Seastar
High performance C++ framework for concurrent servers
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defer.hh
1/*
2 * This file is open source software, licensed to you under the terms
3 * of the Apache License, Version 2.0 (the "License"). See the NOTICE file
4 * distributed with this work for additional information regarding copyright
5 * ownership. You may not use this file except in compliance with the License.
6 *
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing,
12 * software distributed under the License is distributed on an
13 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14 * KIND, either express or implied. See the License for the
15 * specific language governing permissions and limitations
16 * under the License.
17 */
18/*
19 * Copyright (C) 2014 Cloudius Systems, Ltd.
20 */
21
22#pragma once
23
24#include "modules.hh"
25#ifndef SEASTAR_MODULE
26#include <concepts>
27#include <type_traits>
28#include <utility>
29#endif
30#include <seastar/util/modules.hh>
31
32
33#ifdef SEASTAR_DEFERRED_ACTION_REQUIRE_NOEXCEPT
34#define SEASTAR_DEFERRED_ACTION_NOEXCEPT noexcept
35#else
36#define SEASTAR_DEFERRED_ACTION_NOEXCEPT
37#endif
38
39template <typename Func>
40concept deferrable_action = requires (Func func) {
41 { func() } SEASTAR_DEFERRED_ACTION_NOEXCEPT -> std::same_as<void>;
42};
43
44namespace seastar {
45
46template <typename Func>
47requires deferrable_action<Func>
48class [[nodiscard]] deferred_action {
49 Func _func;
50 bool _cancelled = false;
51public:
52 static_assert(std::is_nothrow_move_constructible_v<Func>, "Func(Func&&) must be noexcept");
53 deferred_action(Func&& func) noexcept : _func(std::move(func)) {}
54 deferred_action(deferred_action&& o) noexcept : _func(std::move(o._func)), _cancelled(o._cancelled) {
55 o._cancelled = true;
56 }
57 deferred_action& operator=(deferred_action&& o) noexcept {
58 if (this != &o) {
59 this->~deferred_action();
60 new (this) deferred_action(std::move(o));
61 }
62 return *this;
63 }
64 deferred_action(const deferred_action&) = delete;
65 ~deferred_action() { if (!_cancelled) { _func(); }; }
66 void cancel() { _cancelled = true; }
67};
68
69SEASTAR_MODULE_EXPORT
70template <typename Func>
71requires deferrable_action<Func>
72inline
74defer(Func&& func) {
75 return deferred_action<Func>(std::forward<Func>(func));
76}
77
78}
Definition: defer.hh:48
Seastar API namespace.
Definition: abort_on_ebadf.hh:26