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Adding documentation about the simple cache PSR-16 implementation
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‎components/cache.rst

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The Cache Component
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===================
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The Cache component provides an extended `PSR-6`_ implementation for adding
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cache to your applications. It is designed to have a low overhead and it
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ships with ready to use adapters for the most common caching backends.
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The Cache component provides an extended `PSR-6`_ implementation as well as
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a `PSR-16`_ "Simple Cache" implementation for adding cache to your applications.
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It is designed to have a low overhead and it ships with ready to use adapters
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for the most common caching backends.
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.. versionadded:: 3.1
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The Cache component was introduced in Symfony 3.1.
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.. versionadded:: 3.3
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The PSR-16 "Simple Cache" implementation was introduced in Symfony 3.3.
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Installation
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------------
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* :doc:`Install it via Composer </components/using_components>` (``symfony/cache`` on `Packagist`_);
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* Use the official Git repository (https://github.com/symfony/cache).
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Key Concepts
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------------
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Cache (PSR-6) Versus Simple Cache (PSR-16)
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------------------------------------------
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This component includes *two* different approaches to caching:
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:ref:`PSR-6 Caching <cache-component-psr6-caching>`:
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A fully-featured cache system, which includes cache "pools", more advanced
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cache "items", and :ref:`cache tagging for invalidation <TODO>`.
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:ref:`PSR-16 Simple Caching <cache-component-psr16-caching>`:
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A simple way to store, fetch and remove items from a cache.
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Both methods support the *same* cache adapters and will give you very similar performance.
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.. _cache-component-psr6-caching:
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Before starting to use the Cache component, it's important that you learn the
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meaning of some key concepts:
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More Advanced Caching (PSR-6)
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-----------------------------
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To use the more-advanced, PSR-6 Caching abilities, you'll need to learn its key
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concepts:
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**Item**
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A single unit of information stored as a key/value pair, where the key is
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filesystem, in a database, etc. The component provides several ready to use
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adapters for common caching backends (Redis, APCu, etc.)
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Basic Usage
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-----------
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Basic Usage (PSR-6)
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-------------------
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This component is an implementation of `PSR-6`_, which means that its basic API
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is the same as defined in the standard. Before starting to cache information,
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This part of the component is an implementation of `PSR-6`_, which means that its
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basic API is the same as defined in the standard. Before starting to cache information,
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create the cache pool using any of the built-in adapters. For example, to create
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a filesystem-based cache, instantiate :class:`Symfony\\Component\\Cache\\Adapter\\FilesystemAdapter`::
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// remove the cache item
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$cache->deleteItem('stats.num_products');
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Advanced Usage
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--------------
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For a list of all of the supported adapters, see :doc:`/components/cache/cache_pools`.
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Advanced Usage (PSR-6)
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----------------------
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.. toctree::
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:glob:
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:maxdepth: 1
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cache/*
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.. _cache-component-psr16-caching:
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Simple Caching (PSR-16)
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-----------------------
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This part of the component is an implementation of `PSR-16`_, which means that its
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basic API is the same as defined in the standard. First, create a cache object from
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one of the built-in cache clases. For example, to create a filesystem-based cache,
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instantiate :class:`Symfony\\Component\\Cache\\Simple\\FilesystemCache`::
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use Symfony\Component\Cache\Simple\FilesystemCache;
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$cache = new FilesystemCache();
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Now you can create, retrieve, update and delete items using this object::
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// save a new item in the cache
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$cache->set('stats.num_products', 4711);
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// or set it with a custom ttl
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// $cache->set('stats.num_products', 4711, 3600);
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// retrieve the cache item
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if (!$cache->has('stats.num_products')) {
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// ... item does not exists in the cache
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}
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// retrieve the value stored by the item
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$numProducts = $cache->get('stats.num_products');
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// or specify a default value, if the key doesn't exist
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// $numProducts = $cache->get('stats.num_products', 100);
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// remove the cache key
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$cache->deleteItem('stats.num_products');
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// clear *all* cache keys
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$cache->clear();
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You can also work with multiple items at once::
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$cache->setMultiple([
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'stats.num_products' => 4711,
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'stats.num_users' => 1356,
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]);
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$stats = $cache->getMultiple([
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'stats.num_products',
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'stats.num_users',
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]);
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$cache->deleteMultiple([
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'stats.num_products',
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'stats.num_users',
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]);
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Available Simple Cache (PSR-16) Classes
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The following cache adapters are available:
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.. tip::
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To find out more about each of these classes, you can read th
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:doc:`PSR-6 Cache Pool </components/cache/cache_pools>` page. These "Simple"
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(PSR-16) cache classes aren't identical to the PSR-6 Adapters on that page, but
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each share constructor arguments and use-cases.
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* :class:`Symfony\\Component\\Cache\\Simple\\ApcuCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\ArrayCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\ChainCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\DoctrineCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\FilesystemCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\MemcachedCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\NullCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\PdoCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\PhpArrayCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\PhpFilesCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\RedisCache`
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* :class:`Symfony\\Component\\Cache\\Simple\\TraceableCache`
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.. _`PSR-6`: http://www.php-fig.org/psr/psr-6/
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.. _`PSR-16`: http://www.php-fig.org/psr/psr-16/
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.. _Packagist: https://packagist.org/packages/symfony/cache

‎components/cache/cache_pools.rst

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single: Redis Cache
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single: PDO Cache, Doctrine DBAL Cache
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Cache Pools
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===========
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Cache Pools & Supported Adapters
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================================
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Cache Pools are the logical repositories of cache items. They perform all the
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common operations on items, such as saving them or looking for them. Cache pools
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adapter, it's not limited to the shared memory of the current server, so you can
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store contents in a cluster of servers if needed.
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It requires to have installed Redis and have created a connection that implements
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the ``\Redis``, ``\RedisArray``, ``\RedisCluster`` or ``\Predis`` classes::
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Before you start, make sure you have Redis running and have created a connection
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that implements the ``\Redis``, ``\RedisArray``, ``\RedisCluster`` or ``\Predis``
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classes::
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use Symfony\Component\Cache\Adapter\RedisAdapter;
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$redisConnection = RedisAdapter::createConnection('redis://localhost');
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$cache = new RedisAdapter($redisConnection);
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See the method's docblock for more options.
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Memcached Cache Adapter
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~~~~~~~~~~~~~~~~~~~~~~~
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This adapter stores the contents into a set of `Memcached`_ servers.
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Before you start, make sure you have Memcached running and have created a
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:phpclass:`Memcached` object::
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use Symfony\Component\Cache\Adapter\MemcachedAdapter;
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$cache = new MemcachedAdapter(
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// the object that stores a valid connection to your Memcached servers
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\Memcached $client,
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// the string prefixed to the keys of the items stored in this cache
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$namespace = '',
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// in seconds; applied to cache items that don't define their own lifetime
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// 0 means to store the cache items indefinitely (i.e. until the Memcached memory is deleted)
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$defaultLifetime = 0
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);
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The :method:`Symfony\\Component\\Cache\\Adapter\\Memcached::createConnection`
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helper allows creating a connection to a pool of Memcached server using a DSN configuration::
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$memcachedClient = MemcachedAdapter::createConnection(
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'memcached://user:pass@localhost?weight=33',
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// options, including username, password and Memcached::OPT_* options
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['persistent_id' => '_products_cache']
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);
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$memcachedClient = MemcachedAdapter::createConnection([
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array('192.168.1.100', 11211, 33),
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array('192.168.1.101', 11211, 33)
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]);
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$cache = new MemcachedAdapter($memcachedClient);
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See the method's docblock for more options.
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PDO & Doctrine DBAL Cache Adapter
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of a cache item, the second optional argument of ``ChainAdapter`` is the default
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lifetime applied to those cache items (by default it's ``0``).
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Traceable Adapter
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~~~~~~~~~~~~~~~~~
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This adapter wraps another adapter, and allows you to read a report of all of the
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"calls" made to the adapter, including how long actions took, cache hits, misses
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and more::
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use Symfony\Component\Cache\Adapter\TraceableAdapter;
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use Symfony\Component\Cache\Adapter\FilesystemAdapter;
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$fileCache = new FilesystemAdapter();
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$cache = new TraceableAdapter(array($fileCache));
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// work with the $cache adapter like normal
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// returns an array of TraceableAdapterEvent describing the calls
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$events = $cache->getCalls();
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Proxy Cache Adapter
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~~~~~~~~~~~~~~~~~~~
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$cacheIsEmpty = $cache->clear();
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.. _`Doctrine Cache`: https://github.com/doctrine/cache
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.. _`Memcached`: http://php.net/manual/en/book.memcached.php

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