Cache

Version: 4.2
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Warning: You are browsing the documentation for Symfony 4.2, which is no longer maintained.

Read the updated version of this page for Symfony 5.3 (the current stable version).

Cache

Using cache is a great way of making your application run quicker. The Symfony cache component is shipped with many adapters to different storages. Every adapter is developed for high performance.

Basic uses of the cache looks like this:

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use Symfony\Contracts\Cache\ItemInterface;

// The callable will only be executed on a cache miss.
$value = $pool->get('my_cache_key', function (ItemInterface $item) {
    $item->expiresAfter(3600);

    // ... do some HTTP request or heavy computations
    $computedValue = 'foobar';

    return $computedValue;
});

echo $value; // 'foobar'

// ... and to remove the cache key
$pool->delete('my_cache_key');

Symfony supports the Cache Contracts, PSR-6/16 and Doctrine Cache interfaces. You can read more about these at the component documentation.

New in version 4.2

The cache contracts were introduced in Symfony 4.2.

Configuring Cache with FrameworkBundle

When configuring the cache component there are a few concepts you should know of:

Pool
This is a service that you will interact with. Each pool will always have its own namespace and cache items. There is never a conflict between pools.
Adapter
An adapter is a template that you use to create Pools.
Provider
A provider is a service that some adapters are using to connect to the storage. Redis and Memcached are example of such adapters. If a DSN is used as the provider then a service is automatically created.

There are two pools that are always enabled by default. They are cache.app and cache.system. The system cache is used for things like annotations, serializer, and validation. The cache.app can be used in your code. You can configure which adapter (template) they use by using the app and system key like:

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# config/packages/cache.yaml
framework:
    cache:
        app: cache.adapter.filesystem
        system: cache.adapter.system

The Cache component comes with a series of adapters pre-configured:

Some of these adapters could be configured via shortcuts. Using these shortcuts will create pool with service id of cache.[type]

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# config/packages/cache.yaml
framework:
    cache:
        directory: '%kernel.cache_dir%/pools' # Only used with cache.adapter.filesystem

        # service: cache.doctrine
        default_doctrine_provider: 'app.doctrine_cache'
        # service: cache.psr6
        default_psr6_provider: 'app.my_psr6_service'
        # service: cache.redis
        default_redis_provider: 'redis://localhost'
        # service: cache.memcached
        default_memcached_provider: 'memcached://localhost'
        # service: cache.pdo
        default_pdo_provider: 'doctrine.dbal.default_connection'

Creating Custom (Namespaced) Pools

You can also create more customized pools:

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# config/packages/cache.yaml
framework:
    cache:
        default_memcached_provider: 'memcached://localhost'

        pools:
            # creates a "custom_thing.cache" service
            # autowireable via "CacheInterface $customThingCache"
            # uses the "app" cache configuration
            custom_thing.cache:
                adapter: cache.app

            # creates a "my_cache_pool" service
            # autowireable via "CacheInterface $myCachePool"
            my_cache_pool:
                adapter: cache.adapter.array

            # uses the default_memcached_provider from above
            acme.cache:
                adapter: cache.adapter.memcached

            # control adapter's configuration
            foobar.cache:
                adapter: cache.adapter.memcached
                provider: 'memcached://user:[email protected]'

            # uses the "foobar.cache" pool as its backend but controls
            # the lifetime and (like all pools) has a separate cache namespace
            short_cache:
                adapter: foobar.cache
                default_lifetime: 60

Each pool manages a set of independent cache keys: keys of different pools never collide, even if they share the same backend. This is achieved by prefixing keys with a namespace that's generated by hashing the name of the pool, the name of the compiled container class and a configurable seed that defaults to the project directory.

Each custom pool becomes a service where the service id is the name of the pool (e.g. custom_thing.cache). An autowiring alias is also created for each pool using the camel case version of its name - e.g. custom_thing.cache can be injected automatically by naming the argument $customThingCache and type-hinting it with either CacheInterface or Psr\Cache\CacheItemPoolInterface:

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use Symfony\Contracts\Cache\CacheInterface;

// from a controller method
public function listProducts(CacheInterface $customThingCache)
{
    // ...
}

// in a service
public function __construct(CacheInterface $customThingCache)
{
    // ...
}

Custom Provider Options

Some providers have specific options that can be configured. The RedisAdapter allows you to create providers with option timeout, retry_interval. etc. To use these options with non-default values you need to create your own \Redis provider and use that when configuring the pool.

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# config/packages/cache.yaml
framework:
    cache:
        pools:
            cache.my_redis:
                adapter: cache.adapter.redis
                provider: app.my_custom_redis_provider

services:
    app.my_custom_redis_provider:
        class: \Redis
        factory: ['Symfony\Component\Cache\Adapter\RedisAdapter', 'createConnection']
        arguments:
            - 'redis://localhost'
            - { retry_interval: 2, timeout: 10 }

Creating a Cache Chain

Different cache adapters have different strengths and weaknesses. Some might be really quick but small and some may be able to contain a lot of data but are quite slow. To get the best of both worlds you may use a chain of adapters. The idea is to first look at the quick adapter and then move on to slower adapters. In the worst case the value needs to be recalculated.

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# config/packages/cache.yaml
framework:
    cache:
        pools:
            my_cache_pool:
                adapter: cache.adapter.psr6
                provider: app.my_cache_chain_adapter
            cache.my_redis:
                adapter: cache.adapter.redis
                provider: 'redis://user:[email protected]'
            cache.apcu:
                adapter: cache.adapter.apcu
            cache.array:
                adapter: cache.adapter.array


services:
    app.my_cache_chain_adapter:
        class: Symfony\Component\Cache\Adapter\ChainAdapter
        arguments:
            - ['@cache.array', '@cache.apcu', '@cache.my_redis']
            - 31536000 # One year

Note

In this configuration the my_cache_pool pool is using the cache.adapter.psr6 adapter and the app.my_cache_chain_adapter service as a provider. That is because ChainAdapter does not support the cache.pool tag. So it is decorated with the ProxyAdapter.

Using Cache Tags

In applications with many cache keys it could be useful to organize the data stored to be able to invalidate the cache more efficient. One way to achieve that is to use cache tags. One or more tags could be added to the cache item. All items with the same key could be invalidate with one function call:

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use Symfony\Contracts\Cache\ItemInterface;

$value0 = $pool->get('item_0', function (ItemInterface $item) {
    $item->tag(['foo', 'bar'])

    return 'debug';
});

$value1 = $pool->get('item_1', function (ItemInterface $item) {
    $item->tag('foo')

    return 'debug';
});

// Remove all cache keys tagged with "bar"
$pool->invalidateTags(['bar']);

The cache adapter needs to implement TagAwareCacheInterface` to enable this feature. This could be added by using the following configuration.

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# config/packages/cache.yaml
framework:
    cache:
        pools:
            my_cache_pool:
                adapter: cache.adapter.redis
                tags: true

Tags are stored in the same pool by default. This is good in most scenarios. But sometimes it might be better to store the tags in a different pool. That could be achieved by specifying the adapter.

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# config/packages/cache.yaml
framework:
    cache:
        pools:
            my_cache_pool:
                adapter: cache.adapter.redis
                tags: tag_pool
            tag_pool:
                adapter: cache.adapter.apcu

Clearing the Cache

To clear the cache you can use the bin/console cache:pool:clear [pool] command. That will remove all the entries from your storage and you will have to recalculate all values. You can also group your pools into "cache clearers". There are 3 cache clearers by default:

  • cache.global_clearer
  • cache.system_clearer
  • cache.app_clearer

The global clearer clears all the cache in every pool. The system cache clearer is used in the bin/console cache:clear command. The app clearer is the default clearer.

Clear one pool:

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$ php bin/console cache:pool:clear my_cache_pool

Clear all custom pools:

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$ php bin/console cache:pool:clear cache.app_clearer

Clear all caches everywhere:

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$ php bin/console cache:pool:clear cache.global_clearer
This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.