53 lines
1.2 KiB
C++
53 lines
1.2 KiB
C++
#include <iostream>
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#include <string>
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#include <thread>
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#include <mutex>
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#include <condition_variable>
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std::mutex mtx;
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std::condition_variable cv;
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std::string data;
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bool ready = false;
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bool processed = false;
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void worker_thread() {
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std::unique_lock<std::mutex> ulk(mtx);
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// wait中的谓词返回false为虚假唤醒，继续阻塞；为true，则真实唤醒
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cv.wait(ulk, []{ return ready;});
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// 占有锁
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std::cout << "Worker thread is processing data\n";
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data += " after processing";
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// 处理完成
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processed = true;
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std::cout << "Worker thread signals data processing complated\n";
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// 通知前完成手动解锁，以避免主线程才被唤醒就阻塞
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ulk.unlock();
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cv.notify_one();
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}
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int main() {
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std::thread worker(worker_thread);
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data = "Example data";
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// 发送数据到 worker 线程
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{
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std::lock_guard<std::mutex> ulk(mtx);
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ready = true;
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std::cout << "main() signals data ready for processing\n";
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}
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cv.notify_one();
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// 等候 worker
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{
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std::unique_lock<std::mutex> ulk(mtx);
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cv.wait(ulk, []{ return processed;});
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}
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std::cout << "Back in main() , data = " << data << '\n';
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worker.join();
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} |