func()

in exporter/collector/metrics.go [615:664]

• 46 lines of code
• 12 McCabe index (conditional complexity)

func (me *MetricsExporter) watchWALFile(ctx context.Context) error {
	me.goroutines.Add(1)
	defer me.goroutines.Done()
	walWatcher, err := fsnotify.NewWatcher()
	if err != nil {
		return err
	}
	err = walWatcher.Add(me.wal.path)

	if err != nil {
		return err
	}
	watchCh := make(chan error)
	var wErr error
	go func() {
		defer func() {
			watchCh <- wErr
			close(watchCh)
			walWatcher.Close()
		}()

		select {
		case <-me.shutdownC:
			return
		case <-ctx.Done():
			wErr = ctx.Err()
			return

		case event, ok := <-walWatcher.Events:
			if !ok {
				return
			}
			switch event.Op {
			case fsnotify.Remove:
				wErr = fmt.Errorf("WAL file deleted")
			case fsnotify.Rename:
				wErr = fmt.Errorf("WAL file renamed")
			case fsnotify.Write:
				wErr = nil
			}

		case watchErr, ok := <-walWatcher.Errors:
			if ok {
				wErr = watchErr
			}
		}
	}()
	err = <-watchCh
	return err
}