From 3ebbfa966093e1d90297dcaa5d0470d1625c32cf Mon Sep 17 00:00:00 2001
From: martinlanghoff <martinlanghoff>
Date: Mon, 19 Mar 2007 05:50:00 +0000
Subject: [PATCH] Auto-linking filters: fix serious caching bug in forum
 mailouts

Autolinking of glossaries, activity, resources and wiki names were using a
trivial single-entry cache implemented with static vars. The cache was _not_
keyed on course.

This bug was visible during forum_cron() which walks many courses. The cache
would get "stuck" on the first course that had something to put in the cache.
All mailouts from there onwards would autolink to stuff in the wrong course.
---
 filter/activitynames/filter.php |  8 ++++++++
 mod/glossary/filter.php         | 17 +++++++++++++----
 mod/resource/filter.php         | 17 +++++++++++++----
 mod/wiki/filter.php             | 17 +++++++++++++----
 4 files changed, 47 insertions(+), 12 deletions(-)

diff --git a/filter/activitynames/filter.php b/filter/activitynames/filter.php
index 21c37582580..7fb4fe4201d 100644
--- a/filter/activitynames/filter.php
+++ b/filter/activitynames/filter.php
@@ -8,12 +8,20 @@
 
         global $CFG;
 
+        // Trivial-cache - keyed on $cachedcourseid
         static $activitylist;
+        static $cachedcourse;
 
         if (empty($courseid)) {
             $courseid = SITEID;
         }
 
+        // Initialise/invalidate our trivial cache if dealing with a different course
+        if (!isset($cachedcourseid) || $cachedcourseid !== (int)$courseid) {
+            $activitylist = array();
+        } 
+        $cachedcourseid = (int)$courseid;
+
         /// It may be cached
 
         if (empty($activitylist)) {
diff --git a/mod/glossary/filter.php b/mod/glossary/filter.php
index 5175dc3a2fc..6ba900518c1 100644
--- a/mod/glossary/filter.php
+++ b/mod/glossary/filter.php
@@ -3,17 +3,26 @@
 function glossary_filter($courseid, $text) {
     global $CFG;
 
+    // Trivial-cache - keyed on $cachedcourseid
     static $nothingtodo;
     static $conceptlist;
-
-    if (!empty($nothingtodo)) {   // We've been here in this page already
-        return $text;
-    }
+    static $cachedcourseid;
 
     if (empty($courseid)) {
         $courseid = SITEID;
     }
 
+    // Initialise/invalidate our trivial cache if dealing with a different course
+    if (!isset($cachedcourseid) || $cachedcourseid !== (int)$courseid) {
+        $conceptlist = array();
+        $nothingtodo = false;
+    } 
+    $cachedcourseid = (int)$courseid;
+
+    if ($nothingtodo === true) {
+        return $text;
+    }
+
 /// Create a list of all the concepts to search for.  It may be cached already.
 
     if (empty($conceptlist)) {
diff --git a/mod/resource/filter.php b/mod/resource/filter.php
index 33103379473..954ee9feab6 100644
--- a/mod/resource/filter.php
+++ b/mod/resource/filter.php
@@ -7,17 +7,26 @@
 
         global $CFG;
 
+        // Trivial-cache - keyed on $cachedcourseid
         static $nothingtodo;
         static $resourcelist;
-
-        if (!empty($nothingtodo)) {   // We've been here in this page already
-            return $text;
-        }
+        static $cachedcourseid;
 
         // if we don't have a courseid, we can't run the query, so
         if (empty($courseid)) {
             return $text;
         }
+
+        // Initialise/invalidate our trivial cache if dealing with a different course
+        if (!isset($cachedcourseid) || $cachedcourseid !== (int)$courseid) {
+            $resourcelist = array();
+            $nothingtodo = false;
+        } 
+        $cachedcourseid = (int)$courseid;
+
+        if ($nothingtodo === true) {
+            return $text;
+        }
         
     /// Create a list of all the resources to search for.  It may be cached already.
 
diff --git a/mod/wiki/filter.php b/mod/wiki/filter.php
index 554a888c754..d116790a643 100755
--- a/mod/wiki/filter.php
+++ b/mod/wiki/filter.php
@@ -10,17 +10,26 @@
 
         global $CFG;
 
+        // Trivial-cache - keyed on $cachedcourseid
         static $nothingtodo;
         static $wikipagelist;
-
-        if (!empty($nothingtodo)) {   // We've been here in this page already
-            return $text;
-        }
+        static $cachedcourseid;
 
         if (empty($courseid)) {
             $courseid = SITEID;
         }
 
+        // Initialise/invalidate our trivial cache if dealing with a different course
+        if (!isset($cachedcourseid) || $cachedcourseid !== (int)$courseid) {
+            $wikipagelist = array();
+            $nothingtodo = false;
+        } 
+        $cachedcourseid = (int)$courseid;
+
+        if (!empty($nothingtodo)) {   // We've been here in this page already
+            return $text;
+        }
+
 /// Create a list of all the wikis to search for.  It may be cached already.
 
         if (empty($wikipagelist)) {