yii2

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<?php
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/**
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 * @link https://www.yiiframework.com/
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 * @copyright Copyright (c) 2008 Yii Software LLC
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 * @license https://www.yiiframework.com/license/
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 */
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namespace yii\caching;
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/**
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 * DummyCache is a placeholder cache component.
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 *
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 * DummyCache does not cache anything. It is provided so that one can always configure
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 * a 'cache' application component and save the check of existence of `\Yii::$app->cache`.
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 * By replacing DummyCache with some other cache component, one can quickly switch from
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 * non-caching mode to caching mode.
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 *
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 * For more details and usage information on Cache, see the [guide article on caching](guide:caching-overview).
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 *
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 * @author Qiang Xue <qiang.xue@gmail.com>
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 * @since 2.0
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 */
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class DummyCache extends Cache
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{
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    /**
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     * Retrieves a value from cache with a specified key.
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     * This is the implementation of the method declared in the parent class.
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     * @param string $key a unique key identifying the cached value
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     * @return mixed|false the value stored in cache, false if the value is not in the cache or expired.
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     */
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    protected function getValue($key)
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    {
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        return false;
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    }
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    /**
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     * Stores a value identified by a key in cache.
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     * This is the implementation of the method declared in the parent class.
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     *
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     * @param string $key the key identifying the value to be cached
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     * @param mixed $value the value to be cached
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     * @param int $duration the number of seconds in which the cached value will expire. 0 means never expire.
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     * @return bool true if the value is successfully stored into cache, false otherwise
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     */
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    protected function setValue($key, $value, $duration)
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    {
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        return true;
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    }
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    /**
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     * Stores a value identified by a key into cache if the cache does not contain this key.
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     * This is the implementation of the method declared in the parent class.
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     * @param string $key the key identifying the value to be cached
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     * @param mixed $value the value to be cached
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     * @param int $duration the number of seconds in which the cached value will expire. 0 means never expire.
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     * @return bool true if the value is successfully stored into cache, false otherwise
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     */
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    protected function addValue($key, $value, $duration)
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    {
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        return true;
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    }
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    /**
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     * Deletes a value with the specified key from cache
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     * This is the implementation of the method declared in the parent class.
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     * @param string $key the key of the value to be deleted
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     * @return bool if no error happens during deletion
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     */
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    protected function deleteValue($key)
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    {
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        return true;
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    }
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    /**
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     * Deletes all values from cache.
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     * This is the implementation of the method declared in the parent class.
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     * @return bool whether the flush operation was successful.
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     */
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    protected function flushValues()
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    {
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        return true;
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    }
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}
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