Reader-Writer Lock

Difficulty

Asked at Chicago Trading Company, Squarepoint Capital

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Language: C++23RwLock

#include <atomic>
#include <condition_variable>
#include <cstddef>
#include <mutex>
#include <thread>
#include <vector>

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class RwLock {
public:
    void lock_shared() {
        // ...
    }

    void unlock_shared() {
        // ...
    }

    void lock() {
        // ...
    }

    void unlock() {
        // ...
    }

    long long readers_now() const { return readers_.load(); }
    bool writer_now() const { return writer_.load(); }
    long long waiting_writers() const { return waiting_.load(); }

private:
    std::mutex mutex_;
    std::condition_variable cv_;
    std::atomic<long long> readers_{0};
    std::atomic<bool> writer_{false};
    std::atomic<long long> waiting_{0};
};

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