1 | /* |
---|---|
2 | * Copyright 2017-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 <folly/MPMCQueue.h> |
20 | #include <folly/executors/task_queue/BlockingQueue.h> |
21 | #include <folly/synchronization/LifoSem.h> |
22 | |
23 | namespace folly { |
24 | |
25 | template <class T, QueueBehaviorIfFull kBehavior = QueueBehaviorIfFull::THROW> |
26 | class LifoSemMPMCQueue : public BlockingQueue<T> { |
27 | public: |
28 | // Note: The queue pre-allocates all memory for max_capacity |
29 | explicit LifoSemMPMCQueue(size_t max_capacity) : queue_(max_capacity) {} |
30 | |
31 | BlockingQueueAddResult add(T item) override { |
32 | switch (kBehavior) { // static |
33 | case QueueBehaviorIfFull::THROW: |
34 | if (!queue_.write(std::move(item))) { |
35 | throw QueueFullException("LifoSemMPMCQueue full, can't add item"); |
36 | } |
37 | break; |
38 | case QueueBehaviorIfFull::BLOCK: |
39 | queue_.blockingWrite(std::move(item)); |
40 | break; |
41 | } |
42 | return sem_.post(); |
43 | } |
44 | |
45 | T take() override { |
46 | T item; |
47 | while (!queue_.readIfNotEmpty(item)) { |
48 | sem_.wait(); |
49 | } |
50 | return item; |
51 | } |
52 | |
53 | folly::Optional<T> try_take_for(std::chrono::milliseconds time) override { |
54 | T item; |
55 | while (!queue_.readIfNotEmpty(item)) { |
56 | if (!sem_.try_wait_for(time)) { |
57 | return folly::none; |
58 | } |
59 | } |
60 | return std::move(item); |
61 | } |
62 | |
63 | size_t capacity() { |
64 | return queue_.capacity(); |
65 | } |
66 | |
67 | size_t size() override { |
68 | return queue_.size(); |
69 | } |
70 | |
71 | private: |
72 | folly::LifoSem sem_; |
73 | folly::MPMCQueue<T> queue_; |
74 | }; |
75 | |
76 | } // namespace folly |
77 |