Example #1
0
// TailFile begins tailing the file. Output stream is made available
// via the `Tail.Lines` channel. To handle errors during tailing,
// invoke the `Wait` or `Err` method after finishing reading from the
// `Lines` channel.
func TailFile(filename string, config Config) (*Tail, error) {
	if config.ReOpen && !config.Follow {
		util.Fatal("cannot set ReOpen without Follow.")
	}

	t := &Tail{
		Filename: filename,
		Lines:    make(chan *Line),
		Config:   config,
	}

	// when Logger was not specified in config, use default logger
	if t.Logger == nil {
		t.Logger = log.New(os.Stderr, "", log.LstdFlags)
	}

	if t.Poll {
		t.watcher = watch.NewPollingFileWatcher(filename)
	} else {
		t.watcher = watch.NewInotifyFileWatcher(filename)
	}

	if t.MustExist {
		var err error
		t.file, err = OpenFile(t.Filename)
		if err != nil {
			return nil, err
		}
	}

	go t.tailFileSync()

	return t, nil
}
Example #2
0
func (fw *InotifyFileWatcher) ChangeEvents(t *tomb.Tomb, fi os.FileInfo) *FileChanges {
	changes := NewFileChanges()

	w, err := inotifyTracker.NewWatcher()
	if err != nil {
		util.Fatal("Error creating fsnotify watcher: %v", err)
	}
	err = w.Watch(fw.Filename)
	if err != nil {
		util.Fatal("Error watching %v: %v", fw.Filename, err)
	}

	fw.Size = fi.Size()

	go func() {
		defer inotifyTracker.CloseWatcher(w)

		for {
			prevSize := fw.Size

			var evt *fsnotify.FileEvent
			var ok bool

			select {
			case evt, ok = <-w.Event:
				if !ok {
					return
				}
			case <-t.Dying():
				return
			}

			switch {
			case evt.IsDelete():
				fallthrough

			case evt.IsRename():
				changes.NotifyDeleted()
				return

			case evt.IsModify():
				fi, err := os.Stat(fw.Filename)
				if err != nil {
					if os.IsNotExist(err) {
						changes.NotifyDeleted()
						return
					}
					// XXX: report this error back to the user
					util.Fatal("Failed to stat file %v: %v", fw.Filename, err)
				}
				fw.Size = fi.Size()

				if prevSize > 0 && prevSize > fw.Size {
					changes.NotifyTruncated()
				} else {
					changes.NotifyModified()
				}
				prevSize = fw.Size
			}
		}
	}()

	return changes
}
Example #3
0
func (fw *PollingFileWatcher) ChangeEvents(t *tomb.Tomb, origFi os.FileInfo) *FileChanges {
	changes := NewFileChanges()
	var prevModTime time.Time

	// XXX: use tomb.Tomb to cleanly manage these goroutines. replace
	// the fatal (below) with tomb's Kill.

	fw.Size = origFi.Size()

	go func() {
		var retry int = 0

		prevSize := fw.Size
		for {
			select {
			case <-t.Dying():
				return
			default:
			}

			time.Sleep(POLL_DURATION)
			fi, err := os.Stat(fw.Filename)
			if err != nil {
				if os.IsNotExist(err) {
					// File does not exist (has been deleted).
					changes.NotifyDeleted()
					return
				}

				if permissionErrorRetry(err, &retry) {
					continue
				}

				// XXX: report this error back to the user
				util.Fatal("Failed to stat file %v: %v", fw.Filename, err)
			}

			// File got moved/renamed?
			if !os.SameFile(origFi, fi) {
				changes.NotifyDeleted()
				return
			}

			// File got truncated?
			fw.Size = fi.Size()
			if prevSize > 0 && prevSize > fw.Size {
				changes.NotifyTruncated()
				prevSize = fw.Size
				continue
			}
			prevSize = fw.Size

			// File was appended to (changed)?
			modTime := fi.ModTime()
			if modTime != prevModTime {
				prevModTime = modTime
				changes.NotifyModified()
			}
		}
	}()

	return changes
}