net/rpc: missing a test scenario for using done channel for two calls

[yaojingguo]

After skimming Go net/rpc source code (last commit: e9e0d1e), I found that no test scenario exists for using done channel for two RPC calls. I suggest adding a test scenario for this case.

The following code shows the scenario details:

client.Go(serviceMethod, &args1, &reply1, done)
client.Go(serviceMethod, &args2, &reply2, done)

c1 := <- done
log.Println("get:", c1.Reply.(*GetReply).Value)

c2 := <- done
log.Println("get:", c2.Reply.(*GetReply).Value)

[seankhliao]

What is the actual problem here?

[yaojingguo]

https://pkg.go.dev/net/rpc@go1.17#Client.Go allows using done argument for two RPC calls. But such a scenario is not included in the net/rpc's test cases.

[mknyszek]

If you have a suggested improvement for tests, you don't have to create an issue for it. You can just send the change. If you want to check with maintainers first, https://groups.google.com/g/golang-dev is a good place for this kind of communication (specifically, for working on the Go project itself). See https://golang.org/doc/contribute.

[mknyszek]

CC @neild

[neild]

The net/rpc package is frozen and not accepting new features. While a new test is not a feature, aside from tests associated with bugfixes adding more test cases doesn't seem like a good use of anyone's time.

[yaojingguo]

The Go function allows the reuse of the done channel argument. But neither net/rpc's doc nor its test cases show such a usage. So I think that it is worth of time to add such a test scenario.