Upstream: $upstream_cache_age variable. The variable reflects response age, including the time spent in the cache and the upstream response age as obtained from the "Age" header. If the response wasn't cached, the variable reflects the "Age" header of the upstream response. If the intended use case is to cache responses as per HTTP/1.1 caching model, the $upstream_cache_age variable can be used to provide the "Age" header with the "add_header" directive, such as: add_header Age $upstream_cache_age; This now removes the "Age" header if it was present. Further, the "expires" directives now removes the "Age" header if it was present in the response, as the "expires" directive assumes zero age when it adds "Expires" and "Cache-Control" headers.

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


#ifndef _NGX_THREAD_H_INCLUDED_
#define _NGX_THREAD_H_INCLUDED_


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


typedef HANDLE  ngx_tid_t;
typedef DWORD   ngx_thread_value_t;


ngx_err_t ngx_create_thread(ngx_tid_t *tid,
    ngx_thread_value_t (__stdcall *func)(void *arg), void *arg, ngx_log_t *log);

#define ngx_log_tid                 GetCurrentThreadId()
#define NGX_TID_T_FMT               "%ud"


#endif /* _NGX_THREAD_H_INCLUDED_ */