Merge pull request #18 from miraclesu/fix_stop_hang

Fix a hang in `Stop` when tailing a non-existent file

Reproducible on linux, but not on mac.

tail.go

@@ -130,7 +130,10 @@ func (tail *Tail) reopen() error {
 		if err != nil {
 			if os.IsNotExist(err) {
 				log.Printf("Waiting for %s to appear...", tail.Filename)
-				if err := tail.watcher.BlockUntilExists(tail.Tomb); err != nil {
+				if err := tail.watcher.BlockUntilExists(&tail.Tomb); err != nil {
+					if err == tomb.ErrDying {
+						return err
+					}
 					return fmt.Errorf("Failed to detect creation of %s: %s", tail.Filename, err)
 				}
 				continue
@@ -155,7 +158,9 @@ func (tail *Tail) tailFileSync() {
 		// deferred first open.
 		err := tail.reopen()
 		if err != nil {
-			tail.Kill(err)
+			if err != tomb.ErrDying {
+				tail.Kill(err)
+			}
 			return
 		}
 	}
@@ -236,7 +241,7 @@ func (tail *Tail) waitForChanges() error {
 		if err != nil {
 			return err
 		}
-		tail.changes = tail.watcher.ChangeEvents(tail.Tomb, st)
+		tail.changes = tail.watcher.ChangeEvents(&tail.Tomb, st)
 	}
 
 	select {

tail_test.go

@@ -40,6 +40,16 @@ func TestMustExist(t *testing.T) {
 	tail.Stop()
 }
 
+func TestStop(t *testing.T) {
+	tail, err := TailFile("_no_such_file", Config{Follow: true, MustExist: false})
+	if err != nil {
+		t.Error("MustExist:false is violated")
+	}
+	if tail.Stop() != nil {
+		t.Error("Should be stoped successfully")
+	}
+}
+
 func TestMaxLineSize(_t *testing.T) {
 	t := NewTailTest("maxlinesize", _t)
 	t.CreateFile("test.txt", "hello\nworld\nfin\nhe")

watch/inotify.go

@@ -4,9 +4,9 @@ package watch
 
 import (
 	"github.com/howeyc/fsnotify"
+	"launchpad.net/tomb"
 	"os"
 	"path/filepath"
-	"launchpad.net/tomb"
 )
 
 // InotifyFileWatcher uses inotify to monitor file changes.
@@ -20,7 +20,7 @@ func NewInotifyFileWatcher(filename string) *InotifyFileWatcher {
 	return fw
 }
 
-func (fw *InotifyFileWatcher) BlockUntilExists(t tomb.Tomb) error {
+func (fw *InotifyFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 	w, err := fsnotify.NewWatcher()
 	if err != nil {
 		return err
@@ -56,9 +56,9 @@ func (fw *InotifyFileWatcher) BlockUntilExists(t tomb.Tomb) error {
 	panic("unreachable")
 }
 
-func (fw *InotifyFileWatcher) ChangeEvents(t tomb.Tomb, fi os.FileInfo) *FileChanges {
+func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileChanges {
 	changes := NewFileChanges()
-	
+
 	w, err := fsnotify.NewWatcher()
 	if err != nil {
 		panic(err)
@@ -108,7 +108,7 @@ func (fw *InotifyFileWatcher) ChangeEvents(t tomb.Tomb, fi os.FileInfo) *FileCha
 
 				if prevSize > 0 && prevSize > fw.Size {
 					changes.NotifyTruncated()
-				}else{
+				} else {
 					changes.NotifyModified()
 				}
 				prevSize = fw.Size

watch/polling.go

@@ -21,7 +21,7 @@ func NewPollingFileWatcher(filename string) *PollingFileWatcher {
 
 var POLL_DURATION time.Duration
 
-func (fw *PollingFileWatcher) BlockUntilExists(t tomb.Tomb) error {
+func (fw *PollingFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
 	for {
 		if _, err := os.Stat(fw.Filename); err == nil {
 			return nil
@@ -38,7 +38,7 @@ func (fw *PollingFileWatcher) BlockUntilExists(t tomb.Tomb) error {
 	panic("unreachable")
 }
 
-func (fw *PollingFileWatcher) ChangeEvents(t tomb.Tomb, origFi os.FileInfo) *FileChanges {
+func (fw *PollingFileWatcher) ChangeEvents(t *tomb.Tomb, origFi os.FileInfo) *FileChanges {
 	changes := NewFileChanges()
 	var prevModTime time.Time
 
@@ -49,7 +49,7 @@ func (fw *PollingFileWatcher) ChangeEvents(t tomb.Tomb, origFi os.FileInfo) *Fil
 
 	go func() {
 		defer changes.Close()
-		
+
 		prevSize := fw.Size
 		for {
 			select {

watch/watch.go

@@ -3,19 +3,18 @@
 package watch
 
 import (
-	"os"
 	"launchpad.net/tomb"
+	"os"
 )
 
 // FileWatcher monitors file-level events.
 type FileWatcher interface {
 	// BlockUntilExists blocks until the file comes into existence.
-	BlockUntilExists(tomb.Tomb) error
+	BlockUntilExists(*tomb.Tomb) error
 
 	// ChangeEvents reports on changes to a file, be it modification,
 	// deletion, renames or truncations. Returned FileChanges group of
 	// channels will be closed, thus become unusable, after a deletion
 	// or truncation event.
-	ChangeEvents(tomb.Tomb, os.FileInfo) *FileChanges
+	ChangeEvents(*tomb.Tomb, os.FileInfo) *FileChanges
 }
-