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/*
* (C) 2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_RWLOCK_H_
#define BOTAN_RWLOCK_H_
#include <botan/types.h>
#include <mutex>
#include <condition_variable>
namespace Botan {
/**
* A read-write lock. Writers are favored.
*/
class BOTAN_TEST_API RWLock final
{
public:
RWLock();
void lock();
void unlock();
void lock_shared();
void unlock_shared();
private:
std::mutex m_mutex;
std::condition_variable m_gate1;
std::condition_variable m_gate2;
uint32_t m_state;
// 2**31 concurrent readers should be enough for anyone
static const uint32_t is_writing = static_cast<uint32_t>(1) << 31;
static const uint32_t readers_mask = ~is_writing;
};
}
#endif
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