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#include "spin_wait.h"
#include "yield.h"
#include "compat.h"
#include "thread.h"
#include "spinlock.h"
#include <util/digest/numeric.h>
#include <util/generic/utility.h>
template <class T>
static inline T RandomizeSleepTime(T t) noexcept {
static TAtomic counter = 0;
const T rndNum = IntHash((T)AtomicIncrement(counter));
return (t * (T)4 + (rndNum % t) * (T)2) / (T)5;
}
//arbitrary values
#define MIN_SLEEP_TIME 500
#define MAX_SPIN_COUNT 0x7FF
TSpinWait::TSpinWait() noexcept
: T(MIN_SLEEP_TIME)
, C(0)
{
}
void TSpinWait::Sleep() noexcept {
++C;
if (C == MAX_SPIN_COUNT) {
ThreadYield();
} else if ((C & MAX_SPIN_COUNT) == 0) {
usleep(RandomizeSleepTime(T));
T = Min<unsigned>((T * 3) / 2, 20000);
} else {
SpinLockPause();
}
}
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