37 lines
1.1 KiB
C++
37 lines
1.1 KiB
C++
#pragma once
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#include <mutex>
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#include <atomic>
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namespace Psc {
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template<typename Derived>
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class Singleton {
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public:
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static Derived *instance() {
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Derived *temp = instance_.load(std::memory_order_acquire);
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if (temp == nullptr) {
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std::lock_guard<std::mutex> lock(mutex_);
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temp = instance_.load(std::memory_order_relaxed);
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if (temp == nullptr) {
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temp = new Derived;
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instance_.store(temp, std::memory_order_release);
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}
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}
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return temp;
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}
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static void destroy() {
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Derived* temp = instance_.exchange(nullptr, std::memory_order_acq_rel);
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delete temp; // 若为 nullptr，delete 安全
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}
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Singleton(const Singleton &) = delete;
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Singleton &operator=(const Singleton &) = delete;
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protected:
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Singleton() = default;
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~Singleton() = default;
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private:
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static std::atomic<Derived *> instance_;
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static std::mutex mutex_;
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};
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template<typename Derived>
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std::atomic<Derived *> Singleton<Derived>::instance_(nullptr);
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template<typename Derived>
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std::mutex Singleton<Derived>::mutex_;
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} |