MDL-74271 context: Improve performance of block context creation

lib/accesslib.php

@@ -7603,16 +7603,23 @@ class context_block extends context {
     protected static function create_level_instances() {
         global $DB;
 
-        $sql = "SELECT ".CONTEXT_BLOCK.", bi.id
-                  FROM {block_instances} bi
-                 WHERE NOT EXISTS (SELECT 'x'
-                                     FROM {context} cx
-                                    WHERE bi.id = cx.instanceid AND cx.contextlevel=".CONTEXT_BLOCK.")";
-        $contextdata = $DB->get_recordset_sql($sql);
-        foreach ($contextdata as $context) {
-            context::insert_context_record(CONTEXT_BLOCK, $context->id, null);
-        }
-        $contextdata->close();
+        $sql = <<<EOF
+            INSERT INTO {context} (
+                contextlevel,
+                instanceid
+            ) SELECT
+                :contextlevel,
+                bi.id as instanceid
+               FROM {block_instances} bi
+               WHERE NOT EXISTS (
+                   SELECT 'x' FROM {context} cx WHERE bi.id = cx.instanceid AND cx.contextlevel = :existingcontextlevel
+               )
+        EOF;
+
+        $DB->execute($sql, [
+            'contextlevel' => CONTEXT_BLOCK,
+            'existingcontextlevel' => CONTEXT_BLOCK,
+        ]);
     }
 
     /**

lib/tests/context_block_test.php

@@ -0,0 +1,108 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+// Note: Technically this namespace is incorrect, but we should be moving to namespace things and core anyway.
+namespace core;
+
+/**
+ * Unit tests specifically for context_block.
+ *
+ * @package   core
+ * @category  phpunit
+ * @copyright 2022 Andrew Lyons <[email protected]>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @coversDefaultClass \context_block
+ */
+class context_block_test extends \advanced_testcase {
+
+    /**
+     * Test setup.
+     */
+    public function setUp(): void {
+        global $CFG;
+        require_once("{$CFG->libdir}/accesslib.php");
+    }
+
+    /**
+     * Ensure that block contexts are correctly created for blocks where they are missing.
+     *
+     * @covers ::create_level_instances
+     */
+    public function test_context_creation(): void {
+        global $DB;
+
+        $this->resetAfterTest();
+
+        // Create some parent contexts.
+        $generator = $this->getDataGenerator();
+        $user = $generator->create_user();
+        $coursecat = $generator->create_category();
+        $course = $generator->create_course(['category' => $coursecat->id]);
+        $activity = $generator->create_module('forum', ['course' => $course->id]);
+
+        $contextlist = [
+            \context_system::instance(),
+            \context_user::instance($user->id),
+            \context_coursecat::instance($coursecat->id),
+            \context_course::instance($course->id),
+            \context_module::instance($activity->cmid),
+        ];
+
+        // Create a number of blocks of different types in the DB only.
+        // This is typically seen when creating large numbers in an upgrade script.
+        $blocks = [];
+        for ($i = 0; $i < 10; $i++) {
+            foreach ($contextlist as $context) {
+                $blocks[] = $DB->insert_record('block_instances', [
+                    'blockname' => 'calendar_month',
+                    'parentcontextid' => $context->id,
+                    'showinsubcontexts' => 1,
+                    'requiredbytheme' => 0,
+                    'pagetypepattern' => 'my-index',
+                    'subpagepattern' => 1,
+                    'defaultregion' => 'content',
+                    'defaultweight' => 1,
+                    'timecreated' => time(),
+                    'timemodified' => time(),
+                ]);
+            }
+        }
+
+        // Test data created. Call \context_helper::create_instances() which will create the records, and fix the paths.
+        \context_helper::create_instances(CONTEXT_BLOCK);
+
+        foreach ($blocks as $blockid) {
+            $block = $DB->get_record('block_instances', ['id' => $blockid]);
+            $context = \context_block::instance($block->id);
+            $this->assertInstanceOf(\context_block::class, $context);
+
+            // Note. There is no point checking the instanceid because the context was fetched using this.
+
+            // Ensure that the contextlevel is correct.
+            $this->assertEquals(CONTEXT_BLOCK, $context->contextlevel);
+
+            // Fetch the parent context.
+            $parentcontext = $context->get_parent_context();
+
+            // This hsould match the parent context specified in the block instance configuration.
+            $this->assertEquals($block->parentcontextid, $parentcontext->id);
+
+            // Ensure that the path and depth are correctly specified.
+            $this->assertEquals($parentcontext->path . "/{$context->id}", $context->path);
+            $this->assertEquals($parentcontext->depth + 1, $context->depth);
+        }
+    }
+}