Initial

system/Session/Handlers/MemcachedHandler.php

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+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Session\Handlers;
+
+use CodeIgniter\Session\Exceptions\SessionException;
+use Config\App as AppConfig;
+use Memcached;
+use ReturnTypeWillChange;
+
+/**
+ * Session handler using Memcache for persistence
+ */
+class MemcachedHandler extends BaseHandler
+{
+    /**
+     * Memcached instance
+     *
+     * @var Memcached|null
+     */
+    protected $memcached;
+
+    /**
+     * Key prefix
+     *
+     * @var string
+     */
+    protected $keyPrefix = 'ci_session:';
+
+    /**
+     * Lock key
+     *
+     * @var string|null
+     */
+    protected $lockKey;
+
+    /**
+     * Number of seconds until the session ends.
+     *
+     * @var int
+     */
+    protected $sessionExpiration = 7200;
+
+    /**
+     * @throws SessionException
+     */
+    public function __construct(AppConfig $config, string $ipAddress)
+    {
+        parent::__construct($config, $ipAddress);
+
+        if (empty($this->savePath)) {
+            throw SessionException::forEmptySavepath();
+        }
+
+        if ($this->matchIP === true) {
+            $this->keyPrefix .= $this->ipAddress . ':';
+        }
+
+        if (! empty($this->keyPrefix)) {
+            ini_set('memcached.sess_prefix', $this->keyPrefix);
+        }
+
+        $this->sessionExpiration = $config->sessionExpiration;
+    }
+
+    /**
+     * Re-initialize existing session, or creates a new one.
+     *
+     * @param string $path The path where to store/retrieve the session
+     * @param string $name The session name
+     */
+    public function open($path, $name): bool
+    {
+        $this->memcached = new Memcached();
+        $this->memcached->setOption(Memcached::OPT_BINARY_PROTOCOL, true); // required for touch() usage
+
+        $serverList = [];
+
+        foreach ($this->memcached->getServerList() as $server) {
+            $serverList[] = $server['host'] . ':' . $server['port'];
+        }
+
+        if (! preg_match_all('#,?([^,:]+)\:(\d{1,5})(?:\:(\d+))?#', $this->savePath, $matches, PREG_SET_ORDER)) {
+            $this->memcached = null;
+            $this->logger->error('Session: Invalid Memcached save path format: ' . $this->savePath);
+
+            return false;
+        }
+
+        foreach ($matches as $match) {
+            // If Memcached already has this server (or if the port is invalid), skip it
+            if (in_array($match[1] . ':' . $match[2], $serverList, true)) {
+                $this->logger->debug('Session: Memcached server pool already has ' . $match[1] . ':' . $match[2]);
+
+                continue;
+            }
+
+            if (! $this->memcached->addServer($match[1], $match[2], $match[3] ?? 0)) {
+                $this->logger->error('Could not add ' . $match[1] . ':' . $match[2] . ' to Memcached server pool.');
+            } else {
+                $serverList[] = $match[1] . ':' . $match[2];
+            }
+        }
+
+        if (empty($serverList)) {
+            $this->logger->error('Session: Memcached server pool is empty.');
+
+            return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Reads the session data from the session storage, and returns the results.
+     *
+     * @param string $id The session ID
+     *
+     * @return false|string Returns an encoded string of the read data.
+     *                      If nothing was read, it must return false.
+     */
+    #[ReturnTypeWillChange]
+    public function read($id)
+    {
+        if (isset($this->memcached) && $this->lockSession($id)) {
+            if (! isset($this->sessionID)) {
+                $this->sessionID = $id;
+            }
+
+            $data = (string) $this->memcached->get($this->keyPrefix . $id);
+
+            $this->fingerprint = md5($data);
+
+            return $data;
+        }
+
+        return '';
+    }
+
+    /**
+     * Writes the session data to the session storage.
+     *
+     * @param string $id   The session ID
+     * @param string $data The encoded session data
+     */
+    public function write($id, $data): bool
+    {
+        if (! isset($this->memcached)) {
+            return false;
+        }
+
+        if ($this->sessionID !== $id) {
+            if (! $this->releaseLock() || ! $this->lockSession($id)) {
+                return false;
+            }
+
+            $this->fingerprint = md5('');
+            $this->sessionID   = $id;
+        }
+
+        if (isset($this->lockKey)) {
+            $this->memcached->replace($this->lockKey, time(), 300);
+
+            if ($this->fingerprint !== ($fingerprint = md5($data))) {
+                if ($this->memcached->set($this->keyPrefix . $id, $data, $this->sessionExpiration)) {
+                    $this->fingerprint = $fingerprint;
+
+                    return true;
+                }
+
+                return false;
+            }
+
+            return $this->memcached->touch($this->keyPrefix . $id, $this->sessionExpiration);
+        }
+
+        return false;
+    }
+
+    /**
+     * Closes the current session.
+     */
+    public function close(): bool
+    {
+        if (isset($this->memcached)) {
+            if (isset($this->lockKey)) {
+                $this->memcached->delete($this->lockKey);
+            }
+
+            if (! $this->memcached->quit()) {
+                return false;
+            }
+
+            $this->memcached = null;
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Destroys a session
+     *
+     * @param string $id The session ID being destroyed
+     */
+    public function destroy($id): bool
+    {
+        if (isset($this->memcached, $this->lockKey)) {
+            $this->memcached->delete($this->keyPrefix . $id);
+
+            return $this->destroyCookie();
+        }
+
+        return false;
+    }
+
+    /**
+     * Cleans up expired sessions.
+     *
+     * @param int $max_lifetime Sessions that have not updated
+     *                          for the last max_lifetime seconds will be removed.
+     *
+     * @return false|int Returns the number of deleted sessions on success, or false on failure.
+     */
+    #[ReturnTypeWillChange]
+    public function gc($max_lifetime)
+    {
+        return 1;
+    }
+
+    /**
+     * Acquires an emulated lock.
+     *
+     * @param string $sessionID Session ID
+     */
+    protected function lockSession(string $sessionID): bool
+    {
+        if (isset($this->lockKey)) {
+            return $this->memcached->replace($this->lockKey, time(), 300);
+        }
+
+        $lockKey = $this->keyPrefix . $sessionID . ':lock';
+        $attempt = 0;
+
+        do {
+            if ($this->memcached->get($lockKey)) {
+                sleep(1);
+
+                continue;
+            }
+
+            if (! $this->memcached->set($lockKey, time(), 300)) {
+                $this->logger->error('Session: Error while trying to obtain lock for ' . $this->keyPrefix . $sessionID);
+
+                return false;
+            }
+
+            $this->lockKey = $lockKey;
+            break;
+        } while (++$attempt < 30);
+
+        if ($attempt === 30) {
+            $this->logger->error('Session: Unable to obtain lock for ' . $this->keyPrefix . $sessionID . ' after 30 attempts, aborting.');
+
+            return false;
+        }
+
+        $this->lock = true;
+
+        return true;
+    }
+
+    /**
+     * Releases a previously acquired lock
+     */
+    protected function releaseLock(): bool
+    {
+        if (isset($this->memcached, $this->lockKey) && $this->lock) {
+            if (
+                ! $this->memcached->delete($this->lockKey)
+                && $this->memcached->getResultCode() !== Memcached::RES_NOTFOUND
+            ) {
+                $this->logger->error('Session: Error while trying to free lock for ' . $this->lockKey);
+
+                return false;
+            }
+
+            $this->lockKey = null;
+            $this->lock    = false;
+        }
+
+        return true;
+    }
+}