maj conversion task

classes/task/convert_submissions.php

@@ -58,15 +58,21 @@ class convert_submissions extends scheduled_task {
 
         $assignmentcache = array();
 
+        $conversionattemptlimit = !empty($CFG->conversionattemptlimit) ? $CFG->conversionattemptlimit : 3;
         foreach ($records as $record) {
             $submissionid = $record->submissionid;
             $submission = $DB->get_record('assign_submission', array('id' => $submissionid), '*', IGNORE_MISSING);
-            if (!$submission) {
-                // Submission no longer exists.
+            if (!$submission || $record->attemptedconversions >= $conversionattemptlimit) {
+                // Submission no longer exists; or we've exceeded the conversion attempt limit.
                 $DB->delete_records('assignfeedback_editpp_queue', array('id' => $record->id));
                 continue;
             }
 
+            // Record that we're attempting the conversion ahead of time.
+            // We can't do this afterwards as its possible for the conversion process to crash the script entirely.
+            $DB->set_field('assignfeedback_editpp_queue', 'attemptedconversions',
+                    $record->attemptedconversions + 1, ['id' => $record->id]);
+
             $assignmentid = $submission->assignment;
             $attemptnumber = $record->submissionattempt;
 
@@ -96,13 +102,12 @@ class convert_submissions extends scheduled_task {
             foreach ($users as $userid) {
                 try {
                     $combineddocument = document_services::get_combined_pdf_for_attempt($assignment, $userid, $attemptnumber);
-                    $status = $combineddocument->get_status();
-
                     switch ($combineddocument->get_status()) {
                         case combined_document::STATUS_READY:
+                        case combined_document::STATUS_READY_PARTIAL:
                         case combined_document::STATUS_PENDING_INPUT:
                             // The document has not been converted yet or is somehow still ready.
-                            continue;
+                            continue 2;
                     }
                     document_services::get_page_images_for_attempt(
                             $assignment, $userid, $attemptnumber, false