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


#ifndef _NGX_ALLOC_H_INCLUDED_
#define _NGX_ALLOC_H_INCLUDED_


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


void *ngx_alloc(size_t size, ngx_log_t *log);
void *ngx_calloc(size_t size, ngx_log_t *log);

#define ngx_free          free


/*
 * Linux has memalign() or posix_memalign()
 * Solaris has memalign()
 * FreeBSD 7.0 has posix_memalign(), besides, early version's malloc()
 * aligns allocations bigger than page size at the page boundary
 */

#if (NGX_HAVE_POSIX_MEMALIGN || NGX_HAVE_MEMALIGN)

void *ngx_memalign(size_t alignment, size_t size, ngx_log_t *log);

#else

#define ngx_memalign(alignment, size, log)  ngx_alloc(size, log)

#endif


extern ngx_uint_t  ngx_pagesize;
extern ngx_uint_t  ngx_pagesize_shift;
extern ngx_uint_t  ngx_cacheline_size;


#endif /* _NGX_ALLOC_H_INCLUDED_ */