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vendor/yiisoft/yii2/web/CacheSession.php

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+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\web;
+
+use Yii;
+use yii\caching\CacheInterface;
+use yii\di\Instance;
+
+/**
+ * CacheSession implements a session component using cache as storage medium.
+ *
+ * The cache being used can be any cache application component.
+ * The ID of the cache application component is specified via [[cache]], which defaults to 'cache'.
+ *
+ * Beware, by definition cache storage are volatile, which means the data stored on them
+ * may be swapped out and get lost. Therefore, you must make sure the cache used by this component
+ * is NOT volatile. If you want to use database as storage medium, [[DbSession]] is a better choice.
+ *
+ * The following example shows how you can configure the application to use CacheSession:
+ * Add the following to your application config under `components`:
+ *
+ * ```php
+ * 'session' => [
+ *     'class' => 'yii\web\CacheSession',
+ *     // 'cache' => 'mycache',
+ * ]
+ * ```
+ *
+ * @property bool $useCustomStorage Whether to use custom storage. This property is read-only.
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class CacheSession extends Session
+{
+    /**
+     * @var CacheInterface|array|string the cache object or the application component ID of the cache object.
+     * The session data will be stored using this cache object.
+     *
+     * After the CacheSession object is created, if you want to change this property,
+     * you should only assign it with a cache object.
+     *
+     * Starting from version 2.0.2, this can also be a configuration array for creating the object.
+     */
+    public $cache = 'cache';
+
+
+    /**
+     * Initializes the application component.
+     */
+    public function init()
+    {
+        parent::init();
+        $this->cache = Instance::ensure($this->cache, 'yii\caching\CacheInterface');
+    }
+
+    /**
+     * Returns a value indicating whether to use custom session storage.
+     * This method overrides the parent implementation and always returns true.
+     * @return bool whether to use custom storage.
+     */
+    public function getUseCustomStorage()
+    {
+        return true;
+    }
+
+    /**
+     * Session read handler.
+     * @internal Do not call this method directly.
+     * @param string $id session ID
+     * @return string the session data
+     */
+    public function readSession($id)
+    {
+        $data = $this->cache->get($this->calculateKey($id));
+
+        return $data === false ? '' : $data;
+    }
+
+    /**
+     * Session write handler.
+     * @internal Do not call this method directly.
+     * @param string $id session ID
+     * @param string $data session data
+     * @return bool whether session write is successful
+     */
+    public function writeSession($id, $data)
+    {
+        return $this->cache->set($this->calculateKey($id), $data, $this->getTimeout());
+    }
+
+    /**
+     * Session destroy handler.
+     * @internal Do not call this method directly.
+     * @param string $id session ID
+     * @return bool whether session is destroyed successfully
+     */
+    public function destroySession($id)
+    {
+        $cacheId = $this->calculateKey($id);
+        if ($this->cache->exists($cacheId) === false) {
+            return true;
+        }
+
+        return $this->cache->delete($cacheId);
+    }
+
+    /**
+     * Generates a unique key used for storing session data in cache.
+     * @param string $id session variable name
+     * @return mixed a safe cache key associated with the session variable name
+     */
+    protected function calculateKey($id)
+    {
+        return [__CLASS__, $id];
+    }
+}