nginx 1.1.16 *) Change: the simultaneous subrequest limit has been raised to 200. *) Feature: the "from" parameter of the "disable_symlinks" directive. *) Feature: the "return" and "error_page" directives can be used to return 307 redirections. *) Bugfix: a segmentation fault might occur in a worker process if the "resolver" directive was used and there was no "error_log" directive specified at global level. Thanks to Roman Arutyunyan. *) Bugfix: a segmentation fault might occur in a worker process if the "proxy_http_version 1.1" or "fastcgi_keep_conn on" directives were used. *) Bugfix: memory leaks. Thanks to Lanshun Zhou. *) Bugfix: in the "disable_symlinks" directive. *) Bugfix: on ZFS filesystem disk cache size might be calculated incorrectly; the bug had appeared in 1.0.1. *) Bugfix: nginx could not be built by the icc 12.1 compiler. *) Bugfix: nginx could not be built by gcc on Solaris; the bug had appeared in 1.1.15.

/*
 * 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

}