Cache locks initial implementation. New directives: proxy_cache_lock on/off, proxy_cache_lock_timeout. With proxy_cache_lock set to on, only one request will be allowed to go to upstream for a particular cache item. Others will wait for a response to appear in cache (or cache lock released) up to proxy_cache_lock_timeout. Waiting requests will recheck if they have cached response ready (or are allowed to run) every 500ms. Note: we intentionally don't intercept NGX_DECLINED possibly returned by ngx_http_file_cache_read(). This needs more work (possibly safe, but needs further investigation). Anyway, it's exceptional situation. Note: probably there should be a way to disable caching of responses if there is already one request fetching resource to cache (without waiting at all). Two possible ways include another cache lock option ("no_cache") or using proxy_no_cache with some supplied variable. Note: probably there should be a way to lock updating requests as well. For now "proxy_cache_use_stale updating" is available.

/*
 * Copyright (C) Igor Sysoev
 */


#ifndef _NGX_SHA1_H_INCLUDED_
#define _NGX_SHA1_H_INCLUDED_


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


#if (NGX_HAVE_OPENSSL_SHA1_H)
#include <openssl/sha.h>
#else
#include <sha.h>
#endif


typedef SHA_CTX  ngx_sha1_t;


#define ngx_sha1_init    SHA1_Init
#define ngx_sha1_update  SHA1_Update
#define ngx_sha1_final   SHA1_Final


#endif /* _NGX_SHA1_H_INCLUDED_ */