nginx 1.0.3 *) Feature: the "auth_basic_user_file" directive supports "$apr1", "{PLAIN}", and "{SSHA}" password encryption methods. Thanks to Maxim Dounin. *) Feature: the "geoip_org" directive and $geoip_org variable. Thanks to Alexander Uskov, Arnaud Granal, and Denis F. Latypoff. *) Feature: ngx_http_geo_module and ngx_http_geoip_module support IPv4 addresses mapped to IPv6 addresses. *) Bugfix: a segmentation fault occurred in a worker process during testing IPv4 address mapped to IPv6 address, if access or deny rules were defined only for IPv6; the bug had appeared in 0.8.22. *) Bugfix: a cached reponse may be broken if proxy/fastcgi/scgi/ uwsgi_cache_bypass and proxy/fastcgi/scgi/uwsgi_no_cache directive values were different; the bug had appeared in 0.8.46.

/*
 * 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

}