view src/core/ngx_spinlock.c @ 541:b09ee85d0ac8 release-0.1.45

nginx-0.1.45-RELEASE import *) Change: the "ssl_engine" directive was canceled in the ngx_http_ssl_module and now is introduced at global level. *) Bugfix: the responses with SSI subrequests did not transferred via SSL connection. *) Various bug fixes in the IMAP/POP3 proxy.
author Igor Sysoev <igor@sysoev.ru>
date Thu, 08 Sep 2005 14:36:09 +0000
parents 975f62e77f02
children 9c2f3ed7a247
line wrap: on
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/*
 * 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

}