From bf1c8747a431d01086239deefc0117792c38aa29 Mon Sep 17 00:00:00 2001
From: qicosmos <qicosmos@linux.alibaba.com>
Date: Sat, 20 Sep 2025 08:12:32 +0800
Subject: [PATCH] update

---
 examples/server/qps.h                  |   7 +-
 include/rest_rpc/asio_util.hpp         |  34 +++++
 include/rest_rpc/client.hpp            | 174 +++++++++++++++++++++++++
 include/rest_rpc/codec.h               |   6 +
 include/rest_rpc/error_code.h          |  75 +++++++++++
 include/rest_rpc/io_context_pool.hpp   |  16 +++
 include/rest_rpc/logger.hpp            |  72 ++++++++++
 include/rest_rpc/meta_util.hpp         |   8 +-
 include/rest_rpc/rest_rpc_protocol.hpp |  35 +++++
 include/rest_rpc/rest_rpc_server.hpp   | 173 ++++++++++++++++++++++++
 include/rest_rpc/rpc_connection.hpp    |  72 ++++++++++
 include/rest_rpc/rpc_router.hpp        | 168 ++++++++++++++++++++++++
 include/rest_rpc/string_resize.hpp     | 126 ++++++++++++++++++
 include/rest_rpc/traits.h              | 174 +++++++++++++++++++++++++
 include/rest_rpc/use_asio.hpp          |   3 +
 tests/CMakeLists.txt                   |   3 +
 tests/doctest/doctest.h                |   2 +-
 tests/test_rest_rpc1.cpp               | 114 ++++++++++++++++
 18 files changed, 1258 insertions(+), 4 deletions(-)
 create mode 100644 include/rest_rpc/asio_util.hpp
 create mode 100644 include/rest_rpc/client.hpp
 create mode 100644 include/rest_rpc/error_code.h
 create mode 100644 include/rest_rpc/logger.hpp
 create mode 100644 include/rest_rpc/rest_rpc_protocol.hpp
 create mode 100644 include/rest_rpc/rest_rpc_server.hpp
 create mode 100644 include/rest_rpc/rpc_connection.hpp
 create mode 100644 include/rest_rpc/rpc_router.hpp
 create mode 100644 include/rest_rpc/string_resize.hpp
 create mode 100644 include/rest_rpc/traits.h
 create mode 100644 tests/test_rest_rpc1.cpp

diff --git a/examples/server/qps.h b/examples/server/qps.h
index 5a700bf..d29d5e1 100644
--- a/examples/server/qps.h
+++ b/examples/server/qps.h
@@ -10,7 +10,12 @@ public:
   qps() : counter_(0) {
     thd_ = std::thread([this] {
       while (!stop_) {
-        std::cout << "qps: " << counter_.load(std::memory_order_acquire)
+        auto val = counter_.load(std::memory_order_acquire);
+        if(val==0) {
+          continue;
+        }
+        
+        std::cout << "qps: " << val
                   << '\n';
         std::this_thread::sleep_for(std::chrono::seconds(1));
         // counter_.store(0, std::memory_order_release);
diff --git a/include/rest_rpc/asio_util.hpp b/include/rest_rpc/asio_util.hpp
new file mode 100644
index 0000000..d8cdd2a
--- /dev/null
+++ b/include/rest_rpc/asio_util.hpp
@@ -0,0 +1,34 @@
+#pragma once
+#include "use_asio.hpp"
+
+namespace rest_rpc {
+inline auto async_start(auto executor, auto &&coro) {
+  using R = typename std::remove_cvref_t<decltype(coro)>::value_type;
+  static_assert(std::is_void_v<R>);
+  asio::co_spawn(executor, std::move(coro), asio::detached);
+}
+
+inline auto async_future(auto executor, auto &&coro) {
+  return asio::co_spawn(executor, std::move(coro), asio::use_future);
+}
+
+inline auto sync_wait(auto executor, auto &&coro) {
+  return async_future(executor, std::move(coro)).get();
+}
+
+inline auto async_start(auto executor, auto &&coro, auto callback) {
+  using R = typename std::remove_cvref_t<decltype(coro)>::value_type;
+  if constexpr (std::is_void_v<R>) {
+    asio::co_spawn(
+        executor, std::move(coro),
+        asio::any_completion_handler<void(std::exception_ptr)>(
+            [cb = std::move(callback)](std::exception_ptr e) { cb(e); }));
+  } else {
+    asio::co_spawn(executor, std::move(coro),
+                   asio::any_completion_handler<void(std::exception_ptr, R)>(
+                       [cb = std::move(callback)](std::exception_ptr e, R r) {
+                         cb(e, std::move(r));
+                       }));
+  }
+}
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/client.hpp b/include/rest_rpc/client.hpp
new file mode 100644
index 0000000..e4744ce
--- /dev/null
+++ b/include/rest_rpc/client.hpp
@@ -0,0 +1,174 @@
+#pragma once
+#include "asio_util.hpp"
+#include "codec.h"
+#include "error_code.h"
+#include "io_context_pool.hpp"
+#include "logger.hpp"
+#include "meta_util.hpp"
+#include "rest_rpc_protocol.hpp"
+#include "traits.h"
+#include "use_asio.hpp"
+#include <asio/experimental/awaitable_operators.hpp>
+#include <asio/steady_timer.hpp>
+using namespace asio::experimental::awaitable_operators;
+
+namespace rest_rpc {
+template <typename R> struct call_result {
+  rpc_errc ec;
+  R value;
+};
+
+class client {
+public:
+  client() : socket_(get_global_executor()) {}
+
+  auto get_executor() { return socket_.get_executor(); }
+
+  asio::awaitable<std::error_code> connect(
+      std::string_view host, std::string_view port,
+      std::chrono::steady_clock::duration duration = std::chrono::seconds(5)) {
+    asio::ip::tcp::resolver resolver(socket_.get_executor());
+
+    auto r = co_await (watchdog(duration) ||
+                       resolver.async_resolve(
+                           host, port, asio::as_tuple(asio::use_awaitable)));
+    if (r.index() == 0) {
+      REST_LOG_ERROR << "resolve timeout";
+      co_return make_error_code(rpc_errc::resolve_timeout);
+    }
+
+    auto [ec, endpoints] = std::get<1>(r);
+    if (ec) {
+      REST_LOG_ERROR << "resolve failed";
+      co_return ec;
+    }
+    auto it = endpoints.begin();
+
+    if (it == endpoints.end()) {
+      REST_LOG_ERROR << "resolve failed";
+      co_return std::make_error_code(std::errc::bad_address);
+    }
+
+    auto endpoint = it->endpoint();
+    auto conn_r = co_await (
+        watchdog(duration) ||
+        socket_.async_connect(endpoint, asio::as_tuple(asio::use_awaitable)));
+    if (conn_r.index() == 0) {
+      REST_LOG_ERROR << "connect timeout";
+      co_return make_error_code(rpc_errc::connection_timeout);
+    }
+
+    auto [conn_ec] = std::get<1>(conn_r);
+    if (conn_ec) {
+      REST_LOG_ERROR << "connect failed";
+      co_return conn_ec;
+    }
+
+    co_return std::error_code{};
+  }
+
+  asio::awaitable<std::error_code> connect(
+      std::string_view address,
+      std::chrono::steady_clock::duration duration = std::chrono::seconds(5)) {
+    std::string_view host;
+    std::string_view port;
+    size_t pos = address.find(':');
+    if (pos != std::string::npos) {
+      host = address.substr(0, pos);
+      port = address.substr(pos + 1);
+    }
+
+    return connect(host, port, duration);
+  }
+
+  template <auto func, typename... Args>
+  asio::awaitable<
+      call_result<typename function_traits<decltype(func)>::return_type>>
+  call(Args &&...args) {
+    return call_for<func>(std::chrono::seconds(5), std::forward<Args>(args)...);
+  }
+
+  template <auto func, typename... Args>
+  asio::awaitable<
+      call_result<typename function_traits<decltype(func)>::return_type>>
+  call_for(auto duration, Args &&...args) {
+    using args_tuple = typename function_traits<decltype(func)>::tuple_type;
+    static_assert(std::is_constructible_v<args_tuple, Args...>,
+                  "called rpc function and arguments are not match");
+
+    using R = typename function_traits<decltype(func)>::return_type;
+    auto r = co_await (watchdog(duration) ||
+                       call_impl<func>(std::forward<Args>(args)...));
+    if (r.index() == 0) {
+      co_return call_result<R>{rpc_errc::request_timeout};
+    }
+    co_return std::get<1>(r);
+  }
+
+private:
+  template <auto func, typename... Args>
+  asio::awaitable<
+      call_result<typename function_traits<decltype(func)>::return_type>>
+  call_impl(Args &&...args) {
+    rest_rpc_header header{};
+    header.magic = 39;
+    header.function_id = get_key<func>();
+    rpc_service::msgpack_codec codec;
+    auto buf = codec.pack_args(std::forward<Args>(args)...);
+    header.body_len = buf.size();
+    prepare_for_send(header);
+
+    std::vector<asio::const_buffer> buffers;
+    buffers.reserve(2);
+    buffers.push_back(asio::buffer(&header, sizeof(rest_rpc_header)));
+    buffers.push_back(asio::buffer(buf.data(), buf.size()));
+
+    using R = typename function_traits<decltype(func)>::return_type;
+    call_result<R> result{};
+    std::error_code ec;
+    size_t size;
+    std::tie(ec, size) = co_await asio::async_write(
+        socket_, buffers, asio::as_tuple(asio::use_awaitable));
+    if (ec) {
+      result.ec = rpc_errc::write_error;
+      co_return result;
+    }
+
+    rest_rpc_header resp_header;
+    std::tie(ec, size) = co_await asio::async_read(
+        socket_, asio::buffer(&resp_header, sizeof(rest_rpc_header)),
+        asio::as_tuple(asio::use_awaitable));
+    if (ec) {
+      result.ec = rpc_errc::write_error;
+      co_return result;
+    }
+    if (resp_header.magic != 39) {
+      result.ec = rpc_errc::protocol_error;
+      co_return result;
+    }
+    parse_recieved(resp_header);
+
+    detail::resize(body_, resp_header.body_len);
+    std::tie(ec, size) = co_await asio::async_read(
+        socket_, asio::buffer(body_), asio::as_tuple(asio::use_awaitable));
+    if (ec) {
+      REST_LOG_WARNING << "read body error: " << ec.message();
+      result.ec = rpc_errc::read_error;
+      co_return result;
+    }
+    result.ec = (rpc_errc)body_[0];
+    result.value = codec.unpack<R>(body_.data() + 1, resp_header.body_len - 1);
+    co_return result;
+  }
+
+  asio::awaitable<std::error_code> watchdog(auto duration) {
+    asio::steady_timer timer(socket_.get_executor());
+    timer.expires_after(duration);
+    auto [ec] = co_await timer.async_wait(asio::as_tuple(asio::use_awaitable));
+    co_return ec;
+  }
+
+  tcp_socket socket_;
+  std::string body_;
+};
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/codec.h b/include/rest_rpc/codec.h
index 5c95b80..07c1717 100644
--- a/include/rest_rpc/codec.h
+++ b/include/rest_rpc/codec.h
@@ -16,6 +16,12 @@ struct msgpack_codec {
     return buffer;
   }
 
+  template <typename Arg> static std::string pack_to_string(Arg &arg) {
+    buffer_type buffer(init_size);
+    msgpack::pack(buffer, arg);
+    return std::string(buffer.data(), buffer.size());
+  }
+
   template <typename Arg, typename... Args,
             typename = typename std::enable_if<std::is_enum<Arg>::value>::type>
   static std::string pack_args_str(Arg arg, Args &&...args) {
diff --git a/include/rest_rpc/error_code.h b/include/rest_rpc/error_code.h
new file mode 100644
index 0000000..042f764
--- /dev/null
+++ b/include/rest_rpc/error_code.h
@@ -0,0 +1,75 @@
+#pragma once
+#include <string>
+#include <system_error>
+
+namespace rest_rpc {
+enum class rpc_errc : std::int8_t {
+  ok = 0,
+  no_such_function,
+  no_such_key,
+  invalid_req_type,
+  function_exception,
+  function_unknown_exception,
+  invalid_argument,
+  write_error,
+  read_error,
+  socket_closed,
+  resolve_timeout,
+  connection_timeout,
+  request_timeout,
+  protocol_error
+};
+
+class rpc_error_category : public std::error_category {
+public:
+  const char *name() const noexcept override { return "rest_rpc_error"; }
+
+  std::string message(int ev) const override {
+    switch (static_cast<rpc_errc>(ev)) {
+    case rpc_errc::ok:
+      return "ok";
+    case rpc_errc::no_such_function:
+      return "no such function";
+    case rpc_errc::no_such_key:
+      return "resolve failed";
+    case rpc_errc::invalid_req_type:
+      return "invalid request type";
+    case rpc_errc::function_exception:
+      return "logic function exception happend";
+    case rpc_errc::function_unknown_exception:
+      return "unknown function exception happend";
+    case rpc_errc::invalid_argument:
+      return "invalid argument";
+    case rpc_errc::write_error:
+      return "write failed";
+    case rpc_errc::read_error:
+      return "read failed";
+    case rpc_errc::socket_closed:
+      return "socket closed";
+    case rpc_errc::resolve_timeout:
+      return "resolve timeout";
+    case rpc_errc::connection_timeout:
+      return "connect timeout";
+    case rpc_errc::request_timeout:
+      return "request timeout";
+    case rpc_errc::protocol_error:
+      return "protocol error";
+    default:
+      return "unknown error";
+    }
+  }
+};
+
+inline rest_rpc::rpc_error_category &category() {
+  static rest_rpc::rpc_error_category instance;
+  return instance;
+}
+
+inline std::error_code make_error_code(rpc_errc e) {
+  return {static_cast<int>(e), category()};
+}
+
+inline bool operator==(const std::error_code &code, rpc_errc ec) {
+  return code.value() == (int)ec;
+}
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/io_context_pool.hpp b/include/rest_rpc/io_context_pool.hpp
index 2e8ca9a..4f82c25 100644
--- a/include/rest_rpc/io_context_pool.hpp
+++ b/include/rest_rpc/io_context_pool.hpp
@@ -45,6 +45,11 @@ public:
 
   asio::io_context &get_io_context() { return *get_io_context_ptr(); }
 
+  auto get_executor() {
+    auto &ctx = get_io_context();
+    return ctx.get_executor();
+  }
+
 private:
   std::vector<std::shared_ptr<asio::io_context>> io_contexts_;
   std::vector<asio::executor_work_guard<asio::io_context::executor_type>>
@@ -53,4 +58,15 @@ private:
   std::once_flag stop_flag_;
   std::atomic<size_t> next_ = 0;
 };
+
+inline auto
+get_global_executor(unsigned pool_size = std::thread::hardware_concurrency()) {
+  static auto g_io_context_pool = std::make_shared<io_context_pool>(pool_size);
+  [[maybe_unused]] static bool run_helper = [](auto pool) {
+    std::thread thrd{[pool] { pool->run(); }};
+    thrd.detach();
+    return true;
+  }(g_io_context_pool);
+  return g_io_context_pool->get_executor();
+}
 } // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/logger.hpp b/include/rest_rpc/logger.hpp
new file mode 100644
index 0000000..b44d322
--- /dev/null
+++ b/include/rest_rpc/logger.hpp
@@ -0,0 +1,72 @@
+#pragma once
+#include <iostream>
+
+namespace rest_rpc {
+struct null_logger_t {
+  template <typename T> const null_logger_t &operator<<(T &&) const {
+    return *this;
+  }
+};
+struct cout_logger_t {
+  template <typename T> const cout_logger_t &operator<<(T &&t) const {
+    std::cout << std::forward<T>(t);
+    return *this;
+  }
+  ~cout_logger_t() { std::cout << std::endl; }
+};
+struct cerr_logger_t {
+  template <typename T> const cerr_logger_t &operator<<(T &&t) const {
+    std::cerr << std::forward<T>(t);
+    return *this;
+  }
+  ~cerr_logger_t() { std::cerr << std::endl; }
+};
+
+constexpr inline rest_rpc::null_logger_t NULL_LOGGER;
+} // namespace rest_rpc
+
+#ifdef REST_LOG_ERROR
+#else
+#define REST_LOG_ERROR                                                         \
+  rest_rpc::cerr_logger_t {}
+#endif
+
+#ifdef REST_LOG_WARNING
+#else
+#ifndef NDEBUG
+#define REST_LOG_WARNING                                                       \
+  rest_rpc::cerr_logger_t {}
+#else
+#define REST_LOG_WARNING rest_rpc::NULL_LOGGER
+#endif
+#endif
+
+#ifdef REST_LOG_INFO
+#else
+#ifndef NDEBUG
+#define REST_LOG_INFO                                                          \
+  rest_rpc::cout_logger_t {}
+#else
+#define REST_LOG_INFO rest_rpc::NULL_LOGGER
+#endif
+#endif
+
+#ifdef REST_LOG_DEBUG
+#else
+#ifndef NDEBUG
+#define REST_LOG_DEBUG                                                         \
+  rest_rpc::cout_logger_t {}
+#else
+#define REST_LOG_DEBUG rest_rpc::NULL_LOGGER
+#endif
+#endif
+
+#ifdef REST_LOG_TRACE
+#else
+#ifndef NDEBUG
+#define REST_LOG_TRACE                                                         \
+  rest_rpc::cout_logger_t {}
+#else
+#define REST_LOG_TRACE rest_rpc::NULL_LOGGER
+#endif
+#endif
\ No newline at end of file
diff --git a/include/rest_rpc/meta_util.hpp b/include/rest_rpc/meta_util.hpp
index abbb2b8..a62f02a 100644
--- a/include/rest_rpc/meta_util.hpp
+++ b/include/rest_rpc/meta_util.hpp
@@ -3,6 +3,7 @@
 
 #include "cplusplus_14.h"
 #include <functional>
+#include <type_traits>
 
 namespace rest_rpc {
 
@@ -31,12 +32,15 @@ public:
   using stl_function_type = std::function<function_type>;
   typedef Ret (*pointer)(Arg, Args...);
 
-  typedef std::tuple<Arg, Args...> tuple_type;
+  typedef std::tuple<std::remove_const_t<std::remove_reference_t<Arg>>,
+                     std::remove_const_t<std::remove_reference_t<Args>>...>
+      tuple_type;
   typedef std::tuple<
       nonstd::remove_const_t<nonstd::remove_reference_t<Args>>...>
       bare_tuple_type;
   using args_tuple =
-      std::tuple<std::string, Arg,
+      std::tuple<std::string,
+                 nonstd::remove_const_t<nonstd::remove_reference_t<Arg>>,
                  nonstd::remove_const_t<nonstd::remove_reference_t<Args>>...>;
   using args_tuple_2nd =
       std::tuple<std::string,
diff --git a/include/rest_rpc/rest_rpc_protocol.hpp b/include/rest_rpc/rest_rpc_protocol.hpp
new file mode 100644
index 0000000..1fe6927
--- /dev/null
+++ b/include/rest_rpc/rest_rpc_protocol.hpp
@@ -0,0 +1,35 @@
+#pragma once
+#include <cstdint>
+#ifdef _WIN32
+#include <winsock2.h>
+#else
+#include <arpa/inet.h>
+#endif
+
+namespace rest_rpc {
+inline constexpr uint8_t REST_MAGIC_NUM = 39;
+struct rest_rpc_header {
+  uint8_t magic;
+  uint8_t version;
+  uint8_t serialize_type;
+  uint8_t msg_type;
+  uint32_t function_id;
+  uint64_t seq_num;
+  uint64_t body_len;
+  uint64_t attach_length;
+};
+
+inline void prepare_for_send(rest_rpc_header &header) {
+  header.function_id = htonl(header.function_id);
+  header.seq_num = htonll(header.seq_num);
+  header.body_len = htonll(header.body_len);
+  header.attach_length = htonll(header.attach_length);
+}
+
+inline void parse_recieved(rest_rpc_header &header) {
+  header.function_id = ntohl(header.function_id);
+  header.seq_num = ntohll(header.seq_num);
+  header.body_len = ntohll(header.body_len);
+  header.attach_length = ntohll(header.attach_length);
+}
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/rest_rpc_server.hpp b/include/rest_rpc/rest_rpc_server.hpp
new file mode 100644
index 0000000..265baea
--- /dev/null
+++ b/include/rest_rpc/rest_rpc_server.hpp
@@ -0,0 +1,173 @@
+#pragma once
+#include "io_context_pool.hpp"
+#include "logger.hpp"
+#include "rpc_connection.hpp"
+#include "use_asio.hpp"
+#include <string>
+#include <thread>
+namespace rest_rpc {
+class rest_rpc_server {
+public:
+  rest_rpc_server(std::string address,
+                  size_t num_thread = std::thread::hardware_concurrency())
+      : io_context_pool_(num_thread),
+        acceptor_(io_context_pool_.get_io_context()) {
+    size_t pos = address.find(':');
+    if (pos != std::string::npos) {
+      host_ = address.substr(0, pos);
+      port_ = address.substr(pos + 1);
+    }
+  }
+
+  rest_rpc_server(std::string host, std::string port,
+                  size_t num_thread = std::thread::hardware_concurrency())
+      : io_context_pool_(num_thread),
+        acceptor_(io_context_pool_.get_io_context()), host_(std::move(host)),
+        port_(std::move(port)) {}
+  ~rest_rpc_server() { stop(); }
+
+  std::error_code start() { return start_impl(false); }
+
+  std::error_code async_start() { return start_impl(true); }
+
+  void stop() {
+    if (has_stop_.load(std::memory_order_acquire)) {
+      return;
+    }
+
+    std::call_once(stop_flag_, [this] {
+      has_stop_.store(true, std::memory_order_release);
+      asio::dispatch(acceptor_.get_executor(), [this]() {
+        asio::error_code ec;
+        (void)acceptor_.cancel(ec);
+        (void)acceptor_.close(ec);
+      });
+
+      io_context_pool_.stop();
+    });
+
+    if (thd_.joinable()) {
+      thd_.join();
+    }
+  }
+
+  bool has_stopped() const { return has_stop_.load(std::memory_order_acquire); }
+
+  template <typename Function, typename Self = void>
+  void register_handler(std::string_view name, const Function &f,
+                        Self *self = nullptr) {
+    router_.register_handler(name, f, self);
+  }
+
+  template <auto func, typename Self = void>
+  void register_handler(Self *self = nullptr) {
+    router_.register_handler<func>(self);
+  }
+
+  void remove_handler(std::string_view name) { router_.remove_handler(name); }
+
+  template <auto func> void remove_handler() { router_.remove_handler<func>(); }
+
+private:
+  std::error_code listen() {
+    using asio::ip::tcp;
+    asio::error_code ec;
+    asio::ip::tcp::resolver resolver(acceptor_.get_executor());
+    auto endpoints = resolver.resolve(host_, port_, ec);
+    if (ec) {
+      return ec;
+    }
+
+    auto it = endpoints.begin();
+
+    if (it == endpoints.end()) {
+      return std::make_error_code(std::errc::bad_address);
+    }
+
+    auto endpoint = it->endpoint();
+    acceptor_.open(endpoint.protocol(), ec);
+    if (ec) {
+      return ec;
+    }
+
+#ifdef __GNUC__
+    acceptor_.set_option(tcp::acceptor::reuse_address(true), ec);
+#endif
+    acceptor_.bind(endpoint, ec);
+    if (ec) {
+      std::error_code ignore;
+      acceptor_.cancel(ignore);
+      acceptor_.close(ignore);
+      return ec;
+    }
+#ifdef _MSC_VER
+    acceptor_.set_option(tcp::acceptor::reuse_address(true));
+#endif
+    acceptor_.listen(asio::socket_base::max_listen_connections, ec);
+    if (ec) {
+      std::error_code ignore;
+      acceptor_.cancel(ignore);
+      acceptor_.close(ignore);
+      return ec;
+    }
+    return ec;
+  }
+
+  asio::awaitable<void> accept() {
+    uint64_t conn_id = 0;
+    while (true) {
+      tcp_socket socket(io_context_pool_.get_io_context());
+      auto [ec] = co_await acceptor_.async_accept(
+          socket, asio::as_tuple(asio::use_awaitable));
+      if (ec == asio::error::operation_aborted ||
+          ec == asio::error::bad_descriptor) {
+        REST_LOG_WARNING << "acceptor error: " << ec.message();
+        co_return;
+      }
+
+      REST_LOG_INFO << "new connction comming...";
+      auto conn =
+          std::make_shared<rpc_connection>(std::move(socket), conn_id, router_);
+      conns_.emplace(conn_id++, conn);
+      co_spawn(socket.get_executor(), conn->start(), asio::detached);
+    }
+  }
+
+  std::error_code start_impl(bool async) {
+    if (has_stop_.load(std::memory_order_acquire)) {
+      return std::make_error_code(std::errc::operation_canceled);
+    }
+
+    static std::error_code ec{};
+    std::call_once(start_flag_, [this, async] {
+      ec = listen();
+      if (ec) {
+        return;
+      }
+
+      thd_ = std::thread([this] { io_context_pool_.run(); });
+
+      if (async) {
+        asio::co_spawn(acceptor_.get_executor(), accept(), asio::detached);
+      } else {
+        auto future = asio::co_spawn(acceptor_.get_executor(), accept(),
+                                     asio::use_future);
+        future.wait();
+      }
+    });
+
+    return ec;
+  }
+
+  io_context_pool io_context_pool_;
+  std::thread thd_;
+  asio::ip::tcp::acceptor acceptor_;
+  std::string host_;
+  std::string port_;
+  std::once_flag start_flag_;
+  std::once_flag stop_flag_;
+  std::atomic<bool> has_stop_ = false;
+  std::unordered_map<uint64_t, std::shared_ptr<rpc_connection>> conns_;
+  rpc_router router_;
+};
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/rpc_connection.hpp b/include/rest_rpc/rpc_connection.hpp
new file mode 100644
index 0000000..3e8ca05
--- /dev/null
+++ b/include/rest_rpc/rpc_connection.hpp
@@ -0,0 +1,72 @@
+#pragma once
+#include "logger.hpp"
+#include "rest_rpc_protocol.hpp"
+#include "rpc_router.hpp"
+#include "string_resize.hpp"
+#include "use_asio.hpp"
+
+namespace rest_rpc {
+class rpc_connection {
+public:
+  rpc_connection(tcp_socket socket, uint64_t conn_id, rpc_router &router)
+      : socket_(std::move(socket)), conn_id_(conn_id), router_(router) {}
+
+  asio::awaitable<void> start() {
+    rest_rpc_header header;
+
+    while (true) {
+      std::error_code ec;
+      size_t size;
+      std::tie(ec, size) = co_await asio::async_read(
+          socket_, asio::buffer(&header, sizeof(rest_rpc_header)),
+          asio::as_tuple(asio::use_awaitable));
+      if (ec) {
+        REST_LOG_INFO << "read head error: " << ec.message();
+        break;
+      }
+
+      parse_recieved(header);
+      if (header.magic != REST_MAGIC_NUM) {
+        REST_LOG_ERROR << "protocol error";
+        break;
+      }
+
+      detail::resize(body_, header.body_len);
+      std::tie(ec, size) = co_await asio::async_read(
+          socket_, asio::buffer(body_), asio::as_tuple(asio::use_awaitable));
+      if (ec) {
+        REST_LOG_WARNING << "read body error: " << ec.message();
+        break;
+      }
+
+      // route
+      auto result = router_.route(header.function_id, body_);
+      rest_rpc_header resp_header{};
+      resp_header.magic = 39;
+      resp_header.body_len = result.result.size() + 1;
+      prepare_for_send(resp_header);
+      std::vector<asio::const_buffer> buffers;
+      buffers.reserve(3);
+      buffers.push_back(asio::buffer(&resp_header, sizeof(rest_rpc_header)));
+      buffers.push_back(asio::buffer(&result.ec, 1));
+      buffers.push_back(asio::buffer(result.result));
+      std::tie(ec, size) = co_await asio::async_write(
+          socket_, buffers, asio::as_tuple(asio::use_awaitable));
+      if (ec) {
+        REST_LOG_WARNING << "write error: " << ec.message();
+        break;
+      }
+    }
+
+    co_return;
+  }
+
+  uint64_t id() const { return conn_id_; }
+
+private:
+  tcp_socket socket_;
+  uint64_t conn_id_;
+  std::string body_;
+  rpc_router &router_;
+};
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/rpc_router.hpp b/include/rest_rpc/rpc_router.hpp
new file mode 100644
index 0000000..a39cc26
--- /dev/null
+++ b/include/rest_rpc/rpc_router.hpp
@@ -0,0 +1,168 @@
+#pragma once
+#include "codec.h"
+#include "error_code.h"
+#include "function_name.h"
+#include "md5.hpp"
+#include "meta_util.hpp"
+#include <cstdint>
+#include <functional>
+#include <string>
+#include <string_view>
+
+namespace rest_rpc {
+struct rpc_result {
+  rpc_errc ec = rpc_errc::ok;
+  std::string result;
+};
+
+template <auto func> constexpr uint32_t get_key() {
+  constexpr auto name = get_func_name<func>();
+  constexpr uint32_t key = MD5::MD5Hash32(name.data(), name.length());
+  return key;
+}
+
+class rpc_router {
+public:
+  template <typename Function, typename Self = void>
+  void register_handler(std::string_view name, const Function &f,
+                        Self *self = nullptr) {
+    uint32_t key = MD5::MD5Hash32(name.data(), name.length());
+    register_handler_impl(key, name, f, self);
+  }
+
+  template <auto func, typename Self = void>
+  void register_handler(Self *self = nullptr) {
+    constexpr auto name = get_func_name<func>();
+    return register_handler(name, func, self);
+  }
+
+  void remove_handler(std::string_view name) {
+    uint32_t key = MD5::MD5Hash32(name.data(), name.length());
+    this->map_invokers_.erase(key);
+    key2func_name_.erase(key);
+  }
+
+  template <auto func> void remove_handler() {
+    constexpr std::string_view name = get_func_name<func>();
+    remove_handler(name);
+  }
+
+  std::string get_name_by_key(uint32_t key) {
+    auto it = key2func_name_.find(key);
+    if (it != key2func_name_.end()) {
+      return it->second;
+    }
+    return std::to_string(key);
+  }
+
+  rpc_result route(uint32_t key, std::string_view data) {
+    rpc_result route_result{};
+    std::string result;
+    try {
+      rpc_service::msgpack_codec codec;
+      auto it = map_invokers_.find(key);
+      if (it == map_invokers_.end()) {
+        result = "unknown function: " + get_name_by_key(key);
+        route_result.ec = rpc_errc::no_such_function;
+      } else {
+        it->second(data, route_result.ec, result);
+        route_result.ec = rpc_errc::ok;
+      }
+    } catch (const std::exception &ex) {
+      rpc_service::msgpack_codec codec;
+      result = std::string("exception occur when call").append(ex.what());
+      route_result.ec = rpc_errc::function_exception;
+    } catch (...) {
+      rpc_service::msgpack_codec codec;
+      result = std::string("unknown exception occur when call ")
+                   .append(get_name_by_key(key));
+      route_result.ec = rpc_errc::function_unknown_exception;
+    }
+
+    route_result.result = std::move(result);
+
+    return route_result;
+  }
+
+private:
+  template <typename Function, typename Self = void>
+  auto register_handler_impl(uint32_t key, std::string_view name,
+                             const Function &f, Self *self = nullptr) {
+    if (key2func_name_.find(key) != key2func_name_.end()) {
+      throw std::invalid_argument("duplicate registration key !");
+    } else {
+      key2func_name_.emplace(key, name);
+      if constexpr (std::is_void_v<Self>) {
+        return register_nonmember_func(key, f);
+      } else {
+        return register_member_func(key, f, self);
+      }
+    }
+  }
+
+  template <typename Function>
+  void register_nonmember_func(uint32_t key, Function f) {
+    this->map_invokers_[key] = [f = std::move(f)](std::string_view str,
+                                                  rpc_errc &ec,
+                                                  std::string &result) mutable {
+      using args_tuple = typename function_traits<Function>::tuple_type;
+      using R = typename function_traits<Function>::return_type;
+      rpc_service::msgpack_codec codec;
+      try {
+        auto tp = codec.unpack<args_tuple>(str.data(), str.size());
+        if constexpr (std::is_void_v<R>) {
+          std::apply(f, tp);
+        } else {
+          auto r = std::apply(f, tp);
+          result = rpc_service::msgpack_codec::pack_to_string(r);
+        }
+      } catch (std::invalid_argument &e) {
+        ec = rpc_errc::invalid_argument;
+        result = e.what();
+      } catch (const std::exception &e) {
+        ec = rpc_errc::function_exception;
+        result = e.what();
+      }
+    };
+  }
+
+  template <typename Function, typename Self>
+  void register_member_func(uint32_t key, const Function &f, Self *self) {
+    this->map_invokers_[key] = [f, self](std::string_view str, rpc_errc &ec,
+                                         std::string &result) {
+      using args_tuple = typename function_traits<Function>::tuple_type;
+      using R = typename function_traits<Function>::return_type;
+      rpc_service::msgpack_codec codec;
+      try {
+        auto tp = codec.unpack<args_tuple>(str.data(), str.size());
+
+        if constexpr (std::is_void_v<R>) {
+          std::apply(
+              [self, &f](auto &&...args) {
+                return (*self.*f)(std::forward<decltype(args)>(args)...);
+              },
+              tp);
+        } else {
+          auto r = std::apply(
+              [self, &f](auto &&...args) {
+                return (*self.*f)(std::forward<decltype(args)>(args)...);
+              },
+              tp);
+          result = rpc_service::msgpack_codec::pack_to_string(r);
+        }
+      } catch (std::invalid_argument &e) {
+        ec = rpc_errc::invalid_argument;
+        result = e.what();
+      } catch (const std::exception &e) {
+        ec = rpc_errc::function_exception;
+        result = e.what();
+      }
+    };
+  }
+
+  std::unordered_map<uint32_t, std::function<void(std::string_view, rpc_errc &,
+                                                  std::string &)>>
+      map_invokers_;
+  std::unordered_map<uint32_t, std::string> key2func_name_;
+};
+} // namespace rest_rpc
\ No newline at end of file
diff --git a/include/rest_rpc/string_resize.hpp b/include/rest_rpc/string_resize.hpp
new file mode 100644
index 0000000..91c2ec3
--- /dev/null
+++ b/include/rest_rpc/string_resize.hpp
@@ -0,0 +1,126 @@
+#pragma once
+#include <cstddef>
+#include <string>
+#include <utility>
+
+namespace rest_rpc::detail {
+
+#if __cpp_lib_string_resize_and_overwrite >= 202110L
+template <typename ch>
+inline void resize(std::basic_string<ch> &str, std::size_t sz) {
+  str.resize_and_overwrite(sz, [sz](ch *, std::size_t) { return sz; });
+}
+#elif (defined(_MSC_VER) && _MSC_VER <= 1920)
+// old msvc don't support visit private, discard it.
+
+#else
+
+template <typename Function, Function func_ptr> class string_thief {
+public:
+  friend void string_set_length_hacker(std::string &self, std::size_t sz) {
+#if defined(_MSVC_STL_VERSION)
+    (self.*func_ptr)._Myval2._Mysize = sz;
+#else
+#if defined(_LIBCPP_VERSION)
+    (self.*func_ptr)(sz);
+#else
+#if (_GLIBCXX_USE_CXX11_ABI == 0) && defined(__GLIBCXX__)
+    (self.*func_ptr)()->_M_set_length_and_sharable(sz);
+#else
+#if defined(__GLIBCXX__)
+    (self.*func_ptr)(sz);
+#endif
+#endif
+#endif
+#endif
+  }
+};
+
+#if defined(__GLIBCXX__) // libstdc++
+#if (_GLIBCXX_USE_CXX11_ABI == 0)
+template class string_thief<decltype(&std::string::_M_rep),
+                            &std::string::_M_rep>;
+#else
+template class string_thief<decltype(&std::string::_M_set_length),
+                            &std::string::_M_set_length>;
+#endif
+#elif defined(_LIBCPP_VERSION)
+template class string_thief<decltype(&std::string::__set_size),
+                            &std::string::__set_size>;
+#elif defined(_MSVC_STL_VERSION)
+template class string_thief<decltype(&std::string::_Mypair),
+                            &std::string::_Mypair>;
+#endif
+
+void string_set_length_hacker(std::string &, std::size_t);
+
+template <typename ch>
+inline void resize(std::basic_string<ch> &raw_str, std::size_t sz) {
+  std::string &str = *reinterpret_cast<std::string *>(&raw_str);
+#if defined(__GLIBCXX__) || defined(_LIBCPP_VERSION) ||                        \
+    defined(_MSVC_STL_VERSION)
+  if (sz > str.capacity()) {
+    str.reserve(sz);
+  }
+  string_set_length_hacker(str, sz);
+  str[sz] = '\0';
+#else
+  raw_str.resize(sz);
+#endif
+}
+
+#endif
+
+#if (defined(_MSC_VER) && _MSC_VER <= 1920)
+#else
+void vector_set_length_hacker(std::vector<char> &self, std::size_t sz);
+
+template <typename Function, Function func_ptr> class vector_thief {
+public:
+  friend void vector_set_length_hacker(std::vector<char> &self,
+                                       std::size_t sz) {
+#if defined(_MSVC_STL_VERSION)
+    (self.*func_ptr)._Myval2._Mylast = self.data() + sz;
+#else
+#if defined(_LIBCPP_VERSION)
+#if _LIBCPP_VERSION < 14000
+    ((*(std::__vector_base<char, std::allocator<char>> *)(&self)).*func_ptr) =
+        self.data() + sz;
+#else
+    (self.*func_ptr) = self.data() + sz;
+#endif
+#else
+#if defined(__GLIBCXX__)
+    ((*(std::_Vector_base<char, std::allocator<char>> *)(&self)).*func_ptr)
+        ._M_finish = self.data() + sz;
+#endif
+#endif
+#endif
+  }
+};
+
+#if defined(__GLIBCXX__) // libstdc++
+template class vector_thief<decltype(&std::vector<char>::_M_impl),
+                            &std::vector<char>::_M_impl>;
+#elif defined(_LIBCPP_VERSION)
+template class vector_thief<decltype(&std::vector<char>::__end_),
+                            &std::vector<char>::__end_>;
+#elif defined(_MSVC_STL_VERSION)
+template class vector_thief<decltype(&std::vector<char>::_Mypair),
+                            &std::vector<char>::_Mypair>;
+#endif
+
+template <typename ch>
+inline void resize(std::vector<ch> &raw_vec, std::size_t sz) {
+#if defined(__GLIBCXX__) ||                                                    \
+    (defined(_LIBCPP_VERSION) && defined(_LIBCPP_HAS_NO_ASAN)) ||              \
+    defined(_MSVC_STL_VERSION)
+  std::vector<char> &vec = *reinterpret_cast<std::vector<char> *>(&raw_vec);
+  vec.reserve(sz);
+  vector_set_length_hacker(vec, sz);
+#else
+  raw_vec.resize(sz);
+#endif
+}
+#endif
+}; // namespace rest_rpc::detail
\ No newline at end of file
diff --git a/include/rest_rpc/traits.h b/include/rest_rpc/traits.h
new file mode 100644
index 0000000..44a3d5e
--- /dev/null
+++ b/include/rest_rpc/traits.h
@@ -0,0 +1,174 @@
+#pragma once
+#include <functional>
+#include <memory>
+
+namespace rest_rpc::util {
+template <typename Function> struct function_traits;
+
+template <typename Return, typename... Arguments>
+struct function_traits<Return (*)(Arguments...)> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+};
+
+template <typename Return, typename... Arguments>
+struct function_traits<Return (*)(Arguments...) noexcept> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+};
+
+template <typename Return, typename... Arguments>
+struct function_traits<Return(Arguments...)> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+};
+
+template <typename Return, typename... Arguments>
+struct function_traits<Return(Arguments...) noexcept> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+};
+
+template <typename This, typename Return, typename... Arguments>
+struct function_traits<Return (This::*)(Arguments...)> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename This, typename Return, typename... Arguments>
+struct function_traits<Return (This::*)(Arguments...) noexcept> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename This, typename Return, typename... Arguments>
+struct function_traits<Return (This::*)(Arguments...) const> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename This, typename Return, typename... Arguments>
+struct function_traits<Return (This::*)(Arguments...) const noexcept> {
+  using parameters_type = std::tuple<std::remove_cvref_t<Arguments>...>;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename Return> struct function_traits<Return (*)()> {
+  using parameters_type = void;
+  using return_type = Return;
+};
+
+template <typename Return> struct function_traits<Return (*)() noexcept> {
+  using parameters_type = void;
+  using return_type = Return;
+};
+
+template <typename Return> struct function_traits<Return (&)()> {
+  using parameters_type = void;
+  using return_type = Return;
+};
+
+template <typename Return> struct function_traits<Return (&)() noexcept> {
+  using parameters_type = void;
+  using return_type = Return;
+};
+
+template <typename Return> struct function_traits<Return()> {
+  using parameters_type = void;
+  using return_type = Return;
+};
+
+template <typename Return> struct function_traits<Return() noexcept> {
+  using parameters_type = void;
+  using return_type = Return;
+};
+
+template <typename This, typename Return>
+struct function_traits<Return (This::*)()> {
+  using parameters_type = void;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename This, typename Return>
+struct function_traits<Return (This::*)() noexcept> {
+  using parameters_type = void;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename This, typename Return>
+struct function_traits<Return (This::*)() const> {
+  using parameters_type = void;
+  using return_type = Return;
+  using class_type = This;
+};
+
+template <typename This, typename Return>
+struct function_traits<Return (This::*)() const noexcept> {
+  using parameters_type = void;
+  using return_type = Return;
+  using class_type = This;
+};
+
+// Support function object and lambda expression
+template <class Function>
+struct function_traits : function_traits<decltype(&Function::operator())> {};
+
+template <typename Function>
+using function_parameters_t =
+    typename function_traits<std::remove_cvref_t<Function>>::parameters_type;
+
+template <typename Function>
+using last_parameters_type_t =
+    std::tuple_element_t<std::tuple_size_v<function_parameters_t<Function>> - 1,
+                         function_parameters_t<Function>>;
+
+template <typename Function>
+using function_return_type_t =
+    typename function_traits<std::remove_cvref_t<Function>>::return_type;
+
+template <typename Function>
+using class_type_t =
+    typename function_traits<std::remove_cvref_t<Function>>::class_type;
+
+template <typename F, typename... Args>
+struct is_invocable
+    : std::is_constructible<
+          std::function<void(std::remove_reference_t<Args>...)>,
+          std::reference_wrapper<typename std::remove_reference<F>::type>> {};
+
+template <typename F, typename... Args>
+inline constexpr bool is_invocable_v = is_invocable<F, Args...>::value;
+
+template <typename T> struct remove_first { using type = T; };
+
+template <class First, class... Second>
+struct remove_first<std::tuple<First, Second...>> {
+  using type = std::tuple<Second...>;
+};
+
+template <typename T> using remove_first_t = typename remove_first<T>::type;
+
+template <bool has_conn, typename T> inline auto get_args() {
+  if constexpr (has_conn) {
+    using args_type = remove_first_t<T>;
+    return args_type{};
+  } else {
+    return T{};
+  }
+}
+
+template <typename Test, template <typename...> class Ref>
+struct is_specialization : std::false_type {};
+
+template <template <typename...> class Ref, typename... Args>
+struct is_specialization<Ref<Args...>, Ref> : std::true_type {};
+
+template <typename Test, template <typename...> class Ref>
+inline constexpr bool is_specialization_v = is_specialization<Test, Ref>::value;
+} // namespace rest_rpc::util
diff --git a/include/rest_rpc/use_asio.hpp b/include/rest_rpc/use_asio.hpp
index acb7dfc..16ffd6b 100644
--- a/include/rest_rpc/use_asio.hpp
+++ b/include/rest_rpc/use_asio.hpp
@@ -4,6 +4,9 @@
 #ifdef CINATRA_ENABLE_SSL
 #include <asio/ssl.hpp>
 #endif
+#include <asio/as_tuple.hpp>
+#include <asio/co_spawn.hpp>
+#include <asio/detached.hpp>
 #include <asio/detail/noncopyable.hpp>
 #include <asio/executor_work_guard.hpp>
 #include <asio/post.hpp>
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 05db6f1..58871e1 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -12,4 +12,7 @@ add_executable(${project_name}
         main.cpp
         )
 
+add_executable(test_rpc test_rest_rpc1.cpp)
+
 add_test(NAME ${project_name} COMMAND test_rest_rpc)
+#add_test(NAME test_rpc COMMAND test_rpc)
\ No newline at end of file
diff --git a/tests/doctest/doctest.h b/tests/doctest/doctest.h
index 3e86889..b04bafd 100644
--- a/tests/doctest/doctest.h
+++ b/tests/doctest/doctest.h
@@ -3718,7 +3718,7 @@ String toString(double long in) { return fpToString(in, 15); }
 #define DOCTEST_TO_STRING_OVERLOAD(type, fmt)                                                      \
     String toString(type in) {                                                                     \
         char buf[64];                                                                              \
-        std::sprintf(buf, fmt, in);                                                                \
+        std::snprintf(buf, sizeof(buf), fmt, in);                                                                \
         return buf;                                                                                \
     }
 
diff --git a/tests/test_rest_rpc1.cpp b/tests/test_rest_rpc1.cpp
new file mode 100644
index 0000000..3c30dea
--- /dev/null
+++ b/tests/test_rest_rpc1.cpp
@@ -0,0 +1,114 @@
+#define DOCTEST_CONFIG_IMPLEMENT
+
+#include "doctest/doctest.h"
+#include <asio/any_completion_handler.hpp>
+#include <rest_rpc/client.hpp>
+#include <rest_rpc/rest_rpc_server.hpp>
+#include <rest_rpc/traits.h>
+
+using namespace rest_rpc;
+
+struct dummy {
+  int add(int a, int b) { return a + b; }
+
+  void foo(std::string str) { std::cout << str << "\n"; }
+};
+
+int add(int a, int b) { return a + b; }
+
+void foo(std::string str) { std::cout << str << "\n"; }
+
+TEST_CASE("test router") {
+  rpc_router router;
+  router.register_handler<add>();
+  router.register_handler<foo>();
+
+  dummy d{};
+  router.register_handler<&dummy::add>(&d);
+  router.register_handler<&dummy::foo>(&d);
+  rpc_service::msgpack_codec codec;
+  auto args = codec.pack_args(1, 2);
+  std::string_view str(args.data(), args.size());
+
+  auto args1 = codec.pack_args("it is a test");
+  std::string_view str1(args1.data(), args1.size());
+
+  {
+    auto result = router.route(get_key<&dummy::add>(), str);
+    auto r = codec.unpack<int>(result.result.data(), result.result.size());
+    auto result1 = router.route(get_key<&dummy::foo>(), str1);
+    CHECK(r == 3);
+    CHECK(result1.ec == rpc_errc::ok);
+  }
+
+  auto result = router.route(get_key<add>(), str);
+  CHECK(result.ec == rpc_errc::ok);
+
+  auto result1 = router.route(get_key<foo>(), str1);
+  CHECK(result1.ec == rpc_errc::ok);
+}
+
+asio::awaitable<void> void_returning_coroutine() { co_return; }
+
+TEST_CASE("test server start") {
+  rest_rpc_server server("127.0.0.1:9005");
+  server.register_handler<add>();
+  server.register_handler<foo>();
+  auto ec = server.async_start();
+  CHECK(!ec);
+  client cl;
+  //  auto future = asio::co_spawn(cl.get_executor(),
+  //  cl.connect("127.0.0.1:9005"), asio::use_future); auto conn_ec =
+  //  future.get();
+  auto conn_ec = sync_wait(cl.get_executor(), cl.connect("127.0.0.1:9005"));
+  //  async_start(cl.get_executor(), cl.connect("127.0.0.1:9005"), [](auto
+  //  exptr, auto r){}); async_start(cl.get_executor(),
+  //  cl.connect("127.0.0.1:9005")); auto future =
+  //  async_future(cl.get_executor(), cl.connect("127.0.0.1:9005")); auto ec1 =
+  //  future.get();
+  //
+  //  auto future1 = async_future(cl.get_executor(),
+  //  void_returning_coroutine()); future1.get();
+
+  //  auto future1 = asio::co_spawn(cl.get_executor(), cl.call<add>(1, 2),
+  //  asio::use_future); auto result = future1.get();
+
+  auto result = sync_wait(cl.get_executor(), cl.call<add>(1, 2));
+
+  ec = server.async_start();
+  CHECK(!ec);
+  ec = server.async_start();
+  CHECK(!ec);
+  server.stop();
+  server.stop();
+
+  ec = server.async_start();
+  CHECK(ec);
+  std::cout << ec.message() << "\n";
+
+  rest_rpc_server server1("127.0.0.1:9007");
+  ec = server1.async_start();
+  CHECK(!ec);
+
+  rest_rpc_server server2("127.0.0.1:9007");
+  ec = server2.async_start();
+  CHECK(ec);
+  std::cout << ec.message() << "\n";
+  ec = server2.async_start();
+  CHECK(ec);
+  std::cout << ec.message() << "\n";
+
+  // if server has stopped, start server will be failed.
+  rest_rpc_server server3("127.0.0.1:9005");
+  server3.stop();
+  CHECK(server3.has_stopped());
+  ec = server3.start();
+  CHECK(ec);
+  std::cout << ec.message() << "\n";
+}
+
+// doctest comments
+// 'function' : must be 'attribute' - see issue #182
+DOCTEST_MSVC_SUPPRESS_WARNING_WITH_PUSH(4007)
+int main(int argc, char **argv) { return doctest::Context(argc, argv).run(); }
+DOCTEST_MSVC_SUPPRESS_WARNING_POP
\ No newline at end of file