Log reason for cache decline.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97646 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 46 insertions, 26 deletions

diff --git a/modules/experimental/mod_cache.c b/modules/experimental/mod_cache.c
index 5a0de969ba..9750b8c3a3 100644
--- a/modules/experimental/mod_cache.c
+++ b/modules/experimental/mod_cache.c
@@ -460,7 +460,8 @@ static int cache_in_filter(ap_filter_t *f, apr_bucket_brigade *in)
         info = cache->info;
     }
     else {
-
+        char *reason = NULL;
+        apr_pool_t *p = r->pool;
         /*
          * Pass Data to Cache
          * ------------------
@@ -526,45 +527,64 @@ static int cache_in_filter(ap_filter_t *f, apr_bucket_brigade *in)
          * a whole lot of conditions that prevent us from caching this data.
          * They are tested here one by one to be clear and unambiguous. 
          */
-
-        /* RFC2616 13.4 we are allowed to cache 200, 203, 206, 300, 301 or 410
-         * We don't cache 206, because we don't (yet) cache partial responses.
-         * We include 304 Not Modified here too as this is the origin server
-         * telling us to serve the cached copy.
-         */
-        if ((r->status != HTTP_OK && r->status != HTTP_NON_AUTHORITATIVE
-             && r->status != HTTP_MULTIPLE_CHOICES
-             && r->status != HTTP_MOVED_PERMANENTLY
-             && r->status != HTTP_NOT_MODIFIED)
+        if (r->status != HTTP_OK && r->status != HTTP_NON_AUTHORITATIVE
+            && r->status != HTTP_MULTIPLE_CHOICES
+            && r->status != HTTP_MOVED_PERMANENTLY
+            && r->status != HTTP_NOT_MODIFIED) {
+            /* RFC2616 13.4 we are allowed to cache 200, 203, 206, 300, 301 or 410
+             * We don't cache 206, because we don't (yet) cache partial responses.
+             * We include 304 Not Modified here too as this is the origin server
+             * telling us to serve the cached copy.
+             */
+              reason = apr_pstrcat(p, "Response status %d", r->status);
+        } 
+        else if (exps != NULL && exp == APR_DATE_BAD) {
             /* if a broken Expires header is present, don't cache it */
-            || (exps != NULL && exp == APR_DATE_BAD)
+            reason = apr_pstrcat(p, "Broken expires header %s", exp);
+        }
+        else if (r->args && exps == NULL) {
             /* if query string present but no expiration time, don't cache it
              * (RFC 2616/13.9)
              */
-            || (r->args && exps == NULL)
+            reason = "Query string present but no expires header";
+        }
+        else if (r->status == HTTP_NOT_MODIFIED && (NULL == cache->handle)) {
             /* if the server said 304 Not Modified but we have no cache
              * file - pass this untouched to the user agent, it's not for us.
              */
-            || (r->status == HTTP_NOT_MODIFIED && (NULL == cache->handle))
+            reason = "HTTP Status 304 Not Modified";
+        }
+        else if (r->status == HTTP_OK && lastmods == NULL && etag == NULL 
+                 && (conf->no_last_mod_ignore ==0)) {
             /* 200 OK response from HTTP/1.0 and up without a Last-Modified
              * header/Etag 
              */
             /* XXX mod-include clears last_modified/expires/etags - this
              * is why we have an optional function for a key-gen ;-) 
              */
-            || (r->status == HTTP_OK && lastmods == NULL && etag == NULL 
-                && (conf->no_last_mod_ignore ==0))
+            reason = "No Last-Modified or Etag header";
+        }
+        else if (r->header_only) {
             /* HEAD requests */
-            || r->header_only
+            reason = "HTTP HEAD request";
+        }
+        else if (ap_cache_liststr(NULL, cc_out, "no-store", NULL)) {
             /* RFC2616 14.9.2 Cache-Control: no-store response
              * indicating do not cache, or stop now if you are
              * trying to cache it */
-            || ap_cache_liststr(NULL, cc_out, "no-store", NULL)
+            reason = "Cache-Control: no-store present";
+        }
+        else if (ap_cache_liststr(NULL, cc_out, "private", NULL)) {
             /* RFC2616 14.9.1 Cache-Control: private
              * this object is marked for this user's eyes only. Behave
              * as a tunnel.
              */
-            || ap_cache_liststr(NULL, cc_out, "private", NULL)
+            reason = "Cache-Control: private present";
+        }
+        else if (apr_table_get(r->headers_in, "Authorization") != NULL
+                 && !(ap_cache_liststr(NULL, cc_out, "s-maxage", NULL)
+                      || ap_cache_liststr(NULL, cc_out, "must-revalidate", NULL)
+                      || ap_cache_liststr(NULL, cc_out, "public", NULL))) {
             /* RFC2616 14.8 Authorisation:
              * if authorisation is included in the request, we don't cache,
              * but we can cache if the following exceptions are true:
@@ -572,16 +592,16 @@ static int cache_in_filter(ap_filter_t *f, apr_bucket_brigade *in)
              * 2) If Cache-Control: must-revalidate is included
              * 3) If Cache-Control: public is included
              */
-            || (apr_table_get(r->headers_in, "Authorization") != NULL
-                && !(ap_cache_liststr(NULL, cc_out, "s-maxage", NULL)
-                     || ap_cache_liststr(NULL, cc_out, "must-revalidate", NULL)
-                     || ap_cache_liststr(NULL, cc_out, "public", NULL)))
+            reason = "Authorization required";
+        }
+        else if (r->no_cache) {
             /* or we've been asked not to cache it above */
-            || r->no_cache) {
+            reason = "no_cache present";
+        }
 
+        if (reason) {
             ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
-                         "cache: response is not cachable");
-
+                         "cache: response not cached. Reason: %s", reason);
             /* remove this object from the cache 
              * BillS Asks.. Why do we need to make this call to remove_url?
              * leave it in for now..