Let me suggest, instead, that every proxy between here and
Timbuktu suffers the same problem from your example.
Better, methinks, is for mod_rewrite to toggle Vary: for the
envvar that triggered its rewrite. This is symptomatic of a
more sinister side effect of mod_rewrite.
Bill
At 03:29 AM 5/12/2005, Paul Querna wrote:
>Okay, because of the quirky behavior of a 'sometimes' cached page, this
>one had me going in circles for a little while.
>
>What this patch does, is add a new command to mod_cache,
>'CacheRunAfterOthers_RenameThisCmd'[1]
>
>The effect this has is to run mod_cache as a normal handler, instead of
>a Quick Handler. This means all the other Translate Name, Map to
>Storage, and Fixup hooks are ran. These include mod_rewrite and
>mod_alias, among others.
>
>What this allows, is configurations like the following:
>CacheEnable disk /
>CacheRoot /tmp/cacheroot
>RewriteEngine On
>CacheIgnoreNoLastMod on
>CacheDefaultExpire 90
>CacheMaxExpire 90
>RewriteCond %{HTTP_USER_AGENT} ^Mozilla.*\sFirefox/1\.0\.[1234]\b
>RewriteRule .* http://www.mozilla.org/products/firefox/upgrade/ [R=302,L]
>
>Since mod_cache is ran as a quick handler, once the / page was cached,
>the RewriteRule would never be ran. So, after the first non-Firefox
>Client connected, all clients, even those that are Firefox, would get a
>cached page, not the redirect.
>
>Add this:
>CacheRunAfterOthers_RenameThisCmd on
>
>And now it works. It does take a slight performance hit, but this is
>nothing compared to using a mod_proxy backend.
>
>Moving the Cache handler to be ran as an APR_HOOK_REALLY_FIRST means
>mod_rewrite will get it's chance to rewrite it, but it will still run
>before a really expensive handler, like a Proxy Backend or a PHP Script.
> This won't be useful to everyone, but for most configurations, the
>initial hooks are insignificant compared to the Content Handler, so
>allowing mod_cache to be called like this still makes sense.
>
>I have lightly tested the attached patch, and it fixes my test cases.
>
>Some details on this are also in PR 34885:
>http://issues.apache.org/bugzilla/show_bug.cgi?id=34885
>
>Thoughts/Comments/Code Review... all welcome.
>
>-Paul
>
>[1] Yes, I did name it 'CacheRunAfterOthers_RenameThisCmd'. I hope that
>before this patch is committed, someone thinks of a good name for this
>behavior, because I can't think of one.
>
>Index: modules/cache/mod_cache.c
>=================================================================== ---
>modules/cache/mod_cache.c (revision 169788) +++ modules/cache/mod_cache.c
>(working copy) @@ -45,7 +45,8 @@ * oh well. */ -static int
>cache_url_handler(request_rec *r, int lookup) +static int
>cache_url_real_handler(request_rec *r, int lookup, +
> cache_server_conf *conf, int is_quick) { apr_status_t rv;
>const char *auth; @@ -55,22 +56,13 @@ cache_provider_list *providers;
> cache_info *info; cache_request_rec *cache; - cache_server_conf
>*conf; apr_bucket_brigade *out; - /* Delay initialization until we
>know we are handling a GET */ - if (r->method_number != M_GET) { -
>return DECLINED; - } - uri = r->parsed_uri; url =
>r->unparsed_uri; path = uri.path; info = NULL; - conf =
>(cache_server_conf *) ap_get_module_config(r->server->module_config, -
> &cache_module); - /* *
>Which cache module (if any) should handle this request? */ @@ -156,9
>+148,12 @@ /* We are in the quick handler hook, which means that no
>output * filters have been set. So lets run the insert_filter hook.
> */ - ap_run_insert_filter(r); + if (is_quick) { +
>ap_run_insert_filter(r); + } +
>ap_add_output_filter_handle(cache_out_filter_handle, NULL, -
> r, r->connection); + r,
>r->connection); /* kick off the filter stack */ out =
>apr_brigade_create(r->pool, r->connection->bucket_alloc); @@ -174,6 +169,45 @@
> return OK; } +static int cache_url_quick_handler(request_rec *r, int
>lookup) +{ + cache_server_conf *conf; + + /* Delay initialization until
>we know we are handling a GET */ + if (r->method_number != M_GET) { +
> return DECLINED; + } + + conf = (cache_server_conf *)
>ap_get_module_config(r->server->module_config, +
> &cache_module); + + if (conf->run_handler_later) { +
> return DECLINED; + } + + return cache_url_real_handler(r, lookup,
>conf, 1); +} + +static int cache_url_late_handler(request_rec *r) +{ +
>cache_server_conf *conf; + + /* Delay initialization until we know we are
>handling a GET */ + if (r->method_number != M_GET) { + return
>DECLINED; + } + + conf = (cache_server_conf *)
>ap_get_module_config(r->server->module_config, +
> &cache_module); + + if (conf->run_handler_later) { +
> return cache_url_real_handler(r, 0, conf, 0); + } + + return
>DECLINED; +} + + /* * CACHE_OUT filter * ---------------- @@ -742,6 +776,7
>@@ /* array of headers that should not be stored in cache */
>ps->ignore_headers = apr_array_make(p, 10, sizeof(char *));
>ps->ignore_headers_set = CACHE_IGNORE_HEADERS_UNSET; +
>ps->run_handler_later = 0; return ps; } @@ -787,6 +822,10 @@
>(overrides->ignore_headers_set == CACHE_IGNORE_HEADERS_UNSET) ?
>base->ignore_headers : overrides->ignore_headers; +
>ps->run_handler_later = + (overrides->run_handler_later == 0) +
>? base->run_handler_later + : overrides->run_handler_later; return
>ps; } static const char *set_cache_ignore_no_last_mod(cmd_parms *parms, void
>*dummy, @@ -829,6 +868,18 @@ return NULL; } +static const char
>*set_cache_run_later(cmd_parms *parms, void *dummy, +
> int flag) +{ + cache_server_conf *conf; + + conf = +
> (cache_server_conf *)ap_get_module_config(parms->server->module_config, +
> &cache_module); +
>conf->run_handler_later = flag; + return NULL; +} + static const char
>*set_cache_store_nostore(cmd_parms *parms, void *dummy,
> int flag) { @@ -993,6 +1044,9 @@
>AP_INIT_FLAG("CacheStorePrivate", set_cache_store_private,
>NULL, RSRC_CONF, "Ignore 'Cache-Control: private' and store
>private content"), + AP_INIT_FLAG("CacheRunAfterOthers_RenameThisCmd",
>set_cache_run_later, + NULL, RSRC_CONF, + "Run
>the Cache Handler as a Normal Handler."),
>AP_INIT_FLAG("CacheStoreNoStore", set_cache_store_nostore,
>NULL, RSRC_CONF, "Ignore 'Cache-Control: no-store' and store
>sensitive content"), @@ -1007,9 +1061,12 @@ static void
>register_hooks(apr_pool_t *p) { - /* cache initializer */ - /* cache
>handler */ - ap_hook_quick_handler(cache_url_handler, NULL, NULL,
>APR_HOOK_FIRST); + /* cache handlers */ +
>ap_hook_quick_handler(cache_url_quick_handler, NULL, NULL, +
> APR_HOOK_FIRST); + ap_hook_handler(cache_url_late_handler, NULL,
>NULL, + APR_HOOK_REALLY_FIRST); + /* cache filters
> * XXX The cache filters need to run right after the handlers and before
> * any other filters. Consider creating AP_FTYPE_CACHE for this purpose. @@
>-1030,6 +1087,8 @@ cache_out_filter,
> NULL,
>AP_FTYPE_CONTENT_SET-1); + + /* cache initializer */
>ap_hook_post_config(cache_post_config, NULL, NULL, APR_HOOK_REALLY_FIRST); }
>Index: modules/cache/mod_cache.h
>=================================================================== ---
>modules/cache/mod_cache.h (revision 169788) +++
>modules/cache/mod_cache.h (working copy) @@ -145,6 +145,8 @@ #define
>CACHE_IGNORE_HEADERS_SET 1 #define CACHE_IGNORE_HEADERS_UNSET 0
>int ignore_headers_set; + /** Flag to disable the Quick Handler, and run
>after meta-hooks */ + int run_handler_later; } cache_server_conf; /* cache
>info information */
