Upstream: avoid closing client connection in edge case. If proxy_cache is enabled, and proxy_no_cache tests true, it was previously possible for the client connection to be closed after a 304. The fix is to recheck r->header_only after the final cacheability is determined, and end the request if no longer cacheable. Example configuration: proxy_cache foo; proxy_cache_bypass 1; proxy_no_cache 1; If a client sends If-None-Match, and the upstream server returns 200 with a matching ETag, no body should be returned to the client. At the start of ngx_http_upstream_send_response proxy_no_cache is not yet tested, thus cacheable is still 1 and downstream_error is set. However, by the time the downstream_error check is done in process_request, proxy_no_cache has been tested and cacheable is set to 0. The client connection is then closed, regardless of keepalive.

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


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


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

    *tid = CreateThread(NULL, 0, func, arg, 0, &id);

    if (*tid != NULL) {
        ngx_log_error(NGX_LOG_NOTICE, log, 0,
                      "create thread " NGX_TID_T_FMT, id);
        return 0;
    }

    err = ngx_errno;
    ngx_log_error(NGX_LOG_ALERT, log, err, "CreateThread() failed");
    return err;
}