Merge branch 'stop-at-eof' of https://github.com/flynn/tail into flynn-stop-at-eof

tail.go

@@ -4,6 +4,7 @@ package tail
 
 import (
 	"bufio"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -156,6 +157,14 @@ func (tail *Tail) Stop() error {
 	return tail.Wait()
 }
 
+// StopAtEOF stops tailing as soon as the end of the file is reached.
+func (tail *Tail) StopAtEOF() error {
+	tail.Kill(errStopAtEOF)
+	return tail.Wait()
+}
+
+var errStopAtEOF = errors.New("tail: stop at eof")
+
 func (tail *Tail) close() {
 	close(tail.Lines)
 	tail.colseFile()
@@ -236,6 +245,7 @@ func (tail *Tail) tailFileSync() {
 
 	var offset int64 = 0
 	var err error
+
 	// Read line by line.
 	for {
 		// do not seek in named pipes
@@ -265,8 +275,7 @@ func (tail *Tail) tailFileSync() {
 				case <-tail.Dying():
 					return
 				}
-				err = tail.seekEnd()
+				if err := tail.seekEnd(); err != nil {
-				if err != nil {
 					tail.Kill(err)
 					return
 				}
@@ -307,6 +316,9 @@ func (tail *Tail) tailFileSync() {
 
 		select {
 		case <-tail.Dying():
+			if tail.Err() == errStopAtEOF {
+				continue
+			}
 			return
 		default:
 		}

tail_test.go

@@ -55,6 +55,25 @@ func TestStop(t *testing.T) {
 	tail.Cleanup()
 }
 
+func TestStopAtEOF(_t *testing.T) {
+	t := NewTailTest("maxlinesize", _t)
+	t.CreateFile("test.txt", "hello\nthere\nworld\n")
+	tail := t.StartTail("test.txt", Config{Follow: true, Location: nil})
+
+	// read "hello"
+	<-tail.Lines
+
+	done := make(chan struct{})
+	go func() {
+		<-time.After(100 * time.Millisecond)
+		t.VerifyTailOutput(tail, []string{"there", "world"})
+		close(done)
+	}()
+	tail.StopAtEOF()
+	<-done
+	tail.Cleanup()
+}
+
 func MaxLineSizeT(_t *testing.T, follow bool, fileContent string, expected []string) {
 	t := NewTailTest("maxlinesize", _t)
 	t.CreateFile("test.txt", fileContent)

watch/filechanges.go

@@ -23,12 +23,6 @@ func (fc *FileChanges) NotifyDeleted() {
 	sendOnlyIfEmpty(fc.Deleted)
 }
 
-func (fc *FileChanges) Close() {
-	close(fc.Modified)
-	close(fc.Truncated)
-	close(fc.Deleted)
-}
-
 // sendOnlyIfEmpty sends on a bool channel only if the channel has no
 // backlog to be read by other goroutines. This concurrency pattern
 // can be used to notify other goroutines if and only if they are

watch/inotify.go

@@ -66,7 +66,6 @@ func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, pos int64) (*FileChange
 
 	go func() {
 		defer RemoveWatch(fw.Filename)
-		defer changes.Close()
 
 		events := Events(fw.Filename)
 

watch/polling.go

@@ -56,8 +56,6 @@ func (fw *PollingFileWatcher) ChangeEvents(t *tomb.Tomb, pos int64) (*FileChange
 	fw.Size = pos
 
 	go func() {
-		defer changes.Close()
-
 		prevSize := fw.Size
 		for {
 			select {