendLine(line)
 			}
 		case io.EOF:
+			if !tail.Follow {
+				return
+			}
 			// When EOF is reached, wait for more data to become
 			// available. Wait strategy is based on the `tail.watcher`
 			// implementation (inotify or polling).

tail_test.go

@@ -66,6 +66,20 @@ func TestLocationFull(_t *testing.T) {
 	tail.Stop()
 }
 
+func TestLocationFullDontFollow(_t *testing.T) {
+	t := NewTailTest("location-full-dontfollow", _t)
+	t.CreateFile("test.txt", "hello\nworld\n")
+	tail := t.StartTail("test.txt", Config{Follow: false, Location: -1})
+	go t.VerifyTailOutput(tail, []string{"hello", "world"})
+
+	// Add more data only after reasonable delay.
+	<-time.After(100 * time.Millisecond)
+	t.AppendFile("test.txt", "more\ndata\n")
+	<-time.After(100 * time.Millisecond)
+
+	tail.Stop()
+}
+
 func TestLocationEnd(_t *testing.T) {
 	t := NewTailTest("location-end", _t)
 	t.CreateFile("test.txt", "hello\nworld\n")