Merge branch 'MDL-71014-cache-siteid' of https://github.com/brendanhe…

…ywood/moodle
moodle · Sep 2, 2021 · 6ae9f22 · 6ae9f22
2 parents 443a980 + 7b93808
commit 6ae9f22
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Showing 4 changed files with 47 additions and 14 deletions.
diff --git a/lib/accesslib.php b/lib/accesslib.php
@@ -6291,7 +6291,8 @@ public static function instance($instanceid = 0, $strictness = MUST_EXIST, $cach
             debugging('context_system::instance(): invalid $id parameter detected, should be 0');
         }
 
-        if (defined('SYSCONTEXTID') and $cache) { // dangerous: define this in config.php to eliminate 1 query/page
+        // SYSCONTEXTID is cached in local cache to eliminate 1 query per page.
+        if (defined('SYSCONTEXTID') and $cache) {
             if (!isset(context::$systemcontext)) {
                 $record = new stdClass();
                 $record->id           = SYSCONTEXTID;

diff --git a/lib/moodlelib.php b/lib/moodlelib.php
@@ -1457,8 +1457,6 @@ function set_config($name, $value, $plugin=null) {
  *
  * NOTE: this function is called from lib/db/upgrade.php
  *
- * @static string|false $siteidentifier The site identifier is not cached. We use this static cache so
- *     that we need only fetch it once per request.
  * @param string $plugin full component name
  * @param string $name default null
  * @return mixed hash-like object or single value, return false no config found
@@ -1467,8 +1465,6 @@ function set_config($name, $value, $plugin=null) {
 function get_config($plugin, $name = null) {
     global $CFG, $DB;
 
-    static $siteidentifier = null;
-
     if ($plugin === 'moodle' || $plugin === 'core' || empty($plugin)) {
         $forced =& $CFG->config_php_settings;
         $iscore = true;
@@ -1482,12 +1478,11 @@ function get_config($plugin, $name = null) {
         $iscore = false;
     }
 
-    if ($siteidentifier === null) {
+    if (!isset($CFG->siteidentifier)) {
         try {
-            // This may fail during installation.
-            // If you have a look at {@link initialise_cfg()} you will see that this is how we detect the need to
-            // install the database.
-            $siteidentifier = $DB->get_field('config', 'value', array('name' => 'siteidentifier'));
+            // This may throw an exception during installation, which is how we detect the
+            // need to install the database. For more details see {@see initialise_cfg()}.
+            $CFG->siteidentifier = $DB->get_field('config', 'value', array('name' => 'siteidentifier'));
         } catch (dml_exception $ex) {
             // Set siteidentifier to false. We don't want to trip this continually.
             $siteidentifier = false;
@@ -1499,7 +1494,7 @@ function get_config($plugin, $name = null) {
         if (array_key_exists($name, $forced)) {
             return (string)$forced[$name];
         } else if ($name === 'siteidentifier' && $plugin == 'core') {
-            return $siteidentifier;
+            return $CFG->siteidentifier;
         }
     }
 
@@ -1524,7 +1519,7 @@ function get_config($plugin, $name = null) {
     }
 
     if ($plugin === 'core') {
-        $result['siteidentifier'] = $siteidentifier;
+        $result['siteidentifier'] = $CFG->siteidentifier;
     }
 
     foreach ($forced as $key => $value) {

diff --git a/lib/setup.php b/lib/setup.php
@@ -651,6 +651,17 @@
     unset($dbhash);
 }
 
+// Load any immutable bootstrap config from local cache.
+$bootstrapcachefile = $CFG->localcachedir . '/bootstrap.php';
+if (is_readable($bootstrapcachefile)) {
+    try {
+        require_once($bootstrapcachefile);
+    } catch (Throwable $e) {
+        // If it is corrupted then attempt to delete it and it will be rebuilt.
+        @unlink($bootstrapcachefile);
+    }
+}
+
 // Load up any configuration from the config table or MUC cache.
 if (PHPUNIT_TEST) {
     phpunit_util::initialise_cfg();
@@ -752,8 +763,7 @@
 // initialise ME's - this must be done BEFORE starting of session!
 initialise_fullme();
 
-// define SYSCONTEXTID in config.php if you want to save some queries,
-// after install it must match the system context record id.
+// SYSCONTEXTID is cached in local cache to eliminate 1 query per page.
 if (!defined('SYSCONTEXTID')) {
     context_system::instance();
 }
@@ -1056,6 +1066,9 @@
     $PAGE = new moodle_page();
 }
 
+// Cache any immutable config locally to avoid constant DB lookups.
+initialise_local_config_cache();
+
 // Allow plugins to callback as soon possible after setup.php is loaded.
 $pluginswithfunction = get_plugins_with_function('after_config', 'lib.php');
 foreach ($pluginswithfunction as $plugins) {

diff --git a/lib/setuplib.php b/lib/setuplib.php
@@ -795,6 +795,30 @@ function initialise_cfg() {
     }
 }
 
+/**
+ * Cache any immutable config locally to avoid constant DB lookups.
+ *
+ * Only to be used only from lib/setup.php
+ */
+function initialise_local_config_cache() {
+    global $CFG;
+
+    $bootstrapcachefile = $CFG->localcachedir . '/bootstrap.php';
+
+    if (!empty($CFG->siteidentifier) && !file_exists($bootstrapcachefile)) {
+        $contents = "<?php
+// ********** This file is generated DO NOT EDIT **********
+\$CFG->siteidentifier = '" . addslashes($CFG->siteidentifier) . "';
+define('SYSCONTEXTID', ".SYSCONTEXTID.");
+";
+
+        $temp = $bootstrapcachefile . '.tmp' . uniqid();
+        file_put_contents($temp, $contents);
+        @chmod($temp, $CFG->filepermissions);
+        rename($temp, $bootstrapcachefile);
+    }
+}
+
 /**
  * Initialises $FULLME and friends. Private function. Should only be called from
  * setup.php.