Method ProxyAsync

example/coroutine/coroutine_server.cpp:91–103

    }

    Awaitable<void> ProxyAsync(const EchoRequest* request,
                    EchoResponse* response,
                    google::protobuf::Closure* done) {
        brpc::ClosureGuard done_guard(done);
        EchoService_Stub stub(&_channel);
        brpc::Controller cntl;
        AwaitableDone done2;
        stub.Echo(&cntl, request, response, &done2);
        co_await done2.awaitable();
        if (cntl.Failed()) {
            response->set_message(cntl.ErrorText());
        }
    }    

private:
    brpc::Channel _channel;