Upstream: cache revalidation with conditional requests. The following new directives are introduced: proxy_cache_revalidate, fastcgi_cache_revalidate, scgi_cache_revalidate, uwsgi_cache_revalidate. Default is off. When set to on, they enable cache revalidation using conditional requests with If-Modified-Since for expired cache items. As of now, no attempts are made to merge headers given in a 304 response during cache revalidation with headers previously stored in a cache item. Headers in a 304 response are only used to calculate new validity time of a cache item.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


int
ngx_nonblocking(ngx_socket_t s)
{
    unsigned long  nb = 1;

    return ioctlsocket(s, FIONBIO, &nb);
}


int
ngx_blocking(ngx_socket_t s)
{
    unsigned long  nb = 0;

    return ioctlsocket(s, FIONBIO, &nb);
}


int
ngx_tcp_push(ngx_socket_t s)
{
    return 0;
}