state machine bug: calls shutdown if start fails

[weissi]

consider this code

        service.register(label: "thing",
                         start: .sync {
            print("THIS WILL FAIL")
            struct SomeError: Error {}
            throw SomeError()
        },
                         shutdown: .sync {
            print("SHUTDOWN <<< SHOULD NEVER HAPPEN")
        },
        shutdownIfNotStarted: false)

        try service.startAndWait()

clearly, it should never invoke the shutdown handler because the start one failed but it still will. It prints:

THIS WILL FAIL
SHUTDOWN <<< SHOULD NEVER HAPPEN

[tomerd]

@weissi iirc the design thought was that you may have created some state before failing that you want to clean up. obviously this is not always the case. is this behavior causing you issues? ideas on how to trade these off?

[weissi]

@weissi iirc the design thought was that you may have created some state before failing that you want to clean up. obviously this is not always the case. is this behavior causing you issues? ideas on how to trade these off?

I thought the idea was that if you have created the state already, then you use registerShutdown which will unconditionally be called. But if you use register(..., start:, shutdown:) then I would've expected shutdown not to be called if start failed. Is there a situation where you would want shutdown to be called when start failed?

Especially given that I set shutdownIfNotStarted: false I really wouldn't have expected it to shut down if start failed.