MDL-73846 assignfeedback_editpdf: Add limit for convert_submissions task

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

@@ -54,7 +54,12 @@ class convert_submissions extends scheduled_task {
 
         require_once($CFG->dirroot . '/mod/assign/locallib.php');
 
-        $records = $DB->get_records('assignfeedback_editpdf_queue');
+        // Conversion speed varies significantly and mostly depends on the documents content.
+        // We don't want the task to get stuck forever trying to process the whole queue in one go,
+        // so fetch 100 records only to make sure the task will be working for reasonable time.
+        // With the task's default schedule, 100 records per run means the task is capable to process
+        // 9600 conversions per day (100 * 4 * 24).
+        $records = $DB->get_records('assignfeedback_editpdf_queue', [], '', '*', 0, 100);
 
         $assignmentcache = array();
 

mod/assign/feedback/editpdf/tests/editpdf_test.php

@@ -527,4 +527,41 @@ class assignfeedback_editpdf_testcase extends advanced_testcase {
         // No modification.
         $this->assertFalse($plugin->is_feedback_modified($grade, $data));
     }
+
+    /**
+     * Test Convert submissions scheduled task limit.
+     *
+     * @covers \assignfeedback_editpdf\task\convert_submissions
+     */
+    public function test_conversion_task_limit() {
+        global $DB;
+        $this->require_ghostscript();
+        $this->resetAfterTest();
+        cron_setup_user();
+
+        $course = $this->getDataGenerator()->create_course();
+        $assignopts = [
+            'assignsubmission_file_enabled' => 1,
+            'assignsubmission_file_maxfiles' => 1,
+            'assignfeedback_editpdf_enabled' => 1,
+            'assignsubmission_file_maxsizebytes' => 1000000,
+        ];
+        $assign = $this->create_instance($course, $assignopts);
+
+        // Generate 110 submissions.
+        for ($i = 0; $i < 110; $i++) {
+            $student = $this->getDataGenerator()->create_and_enrol($course, 'student');
+            $this->add_file_submission($student, $assign);
+        }
+        $this->assertEquals(110, $DB->count_records('assignfeedback_editpdf_queue'));
+
+        // Run the conversion task.
+        $task = new \assignfeedback_editpdf\task\convert_submissions;
+        ob_start();
+        $task->execute();
+        ob_end_clean();
+
+        // Confirm, that 100 records were processed and 10 were left for the next task run.
+        $this->assertEquals(10, $DB->count_records('assignfeedback_editpdf_queue'));
+    }
 }