Cache: ignore stale-if-error for 4xx and 5xx codes. Previously the stale-if-error extension of the Cache-Control upstream header triggered the return of a stale response for all error conditions that can be specified in the proxy_cache_use_stale directive. The list of these errors includes both network/timeout/format errors, as well as some HTTP codes like 503, 504, 403, 429 etc. The latter prevented a cache entry from being updated by a response with any of these HTTP codes during the stale-if-error period. Now stale-if-error only works for network/timeout/format errors and ignores the upstream HTTP code. The return of a stale response for certain HTTP codes is still possible using the proxy_cache_use_stale directive. This change also applies to the stale-while-revalidate extension of the Cache-Control header, which triggers stale-if-error if it is missing. Reported at http://mailman.nginx.org/pipermail/nginx/2020-July/059723.html.

/*
 * Copyright (C) Maxim Dounin
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_DLOPEN_H_INCLUDED_
#define _NGX_DLOPEN_H_INCLUDED_


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


#define NGX_HAVE_DLOPEN  1


#define ngx_dlopen(path)           LoadLibrary((char *) path)
#define ngx_dlopen_n               "LoadLibrary()"

#define ngx_dlsym(handle, symbol)  (void *) GetProcAddress(handle, symbol)
#define ngx_dlsym_n                "GetProcAddress()"

#define ngx_dlclose(handle)        (FreeLibrary(handle) ? 0 : -1)
#define ngx_dlclose_n              "FreeLibrary()"


char *ngx_dlerror(void);


#endif /* _NGX_DLOPEN_H_INCLUDED_ */