49 lines
1.2 KiB
C
49 lines
1.2 KiB
C
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// C++11 does not support std::shared_mutex and std::shared_lock yet.
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// This piece of Code is based on the proposal for C++14
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#include <mutex>
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#include <condition_variable>
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#include <climits>
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namespace lean {
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class shared_mutex {
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std::mutex m_mutex;
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std::condition_variable m_gate1;
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std::condition_variable m_gate2;
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unsigned m_state;
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static constexpr unsigned write_entered = 1u << (sizeof(unsigned)*8 - 1);
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static constexpr unsigned readers = ~write_entered;
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public:
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shared_mutex();
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~shared_mutex();
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shared_mutex(shared_mutex const &) = delete;
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shared_mutex(shared_mutex &&) = delete;
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shared_mutex& operator=(shared_mutex const &) = delete;
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shared_mutex&& operator=(shared_mutex &&) = delete;
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void lock();
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bool try_lock();
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void unlock();
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void lock_shared();
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bool try_lock_shared();
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void unlock_shared();
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};
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class shared_lock {
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shared_mutex & m_mutex;
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public:
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shared_lock(shared_mutex & m):m_mutex(m) { m_mutex.lock_shared(); }
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~shared_lock() { m_mutex.unlock_shared(); }
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};
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class unique_lock {
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shared_mutex & m_mutex;
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public:
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unique_lock(shared_mutex & m):m_mutex(m) { m_mutex.lock(); }
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~unique_lock() { m_mutex.unlock(); }
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};
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}
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