2017-06-06 17:02:45 +00:00
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#ifndef THREADPOOL_H
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#define THREADPOOL_H
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#include <atomic>
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#include <deque>
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#include <functional>
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#include <mutex>
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#include <thread>
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#include <vector>
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class ThreadPool {
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2017-06-06 17:07:50 +00:00
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long numOfThreads;
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2017-06-06 17:02:45 +00:00
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std::deque<std::function<void()>> _tasks;
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std::mutex _queueLock;
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std::atomic<bool> stopped{false};
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bool startedAlready = false;
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std::condition_variable _queueCond;
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std::condition_variable _threadFinishedCond;
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2017-06-06 17:07:50 +00:00
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long numOfThreadsRunning = 0;
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2017-06-06 17:02:45 +00:00
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std::vector<std::thread> _threads;
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protected:
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inline void threadWorker();
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inline void joinAll();
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public:
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inline ThreadPool();
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inline ~ThreadPool();
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inline void push(const std::function<void()> &task);
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inline void
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2017-06-06 17:07:50 +00:00
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start(const long NumOfThreads = std::thread::hardware_concurrency());
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2017-06-06 17:02:45 +00:00
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inline void finish();
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};
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void ThreadPool::threadWorker() {
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while (true) {
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std::unique_lock<decltype(_queueLock)> lg(_queueLock);
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while (_tasks.empty() && !stopped.load()) {
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_queueCond.wait(lg);
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}
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if (!_tasks.empty()) {
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auto theTask = _tasks[0];
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_tasks.pop_front();
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lg.unlock();
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theTask();
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lg.lock();
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}
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if (_tasks.empty() && stopped.load()) {
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numOfThreadsRunning--;
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_threadFinishedCond.notify_one();
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break;
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}
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}
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}
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void ThreadPool::joinAll() {
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for (long i = 0; i < numOfThreads; i++) {
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if (_threads[i].joinable())
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_threads[i].join();
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}
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}
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ThreadPool::ThreadPool() {}
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ThreadPool::~ThreadPool() { this->finish(); }
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void ThreadPool::push(const std::function<void()> &task) {
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std::unique_lock<decltype(_queueLock)> lg(_queueLock);
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_tasks.push_back(task);
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_queueCond.notify_one();
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}
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2017-06-06 17:07:50 +00:00
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void ThreadPool::start(const long NumOfThreads) {
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2017-06-06 17:02:45 +00:00
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if (!startedAlready)
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startedAlready = true;
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else
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throw std::logic_error("You cannot start the thread pool multiple times.");
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numOfThreads = NumOfThreads;
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_threads.reserve(numOfThreads);
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for (long i = 0; i < numOfThreads; i++) {
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_threads.push_back(std::thread(std::bind(&ThreadPool::threadWorker, this)));
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numOfThreadsRunning++;
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}
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}
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void ThreadPool::finish() {
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std::unique_lock<decltype(_queueLock)> lg(_queueLock);
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stopped.store(true);
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_queueCond.notify_all();
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while (numOfThreadsRunning > 0) {
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_threadFinishedCond.wait(lg);
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}
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lg.unlock();
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joinAll();
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}
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#endif // THREADPOOL_H
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