Lifetime issue in the docs

[criatura2]

This page in the docs provide code that looks like this

void repeatedly_request_example(agrpc::GrpcContext& grpc_context, example::v1::Example::AsyncService& service)
{
    agrpc::repeatedly_request(
        &example::v1::Example::AsyncService::RequestUnary, service,
        AssociatedHandler{grpc_context.get_executor(),
                          [](auto&& request_context, auto&& executor)
                          {
                              auto& writer = request_context.responder();
                              example::v1::Response response;
                              agrpc::finish(writer, response, grpc::Status::OK,
                                            asio::bind_executor(executor, [c = std::move(request_context)](bool) {}));
                          },
                          grpc_context.get_allocator()});
}

The response object inside the lambda won't outlive the finish operation and therefore will give rise to a bug. Suggestion

1. Instantiate response with a make_shared and carry it with the finish completion handler, or use asio::consign.
2. Use the Asio convention that all async functions have the async_ prefix.

At the moment I only get segfault when using agrpc::repeatedly_request and couldn't find the source of problem. I will investigate more and eventually open another issue.

[Tradias]

Thanks for your report.

The example code is correct, agrpc::finish serializes the response object before it returns. This is also mentioned in the documentation

gRPC does not take ownership or a reference to message and status, so it is safe to deallocate once finish returns.

Meaning this cannot be the source of the segfault that you are getting.

I chose not to prefix functions with async_ because I do not provide synchronous versions of them. There are some non-asynchronous functions in this library (not necessarily related to gRPC) which can be identified by not taking a CompletionToken as their last argument.

[criatura2]

Ok thanks. I guess I have to read the docs with more attention. I will close the issue now and come back with a new one if necessary.