ngx_os_init解析

ngx_int_t
ngx_os_init(ngx_log_t *log)
{
    ngx_time_t  *tp;
    ngx_uint_t   n;
#if (NGX_HAVE_LEVEL1_DCACHE_LINESIZE)
    long         size;
#endif

#if (NGX_HAVE_OS_SPECIFIC_INIT)
    // 初始化linux内核版本号
    if (ngx_os_specific_init(log) != NGX_OK) {
        return NGX_ERROR;
    }
#endif
    // 初始化proctitle内存空间
    if (ngx_init_setproctitle(log) != NGX_OK) {
        return NGX_ERROR;
    }

    // 获取page size
    ngx_pagesize = getpagesize();
    // 获取cacheline size
    ngx_cacheline_size = NGX_CPU_CACHE_LINE;

    // 2 ^ ngx_pagesize_shift == ngx_page_size
    for (n = ngx_pagesize; n >>= 1; ngx_pagesize_shift++) { /* void */ }

#if (NGX_HAVE_SC_NPROCESSORS_ONLN)
    if (ngx_ncpu == 0) {
        // 获取CPU核数
        ngx_ncpu = sysconf(_SC_NPROCESSORS_ONLN);
    }
#endif

    if (ngx_ncpu < 1) {
        ngx_ncpu = 1;
    }

#if (NGX_HAVE_LEVEL1_DCACHE_LINESIZE)
    //获取1-cache line size
    size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
    if (size > 0) {
        ngx_cacheline_size = size;
    }
#endif

    // 根据CPU info获取cacheline size
    ngx_cpuinfo();

    //获取打开最多文件数
    if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, errno,
                      "getrlimit(RLIMIT_NOFILE) failed");
        return NGX_ERROR;
    }

    ngx_max_sockets = (ngx_int_t) rlmt.rlim_cur;

#if (NGX_HAVE_INHERITED_NONBLOCK || NGX_HAVE_ACCEPT4)
    ngx_inherited_nonblocking = 1;
#else
    ngx_inherited_nonblocking = 0;
#endif

    tp = ngx_timeofday();
    //初始化rand种子
    srandom(((unsigned) ngx_pid << 16) ^ tp->sec ^ tp->msec);

    return NGX_OK;
}