MDL-57610 assignfeedback_editpdf: integration cleanup

* Add a note to upgrade.php to notify devs/admins of the new setting.
* Replace update_record with set_field.
* Add missing phpdoc.

lib/upgrade.txt

@@ -119,6 +119,8 @@ information provided here is intended especially for developers.
   - phone1
   - phone2
   - address
+* Added $CFG->conversionattemptlimit setting to config.php allowing a maximum number of retries before giving up conversion
+  of a given document by the assignfeedback_editpdf\task\convert_submissions task. Default value: 3.
 
 === 3.5 ===
 

mod/assign/feedback/editpdf/classes/event/observer.php

@@ -48,7 +48,7 @@ class observer {
 
     /**
      * Queue the submission for processing.
-     * @param $event The submission created/updated event.
+     * @param \mod_assign\event\base $event The submission created/updated event.
      */
     protected static function queue_conversion($event) {
         global $DB;

mod/assign/feedback/editpdf/classes/task/convert_submissions.php

@@ -70,8 +70,8 @@ class convert_submissions extends scheduled_task {
 
             // 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.
-            $record->attemptedconversions++;
-            $DB->update_record('assignfeedback_editpdf_queue', $record);
+            $DB->set_field('assignfeedback_editpdf_queue', 'attemptedconversions',
+                    $record->attemptedconversions + 1, ['id' => $record->id]);
 
             $assignmentid = $submission->assignment;
             $attemptnumber = $record->submissionattempt;