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54 lines
1.2 KiB
54 lines
1.2 KiB
#include <condition_variable>
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#include <iostream>
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#include <mutex>
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#include <string>
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#include <thread>
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std::mutex m;
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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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{
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// wait until main() sends data
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std::unique_lock lk(m);
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cv.wait(lk, []{ return ready; });
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// after the wait, we own the lock
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std::cout << "Worker thread is processing data\n";
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data += " after processing";
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// send data back to main()
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processed = true;
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std::cout << "Worker thread signals data processing completed\n";
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// manual unlocking is done before notifying, to avoid waking up
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// the waiting thread only to block again (see notify_one for details)
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lk.unlock();
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cv.notify_one();
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}
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int main()
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{
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std::thread worker(worker_thread);
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data = "Example data";
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// send data to the worker thread
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{
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std::lock_guard lk(m);
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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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// wait for the worker
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{
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std::unique_lock lk(m);
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cv.wait(lk, []{ 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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}
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