1 | /* |
---|---|
2 | * Copyright 2014-present Facebook, Inc. |
3 | * |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | * you may not use this file except in compliance with the License. |
6 | * You may obtain a copy of the License at |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
10 | * Unless required by applicable law or agreed to in writing, software |
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | * See the License for the specific language governing permissions and |
14 | * limitations under the License. |
15 | */ |
16 | |
17 | #pragma once |
18 | |
19 | #include <atomic> |
20 | |
21 | #include <folly/CPortability.h> |
22 | #include <folly/CppAttributes.h> |
23 | #include <folly/Executor.h> |
24 | |
25 | namespace folly { |
26 | |
27 | /// When work is "queued", execute it immediately inline. |
28 | /// Usually when you think you want this, you actually want a |
29 | /// QueuedImmediateExecutor. |
30 | class InlineExecutor : public Executor { |
31 | public: |
32 | FOLLY_ATTR_VISIBILITY_HIDDEN FOLLY_ALWAYS_INLINE static InlineExecutor& |
33 | instance() noexcept { |
34 | auto const value = cache.load(std::memory_order_acquire); |
35 | return value ? *value : instance_slow(); |
36 | } |
37 | |
38 | void add(Func f) override { |
39 | f(); |
40 | } |
41 | |
42 | private: |
43 | FOLLY_COLD static InlineExecutor& instance_slow() noexcept; |
44 | |
45 | static std::atomic<InlineExecutor*> cache; |
46 | }; |
47 | |
48 | } // namespace folly |
49 |