io_service_base.h

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/*
  Copyright (c) 2020, 2024, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  as designated in a particular file or component or in included license
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  permission to link the program and your derivative works with the
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  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef MYSQL_HARNESS_NET_TS_IMPL_IO_SERVICE_BASE_H_
#define MYSQL_HARNESS_NET_TS_IMPL_IO_SERVICE_BASE_H_
 
#include <chrono>
#include <system_error>
 
#include "mysql/harness/net_ts/impl/socket.h"
#include "mysql/harness/stdx/expected.h"
 
namespace net {
enum class io_service_errc {
  no_fds = 1,
};
}
 
namespace std {
template <>
struct is_error_code_enum<net::io_service_errc> : public std::true_type {};
}  // namespace std
 
namespace net {
inline const std::error_category &io_service_category() noexcept {
  class io_service_category_impl : public std::error_category {
   public:
    const char *name() const noexcept override { return "io_service"; }
    std::string message(int ev) const override {
      switch (static_cast<io_service_errc>(ev)) {
        case io_service_errc::no_fds:
          return "no file-descriptors";
        default:
          return "unknown";
      }
    }
  };
 
  static io_service_category_impl instance;
  return instance;
}
 
inline std::error_code make_error_code(net::io_service_errc e) noexcept {
  return {static_cast<int>(e), net::io_service_category()};
}
 
struct fd_event {
  using native_handle_type = impl::socket::native_handle_type;
 
  fd_event() = default;
  fd_event(native_handle_type _fd, short _event) : fd{_fd}, event{_event} {}
 
  native_handle_type fd{net::impl::socket::kInvalidSocket};
  short event{};
};
 
inline constexpr bool operator==(const fd_event &a, const fd_event &b) {
  return a.event == b.event && a.fd == b.fd;
}
 
inline constexpr bool operator!=(const fd_event &a, const fd_event &b) {
  return !(a == b);
}
 
class IoServiceBase {
 public:
  using native_handle_type = impl::socket::native_handle_type;
 
  virtual ~IoServiceBase() = default;
 
  /**
   * open the io-service.
   *
   * MUST be called before any of the other functions is called.
   *
   * may fail if out of file-descriptors.
   *
   * @returns an std::error_code on error
   */
  virtual stdx::expected<void, std::error_code> open() = 0;
 
  virtual void notify() = 0;
 
  virtual stdx::expected<void, std::error_code> add_fd_interest(
      native_handle_type fd, impl::socket::wait_type event) = 0;
  virtual stdx::expected<fd_event, std::error_code> poll_one(
      std::chrono::milliseconds timeout) = 0;
 
  virtual stdx::expected<void, std::error_code> remove_fd(
      native_handle_type fd) = 0;
};
}  // namespace net
 
#endif