nginx 0.8.22 *) Feature: the "proxy_bind", "fastcgi_bind", and "memcached_bind" directives. *) Feature: the "access" and the "deny" directives support IPv6. *) Feature: the "set_real_ip_from" directive supports IPv6 addresses in request headers. *) Feature: the "unix:" parameter of the "set_real_ip_from" directive. *) Bugfix: nginx did not delete unix domain socket after configuration testing. *) Bugfix: nginx deleted unix domain socket while online upgrade. *) Bugfix: the "!-x" operator did not work. Thanks to Maxim Dounin. *) Bugfix: a segmentation fault might occur in a worker process, if limit_rate was used in HTTPS server. Thanks to Maxim Dounin. *) Bugfix: a segmentation fault might occur in a worker process while $limit_rate logging. Thanks to Maxim Dounin. *) Bugfix: a segmentation fault might occur in a worker process, if there was no "listen" directive in "server" block; the bug had appeared in 0.8.21.

/*
 * 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

}