One iota Cache Library

Overview

A simple interface to cache sources.

The Cache class wraps a Memcached instance, adding key and value mapping, and default expiry times.

Installation

The best way to autoload this package and its dependencies is to include the standard Composer autoloader, vendor/autoload.php.

Testing

The library's suite of unit tests can be run by calling vendor/bin/phpunit from the root of the repository.

Basic Usage

use \itsoneiota\cache;

$mc = new \Memcached();
// Configure memcached…

$cache = new Cache($mc);

$cache->set('foo', 'bar'); // Caches a value of 'bar' against the key of 'foo'.
$cache->get('foo'); // Returns 'bar'.

Prefixing Cache Keys

If you wish to avoid cache key collisions, you can initialise your cache with a key prefix, this will be added to all keys when getting, setting and deleting. For example:

use \itsoneiota\cache;

$mc = new \Memcached();
// Configure memcached…

$cache = new Cache($mc, 'myStore');

$cache->set('foo', 'bar'); // Caches a value of 'bar' against the key of 'myStore.foo'.
$cache->get('foo'); // Returns 'bar'.

Default Expiry Times

When creating a cache, you can specify a default time to live that can be used when adding and setting. This can be overridden when adding and setting by specifying an explicit expiry time.

use \itsoneiota\cache;

$mc = new \Memcached();
// Configure memcached…

$cache = new Cache($mc, 'myStore', 120);

$cache->set('foo', 'bar'); // Caches for 2 minutes (the default).
$cache->set('bat', 'baz', 30); // Caches for 30 seconds.

Encrypting Cache Contents

SecureCache is a subclass of Cache that encrypts its contents using two-way encryption.

use \itsoneiota\cache;

$mc = new \Memcached();
// Configure memcached…

$cache = new SecureCache($mc, 'myTopSecretEncryptionKey');

If you need to prefix keys in SecureCache, you can always call $cache->setKeyPrefix('myPrefix').

Bonus Caches (Cacheback)

InMemoryCacheFront

If you're likely to make several calls to a cache within a request, possibly to the same value, InMemoryCacheFront can prevent unnecessary network calls to the Memcached server, by providing a read- and write-through cache on top of a Cache instance. The number of items held in memory is limited to 100 by default, but that can be changed with a constructor argument.

use \itsoneiota\cache;

$mc = new \Memcached();
// Configure memcached…

$cache = new Cache($mc, 'myStore', 120);

$superFastCache = new InMemoryCacheFront($cache, 1000); // Store 1000 items in local memory.

InMemoryCache

If you need to simulate a cache, without a Memcached server, InMemoryCache will do the job. It looks just like a Cache, but it holds everything in a plain-old PHP array.

MockCache

For testing purposes, MockCache simulates a cache, and allows you to check that values have been set, and what their expiry times are, without having to go through all the hassle of using PHPUnit mocks. getExpiration() allows you to check the expiration of a key. timePasses() allows you to simulate the passage of time, advancing by a given number of seconds and expiring cache items accordingly.

use \itsoneiota\cache;

$cache = new MockCache();

$cache->set('foo', 'bar', 60);
$cache->get('foo'); // Returns 'bar'.

$cache->timePasses(61);

$cache->get('foo'); // Returns NULL.

To Do…

Things I might add, soon-ish:

• Check-and-set operations
• Cache pile-on prevention