func sendPingRequests()

in swim/ping_request_sender.go [144:208]
50 lines of code
4 McCabe index (conditional complexity)

func sendPingRequests(node *Node, target string, size int, timeout time.Duration) <-chan interface{} {
	var peerAddresses []string
	peers := node.memberlist.RandomPingableMembers(size, map[string]bool{target: true})

	for _, peer := range peers {
		peerAddresses = append(peerAddresses, peer.Address)
	}

	node.EmitEvent(PingRequestsSendEvent{
		Local:  node.Address(),
		Target: target,
		Peers:  peerAddresses,
	})

	var wg sync.WaitGroup
	resC := make(chan interface{}, size)

	for _, peer := range peers {
		wg.Add(1)

		go func(peer Member) {
			defer wg.Done()

			p := newPingRequestSender(node, peer.Address, target, timeout)

			p.logger.WithFields(log.Fields{
				"peer":   peer.Address,
				"target": p.target,
			}).Debug("sending ping request")

			var startTime = time.Now()
			res, err := p.SendPingRequest()

			if err != nil {
				node.EmitEvent(PingRequestSendErrorEvent{
					Local:  node.Address(),
					Target: target,
					Peers:  peerAddresses,
					Peer:   peer.Address,
				})

				resC <- err
				return
			}

			node.EmitEvent(PingRequestsSendCompleteEvent{
				Local:    node.Address(),
				Target:   target,
				Peers:    peerAddresses,
				Peer:     peer.Address,
				Duration: time.Now().Sub(startTime),
			})

			resC <- res
		}(peer)
	}

	// wait for all sends to complete before closing channel
	go func() {
		wg.Wait()
		close(resC)
	}()

	return resC
}