1 /*
2 * Copyright 2021 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 //#define LOG_NDEBUG 0
18 #undef LOG_TAG
19 #define LOG_TAG "BackgroundExecutor"
20 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
21
22 #include <utils/Log.h>
23 #include <mutex>
24
25 #include "BackgroundExecutor.h"
26
27 namespace android {
28
29 ANDROID_SINGLETON_STATIC_INSTANCE(BackgroundExecutor);
30
BackgroundExecutor()31 BackgroundExecutor::BackgroundExecutor() : Singleton<BackgroundExecutor>() {
32 // mSemaphore must be initialized before any calls to
33 // BackgroundExecutor::sendCallbacks. For this reason, we initialize it
34 // within the constructor instead of within mThread.
35 LOG_ALWAYS_FATAL_IF(sem_init(&mSemaphore, 0, 0), "sem_init failed");
36 mThread = std::thread([&]() {
37 while (!mDone) {
38 LOG_ALWAYS_FATAL_IF(sem_wait(&mSemaphore), "sem_wait failed (%d)", errno);
39 auto callbacks = mCallbacksQueue.pop();
40 if (!callbacks) {
41 continue;
42 }
43 for (auto& callback : *callbacks) {
44 callback();
45 }
46 }
47 });
48 }
49
~BackgroundExecutor()50 BackgroundExecutor::~BackgroundExecutor() {
51 mDone = true;
52 LOG_ALWAYS_FATAL_IF(sem_post(&mSemaphore), "sem_post failed");
53 if (mThread.joinable()) {
54 mThread.join();
55 LOG_ALWAYS_FATAL_IF(sem_destroy(&mSemaphore), "sem_destroy failed");
56 }
57 }
58
sendCallbacks(Callbacks && tasks)59 void BackgroundExecutor::sendCallbacks(Callbacks&& tasks) {
60 mCallbacksQueue.push(std::move(tasks));
61 LOG_ALWAYS_FATAL_IF(sem_post(&mSemaphore), "sem_post failed");
62 }
63
flushQueue()64 void BackgroundExecutor::flushQueue() {
65 std::mutex mutex;
66 std::condition_variable cv;
67 bool flushComplete = false;
68 sendCallbacks({[&]() {
69 std::scoped_lock lock{mutex};
70 flushComplete = true;
71 cv.notify_one();
72 }});
73 std::unique_lock<std::mutex> lock{mutex};
74 cv.wait(lock, [&]() { return flushComplete; });
75 }
76
77 } // namespace android
78