nginx 0.5.0 *) Change: the parameters in the "%name" form in the "log_format" directive are not supported anymore. *) Change: the "proxy_upstream_max_fails", "proxy_upstream_fail_timeout", "fastcgi_upstream_max_fails", "fastcgi_upstream_fail_timeout", "memcached_upstream_max_fails", and "memcached_upstream_fail_timeout" directives are not supported anymore. *) Feature: the "server" directive in the "upstream" context supports the "max_fails", "fail_timeout", and "down" parameters. *) Feature: the "ip_hash" directive inside the "upstream" block. *) Feature: the WAIT status in the "Auth-Status" header line of the IMAP/POP3 proxy authentication server response. *) Bugfix: nginx could not be built on 64-bit platforms; bug appeared in 0.4.14.

/*
 * 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

}