=== modified file 'src/external_acl.cc'
--- src/external_acl.cc	2011-01-25 05:31:59 +0000
+++ src/external_acl.cc	2011-01-25 11:25:02 +0000
@@ -730,11 +730,16 @@
     entry = ch->extacl_entry;
 
     if (entry) {
-        if (cbdataReferenceValid(entry) && entry->def == acl->def &&
-                strcmp((char *)entry->key, key) == 0) {
+        if (cbdataReferenceValid(entry) && entry->def == acl->def) {
             /* Ours, use it.. */
         } else {
             /* Not valid, or not ours.. get rid of it */
+            debugs(82, 9, "aclMatchExternal: entry " << entry << " not valid or not ours. Discarded.");
+            if (entry) {
+                debugs(82, 9, "aclMatchExternal: entry def=" << entry->def << ", our def=" << acl->def);
+                key = makeExternalAclKey(ch, acl);
+                debugs(82, 9, "aclMatchExternal: entry key='" << (char *)entry->key << "', our key='" << key << "'");
+            }
             cbdataReferenceDone(ch->extacl_entry);
             entry = NULL;
         }
@@ -743,6 +748,7 @@
     external_acl_message = "MISSING REQUIRED INFORMATION";
 
     if (!entry) {
+        debugs(82, 9, "aclMatchExternal: No helper entry available");
         if (acl->def->require_auth) {
             int ti;
             /* Make sure the user is authenticated */
@@ -850,6 +856,10 @@
 static void
 external_acl_cache_touch(external_acl * def, external_acl_entry * entry)
 {
+    // this must not be done when nothing is being cached.
+    if (def->cache_size <= 0 || (def->ttl <= 0 && entry->result == 1) || (def->negative_ttl <= 0 && entry->result != 1));
+        return;
+
     dlinkDelete(&entry->lru, &def->lru_list);
     dlinkAdd(entry, &entry->lru, &def->lru_list);
 }
@@ -1091,6 +1101,9 @@
 static int
 external_acl_entry_expired(external_acl * def, external_acl_entry * entry)
 {
+    if (def->cache_size <= 0)
+        return 1;
+
     if (entry->date + (entry->result == 1 ? def->ttl : def->negative_ttl) < squid_curtime)
         return 1;
     else
@@ -1100,6 +1113,9 @@
 static int
 external_acl_grace_expired(external_acl * def, external_acl_entry * entry)
 {
+    if (def->cache_size <= 0)
+        return 1;
+
     int ttl;
     ttl = entry->result == 1 ? def->ttl : def->negative_ttl;
     ttl = (ttl * (100 - def->grace)) / 100;
@@ -1113,12 +1129,24 @@
 static external_acl_entry *
 external_acl_cache_add(external_acl * def, const char *key, ExternalACLEntryData const & data)
 {
-    ExternalACLEntry *entry = static_cast<ExternalACLEntry *>(hash_lookup(def->cache, key));
+    ExternalACLEntry *entry;
+
+    // do not bother caching this result if TTL is going to expire it immediately
+    if (def->cache_size <= 0 || (def->ttl <= 0 && data.result == 1) || (def->negative_ttl <= 0 && data.result != 1)) {
+        debugs(82,6, HERE);
+        entry = new ExternalACLEntry;
+        entry->key = xstrdup(key);
+        entry->update(data);
+        entry->def = def;
+        return entry;
+    }
+
+    entry = static_cast<ExternalACLEntry *>(hash_lookup(def->cache, key));
     debugs(82, 2, "external_acl_cache_add: Adding '" << key << "' = " << data.result);
 
     if (entry) {
         debugs(82, 3, "ExternalACLEntry::update: updating existing entry");
-        entry->update (data);
+        entry->update(data);
         external_acl_cache_touch(def, entry);
 
         return entry;
@@ -1126,7 +1154,7 @@
 
     entry = new ExternalACLEntry;
     entry->key = xstrdup(key);
-    entry->update (data);
+    entry->update(data);
 
     def->add(entry);
 
@@ -1136,7 +1164,7 @@
 static void
 external_acl_cache_delete(external_acl * def, external_acl_entry * entry)
 {
-    assert (entry->def == def);
+    assert(def->cache_size > 0 && entry->def == def);
     hash_remove_link(def->cache, entry);
     dlinkDelete(&entry->lru, &def->lru_list);
     def->cache_entries -= 1;
@@ -1200,7 +1228,7 @@
     char *status;
     char *token;
     char *value;
-    char *t;
+    char *t = NULL;
     ExternalACLEntryData entryData;
     entryData.result = 0;
     external_acl_entry *entry = NULL;
@@ -1313,12 +1341,15 @@
         entry = NULL;
 
     /* Check for a pending lookup to hook into */
-    for (node = def->queue.head; node; node = node->next) {
-        externalAclState *oldstatetmp = static_cast<externalAclState *>(node->data);
+    // only possible if we are caching results.
+    if (def->cache_size > 0) {
+        for (node = def->queue.head; node; node = node->next) {
+            externalAclState *oldstatetmp = static_cast<externalAclState *>(node->data);
 
-        if (strcmp(key, oldstatetmp->key) == 0) {
-            oldstate = oldstatetmp;
-            break;
+            if (strcmp(key, oldstatetmp->key) == 0) {
+                oldstate = oldstatetmp;
+                break;
+            }
         }
     }