nginx 0.4.13 *) Feature: the "proxy_pass" directive may be used inside the "limit_except" block. *) Feature: the "limit_except" directive supports all WebDAV methods. *) Bugfix: if the "add_before_body" directive was used without the "add_after_body" directive, then an response did not transferred complete. *) Bugfix: a large request body did not receive if the epoll method and the deferred accept() were used. *) Bugfix: a charset could not be set for ngx_http_autoindex_module responses; bug appeared in 0.3.50. *) Bugfix: the "[alert] zero size buf" error when FastCGI server was used; *) Bugfix: the --group= configuration parameter was ignored. Thanks to Thomas Moschny. *) Bugfix: the 50th subrequest in SSI response did not work; bug appeared in 0.3.50.

/*
 * 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

}