Client cancellations aren't propagated to the server

[jebbench]

When I close a streaming client request with an exception I would expect the corresponding server receive channel to throw an exception upon calling receive (or iterating the channel) but it doesn't seem to do so - am I doing something wrong?

Client:

call.requestChannel.close(Exception("Testing Exception"))

Server:

try {
    for (request in requestChannel) {
        logger.info("Iterating")
    }
    logger.info("Closed normally")
} catch (e: Exception){
    logger.error("Caught exception", e)
}

[marcoferrer]

What you’re describing is the expected behavior. If you’re experiencing something that differs then it might be a bug. Could you provide a little more detail for your example? This way I can try to reproduce it.

What Kroto+ version are you using? What type of method does this occur with? Client Streaming or BiDirectional?

Thanks again for submitting an issue!

[jebbench]

Hi Marco - thanks for the response (and the library).

I've replicated the issue I'm seeing in this repo: https://github.com/jebbench/kotlin-coroutines-gRPC-template

If you need anything else let me know.

[marcoferrer]

I can confirm this is a bug. I think it was introduced when outbound flow control was reworked. It is actually addressed in the streaming machinery rewrite that is currently in progress. Since that rewrite is still in alpha stages, I'll get a fix out for this bug in the very next release. The release is expected to occur on this up coming Monday. Ill get a PR opened tonight and tag you for visibility.

[jebbench]

Brilliant thanks!

[jebbench]

I've retested this using 0.6.0-SNAPSHOT and unfortunately I'm getting the same problem.

Received name: First
Client Streaming Response: message: "Completed without receiving an Exception"

Process finished with exit code 0

[marcoferrer]

I looked into this and it turns out that the snapshot wasnt updated with the most recent changes from PR#95.

If you're still having issues please let me know.

[jebbench]

I've just tried again, I've tried forcing Gradle to re-download dependencies with both the --refresh-dependencies flag and by deleting the cache directory - neither seem to have worked and I'm still getting the same error.

[marcoferrer]

So I tested your branch and you're correct. It is still not propagating cancellation but this time it seems to be due to a race condition. Using the following example the expected behavior is observed.

suspend fun performClientStreamingCall(stub: GreeterCoroutineGrpc.GreeterCoroutineStub) = coroutineScope {

    // Client Streaming RPC
    val (requestChannel, response) = stub.sayHelloClientStreaming()

    launch {
        println("Client Streaming Response: ${response.await().toString().trim()}")
    }
    requestChannel.send { name = "First" }
    requestChannel.close(Exception("This is an exception!"))

}

Im currently working on tracking down the source of the race condition in order to resolve this bug.

[marcoferrer]

Tested the latest SNAPSHOT against your example project and everything seems to behave as expected now.

[jebbench]

Version 0.6.0 resolves this for me.

Many thanks for your help!