MDL-40924 badges: Add caching to external badges

lib/badgeslib.php

@@ -1167,13 +1167,25 @@ function badges_bake($hash, $badgeid, $userid = 0, $pathhash = false) {
 /**
  * Returns external backpack settings and badges from this backpack.
  *
+ * This function first checks if badges for the user are cached and
+ * tries to retrieve them from the cache. Otherwise, badges are obtained
+ * through curl request to the backpack.
+ *
  * @param int $userid Backpack user ID.
+ * @param boolean $refresh Refresh badges collection in cache.
  * @return null|object Returns null is there is no backpack or object with backpack settings.
  */
-function get_backpack_settings($userid) {
+function get_backpack_settings($userid, $refresh = false) {
     global $DB;
     require_once(dirname(dirname(__FILE__)) . '/badges/lib/backpacklib.php');
 
+    // Try to get badges from cache first.
+    $badgescache = cache::make('core', 'externalbadges');
+    $out = $badgescache->get($userid);
+    if ($out !== false && !$refresh) {
+        return $out;
+    }
+    // Get badges through curl request to the backpack.
     $record = $DB->get_record('badge_backpack', array('userid' => $userid));
     if ($record) {
         $backpack = new OpenBadgesBackpackHandler($record);
@@ -1198,6 +1210,7 @@ function get_backpack_settings($userid) {
             $out->totalcollections = 0;
         }
 
+        $badgescache->set($userid, $out);
         return $out;
     }