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#pragma once
#include <atomic>
#include "../thread.h"
#include "../util_bit.h"
#include "../util_likely.h"
namespace dxvk::sync {
/**
* \brief Generic spin function
*
* Blocks calling thread until a condition becomes
* \c true, calling \c yield every few iterations.
* \param [in] spinCount Number of probes between each yield
* \param [in] fn Condition to test
*/
template<typename Fn>
void spin(uint32_t spinCount, const Fn& fn) {
while (unlikely(!fn())) {
for (uint32_t i = 1; i < spinCount; i++) {
_mm_pause();
if (fn())
return;
}
dxvk::this_thread::yield();
}
}
/**
* \brief Spin lock
*
* A low-overhead spin lock which can be used to
* protect data structures for a short duration
* in case the structure is not likely contested.
*/
class Spinlock {
public:
Spinlock() { }
~Spinlock() { }
Spinlock (const Spinlock&) = delete;
Spinlock& operator = (const Spinlock&) = delete;
void lock() {
spin(200, [this] { return try_lock(); });
}
void unlock() {
m_lock.store(0, std::memory_order_release);
}
bool try_lock() {
return likely(!m_lock.load())
&& likely(!m_lock.exchange(1, std::memory_order_acquire));
}
private:
std::atomic<uint32_t> m_lock = { 0 };
};
}
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