Re: Is it a subrequest, a redirect or a fast redirect?

[Bill Stoddard]

André Malo wrote:

* William A. Rowe, Jr. wrote:

 

Looking through the bugreports and the problems we have...
internal_fast_redirect saves some CPU cycles (I guess), but it's finally
(currently) an unclean thing.
     

André,
Would you list the PRs that you believe are related to fast redirects 
not working correctly?  Perhaps there are some simple changes to get 
fast redirect working and perhaps there are some cases where we simply 
should not be using fast redirect.

I am able to fix the mod_expires problem by doing a test to definitively 
identify is a request is a subrequest or not (testing r->main is not 
sufficient).  It would be easy to add code to make_sub_request() to set 
a flag if the SUBREQ_CORE filter is added. This flag would definitively 
identify if a request is a subrequest or not. Then we could test 
(r->is_subreq) rather than (r->main) and be assured of correctly 
identifying a subrequest.

This nasty hack will make mod_expires behave correctly with 
DirectoryIndex responses.

Index: mod_expires.c
===================================================================
RCS file: /home/cvs/httpd-2.0/modules/metadata/mod_expires.c,v
retrieving revision 1.43
diff -u -r1.43 mod_expires.c
--- mod_expires.c    30 May 2003 16:33:57 -0000    1.43
+++ mod_expires.c    31 May 2003 00:05:08 -0000
@@ -547,13 +547,23 @@
        return DECLINED;
    }
-    /* Note: This is broken, DirectoryIndex files will not get an 
expires header
-     * We should say -yes- to fast-redirects (which are not really 
subrequests)
-     * but this check is not granular enough to distinguish between a 
fast-redirect
-     * and a subrequest
+    /* Say no to subrequests but yes to requests about to be fast 
redirected
+     * Note: r->main is not a reliable indicator if a request is a 
subrequest
+     * or not. The best indicator of a subrequest is the presence of the
+     * SUBREQ_CORE filter (which is an AP_FTYPE_CONTENT_SET filter).
+     * This is a hack to cover us till we get a better mechanism for 
distingushing
+     * between subrequests, redirects and fast redirects.
     */
-    if (r->main != NULL) {      /* Say no to subrequests */
-        return DECLINED;
+    if (r->main != NULL) {
+        /* This might be a subrequest */
+        ap_filter_t *f;
+        f = r->output_filters;
+        while (f && f->frec->ftype <= AP_FTYPE_CONTENT_SET) {
+            if (!strcmp(f->frec->name, "subreq_core")) {
+                return DECLINED;
+            }
+            f = f->next;
+        }
    }

    conf = (expires_dir_config *) ap_get_module_config(r->per_dir_config,