コード例 #1
0
ファイル: read.go プロジェクト: msabansal/docker
func watchFile(name string) (filenotify.FileWatcher, error) {
	fileWatcher, err := filenotify.New()
	if err != nil {
		return nil, err
	}

	if err := fileWatcher.Add(name); err != nil {
		logrus.WithField("logger", "json-file").Warnf("falling back to file poller due to error: %v", err)
		fileWatcher.Close()
		fileWatcher = filenotify.NewPollingWatcher()

		if err := fileWatcher.Add(name); err != nil {
			fileWatcher.Close()
			logrus.Debugf("error watching log file for modifications: %v", err)
			return nil, err
		}
	}
	return fileWatcher, nil
}
コード例 #2
0
ファイル: read.go プロジェクト: Cybertinus/docker
func followLogs(f *os.File, logWatcher *logger.LogWatcher, notifyRotate chan interface{}, since time.Time) {
	dec := json.NewDecoder(f)
	l := &jsonlog.JSONLog{}

	fileWatcher, err := filenotify.New()
	if err != nil {
		logWatcher.Err <- err
	}
	defer func() {
		f.Close()
		fileWatcher.Close()
	}()
	name := f.Name()

	if err := fileWatcher.Add(name); err != nil {
		logrus.WithField("logger", "json-file").Warnf("falling back to file poller due to error: %v", err)
		fileWatcher.Close()
		fileWatcher = filenotify.NewPollingWatcher()

		if err := fileWatcher.Add(name); err != nil {
			logrus.Debugf("error watching log file for modifications: %v", err)
			logWatcher.Err <- err
			return
		}
	}

	var retries int
	for {
		msg, err := decodeLogLine(dec, l)
		if err != nil {
			if err != io.EOF {
				// try again because this shouldn't happen
				if _, ok := err.(*json.SyntaxError); ok && retries <= maxJSONDecodeRetry {
					dec = json.NewDecoder(f)
					retries++
					continue
				}

				// io.ErrUnexpectedEOF is returned from json.Decoder when there is
				// remaining data in the parser's buffer while an io.EOF occurs.
				// If the json logger writes a partial json log entry to the disk
				// while at the same time the decoder tries to decode it, the race condition happens.
				if err == io.ErrUnexpectedEOF && retries <= maxJSONDecodeRetry {
					reader := io.MultiReader(dec.Buffered(), f)
					dec = json.NewDecoder(reader)
					retries++
					continue
				}

				return
			}

			select {
			case <-fileWatcher.Events():
				dec = json.NewDecoder(f)
				continue
			case <-fileWatcher.Errors():
				logWatcher.Err <- err
				return
			case <-logWatcher.WatchClose():
				fileWatcher.Remove(name)
				return
			case <-notifyRotate:
				f.Close()
				fileWatcher.Remove(name)

				// retry when the file doesn't exist
				for retries := 0; retries <= 5; retries++ {
					f, err = os.Open(name)
					if err == nil || !os.IsNotExist(err) {
						break
					}
				}

				if err = fileWatcher.Add(name); err != nil {
					logWatcher.Err <- err
					return
				}
				if err != nil {
					logWatcher.Err <- err
					return
				}

				dec = json.NewDecoder(f)
				continue
			}
		}

		retries = 0 // reset retries since we've succeeded
		if !since.IsZero() && msg.Timestamp.Before(since) {
			continue
		}
		select {
		case logWatcher.Msg <- msg:
		case <-logWatcher.WatchClose():
			logWatcher.Msg <- msg
			for {
				msg, err := decodeLogLine(dec, l)
				if err != nil {
					return
				}
				if !since.IsZero() && msg.Timestamp.Before(since) {
					continue
				}
				logWatcher.Msg <- msg
			}
		}
	}
}