1 /*
2  * Copyright 2020 The Android Open Source Project
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 <log/log.h>
20 
21 #include <condition_variable>
22 #include <functional>
23 #include <future>
24 #include <mutex>
25 #include <queue>
26 
27 namespace android {
28 namespace renderengine {
29 namespace skia {
30 
31 namespace {
32 #define PREVENT_COPY_AND_ASSIGN(Type) \
33 private:                              \
34     Type(const Type&) = delete;       \
35     void operator=(const Type&) = delete
36 } // namespace
37 
38 /**
39  * Shamelessly copied from HWUI to execute Skia Capturing on the back thread in
40  * a safe manner.
41  */
42 class CommonPool {
43     PREVENT_COPY_AND_ASSIGN(CommonPool);
44 
45 public:
46     using Task = std::function<void()>;
47     static constexpr auto THREAD_COUNT = 2;
48     static constexpr auto QUEUE_SIZE = 128;
49 
50     static void post(Task&& func);
51 
52 private:
53     static CommonPool& instance();
54 
55     CommonPool();
~CommonPool()56     ~CommonPool() {}
57 
58     void enqueue(Task&&);
59 
60     void workerLoop();
61 
62     std::mutex mLock;
63     std::condition_variable mCondition;
64     int mWaitingThreads = 0;
65     std::queue<Task> mWorkQueue;
66 };
67 
68 } // namespace skia
69 } // namespace renderengine
70 } // namespace android
71