nginx 1.1.15 *) Feature: the "disable_symlinks" directive. *) Feature: the "proxy_cookie_domain" and "proxy_cookie_path" directives. *) Bugfix: nginx might log incorrect error "upstream prematurely closed connection" instead of correct "upstream sent too big header" one. Thanks to Feibo Li. *) Bugfix: nginx could not be built with the ngx_http_perl_module if the --with-openssl option was used. *) Bugfix: internal redirects to named locations were not limited. *) Bugfix: calling $r->flush() multiple times might cause errors in the ngx_http_gzip_filter_module. *) Bugfix: temporary files might be not removed if the "proxy_store" directive were used with SSI includes. *) Bugfix: in some cases non-cacheable variables (such as the $args variable) returned old empty cached value. *) Bugfix: a segmentation fault might occur in a worker process if too many SSI subrequests were issued simultaneously; the bug had appeared in 0.7.25.

/*
 * 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

}