package channel import ( "errors" "io" "sync" ) // WriteCloser is an io.WriteCloser that that proxies Write() calls to a channel // The []byte buffer of the Write() is queued on the channel as one message. type WriteCloser interface { io.WriteCloser Chan() <-chan []byte } type writeCloser struct { ch chan []byte mux sync.Mutex } // NewWriter initializes a new channel writer func NewWriter(c chan []byte) WriteCloser { return &writeCloser{ ch: c, } } // Chan returns the R/O channel behind WriteCloser func (w *writeCloser) Chan() <-chan []byte { return w.ch } // Write method for WriteCloser func (w *writeCloser) Write(b []byte) (bLen int, err error) { if w == nil { return 0, errors.New("use channel.NewWriter() to initialize a WriteCloser") } w.mux.Lock() defer w.mux.Unlock() if w.ch == nil { return 0, errors.New("the channel is closed for Write") } buf := make([]byte, len(b)) copy(buf, b) w.ch <- buf return len(b), nil } // Close method for WriteCloser func (w *writeCloser) Close() error { w.mux.Lock() defer w.mux.Unlock() close(w.ch) w.ch = nil return nil }