MDL-24419 (2): Moved groupings cache to get_all_groupings function

There was a static cache inside course/lib.php. I need to access this
information in other places, so to avoid making two queries, I am
moving the cache into the groups_get_all_groupings function instead.

course/lib.php

@@ -1384,7 +1384,6 @@ function print_section($course, $section, $mods, $modnamesused, $absolute=false,
     static $strmovehere;
     static $strmovefull;
     static $strunreadpostsone;
-    static $groupings;
     static $modulenames;
 
     if (!isset($initialised)) {
@@ -1586,9 +1585,7 @@ function print_section($course, $section, $mods, $modnamesused, $absolute=false,
                 }
 
                 if (!empty($mod->groupingid) && has_capability('moodle/course:managegroups', get_context_instance(CONTEXT_COURSE, $course->id))) {
-                    if (!isset($groupings)) {
-                        $groupings = groups_get_all_groupings($course->id);
-                    }
+                    $groupings = groups_get_all_groupings($course->id);
                     echo " <span class=\"groupinglabel\">(".format_string($groupings[$mod->groupingid]->name).')</span>';
                 }
             } else {

lib/grouplib.php

@@ -229,24 +229,33 @@ function groups_get_user_groups($courseid, $userid=0) {
 }
 
 /**
- * Gets an array of all groupings in a specified course.
+ * Gets an array of all groupings in a specified course. This value is cached
+ * for a single course (so you can call it repeatedly for the same course
+ * without a performance penalty).
  *
  * @category group
- * @param int $courseid return only groupings in this with this courseid
- * @return array|bool Returns an array of the grouping objects or false if no records
- * or an error occurred.
+ * @param int $courseid return all groupings from course with this courseid
+ * @return array Returns an array of the grouping objects (empty if none)
  */
 function groups_get_all_groupings($courseid) {
-    global $CFG, $DB;
+    global $CFG, $DB, $GROUPLIB_CACHE;
 
-    return $DB->get_records_sql("SELECT *
-                                   FROM {groupings}
-                                  WHERE courseid = ?
-                               ORDER BY name ASC", array($courseid));
+    // Use cached data if available. (Note: We only cache a single request, so
+    // as not to waste memory if processing is happening for multiple courses.)
+    if (!empty($GROUPLIB_CACHE->groupings) &&
+            $GROUPLIB_CACHE->groupings->courseid == $courseid) {
+        return $GROUPLIB_CACHE->groupings->result;
+    }
+    if (empty($GROUPLIB_CACHE)) {
+        $GROUPLIB_CACHE = new stdClass();
+    }
+    $GROUPLIB_CACHE->groupings = new stdClass();
+    $GROUPLIB_CACHE->groupings->courseid = $courseid;
+    $GROUPLIB_CACHE->groupings->result =
+            $DB->get_records('groupings', array('courseid' => $courseid), 'name ASC');
+    return $GROUPLIB_CACHE->groupings->result;
 }
 
-
-
 /**
  * Determines if the user is a member of the given group.
  *

lib/phpunit/lib.php

@@ -545,7 +545,7 @@ class phpunit_util {
      * @return void
      */
     public static function reset_all_data($logchanges = false) {
-        global $DB, $CFG, $USER, $SITE, $COURSE, $PAGE, $OUTPUT, $SESSION;
+        global $DB, $CFG, $USER, $SITE, $COURSE, $PAGE, $OUTPUT, $SESSION, $GROUPLIB_CACHE;
 
         // reset global $DB in case somebody mocked it
         $DB = self::get_global_backup('DB');
@@ -615,6 +615,7 @@ class phpunit_util {
         get_string_manager()->reset_caches();
         events_get_handlers('reset');
         textlib::reset_caches();
+        $GROUPLIB_CACHE = null;
         //TODO: add more resets here and probably refactor them to new core function
 
         // purge dataroot directory

lib/setup.php

@@ -342,6 +342,14 @@ global $OUTPUT;
  */
 global $MCACHE;
 
+/**
+ * Cache used within grouplib to cache data within current request only.
+ *
+ * @global object $GROUPLLIB_CACHE
+ * @name $GROUPLIB_CACHE
+ */
+global $GROUPLIB_CACHE;
+
 /**
  * Full script path including all params, slash arguments, scheme and host.
  *