Why does net/rpc/client's Go method require a buffered channel?

user_14059854 0
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I am unable to figure out why the method requires you to specifically provide a buffered channel.

From the documentation,

func (*Client) Go

func (client *Client) Go(serviceMethod string, args interface{}, reply interface{}, done chan *Call) *Call

Go invokes the function asynchronously. It returns the Call structure representing the invocation. The done channel will signal when the call is complete by returning the same Call object. If done is nil, Go will allocate a new channel. If non-nil, done must be buffered or Go will deliberately crash.

go channel rpc
1 Answers

LeGEC alluded to this in their comment.

Digging in further you will find this bit in client.go

func (call *Call) done() {
    select {
    case call.Done <- call:
        // ok
    default:
        // We don't want to block here. It is the caller's responsibility to make
        // sure the channel has enough buffer space. See comment in Go().
        if debugLog {
            log.Println("rpc: discarding Call reply due to insufficient Done chan capacity")
        }
    }
}

From what you can see here is that the library expects the call to be completely asynchronous. This means the done channel must have enough capacity to completely decouple the two processes (i.e. no blocking at all).

Further when the select statement is used as seen, it is the idiomatic way to do a non-blocking channel operation.

user_25118920
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