backport some consistency with trunks mod_cache:

   * mod_cache, mod_disk_cache: Try to use the key of a possible open but
     stale cache entry if there is one. This fixes problem when two different
     cache locks have been created for single stale cache entry leading to two
     requests sent to backend.
     PR 50317

   * Remove useless apr_file_remove() before renaming the cache entry in
     mod_disk_cache. This fixes small time-frame during which stale cache
     entry can be seen as not-cached.
     PR 50317

Subitted By: rpluem, jkaluza, ylavic
Reviewed By: ylavic, rpluem, jkaluza

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1608838 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index d07443274d97e1a6d5c0a3c57be1029a0ccfcf42..2d1b08a54b5810c86d7164294eca483aecfd128c 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,12 +1,17 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.2.28
 
+  *) mod_cache, mod_disk_cache: With CacheLock enabled, responses with a Vary 
+     header might not get the benefit of the thundering herd protection due to 
+     an incorrect internal cache key.  PR 50317. 
+     [Ruediger Pluem, Jan Kaluza, Yann Ylavic]
+
   *) mod_rewrite: Support session cookies with the CO= flag when later parameters
      are used.  The doc for this implied the feature had been backported for
      quite some time.  PR56014 [Eric Covener]
 
   *) mod_cache: Don't remove stale cache entries that cannot be conditionally
-     revalidated. This prevents the thundring herd protection from serving
+     revalidated. This prevents the thundering herd protection from serving
      stale responses during a revalidation. PR 50317.
      [Eric Covener, Jan Kaluza,  Ruediger Pluem]
 

diff --git a/STATUS b/STATUS
index a844325b2055da91f171441d6ffca00eb7fdaa3a..ac2269d4e2b67543ca15be90bd4798e3cfb18d66 100644 (file)
--- a/STATUS
+++ b/STATUS
@@ -99,16 +99,6 @@ RELEASE SHOWSTOPPERS:
 PATCHES ACCEPTED TO BACKPORT FROM TRUNK:
   [ start all new proposals below, under PATCHES PROPOSED. ]
 
-   * mod_cache, mod_disk_cache: Try to use the key of a possible open but
-     stale cache entry if there is one. This fixes problem when two different
-     cache locks have been created for single stale cache entry leading to two
-     requests sent to backend.
-     Remove useless apr_file_remove() before renaming the cache entry in
-     mod_disk_cache. This fixes small time-frame during which stale cache
-     entry can be seen as not-cached.
-     PR 50317
-     2.2.x patch: http://people.apache.org/~jkaluza/patches/httpd-2.2.x-thundering-herd.patch
-     +1: ylavic, rpluem, jkaluza
 
 PATCHES PROPOSED TO BACKPORT FROM TRUNK:
   [ New proposals should be added at the end of the list ]

diff --git a/modules/cache/mod_cache.c b/modules/cache/mod_cache.c
index d2dfff9622da04e7f153fa266ccf312c601ca18e..8492374298a2ff433f1e11e673b933aae05e52f0 100644 (file)
--- a/modules/cache/mod_cache.c
+++ b/modules/cache/mod_cache.c
@@ -113,6 +113,27 @@ static int cache_url_handler(request_rec *r, int lookup)
     if (rv != OK) {
         if (rv == DECLINED) {
             if (!lookup) {
+                char *key;
+                cache_handle_t *h;
+
+                /*
+                 * Try to use the key of a possible open but stall cache
+                 * entry if we have one.
+                 */
+                if (cache->handle != NULL) {
+                    h = cache->handle;
+                }
+                else {
+                    h = cache->stale_handle;
+                }
+                if ((h != NULL) &&
+                    (h->cache_obj != NULL) &&
+                    (h->cache_obj->key != NULL)) {
+                    key = apr_pstrdup(r->pool, h->cache_obj->key);
+                }
+                else {
+                    key = NULL;
+                }
 
                 /* try to obtain a cache lock at this point. if we succeed,
                  * we are the first to try and cache this url. if we fail,
@@ -121,7 +142,7 @@ static int cache_url_handler(request_rec *r, int lookup)
                  * backend without any attempt to cache. this stops
                  * duplicated simultaneous attempts to cache an entity.
                  */
-                rv = ap_cache_try_lock(conf, r, NULL);
+                rv = ap_cache_try_lock(conf, r, key);
                 if (APR_SUCCESS == rv) {
 
                     /*

diff --git a/modules/cache/mod_disk_cache.c b/modules/cache/mod_disk_cache.c
index 13d6c8b300b2a87680b11fee0016ffe99072f452..305fa6b293ef02e69cdcaef36e5cdd3790b67813 100644 (file)
--- a/modules/cache/mod_disk_cache.c
+++ b/modules/cache/mod_disk_cache.c
@@ -962,15 +962,6 @@ static apr_status_t store_headers(cache_handle_t *h, request_rec *r, cache_info
 
     apr_file_close(dobj->hfd); /* flush and close */
 
-    /* Remove old file with the same name. If remove fails, then
-     * perhaps we need to create the directory tree where we are
-     * about to write the new headers file.
-     */
-    rv = apr_file_remove(dobj->hdrsfile, r->pool);
-    if (rv != APR_SUCCESS) {
-        mkdir_structure(conf, dobj->hdrsfile, r->pool);
-    }
-
     rv = safe_file_rename(conf, dobj->tempfile, dobj->hdrsfile, r->pool);
     if (rv != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, rv, r->server,