ceph/src/include/scope_guard.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2016 Red Hat
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef SCOPE_GUARD
  16 #define SCOPE_GUARD
  17
  18 #include <utility>
  19
  20 template <typename F>
  21 struct scope_guard {
  22   F f;
  23   scope_guard() = delete;
  24   scope_guard(const scope_guard &) = delete;
  25   scope_guard(scope_guard &&) = default;
  26   scope_guard & operator=(const scope_guard &) = delete;
  27   scope_guard & operator=(scope_guard &&) = default;
  28   scope_guard(const F& f) : f(f) {}
  29   scope_guard(F &&f) : f(std::move(f)) {}
  30   template<typename... Args>
  31   scope_guard(std::in_place_t, Args&& ...args) : f(std::forward<Args>(args)...) {}
  32   ~scope_guard() {
  33     std::move(f)(); // Support at-most-once functions
  34   }
  35 };
  36
  37 template <typename F>
  38 [[nodiscard("Unassigned scope guards will execute immediately")]]
  39 scope_guard<F> make_scope_guard(F &&f) {
  40   return scope_guard<F>(std::forward<F>(f));
  41 }
  42
  43 template<typename F, typename... Args>
  44 [[nodiscard("Unassigned scope guards will execute immediately")]]
  45 scope_guard<F> make_scope_guard(std::in_place_type_t<F>, Args&& ...args) {
  46   return { std::in_place, std::forward<Args>(args)... };
  47 }
  48
  49 #endif