1. Fan-In Messaging Patterns

Fan-In is a messaging pattern used to create a funnel for work amongst workers (clients: source, server: destination).

We can model fan-in using the Go channels.

// Merge different channels in one channel
func Merge(cs ...<-chan int) <-chan int {
    var wg sync.WaitGroup

    out := make(chan int)

    // Start an send goroutine for each input channel in cs. send
    // copies values from c to out until c is closed, then calls wg.Done.
    send := func(c <-chan int) {
        for n := range c {
            out <- n

    for _, c := range cs {
        go send(c)

    // Start a goroutine to close out once all the send goroutines are
    // done.  This must start after the wg.Add call.
    go func() {
    return out

The Merge function converts a list of channels to a single channel by starting a goroutine for each inbound channel that copies the values to the sole outbound channel.

Once all the output goroutines have been started, Merge a goroutine is started to close the main channel.

Copyright © studygolang.com 2013 all right reserved,powered by Gitbook该文件修订时间: 2017-07-21 20:12:45

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