From 9aa9080756186f8a8a62936d5b0aaf0440b62d2e Mon Sep 17 00:00:00 2001
From: martinlanghoff <martinlanghoff>
Date: Mon, 19 Mar 2007 06:33:45 +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         | 15 ++++++++++++---
 mod/wiki/filter.php             | 17 +++++++++++++----
 4 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/filter/activitynames/filter.php b/filter/activitynames/filter.php
index 8ab80466b5..992f3809bf 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($activitylist)) {
diff --git a/mod/glossary/filter.php b/mod/glossary/filter.php
index a96013b75e..3a8b8a9eb2 100644
--- a/mod/glossary/filter.php
+++ b/mod/glossary/filter.php
@@ -3,17 +3,26 @@
 function glossary_filter($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 8f28f9b5ac..f6080ef906 100644
--- a/mod/resource/filter.php
+++ b/mod/resource/filter.php
@@ -7,15 +7,24 @@
 
         global $CFG;
 
+        // Trivial-cache - keyed on $cachedcourseid
         static $nothingtodo;
         static $resourcelist;
+        static $cachedcourseid;
 
-        if (!empty($nothingtodo)) {   // We've been here in this page already
+        // if we don't have a courseid, we can't run the query, so
+        if (empty($courseid)) {
             return $text;
         }
 
-        // if we don't have a courseid, we can't run the query, so
-        if (empty($courseid)) {
+        // Initialise/invalidate our trivial cache if dealing with a different course
+        if (!isset($cachedcourseid) || $cachedcourseid !== (int)$courseid) {
+            $resourcelist = array();
+            $nothingtodo = false;
+        } 
+        $cachedcourseid = (int)$courseid;
+
+        if ($nothingtodo === true) {
             return $text;
         }
         
diff --git a/mod/wiki/filter.php b/mod/wiki/filter.php
index 554a888c75..d116790a64 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)) {
-- 
2.39.5