lvfulong
40 lines
1.1 KiB
C++
40 lines
1.1 KiB
C++
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#include <condition_variable>
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#include <thread>
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namespace laya {
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class semaphore {
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unsigned int count_;
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std::mutex mutex_;
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std::condition_variable condition_;
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public:
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//构造一个semaphore 初始值为initial.
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explicit semaphore(unsigned int initial) : count_(initial) {}
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//增加计数，并且通知其他的wait醒来检查。
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void signal() {
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{
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std::unique_lock<std::mutex> lock(mutex_);
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++count_;
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}
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condition_.notify_one();
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}
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//等待，直到有人 signal，signal到count>0,wait成功会减count
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void wait() {
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std::unique_lock<std::mutex> lock(mutex_);
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while (count_ == 0) {
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condition_.wait(lock);
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}
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--count_;
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}
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//等待，如果没有人增加计数的的话在时间到后会醒来返回。成功会减count
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//这个不会要求有count
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void wait(int ms) {
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std::unique_lock<std::mutex> lock(mutex_);
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condition_.wait_until(lock, std::chrono::system_clock::now() + std::chrono::milliseconds(ms));
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--count_;
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}
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};
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} |