nginx 1.0.1 *) Change: now the "split_clients" directive uses MurmurHash2 algorithm because of better distribution. Thanks to Oleg Mamontov. *) Change: now long strings starting with zero are not considered as false values. Thanks to Maxim Dounin. *) Change: now nginx uses a default listen backlog value 511 on Linux. *) Feature: the $upstream_... variables may be used in the SSI and perl modules. *) Bugfix: now nginx limits better disk cache size. Thanks to Oleg Mamontov. *) Bugfix: a segmentation fault might occur while parsing incorrect IPv4 address; the bug had appeared in 0.9.3. Thanks to Maxim Dounin. *) Bugfix: nginx could not be built by gcc 4.6 without --with-debug option. *) Bugfix: nginx could not be built on Solaris 9 and earlier; the bug had appeared in 0.9.3. Thanks to Dagobert Michelsen. *) Bugfix: $request_time variable had invalid values if subrequests were used; the bug had appeared in 0.8.47. Thanks to Igor A. Valcov.

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>


void
ngx_spinlock(ngx_atomic_t *lock, ngx_atomic_int_t value, ngx_uint_t spin)
{

#if (NGX_HAVE_ATOMIC_OPS)

    ngx_uint_t  i, n;

    for ( ;; ) {

        if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
            return;
        }

        if (ngx_ncpu > 1) {

            for (n = 1; n < spin; n <<= 1) {

                for (i = 0; i < n; i++) {
                    ngx_cpu_pause();
                }

                if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
                    return;
                }
            }
        }

        ngx_sched_yield();
    }

#else

#if (NGX_THREADS)

#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !

#endif

#endif

}