hello-world-server-arena.cpp

// Copyright 2024 Dennis Hezel
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "awaitable_server_rpc.hpp"
#include "helloworld/helloworld.grpc.pb.h"
#include "rethrow_first_arg.hpp"

#include <agrpc/asio_grpc.hpp>
#include <grpcpp/server.h>
#include <grpcpp/server_builder.h>

namespace asio = boost::asio;

// begin-snippet: server-side-helloworld-arena

// Server-side hello world with google::protobuf::Arena allocation

// end-snippet

class ArenaRequestMessageFactory
{
  public:
    template <class Request>
    Request& create()
    {
        return *google::protobuf::Arena::Create<Request>(&arena_);
    }

    // This method is optional and can be omitted
    template <class Request>
    void destroy(Request&) noexcept
    {
    }

  private:
    google::protobuf::Arena arena_;
};

template <class Handler>
class RPCHandlerWithArenaRequestMessageFactory
{
  public:
    explicit RPCHandlerWithArenaRequestMessageFactory(Handler handler) : handler_(std::move(handler)) {}

    template <class... Args>
    decltype(auto) operator()(Args&&... args)
    {
        return handler_(std::forward<Args>(args)...);
    }

    ArenaRequestMessageFactory request_message_factory() { return {}; }

  private:
    Handler handler_;
};

int main(int argc, const char** argv)
{
    const auto port = argc >= 2 ? argv[1] : "50051";
    const auto host = std::string("0.0.0.0:") + port;

    helloworld::Greeter::AsyncService service;
    std::unique_ptr<grpc::Server> server;

    grpc::ServerBuilder builder;
    agrpc::GrpcContext grpc_context{builder.AddCompletionQueue()};
    builder.AddListeningPort(host, grpc::InsecureServerCredentials());
    builder.RegisterService(&service);
    server = builder.BuildAndStart();

    using RPC = example::AwaitableServerRPC<&helloworld::Greeter::AsyncService::RequestSayHello>;
    agrpc::register_awaitable_rpc_handler<RPC>(
        grpc_context, service,
        RPCHandlerWithArenaRequestMessageFactory{
            [&](RPC& rpc, RPC::Request& request, ArenaRequestMessageFactory&) -> asio::awaitable<void>
            {
                auto& response = *google::protobuf::Arena::Create<RPC::Response>(request.GetArena());
                response.set_message("Hello " + request.name());
                co_await rpc.finish(response, grpc::Status::OK);
                server->Shutdown();
            }},
        example::RethrowFirstArg{});

    grpc_context.run();
}