//
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// Created by YY on 2022/12/30.
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//
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#ifndef MYAPPLICATION3_SEMAPHORE_H
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#define MYAPPLICATION3_SEMAPHORE_H
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#include <mutex>
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#include <condition_variable>
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namespace ilovers{
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class semaphore {
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public:
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semaphore(int value=1): count{value}, wakeups{0} {}
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void wait(void) {
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std::unique_lock<std::mutex> lock{mutex};
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if (--count<0) { // count is not enough ?
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condition.wait(lock, [&]()->bool{ return wakeups>0;}); // suspend and wait ...
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--wakeups; // ok, me wakeup !
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}
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}
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void signal(void) {
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std::lock_guard<std::mutex> lock{mutex};
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if(++count<=0) { // have some thread suspended ?
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++wakeups;
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condition.notify_one(); // notify one !
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}
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}
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private:
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int count;
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int wakeups;
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std::mutex mutex;
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std::condition_variable condition;
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};
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};
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#endif //MYAPPLICATION3_SEMAPHORE_H
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