nginx 0.2.0 *) The pid-file names used during online upgrade was changed and now is not required a manual rename operation. The old master process adds the ".oldbin" suffix to its pid-file and executes a new binary file. The new master process creates usual pid-file without the ".newbin" suffix. If the master process exits, then old master process renames back its pid-file with the ".oldbin" suffix to the pid-file without suffix. *) Change: the "worker_connections" directive, new name of the "connections" directive; now the directive specifies maximum number of connections, but not maximum socket descriptor number. *) Feature: SSL supports the session cache inside one worker process. *) Feature: the "satisfy_any" directive. *) Change: the ngx_http_access_module and ngx_http_auth_basic_module do not run for subrequests. *) Feature: the "worker_rlimit_nofile" and "worker_rlimit_sigpending" directives. *) Bugfix: if all backend using in load-balancing failed after one error, then nginx did not try do connect to them during 60 seconds. *) Bugfix: in IMAP/POP3 command argument parsing. Thanks to Rob Mueller. *) Bugfix: errors while using SSL in IMAP/POP3 proxy. *) Bugfix: errors while using SSI and gzipping. *) Bugfix: the "Expires" and "Cache-Control" header lines were omitted from the 304 responses. Thanks to Alexandr Kukushkin.

/*
 * 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

}