nginx 0.8.31 *) Feature: now the "error_page" directive may redirect the 301 and 302 responses. *) Feature: the $geoip_city_continent_code, $geoip_latitude, and $geoip_longitude variables. Thanks to Arvind Sundararajan. *) Feature: now the ngx_http_image_filter_module deletes always EXIF and other application specific data if the data consume more than 5% of a JPEG file. *) Bugfix: nginx closed a connection if a cached response had an empty body. Thanks to Piotr Sikora. *) Bugfix: nginx might not be built by gcc 4.x if the -O2 or higher optimization option was used. Thanks to Maxim Dounin and Denis F. Latypoff. *) Bugfix: regular expressions in location were always tested in case-sensitive mode; the bug had appeared in 0.8.25. *) Bugfix: nginx cached a 304 response if there was the "If-None-Match" header line in a proxied request. Thanks to Tim Dettrick and David Kostal. *) Bugfix: nginx/Windows tried to delete a temporary file twice if the file should replace an already existent file.

/*
 * 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

}