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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#include "Futex.h"
#include <sys/syscall.h>
#include <linux/futex.h>
spring_futex::spring_futex() noexcept
{
mtx = 0;
}
spring_futex::~spring_futex()
{
mtx = 0;
}
void spring_futex::lock()
{
native_type c;
if ((c = __sync_val_compare_and_swap(&mtx, 0, 1)) == 0)
return;
do {
if ((c == 2) || __sync_val_compare_and_swap(&mtx, 1, 2) != 0)
syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0);
} while((c = __sync_val_compare_and_swap(&mtx, 0, 2)) != 0);
}
bool spring_futex::try_lock() noexcept
{
return __sync_bool_compare_and_swap(&mtx, 0, 1);
}
void spring_futex::unlock()
{
if (__sync_fetch_and_sub(&mtx, 1) != 1) {
mtx = 0;
syscall(SYS_futex, &mtx, FUTEX_WAKE_PRIVATE, 1, NULL, NULL, 0);
}
}
/*
recursive_futex::recursive_futex() noexcept
{
mtx = 0;
}
recursive_futex::~recursive_futex()
{
mtx = 0;
}
void recursive_futex::lock()
{
native_type c;
if ((c = __sync_val_compare_and_swap(&mtx, 0, 1)) == 0)
return;
do {
if ((c == 2) || __sync_val_compare_and_swap(&mtx, 1, 2) != 0)
syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0);
} while((c = __sync_val_compare_and_swap(&mtx, 0, 2)) != 0);
}
bool recursive_futex::try_lock() noexcept
{
return __sync_bool_compare_and_swap(&mtx, 0, 1);
}
void recursive_futex::unlock()
{
if (__sync_fetch_and_sub(&mtx, 1) != 1) {
mtx = 0;
syscall(SYS_futex, &mtx, FUTEX_WAKE_PRIVATE, 1, NULL, NULL, 0);
}
}
*/
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