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This adapter is a high-performance, shared memory cache. It can increase the application performance very significantly because the cache contents are stored in the shared memory of your server, a component that is much faster than others, such as the filesystem.
Requirement: The APCu extension must be installed and active to use this adapter.
This adapter can be provided an optional namespace string as its first parameter, a default cache lifetime as its second parameter, and a version string as its third parameter:
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use Symfony\Component\Cache\Adapter\ApcuAdapter; $cache = new ApcuAdapter( // a string prefixed to the keys of the items stored in this cache $namespace = '', // the default lifetime (in seconds) for cache items that do not define their // own lifetime, with a value 0 causing items to be stored indefinitely (i.e. // until the APCu memory is cleared) $defaultLifetime = 0, // when set, all keys prefixed by $namespace can be invalidated by changing // this $version string $version = null );
It is not recommended to use this adapter when performing a large number of write and delete operations, as these operations result in fragmentation of the APCu memory, resulting in significantly degraded performance.
Note that this adapter's CRUD operations are specific to the PHP SAPI it is running under. This means adding a cache item using the CLI will not result in the item appearing under FPM. Likewise, deletion of an item using CGI will not result in the item being deleted under the CLI.