From 02cca994d02eb53086bc35aacb11f6162c851adf Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Sun, 23 Jun 2013 23:40:26 +0100
Subject: [PATCH 1/1] MDL-40280: Improve performance of
 coursecat::make_categories_list

---
 lib/coursecatlib.php | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/lib/coursecatlib.php b/lib/coursecatlib.php
index ba549e1..6969ed3 100644
--- a/lib/coursecatlib.php
+++ b/lib/coursecatlib.php
@@ -1881,6 +1881,7 @@ class coursecat implements renderable, cacheable_object, IteratorAggregate {
         } else if ($baselist !== false) {
             $thislist = array_keys($baselist);
         }
+        $changedbase = false;
 
         if ($baselist === false) {
             // We don't have $baselist cached, retrieve it. Retrieve $thislist again in any case.
@@ -1912,7 +1913,7 @@ class coursecat implements renderable, cacheable_object, IteratorAggregate {
                 }
             }
             $rs->close();
-            $coursecatcache->set($basecachekey, $baselist);
+            $changedbase = true;
             if (!empty($requiredcapability)) {
                 $coursecatcache->set($thiscachekey, join(',', $thislist));
             }
@@ -1935,14 +1936,36 @@ class coursecat implements renderable, cacheable_object, IteratorAggregate {
         // Now build the array of strings to return, mind $separator and $excludeid.
         $names = array();
         foreach ($thislist as $id) {
-            $path = preg_split('|/|', $baselist[$id]['path'], -1, PREG_SPLIT_NO_EMPTY);
-            if (!$excludeid || !in_array($excludeid, $path)) {
+            if (!isset($baselist[$id])) {
+                // This should not happen - find out why it does.
+                continue;
+            }
+
+            if ($excludeid) {
+                if ($excludeid === $id) {
+                    // This is an exact match.
+                    continue;
+                }
+                if (strpos($baselist[$id]['path'], "/{$excludeid}/") !== false) {
+                    // If an ID is surrounded by the separator, then it is a parent.
+                    continue;
+                }
+            }
+
+            if (!isset($baselist[$id]['namedpath'])) {
+                $path = preg_split('|/|', $baselist[$id]['path'], -1, PREG_SPLIT_NO_EMPTY);
                 $namechunks = array();
                 foreach ($path as $parentid) {
                     $namechunks[] = $baselist[$parentid]['name'];
                 }
-                $names[$id] = join($separator, $namechunks);
+                $baselist[$id]['namedpath'] = join($separator, $namechunks);
+                $changedbase = true;
             }
+            $names[$id] = $baselist[$id]['namedpath'];
+
+        }
+        if ($changedbase) {
+            $coursecatcache->set($basecachekey, $baselist);
         }
         return $names;
     }
-- 
1.8.0.1