Merge branch 'MDL-43421-27' of git://github.com/mr-russ/moodle into M…

…OODLE_27_STABLE
moodle · Jan 26, 2015 · 73502d6 · 73502d6
2 parents cccb0c0 + b2fb93f
commit 73502d6
Showing 1 changed file with 13 additions and 1 deletion.
diff --git a/lib/datalib.php b/lib/datalib.php
@@ -1700,7 +1700,19 @@ function user_accesstime_log($courseid=0) {
             $last->userid     = $USER->id;
             $last->courseid   = $courseid;
             $last->timeaccess = $timenow;
-            $DB->insert_record_raw('user_lastaccess', $last, false);
+            try {
+                $DB->insert_record_raw('user_lastaccess', $last, false);
+            } catch (dml_write_exception $e) {
+                // During a race condition we can fail to find the data, then it appears.
+                // If we still can't find it, rethrow the exception.
+                $lastaccess = $DB->get_field('user_lastaccess', 'timeaccess', array('userid' => $USER->id,
+                                                                                    'courseid' => $courseid));
+                if ($lastaccess === false) {
+                    throw $e;
+                }
+                // If we did find it, the race condition was true and another thread has inserted the time for us.
+                // We can just continue without having to do anything.
+            }
 
         } else if ($timenow - $lastaccess <  LASTACCESS_UPDATE_SECS) {
             // no need to update now, it was updated recently in concurrent login ;-)