watch

type Update struct {
	Path     string
	Contents []byte
	Err      error
}

type Watcher interface {
	// Read blocks and returns the next update for a file.
	//
	// An error is returned when there is an underyling issue in the Watcher
	// preventing Read, or ctx is cancelled. The returned error may indicate a
	// fatal issue requiring a new Watcher to be created.
	//
	// Subsequent calls block until the underlying
	// contents or error changes. When multiple updates have occurred for a file,
	// Read coalesces and returns the latest update.
	Read(ctx context.Context) (Update, error)

	// Add causes Watcher to monitor an additional path. The format is
	// filesystem-specific. If Close has been called, this has no effect.
	Add(path string) error

	// Remove causes Watcher to stop monitoring a path. The path must match one
	// already monitored in the same format. The format is filesystem-specific.
	Remove(path string) error

	// Close causes Watcher to stop watching all files and release its resources.
	Close()
}