46 lines
1.5 KiB
C++
46 lines
1.5 KiB
C++
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/*************************************************************************
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> File Name : demo2.cpp
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> Author : TL Song
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> EMail : songtianlun@frytea.com
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> Created Time : Mon Feb 8 08:49:23 2021
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************************************************************************/
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#include <iostream>
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#include <thread>
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#include <vector>
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#include <mutex>
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#include <chrono>
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#include <stdexcept>
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int counter = 0;
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std::mutex mtx; // 保护counter
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void increase(int time) {
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for (int i = 0; i < time; i++) {
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mtx.lock();
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// 当前线程休眠1毫秒
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std::this_thread::sleep_for(std::chrono::milliseconds(1));
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counter++;
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mtx.unlock();
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}
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}
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/*
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* 总结
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* 1. 对于std::mutex对象，任意时刻最多允许一个线程对其进行上锁
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* 2. mtx.lock()：调用该函数的线程尝试加锁。如果上锁不成功，
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* 即：其它线程已经上锁且未释放，则当前线程block。如果上锁成功，则执行后面的操作，
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* 操作完成后要调用mtx.unlock()释放锁，否则会导致死锁的产生
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* 3. mtx.unlock()：释放锁4. std::mutex还有一个操作：mtx.try_lock()，
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* 字面意思就是：“尝试上锁”，与mtx.lock()的不同点在于：如果上锁不成功，当前线程不阻塞。
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*/
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int main(int argc, char** argv) {
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std::thread t1(increase, 10000);
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std::thread t2(increase, 10000);
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t1.join();
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t2.join();
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std::cout << "counter:" << counter << std::endl;
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return 0;
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}
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