agrpc

Build an elegant GRPC async interface with C++20 coroutine and libunifex (target for C++23 executor).

Get started

mkdir build && cd build
conan install ..
cmake -DCMAKE_CXX_FLAGS:STRING=-fcoroutines ..
cmake --build .

Work in progress

One glance:

native async grpc

agrpc

class CallData { public: void Proceed() { if (status_ == CREATE) { status_ = PROCESS; service_->RequestSayHello(&ctx_, &request_, &responder_, cq_, cq_, this); } else if (status_ == PROCESS) { new CallData(service_, cq_); std::string prefix("Hello "); reply_.set_message(prefix + request_.name()); status_ = FINISH; responder_.Finish(reply_, Status::OK, this); } else { GPR_ASSERT(status_ == FINISH); delete this; } } private: // ... enum CallStatus { CREATE, PROCESS, FINISH }; CallStatus status_{CREATE}; // The current serving state. }; void HandleRpcs() { new CallData(&service_, cq_.get()); void* tag; // uniquely identifies a request. bool ok; while (true) { GPR_ASSERT(cq_->Next(&tag, &ok)); GPR_ASSERT(ok); static_cast<CallData*>(tag)->Proceed(); } }

agrpc::GrpcContext grpc_context{builder.AddCompletionQueue()}; while (true) { grpc::ServerContext server_context; helloworld::HelloRequest request; grpc::ServerAsyncResponseWriter<helloworld::HelloReply> writer{ &server_context}; bool request_ok = co_await agrpc::AsyncRequest( grpc_context.get_scheduler(), &helloworld::Greeter::AsyncService::RequestSayHello, service, server_context, request, writer); if (!request_ok) co_return; helloworld::HelloReply response; response.set_message("Hello " + request.name()); co_await agrpc::AsyncFinish(grpc_context.get_scheduler(), writer, response, grpc::Status::OK); }

Benchmark

1 CPU server

name	req/s	avg. latency	90 % in	95 % in	99 % in	avg. cpu	avg. memory
cpp_agrpc	35385	26.74 ms	39.48 ms	49.60 ms	64.11 ms	92.43%	28.78 MiB
cpp_grpc_st	35364	26.03 ms	48.25 ms	58.39 ms	72.63 ms	80.95%	21.57 MiB
cpp_grpc_mt	35068	26.23 ms	48.16 ms	58.60 ms	72.72 ms	80.29%	18.05 MiB
rust_tonic_st	33407	25.96 ms	54.54 ms	60.15 ms	68.41 ms	66.22%	15.34 MiB
dotnet_grpc	32125	26.78 ms	53.29 ms	66.82 ms	81.76 ms	95.1%	94.31 MiB
rust_tonic_mt	31428	29.06 ms	90.03 ms	97.46 ms	106.46 ms	69.87%	13.52 MiB
cpp_grpc_callback	12283	80.54 ms	103.30 ms	107.25 ms	178.37 ms	100.27%	406.88 MiB
go_grpc	5600	176.37 ms	306.34 ms	397.40 ms	598.96 ms	100.41%	44.02 MiB

2 CPU server

name	req/s	avg. latency	90 % in	95 % in	99 % in	avg. cpu	avg. memory
rust_tonic_mt	77236	11.97 ms	30.99 ms	44.78 ms	68.00 ms	191.33%	17.42 MiB
cpp_agrpc	72084	13.50 ms	20.83 ms	23.73 ms	31.08 ms	202.99%	86.8 MiB
cpp_grpc_mt	68099	14.18 ms	34.95 ms	39.29 ms	45.88 ms	203.08%	61.64 MiB
dotnet_grpc	63479	13.98 ms	20.35 ms	26.62 ms	61.63 ms	201.58%	175.97 MiB
rust_tonic_st	61962	15.83 ms	19.73 ms	21.05 ms	24.13 ms	102.46%	16.32 MiB
cpp_grpc_st	50593	19.47 ms	23.59 ms	25.26 ms	29.66 ms	102.15%	19.53 MiB
cpp_grpc_callback	29612	32.49 ms	74.33 ms	78.51 ms	85.74 ms	202.37%	444.44 MiB
go_grpc	12050	80.52 ms	188.05 ms	194.19 ms	286.45 ms	200.78%	45.11 MiB

Goal

Maybe something like C# interface.

public override async Task RouteChat(Grpc.Core.IAsyncStreamReader<RouteNote> requestStream,
    Grpc.Core.IServerStreamWriter<RouteNote> responseStream,
    Grpc.Core.ServerCallContext context)
{
    while (await requestStream.MoveNext())
    {
        var note = requestStream.Current;
        List<RouteNote> prevNotes = AddNoteForLocation(note.Location, note);
        foreach (var prevNote in prevNotes)
        {
            await responseStream.WriteAsync(prevNote);
        }
    }
}

Reference

• asio-grpc: Asynchronous gRPC with Boost.Asio executors