commit 813fdb4c8e2fc02cf4c5738e46b204f28d0763a3
Author: sf <sf@13f79535-47bb-0310-9956-ffa450edef68>
Date:   Sat Oct 2 14:44:20 2010 +0000

    core: Speed up config parsing if using a very large number of config
    files
    
    PR: 50002
    Submitted by: andrew cloudaccess net
    
    
    git-svn-id: http://svn.apache.org/repos/asf/httpd/httpd/trunk@1003808 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/include/util_cfgtree.h b/include/util_cfgtree.h
index 4da4c7d..791a5cc 100644
--- a/include/util_cfgtree.h
+++ b/include/util_cfgtree.h
@@ -64,6 +64,13 @@ struct ap_directive_t {
     const char *filename;
     /** The line number the directive was on */
     int line_num;
+
+    /** A short-cut towards the last directive node in the tree.
+     *  The value may not always be up-to-date but it always points to
+     *  somewhere in the tree, nearer to the tail.
+     *  This value is only set in the first node
+     */
+    struct ap_directive_t *last;
 };
 
 /**
diff --git a/server/config.c b/server/config.c
index dc9b3b6..a3d67f0 100644
--- a/server/config.c
+++ b/server/config.c
@@ -1284,11 +1284,30 @@ AP_DECLARE(const char *) ap_build_config(cmd_parms *parms,
     ap_directive_t *curr_parent = NULL;
     char *l = apr_palloc (temp_pool, MAX_STRING_LEN);
     const char *errmsg;
+    ap_directive_t **last_ptr = NULL;
+
+    if(current) {
+        /* If we have to traverse the whole tree again for every included
+         * config file, the required time grows as O(n^2) with the number of
+         * files. This can be a significant delay for large configurations.
+         * Therefore we cache a pointer to the last node.
+         */
+        last_ptr = &(current->last);
+
+        if(last_ptr && *last_ptr) {
+            current = *last_ptr;
+        }
+    }
 
     if (current != NULL) {
         while (current->next) {
             current = current->next;
         }
+
+        if(last_ptr) {
+            /* update cached pointer to last node */
+            *last_ptr = current;
+        }
     }
 
     while (!(ap_cfg_getline(l, MAX_STRING_LEN, parms->config_file))) {