Cache

The Cache component offers caching capabilities for utilisation in your application. The component helps with simple storing and retrieval of data from the cache, with possibilities to swap out caching storages almost painlessly, as well as it provides options to write further extensions for caching storages that are not supported by the Cache component. Along with that, sub-components are provided that help with caching of specific parts of your application almost transparently, like caching queries or views.

The Cache component is not a core component and must thus be installed with the Slaxer command line tool:

./slaxwe component:install cache

Note

At this moment only the Database Cache sub-component is available. The View/Template Cache sub-component is planed for future relases.

Warning

The cache does NOT secure or encrypt the data in any way and is stored as a PHP serialized string. If you wish to store sensitive data in the cache you need to make sure you do so in a secure manner!

Configuration

The Cache component comes with a cache.php configuration file. The following settings can be configured there:

handler

  • Data type: string
  • Default: file

The cache handler used by the cache component to store the data. The following handlers are provided:

  • file
  • memcached
  • redis

Note

At the moment only the ‘file’ handler is available. Other handlers are planned for future releases.

location

  • Data type: string
  • Default: __DIR__/../Cache/

The location depends on the handler. For file handler it is the absolute path to the directory where the Cache component may write to.

maxAge

  • Data type: int
  • Default: 3600

Maximum age for data in the cache. This value is used as default for all data stored in the cache, but can be overridden for each one specifically. Maximum age is defined in seconds with a default value of int(3600), equivalent for one hour. If the maximum age is set to int(0), then the data will never expire.

Using the cache

The cache component is available under the cache.service name in the service container, and is obtainable like any other service:

<?php
// code ...
$cache = $app["cache.service"];
// code ...

When the cache service is retrieved it is also instantiated, along with its handler. If an instantiation error occurs with the handler, it will throw an exception at this point.

Write and read

All operations on the cache are done directly on the main cache object returned from the cache.service. It provides simple methods to write, read, and remove from cache.

All entries require a unique string name for the cache. In case of the file storage it needs to be a valid filesystem name. Through this name, the data is also retrieved or removed from the cache.

write

The write method takes the name of the data to cache as the first parameter, the second parameter holds the actual data. This data may be anything, as the manager will serialize the data before storing.

The third, and final parameter is optional and may override the default configured maximum age for the data. The value is in seconds, any negative value will use the default configured maximum age from the cache.php configuration file, a int(0) value will keep the data in the cache indefinitely, unless removed manually.

Example usage:

<?php
// code ...
$foo = new Foo;
$foo->bar = "baz";
$cache = $app["cache.service"];
$cache->write("myFooObject", $foo, 0);
// code ...

read

The read method takes only the name of the cached data as the parameter, and tries to obtain it from the cache. It may throw an \SlaxWeb\Cache\Exception\CacheDataNotFoundException if the data is not found, or the \SlaxWeb\Cache\Exception\CacheDataExpiredException if the data has already expired, or the \SlaxWeb\Cache\Exception\CacheDataInvalidException if the data in the cache is no unserializable, which should happen only if the cache was manually manipulated with. All the exceptions extend from the \SlaxWeb\Cache\Exception\CacheException class.

The read method will return the unserialized data, and may therefore be of different types. Example usage:

<?php
// code ...
$cache = $app["cache.service"];
$foo = $cache->read("myFooObject");
echo $foo->bar; // will output "baz"
// code ...

remove

The remove method takes the full or partial name of the cached data, and a partial flag as the second parameter. If the partial flag is set to true, then all the data that contains the input name in its name is removed.

Example usage:

<?php
// code ...
$cache = $app["cache.service"];
$cache->remove("myFooObject");
$cache->remove("Foo", true); // would remove "myFooObject" as well since it contains "Foo"
// code ...