Merge branch 'MDL-43975-master' of https://github.com/sammarshallou/moodle

config-dist.php

@@ -240,6 +240,14 @@ $CFG->admin = 'admin';
 //      $CFG->session_memcached_acquire_lock_timeout = 120;
 //      $CFG->session_memcached_lock_expire = 7200;       // Ignored if memcached extension <= 2.1.0
 //
+//   Memcache session handler (requires memcached server and memcache extension):
+//      $CFG->session_handler_class = '\core\session\memcache';
+//      $CFG->session_memcache_save_path = '127.0.0.1:11211';
+//      $CFG->session_memcache_acquire_lock_timeout = 120;
+//      ** NOTE: Memcache extension has less features than memcached and may be
+//         less reliable. Use memcached where possible or if you encounter
+//         session problems. **
+//
 // Following setting allows you to alter how frequently is timemodified updated in sessions table.
 //      $CFG->session_update_timemodified_frequency = 20; // In seconds.
 //

lib/classes/session/memcache.php

@@ -0,0 +1,170 @@
+<?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/>.
+
+/**
+ * Memcache based session handler.
+ *
+ * This is based on the memcached code. It lacks some features, such as
+ * locking options, but appears to work in practice.
+ *
+ * @package core
+ * @copyright 2014 The Open University
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core\session;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Memcache based session handler.
+ *
+ * @package core
+ * @copyright 2014 The Open University
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class memcache extends handler {
+    /**
+     * Creates new instance of handler.
+     */
+    public function __construct() {
+        global $CFG;
+
+        if (empty($CFG->session_memcache_save_path)) {
+            $this->savepath = '';
+        } else {
+            $this->savepath = $CFG->session_memcache_save_path;
+        }
+
+        if (empty($this->savepath)) {
+            $this->servers = array();
+        } else {
+            $this->servers = util::connection_string_to_memcache_servers($this->savepath);
+        }
+
+        if (!empty($CFG->session_memcache_acquire_lock_timeout)) {
+            $this->acquiretimeout = (int)$CFG->session_memcache_acquire_lock_timeout;
+        }
+    }
+
+    /**
+     * Starts the session.
+     *
+     * @return bool success
+     */
+    public function start() {
+        $default = ini_get('max_execution_time');
+        set_time_limit($this->acquiretimeout);
+
+        $result = parent::start();
+
+        set_time_limit($default);
+        return $result;
+    }
+
+    /**
+     * Inits session handler.
+     */
+    public function init() {
+        if (!extension_loaded('memcache')) {
+            throw new exception('sessionhandlerproblem', 'error', '', null,
+                    'memcache extension is not loaded');
+        }
+        $version = phpversion('memcache');
+        if (!$version or version_compare($version, '2.2') < 0) {
+            throw new exception('sessionhandlerproblem', 'error', '', null,
+                    'memcache extension version must be at least 2.2');
+        }
+        if (empty($this->savepath)) {
+            throw new exception('sessionhandlerproblem', 'error', '', null,
+                    '$CFG->session_memcache_save_path must be specified in config.php');
+        }
+
+        ini_set('session.save_handler', 'memcache');
+        ini_set('session.save_path', $this->savepath);
+    }
+
+    /**
+     * Checks for existing session with given id.
+     *
+     * Note: this verifies the storage backend only, not the actual session records.
+     *
+     * @param string $sid PHP session ID
+     * @return bool true if session found.
+     */
+    public function session_exists($sid) {
+        if (!$this->servers) {
+            return false;
+        }
+
+        $memcache = $this->get_memcache();
+        $value = $memcache->get($sid);
+        $memcache->close();
+
+        return ($value !== false);
+    }
+
+    /**
+     * Gets the memcache object with all the servers added to it.
+     *
+     * @return \Memcache Initialised memcache object
+     */
+    protected function get_memcache() {
+        $memcache = new \Memcache();
+        foreach ($this->servers as $server) {
+            $memcache->addServer($server[0], $server[1]);
+        }
+        return $memcache;
+    }
+
+    /**
+     * Kills all active sessions, the core sessions table is purged afterwards.
+     */
+    public function kill_all_sessions() {
+        global $DB;
+        if (!$this->servers) {
+            return;
+        }
+
+        $memcache = $this->get_memcache();
+
+        // Note: this can be significantly improved by fetching keys from memcache,
+        // but we need to make sure we are not deleting somebody else's sessions.
+
+        $rs = $DB->get_recordset('sessions', array(), 'id DESC', 'id, sid');
+        foreach ($rs as $record) {
+            $memcache->delete($record->sid);
+        }
+        $rs->close();
+
+        $memcache->close();
+    }
+
+    /**
+     * Kills one session, the session record is removed afterwards.
+     *
+     * @param string $sid PHP session ID
+     */
+    public function kill_session($sid) {
+        if (!$this->servers) {
+            return;
+        }
+
+        $memcache = $this->get_memcache();
+        $memcache->delete($sid);
+        $memcache->close();
+    }
+}

lib/classes/session/memcached.php

@@ -63,7 +63,7 @@ class memcached extends handler {
         if (empty($this->savepath)) {
             $this->servers = array();
         } else {
-            $this->servers = self::connection_string_to_servers($this->savepath);
+            $this->servers = util::connection_string_to_memcache_servers($this->savepath);
         }
 
         if (empty($CFG->session_memcached_prefix)) {
@@ -186,38 +186,4 @@ class memcached extends handler {
         $memcached->quit();
     }
 
-    /**
-     * Convert a connection string to an array of servers
-     *
-     * EG: Converts: "abc:123, xyz:789" to
-     *
-     *  array(
-     *      array('abc', '123'),
-     *      array('xyz', '789'),
-     *  )
-     *
-     * @copyright  2013 Moodlerooms Inc. (http://www.moodlerooms.com)
-     * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
-     * @author     Mark Nielsen
-     *
-     * @param string $str save_path value containing memcached connection string
-     * @return array
-     */
-    protected static function connection_string_to_servers($str) {
-        $servers = array();
-        $parts   = explode(',', $str);
-        foreach ($parts as $part) {
-            $part = trim($part);
-            $pos  = strrpos($part, ':');
-            if ($pos !== false) {
-                $host = substr($part, 0, $pos);
-                $port = substr($part, ($pos + 1));
-            } else {
-                $host = $part;
-                $port = 11211;
-            }
-            $servers[] = array($host, $port);
-        }
-        return $servers;
-    }
 }

lib/classes/session/util.php

@@ -0,0 +1,75 @@
+<?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/>.
+
+/**
+ * Shared utility functions for session handlers.
+ *
+ * This contains functions that are shared between two or more handlers.
+ *
+ * @package core
+ * @copyright 2014 The Open University
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core\session;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Shared utility functions for session handlers.
+ *
+ * This contains functions that are shared between two or more handlers.
+ *
+ * @package core
+ * @copyright 2014 The Open University
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+abstract class util {
+    /**
+     * Convert a connection string to an array of servers
+     *
+     * EG: Converts: "abc:123, xyz:789" to
+     *
+     *  array(
+     *      array('abc', '123'),
+     *      array('xyz', '789'),
+     *  )
+     *
+     * @copyright  2013 Moodlerooms Inc. (http://www.moodlerooms.com)
+     * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+     * @author     Mark Nielsen
+     *
+     * @param string $str save_path value containing memcached connection string
+     * @return array
+     */
+    public static function connection_string_to_memcache_servers($str) {
+        $servers = array();
+        $parts   = explode(',', $str);
+        foreach ($parts as $part) {
+            $part = trim($part);
+            $pos  = strrpos($part, ':');
+            if ($pos !== false) {
+                $host = substr($part, 0, $pos);
+                $port = substr($part, ($pos + 1));
+            } else {
+                $host = $part;
+                $port = 11211;
+            }
+            $servers[] = array($host, $port);
+        }
+        return $servers;
+    }
+}