README

PSR-16 & PSR-6 Cache implementations for WordPress transient and cache the OOP way

Version 2.0 is a BC breaks please read the following documentation

Table Of Contents

• Installation
• Basic Usage
• Advanced Usage
• Contributing
• License
• Credits

Installation

The best way to use this package is through Composer:

composer require italystrap/cache

This package adheres to the SemVer specification and will be fully backward compatible between minor versions.

For more information about the WordPress API:

• WordPress Transients API docs
• WordPress Cache API docs

Why this package?

Initially I created this package to use the PSR-16 cache interface in WordPress, but starting from this issue #4 I decided to extract the drivers and also add the PSR-6 cache interface too.

From version 2.0 I also added the PSR-6 implementation, so you can also use the Pool class to cache your data if you need it.

So this package now support both the PSR-16 and PSR-6 cache interfaces.

The driver required by this package uses the Transients and Object Cache APIs from WordPress to store the data, but if you need to use other APIs, you can create your own driver because just implements the interface \ItalyStrap\Storage\CacheInterface from Storage API.

Moving from Version 1 to Version 2

The first important thing is from the version 2 you need to pass the driver object and the expiration object to the constructor of the class you want to use.

SimpleCache and Pool are the two classes that need the driver and the expiration to be passed to the constructor.

The driver is an object wrapper for the WordPress Transient API and the WordPress Object Cache API.

The expiration object is used to set the expiration time of the cache.

Below in the documentation you will find the name of the drivers that you can use and the expiration object.

The second important thing is that the driver must implement the CacheInterface from Cache API, this way if you need to create your own driver you can do it simply by implementing the interface.

Why the needs of an Expiration object?

The expiration object is used to set the expiration time of the cache.

Because I want to be as close as possible to the PSR-16 and PSR-6 specifications, I have created an object that is responsible for setting the expiration time, this way I can reuse the same logic across all PSR-16 and PSR-6 implementations and I didn't need to create more methods that are not in the specifications.

Basic Usage

Timer constants

Inside WordPress there are some constants that can be used to express time in seconds. Here is a list of them:

const MINUTE_IN_SECONDS  = 60; // (seconds)
const HOUR_IN_SECONDS    = 60 * MINUTE_IN_SECONDS;
const DAY_IN_SECONDS     = 24 * HOUR_IN_SECONDS;
const WEEK_IN_SECONDS    = 7 * DAY_IN_SECONDS;
const MONTH_IN_SECONDS   = 30 * DAY_IN_SECONDS;
const YEAR_IN_SECONDS    = 365 * DAY_IN_SECONDS;

Or you can use the built-in constant from ItalyStrap\Cache\ExpirationInterface:

use ItalyStrap\Cache\ExpirationInterface;

$expirationTime = ExpirationInterface::MINUTE_IN_SECONDS;
$expirationTime = ExpirationInterface::HOUR_IN_SECONDS;
$expirationTime = ExpirationInterface::DAY_IN_SECONDS;
$expirationTime = ExpirationInterface::WEEK_IN_SECONDS;
$expirationTime = ExpirationInterface::MONTH_IN_SECONDS;
$expirationTime = ExpirationInterface::YEAR_IN_SECONDS;

Or you can use the built-in PHP function strtotime() to express time in seconds.

Common usage with builtin WordPress Transients API

if (false === ($special_data_to_save = \get_transient('special_data_to_save'))) {
    // It wasn't there, so regenerate the data and save the transient
    $special_data_to_save = ['some-key' => 'come value'];
    \set_transient('special_data_to_save', $special_data_to_save, 12 * HOUR_IN_SECONDS);
}

The data you can save can be anything that is supported by the Serialization API. In short, you can save any scalar value, array, object.

Common usage with the Pool cache

use ItalyStrap\Cache\Pool;
use ItalyStrap\Cache\Expiration;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()
$expiration = new Expiration();

$pool = new Pool($driver, $expiration);

// Pass the pool object to other classes that need to save data
// then retrieve the data from the pool
$item = $pool->getItem('special_data_to_save');
if (!$item->isHit()) {
    // It wasn't there, so regenerate the data and save the transient
    $item->set(['some-key' => 'some value']);
    $item->expiresAfter(12 * HOUR_IN_SECONDS);
    $pool->save($item);
}
$special_data_to_save = $item->get();

['some-key' => 'some value'] === $special_data_to_save; // True

Common usage with the SimpleCache

Only if you need to parse binary data (as for example image files) you can use the BinaryCacheDecorator class, but remember that if the file is more than 1MB it is better to not use this to save in the database.

And because you are a good developer, you will not save binary data in the database, and you will use the Transient class instead of the BinaryCacheDecorator class.

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

// Pay attention to `SimpleCacheInterface::get()` method because if there is no value will return `null` and not `false` as the WordPress Transient API does.
if (null === ($special_data_to_save = $cache->get('special_data_to_save'))) {
    // It wasn't there, so regenerate the data and save the transient
    $special_data_to_save = ['some-key' => 'some value'];
    $cache->set('special_data_to_save', $special_data_to_save, 12 * HOUR_IN_SECONDS);
}

['some-key' => 'some value'] === $special_data_to_save; // True

Deleting cache with Pool

use ItalyStrap\Cache\Pool;
use ItalyStrap\Cache\Expiration;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()
$expiration = new Expiration();

$pool = new Pool($driver, $expiration);

$item = $pool->getItem('special_data_to_save');
$item->set(['some-key' => 'some value']);
$item->expiresAfter(12 * HOUR_IN_SECONDS);
$pool->save($item);

$pool->deleteItem('special_data_to_save'); // Return bool

// `::getItem()` will return a new item instance, always
$pool->getItem('special_data_to_save')->isHit(); // Return false

Deleting cache with SimpleCache

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

$cache->set('special_data_to_save', ['some-key' => 'some value'], 12 * HOUR_IN_SECONDS);

$cache->delete('special_data_to_save'); // Return bool

$cache->get('special_data_to_save'); // Return null

Check cache exists with Pool

use ItalyStrap\Cache\Pool;
use ItalyStrap\Cache\Expiration;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()
$expiration = new Expiration();
    
$pool = new Pool($driver, $expiration);

$item = $pool->getItem('special_data_to_save');
$item->set(['some-key' => 'some value']);
$item->expiresAfter(12 * HOUR_IN_SECONDS);
$pool->save($item);

$pool->hasItem('special_data_to_save'); // Return true

// But also this will return false if the item is expired or not exists
$pool->hasItem('expired_or_not_existent_value'); // Return false

Check cache exists with SimpleCache

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

$cache->set('special_data_to_save', ['some-key' => 'some value'], 12 * HOUR_IN_SECONDS);
$cache->has('special_data_to_save'); // Return true

// But also this will return false if the item is expired or not exists
$cache->has('expired_or_not_existent_value'); // Return false

Saving multiple cache with SimpleCache

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

$values = [
    'key'       => 'value',
    'key2'      => 'value2',
];

$cache->setMultiple($values, 12 * HOUR_IN_SECONDS); // Return bool

Fetching multiple cache with SimpleCache

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

$values = [
    'key'       => 'value',
    'key2'      => 'value2',
    'key3'      => false, // This will be replaced with 'some default value' because the method pass a default value
];

$fetched_values = $cache->getMultiple(\array_keys($values), 'some default value'); // Return values

Deleting multiple cache with SimpleCache

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

$values = [
    'key'       => 'value',
    'key2'      => 'value2',
    'key3'      => false,
];

$cache->deleteMultiple(\array_keys($values)); // Return bool

Clearing cache with SimpleCache

This method do not clear the entire WordPress cache, only the cache used by client with ::set() and ::setMultiple() methods.

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);
$cache->set('special_data_to_save',['some-key' => 'come value'], 12 * HOUR_IN_SECONDS);

$values = [
    'key'       => 'value',
    'key2'      => 'value2',
];

$cache->setMultiple($values, 12 * HOUR_IN_SECONDS);

$cache->clear(); // Return bool

$cache->get('special_data_to_save'); // Return null
$cache->get('key'); // Return null
$cache->get('key2'); // Return null

Cache::clear() will flush 'special_data_to_save', 'key' and 'key2'.

Other examples

use ItalyStrap\Cache\Expiration;
use ItalyStrap\Cache\SimpleCache;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()

$expiration = new Expiration();
$cache = new SimpleCache($driver, $expiration);

// Get any existing copy of our transient data
if (false === ($special_data_to_save = $cache->get('special_data_to_save'))) {
    // It wasn't there, so regenerate the data and save the transient
     $cache->set('special_data_to_save', ['some-key' => 'some value'], 12 * HOUR_IN_SECONDS);
}
// Use the data like you would have normally...

//Or

// Get any existing copy of our transient data
if (!$cache->has('special_data_to_save')) {
    // It wasn't there, so regenerate the data and save the transient
     $cache->set('special_data_to_save', ['some-key' => 'some value'], 12 * HOUR_IN_SECONDS);
}
// Use the data like you would have normally...

You could also use a Bridge to use the \Psr\SimpleCache\CacheInterface and inject the \Psr\Cache\CacheItemPoolInterface

use ItalyStrap\Cache\Pool;
use ItalyStrap\Cache\Expiration;
use ItalyStrap\Storage\BinaryCacheDecorator;
use ItalyStrap\Storage\Transient;

$driver = new BinaryCacheDecorator(new Transient()); // Or use new Cache()
$expiration = new Expiration();
    
$pool = new Pool($driver, $expiration);

$cache = new \ItalyStrap\Cache\SimpleCacheBridge($pool);
// and use the $cache as \Psr\SimpleCache\CacheInterface

Use the Factory to simplify the creation of the Cache

use ItalyStrap\Cache\Factory;

$cache = (new Factory())->makePool();
$cache = (new Factory())->makePoolTransient();
$cache = (new Factory())->makeSimpleCache();
$cache = (new Factory())->makeSimpleCacheTransient();
$cache = (new Factory())->makeSimpleCacheBridge();
$cache = (new Factory())->makeSimpleCacheBridgeTransient();

Contributing

All feedback / bug reports / pull requests are welcome.

License

Copyright (c) 2019 Enea Overclokk, ItalyStrap

This code is licensed under the MIT.

Credits

• DoctrineSimpleCache
• PHP Cache organisation