nginx 1.3.1 *) Security: now nginx/Windows ignores trailing dot in URI path component, and does not allow URIs with ":$" in it. Thanks to Vladimir Kochetkov, Positive Research Center. *) Feature: the "proxy_pass", "fastcgi_pass", "scgi_pass", "uwsgi_pass" directives, and the "server" directive inside the "upstream" block, now support IPv6 addresses. *) Feature: the "resolver" directive now support IPv6 addresses and an optional port specification. *) Feature: the "least_conn" directive inside the "upstream" block. *) Feature: it is now possible to specify a weight for servers while using the "ip_hash" directive. *) Bugfix: a segmentation fault might occur in a worker process if the "image_filter" directive was used; the bug had appeared in 1.3.0. *) Bugfix: nginx could not be built with ngx_cpp_test_module; the bug had appeared in 1.1.12. *) Bugfix: access to variables from SSI and embedded perl module might not work after reconfiguration. Thanks to Yichun Zhang. *) Bugfix: in the ngx_http_xslt_filter_module. Thanks to Kuramoto Eiji. *) Bugfix: memory leak if $geoip_org variable was used. Thanks to Denis F. Latypoff. *) Bugfix: in the "proxy_cookie_domain" and "proxy_cookie_path" directives.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#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

}