From 86dced433eb402e5f59943104a2e932b2f7acdcf Mon Sep 17 00:00:00 2001
From: Tony Butler <tonyjbutler@gmail.com>
Date: Fri, 11 Jul 2014 12:10:50 +0100
Subject: [PATCH] MDL-43908 mod_assign: Remove redundant code and improve SQL
 query

Signed-off-by: Tony Butler <tonyjbutler@gmail.com>
---
 mod/assign/locallib.php | 34 +++++++++-------------------------
 1 file changed, 9 insertions(+), 25 deletions(-)

diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index bbc79b64874..14962c6ea38 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -1599,17 +1599,17 @@ class assign {
 
         // Collect all submissions from the past 24 hours that require mailing.
         // Submissions are excluded if the assignment is hidden in the gradebook.
-        $sql = 'SELECT g.id as gradeid, a.course, a.name, a.blindmarking, a.revealidentities,
-                       g.*, g.timemodified as lastmodified
+        $sql = "SELECT g.id as gradeid, a.course, a.name, a.blindmarking, a.revealidentities,
+                       g.*, g.timemodified as lastmodified, cm.id as cmid
                  FROM {assign} a
                  JOIN {assign_grades} g ON g.assignment = a.id
             LEFT JOIN {assign_user_flags} uf ON uf.assignment = a.id AND uf.userid = g.userid
-                 JOIN {course_modules} cm ON cm.course = a.course
-                 JOIN {modules} md ON md.id = cm.module
+                 JOIN {course_modules} cm ON cm.course = a.course AND cm.instance = a.id
+                 JOIN {modules} md ON md.id = cm.module AND md.name = 'assign'
                  JOIN {grade_items} gri ON gri.iteminstance = a.id AND gri.courseid = a.course AND gri.itemmodule = md.name
                  WHERE g.timemodified >= :yesterday AND
                        g.timemodified <= :today AND
-                       uf.mailed = 0 AND gri.hidden = 0';
+                       uf.mailed = 0 AND gri.hidden = 0";
 
         $params = array('yesterday' => $yesterday, 'today' => $timenow);
         $submissions = $DB->get_records_sql($sql, $params);
@@ -1642,9 +1642,6 @@ class assign {
             unset($courseidsql);
             unset($params);
 
-            // Simple array we'll use for caching modules.
-            $modcache = array();
-
             // Message students about new feedback.
             foreach ($submissions as $submission) {
 
@@ -1686,22 +1683,10 @@ class assign {
                     continue;
                 }
 
-                if (!array_key_exists($submission->assignment, $modcache)) {
-                    $mod = get_coursemodule_from_instance('assign', $submission->assignment, $course->id);
-                    if (empty($mod)) {
-                        mtrace('Could not find course module for assignment id ' . $submission->assignment);
-                        continue;
-                    }
-                    $modcache[$submission->assignment] = $mod;
-                } else {
-                    $mod = $modcache[$submission->assignment];
-                }
-                // Context lookups are already cached.
-                $contextmodule = context_module::instance($mod->id);
-
-                // Get assignment visibility information for user.
                 $modinfo = get_fast_modinfo($course, $user->id);
-                $cm = $modinfo->get_cm($mod->id);
+                $cm = $modinfo->get_cm($submission->cmid);
+                // Context lookups are already cached.
+                $contextmodule = context_module::instance($cm->id);
 
                 if (!$cm->uservisible) {
                     // Hold mail notification for assignments the user cannot access until later.
@@ -1724,7 +1709,7 @@ class assign {
                                                    $messagetype,
                                                    $eventtype,
                                                    $updatetime,
-                                                   $mod,
+                                                   $cm,
                                                    $contextmodule,
                                                    $course,
                                                    $modulename,
@@ -1752,7 +1737,6 @@ class assign {
 
             // Free up memory just to be sure.
             unset($courses);
-            unset($modcache);
         }
 
         // Update calendar events to provide a description.