nginx 0.3.10 *) Change: the "valid_referers" directive and the "$invalid_referer" variable were moved to the new ngx_http_referer_module from the ngx_http_rewrite_module. *) Change: the "$apache_bytes_sent" variable name was changed to "$body_bytes_sent". *) Feature: the "$sent_http_..." variables. *) Feature: the "if" directive supports the "=" and "!=" operations. *) Feature: the "proxy_pass" directive supports the HTTPS protocol. *) Feature: the "proxy_set_body" directive. *) Feature: the "post_action" directive. *) Feature: the ngx_http_empty_gif_module. *) Feature: the "worker_cpu_affinity" directive for Linux. *) Bugfix: the "rewrite" directive did not unescape URI part in redirect, now it is unescaped except the %00-%25 and %7F-%FF characters. *) Bugfix: nginx could not be built by the icc 9.0 compiler. *) Bugfix: if the SSI was enabled for zero size static file, then the chunked response was encoded incorrectly.

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>


/*
 * TODO: the P4 optimized assembler version with the "pause" operation
 */

void
ngx_spinlock(ngx_atomic_t *lock, ngx_uint_t spin)
{

#if (NGX_HAVE_ATOMIC_OPS)

    ngx_uint_t  tries;

    tries = 0;

    for ( ;; ) {

        if (*lock) {
            if (ngx_ncpu > 1 && tries++ < spin) {
                continue;
            }

            ngx_sched_yield();

            tries = 0;

        } else {
            if (ngx_atomic_cmp_set(lock, 0, 1)) {
                return;
            }
        }
    }

#else

#if (NGX_THREADS)

#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !

#endif

#endif

}