Add openlms Redis Cluster cache store

cache/stores/rediscluster/README.md

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+# RedisCluster Cache Store for Moodle™
+
+A Moodle cache store plugin for [RedisCluster](https://redis.io/topics/cluster-tutorial).
+
+## Requirements
+
+* A Redis Cluster (version 4.0 or better)
+* [PhpRedis](https://github.com/phpredis/phpredis) extension (version 4.0 or better)
+* php-igbinary if using igbinary as the serialization method (recommended)
+
+## Features
+
+### Cache store
+
+This is the main use of this plugin - providing a way to use a Redis Cluster as a Moodle™ cache.
+
+Configurable options:
+* failover mode: how phpredis handles reads/writes, one of:
+  - none
+  - error (reads from a slave on error)
+  - distribute (distributes reads over masters/slaves)
+* serializer: igbinary or php
+* compression: compresses data stored in redis - (de)compression occuring within phpredis
+
+### Session handler
+
+Moodle™ can be configured to use the Redis Cluster (or a different one) as the session store by setting:
+
+`$CFG->session_handler_class = '\cachestore_rediscluster\session';`
+
+Configuration options can be set with:
+
+```
+$CFG->session_rediscluster = [
+    'server' => '192.168.1.100:6379',
+    'serversecondary' => '192.168.1.101:6379:,
+    'prefix' => "mdlsession_{$CFG->dbname}:",
+    'acquire_lock_timeout' => 60,
+    'lock_expire' => 600,
+    'max_waiters' => 10,
+];
+```
+
+The only required setting in the above array is `server`.
+
+The following options govern session locking:
+
+* acquire_lock_timeout: How long to wait for a lock to be released before giving up
+* lock_expire: How long before a lock is released automatically
+* max_waiters: How many threads can a session have waiting for a lock
+
+Max waiters lets you define how many how many php threads a single user is allowed to have waiting for a session lock. Requests that don't take a session lock are unaffected.
+
+By default, max_waiters is set to 10. Set it to 0 to use default Moodle™ behaviour.
+
+Scripts with the `NO_SESSION_LOCK` define set to `true` ignore the max waiter behaviour.
+
+### auth_saml2 session handler
+
+If you use the `auth_saml2` plugin, you can configure it to use Redis Cluster for session storage by setting:
+
+`$CFG->auth_saml2_store = '\\cachestore_rediscluster\\auth_saml2_store';`
+
+Configuration options can then be set with:
+```
+$CFG->auth_saml2_rediscluster = [
+    // The same options as are available in the standard session handler are supported here.
+];
+```
+
+## License
+Copyright (c) 2021 Open LMS (https://www.openlms.net)
+
+This program 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.
+
+This program 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
+this program.  If not, see <http://www.gnu.org/licenses/>.

cache/stores/rediscluster/addinstanceform.php

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+<?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/>.
+
+/**
+ * RedisCluster Cache Store - Add instance form
+ *
+ * @package   cachestore_rediscluster
+ * @copyright 2013 Adam Durana
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+require_once($CFG->dirroot.'/cache/forms.php');
+
+/**
+ * Form for adding instance of RedisCluster Cache Store.
+ *
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class cachestore_rediscluster_addinstance_form extends cachestore_addinstance_form {
+    /**
+     * Builds the form for creating an instance.
+     */
+    protected function configuration_definition() {
+        $form = $this->_form;
+
+        if (!class_exists('RedisCluster')) {
+            return;
+        }
+
+        $form->addElement('text', 'server', get_string('server', 'cachestore_rediscluster'));
+        $form->addHelpButton('server', 'server', 'cachestore_rediscluster');
+        $form->addRule('server', get_string('required'), 'required');
+        $form->setType('server', PARAM_TEXT);
+
+        $form->addElement('text', 'serversecondary', get_string('serversecondary', 'cachestore_rediscluster'));
+        $form->addHelpButton('serversecondary', 'serversecondary', 'cachestore_rediscluster');
+        $form->addRule('serversecondary', get_string('required'), 'required');
+        $form->setType('serversecondary', PARAM_TEXT);
+
+        $form->addElement('text', 'prefix', get_string('prefix', 'cachestore_rediscluster'), array('size' => 16));
+        $form->setType('prefix', PARAM_TEXT); // We set to text but we have a rule to limit to alphanumext.
+        $form->addHelpButton('prefix', 'prefix', 'cachestore_rediscluster');
+        $form->addRule('prefix', get_string('prefixinvalid', 'cachestore_rediscluster'), 'regex', '#^[a-zA-Z0-9\-_]+$#');
+
+        $opts = [
+            RedisCluster::FAILOVER_NONE => get_string('failovernone', 'cachestore_rediscluster'),
+            RedisCluster::FAILOVER_ERROR => get_string('failovererror', 'cachestore_rediscluster'),
+            RedisCluster::FAILOVER_DISTRIBUTE => get_string('failoverdistribute', 'cachestore_rediscluster'),
+        ];
+        // Experimental setting, only add it if its available.
+        // https://github.com/phpredis/phpredis/pull/1896 .
+        if (defined('RedisCluster::FAILOVER_PREFERRED')) {
+            $opts[RedisCluster::FAILOVER_PREFERRED] = get_string('failoverpreferred', 'cachestore_rediscluster');
+        }
+        $form->addElement('select', 'failover', get_string('failover', 'cachestore_rediscluster'), $opts);
+        $form->addHelpButton('failover', 'failover', 'cachestore_rediscluster');
+        $form->setDefault('failover', RedisCluster::FAILOVER_NONE);
+
+        if (defined('RedisCluster::FAILOVER_PREFERRED')) {
+            $form->addElement('text', 'preferrednodes', get_string('preferrednodes', 'cachestore_rediscluster'));
+            $form->addHelpButton('preferrednodes', 'preferrednodes', 'cachestore_rediscluster');
+            $form->disabledIf('preferrednodes', 'failover', 'neq', RedisCluster::FAILOVER_PREFERRED);
+            $form->setType('preferrednodes', PARAM_TEXT);
+            $form->setDefault('preferrednodes', '');
+        }
+
+        $form->addElement('checkbox', 'persist', get_string('persist', 'cachestore_rediscluster'));
+        $form->addHelpButton('persist', 'persist', 'cachestore_rediscluster');
+        $form->setDefault('persist', 0);
+        $form->setType('persist', PARAM_BOOL);
+
+        $form->addElement('text', 'timeout', get_string('timeout', 'cachestore_rediscluster'));
+        $form->addHelpButton('timeout', 'timeout', 'cachestore_rediscluster');
+        $form->setType('timeout', PARAM_FLOAT);
+        $form->setDefault('timeout', '3.0');
+
+        $form->addElement('text', 'readtimeout', get_string('readtimeout', 'cachestore_rediscluster'));
+        $form->addHelpButton('readtimeout', 'readtimeout', 'cachestore_rediscluster');
+        $form->setType('readtimeout', PARAM_FLOAT);
+        $form->setDefault('readtimeout', '3.0');
+
+        $opts = [
+            Redis::SERIALIZER_PHP => get_string('serializerphp', 'cachestore_rediscluster'),
+            Redis::SERIALIZER_IGBINARY => get_string('serializerigbinary', 'cachestore_rediscluster'),
+        ];
+        $form->addElement('select', 'serializer', get_string('serializer', 'cachestore_rediscluster'), $opts);
+        $form->addHelpButton('serializer', 'serializer', 'cachestore_rediscluster');
+        $form->setDefault('serializer', Redis::SERIALIZER_PHP);
+
+        $opts = [
+            Redis::COMPRESSION_NONE => get_string('compressionnone', 'cachestore_rediscluster'),
+        ];
+
+        if (defined('Redis::COMPRESSION_LZ4')) {
+            $opts[Redis::COMPRESSION_LZ4] = get_string('compressionlz4', 'cachestore_rediscluster');
+        }
+
+        if (defined('Redis::COMPRESSION_LZF')) {
+            $opts[Redis::COMPRESSION_LZF] = get_string('compressionlzf', 'cachestore_rediscluster');
+        }
+        if (defined('Redis::COMPRESSION_ZSTD')) {
+            $opts[Redis::COMPRESSION_ZSTD] = get_string('compressionzstd', 'cachestore_rediscluster');
+        }
+        $form->addElement('select', 'compression', get_string('compression', 'cachestore_rediscluster'), $opts);
+        $form->addHelpButton('compression', 'compression', 'cachestore_rediscluster');
+        $form->setDefault('compression', Redis::COMPRESSION_NONE);
+
+    }
+}

cache/stores/rediscluster/classes/auth_saml2_store.php

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+<?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/>.
+
+/**
+ * RedisCluster store simpleSAMLphp class for auth/saml2.
+ *
+ * @package    cachestore_rediscluster
+ * @author     Adam Olley
+ * @copyright  Copyright (c) 2021 Open LMS (https://www.openlms.net)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace cachestore_rediscluster;
+
+defined('MOODLE_INTERNAL') || die();
+
+require_once($CFG->dirroot . '/auth/saml2/extlib/simplesamlphp/lib/SimpleSAML/Store.php');
+
+/**
+ * RedisCluster store simpleSAMLphp class for auth/saml2.
+ *
+ * @package    cachestore_rediscluster
+ * @copyright  Copyright (c) 2021 Open LMS (https://www.openlms.net)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class auth_saml2_store extends \SimpleSAML\Store {
+
+    /**
+     * The connection config for RedisCluster.
+     *
+     * @var string
+     */
+    protected $config;
+
+    /**
+     * The RedisCluster cachestore object.
+     *
+     * @var cachestore_rediscluster
+     */
+    protected $connection = null;
+
+    /**
+     * Create new instance of handler.
+     */
+    public function __construct() {
+        global $CFG;
+
+        $this->config = [
+            'compression' => \Redis::COMPRESSION_NONE,
+            'failover' => \RedisCluster::FAILOVER_NONE,
+            'persist' => false,
+            'preferrednodes' => null,
+            'prefix' => 'simpleSAMLphp.' . $CFG->dbname . '.',
+            'readtimeout' => 3.0,
+            'serializer' => \Redis::SERIALIZER_PHP,
+            'server' => null,
+            'serversecondary' => null,
+            'session' => false,
+            'timeout' => 3.0,
+        ];
+
+        foreach (array_keys($this->config) as $key) {
+            if (!empty($CFG->auth_saml2_rediscluster[$key])) {
+                $this->config[$key] = $CFG->auth_saml2_rediscluster[$key];
+            }
+        }
+
+        if (!$this->init()) {
+            throw new \coding_exception("Could not configure rediscluster for auth_saml2");
+        }
+    }
+
+    /**
+     * Init connection.
+     */
+    protected function init() {
+        global $CFG;
+
+        require_once("{$CFG->dirroot}/cache/stores/rediscluster/lib.php");
+
+        if (!extension_loaded('redis') || empty($this->config['server']) || !class_exists('RedisCluster')) {
+            return false;
+        }
+
+        $this->connection = new \cachestore_rediscluster(null, $this->config);
+        return true;
+    }
+
+    /**
+     * @param string   $type
+     * @param string   $key
+     * @param mixed    $value
+     * @param int|null $expire
+     */
+    public function set($type, $key, $value, $expire = null) {
+        $now = time();
+        if ($expire !== null && $expire > $now) {
+            $this->connection->command('setex', $this->make_key($type, $key), $expire - $now, $value);
+        } else {
+            $this->connection->command('set', $this->make_key($type, $key), $value);
+        }
+    }
+
+    /**
+     * @param string $type
+     * @param string $key
+     * @return mixed|null
+     */
+    public function get($type, $key) {
+        $value = $this->connection->command('get', $this->make_key($type, $key));
+        if ($value === false) {
+            $value = null;
+        }
+
+        return $value;
+    }
+
+    /**
+     * @param string $type
+     * @param string $key
+     */
+    public function delete($type, $key) {
+        $this->connection->command('unlink', $this->make_key($type, $key));
+    }
+
+    /**
+     * @param string $type
+     * @param string $key
+     * @return string
+     */
+    protected function make_key($type, $key) {
+        return $type . '.' . $key;
+    }
+}