1 /*
2 * Copyright (C) 2017 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 #include <broadcastradio-utils/WorkerThread.h>
18
19 namespace android {
20
21 using std::function;
22 using std::lock_guard;
23 using std::mutex;
24 using std::unique_lock;
25 using std::chrono::milliseconds;
26 using std::chrono::steady_clock;
27 using std::this_thread::sleep_for;
28
operator <(const WorkerThread::Task & lhs,const WorkerThread::Task & rhs)29 bool operator<(const WorkerThread::Task& lhs, const WorkerThread::Task& rhs) {
30 return lhs.when > rhs.when;
31 }
32
WorkerThread()33 WorkerThread::WorkerThread() : mIsTerminating(false) {
34 // putting mThread in constructor instead of initializer list
35 // to ensure all class members are init before mThread starts
36 mThread = std::thread(&WorkerThread::threadLoop, this);
37 }
38
~WorkerThread()39 WorkerThread::~WorkerThread() {
40 {
41 lock_guard<mutex> lk(mMut);
42 mIsTerminating = true;
43 mCond.notify_one();
44 }
45 mThread.join();
46 }
47
schedule(function<void ()> task,milliseconds delay)48 void WorkerThread::schedule(function<void()> task, milliseconds delay) {
49 auto cancelTask = []() {};
50 schedule(std::move(task), cancelTask, delay);
51 }
52
schedule(function<void ()> task,function<void ()> cancelTask,milliseconds delay)53 void WorkerThread::schedule(function<void()> task, function<void()> cancelTask,
54 milliseconds delay) {
55 auto when = steady_clock::now() + delay;
56
57 lock_guard<mutex> lk(mMut);
58 mTasks.push(Task({when, std::move(task), std::move(cancelTask)}));
59 mCond.notify_one();
60 }
61
cancelAll()62 void WorkerThread::cancelAll() {
63 lock_guard<mutex> lk(mMut);
64 while (!mTasks.empty()) {
65 auto task = mTasks.top();
66 task.onCanceled();
67 mTasks.pop();
68 }
69 }
70
threadLoop()71 void WorkerThread::threadLoop() {
72 while (true) {
73 unique_lock<mutex> lk(mMut);
74 if (mIsTerminating) {
75 return;
76 }
77 if (mTasks.empty()) {
78 mCond.wait(lk);
79 continue;
80 }
81
82 auto task = mTasks.top();
83 if (task.when > steady_clock::now()) {
84 mCond.wait_until(lk, task.when);
85 continue;
86 }
87
88 mTasks.pop();
89 lk.unlock(); // what() might need to schedule another task
90 task.what();
91 }
92 }
93
94 } // namespace android
95