func()

in agent/session/plugin/client/client.go [510:618]
84 lines of code
19 McCabe index (conditional complexity)

func (c *Client) writeLoop(wg *sync.WaitGroup) int {
	defer wg.Done()
	fname := "writeLoop"

	buff := make([]byte, 2048)

	rdfs := &goselect.FDSet{}
	reader := io.ReadCloser(c.Input)

	pr := NewEscapeProxy(reader, c.EscapeKeys)
	defer reader.Close()

	if c.idleTimeout > 0 {
		log.GetLogger().Infof("Idle timeout %d seconds.", c.idleTimeout)
		go func() {
			// Init timer as 1 seconds,
			timer := time.NewTimer(time.Second)
			defer timer.Stop()
			for {
				select {
				case <-c.poison:
					return
				case <-timer.C:
					elapsedTime := int32(time.Since(c.startTimestamp).Seconds()) - c.lastDataTimestampOffset.Load()
					if elapsedTime >= c.idleTimeout {
						// Idle for too long
						log.GetLogger().Infoln("Idle for too long, close client.")
						c.SendCloseMessage()
						openPoison(fname, c.poison)
					}
					timer.Reset(time.Duration(c.idleTimeout - elapsedTime) * time.Second)
				}

			}
		}()
		go func() {
			// minimumIdleTimeout is 60s, so the period of sending keep-alive
			// package is set to 60s, it does not need to be set too small.
			// But it cannot exceed 180 seconds, because the Agent will
			// disconnect if agent does not receive a data packet within 180s.
			timer := time.NewTicker(time.Minute)
			defer timer.Stop()
			for {
				select {
				case <-c.poison:
					return
				case <-timer.C:
					if err := c.SendKeepAliveDataMessage(); err != nil {
						log.GetLogger().Error("Send keep alive package failed: ", err)
					}
				}
			}
		}()
	}

	for {
		select {
		case <-c.poison:
			return die(fname, c.poison)
		default:
		}

		rdfs.Zero()
		rdfs.Set(reader.(exposeFd).Fd())
		err := goselect.Select(1, rdfs, nil, nil, 50*time.Millisecond)
		if err != nil {
			// log.GetLogger().Errorf("get raw input failed: %v", err)
			continue
			// return openPoison(fname, c.poison)
		}
		if rdfs.IsSet(reader.(exposeFd).Fd()) {
			size, err := pr.Read(buff)

			if err != nil {
				log.GetLogger().Infoln("err in input empty")
				if err == io.EOF {
					log.GetLogger().Infoln("EOF in input empty")
					// Send EOF to GoTTY

					// Send 'Input' marker, as defined in GoTTY::client_context.go,
					// followed by EOT (a translation of Ctrl-D for terminals)
					err = c.SendStreamDataMessage((append([]byte{}, byte(4))))

					return openPoison(fname, c.poison)

					continue
				} else {
					log.GetLogger().Errorln("err in input empty", err)
					return openPoison(fname, c.poison)
				}
			}

			if size <= 0 {
				log.GetLogger().Infoln("user input empty")
				continue
			}

			data := buff[:size]
			if c.verbosemode {
				log.GetLogger().Infoln("begin send user input:", string(data), size)
			}
			err = c.SendStreamDataMessage(data)
			if err != nil {
				return openPoison(fname, c.poison)
			}

		}
	}
}