Cache.php

<?php
namespace Psr\Cache;

use Psr\CacheItem;

interface Cache
{
    
    /**
     * Remove an item from the cache by its unique key
     * 
     * @param string $key The unique cache key of the item to remove
     * @return boolean    The result of the delete operation
     */
    public function remove($key);
    
    /**
     * This will wipe out the entire cache's keys
     * 
     * @return boolean The result of the empty operation
     */
    public function empty();
    
    /**
     * Persisting our data in the cache, uniquely referenced by a key with an optional expiration TTL time.
     * 
     * @param string       $key The key of the item to store
     * @param mixed        $val The value of the item to store
     * @param null|integer $ttl Optional. The TTL value of this item as a timestamp for when it will expire if 
     *                          the implementing library choose to use this value
     * @return boolean
     */
    public function set($key, $val, $ttl = null);
    
    /**
     * Here we pass in a cache key to be fetched from the cache. 
     * A CacheItem object will be constructed and returned to us
     * 
     * @param string $key The unique key of this item in the cache
     * @return CacheItem  The newly populated CacheItem class representing the stored data in the cache
     */
    public function getItem($key);
    
    /**
     * This method can be used for re-persistence of an existing cache item after being retrieved from Cache->
     * It's good if you have an existing CacheItem and just want to change its value then you can stick it back in the cache
     * If the TTL is not null then the TTL value for the Item will be overwritten either by this new TTL value
     * 
     * @param CacheItem     $item   The CacheItem object being passed for persistence in the cache
     * @param null|integer  $ttl    Optional. If there is an expiration time for this object then this parameter is used.
     * @return boolean              The result of the set operation
     */
    public function setItem(CacheItem $item, $ttl = null);
    
    /**
     * Remove multiple cache items in a single operation
     * 
     * @param array  $keys The array of keys to be removed
     * @return array An array of 'key' => result, elements. Each array row has the key being deleted 
     *               and the result of that operation. The result will be a boolean of true or false 
     *               representing if the cache item was removed or not
     */
    public function removeItems($keys);
    
    /**
     * Obtain multiple CacheItems by their unique keys
     * 
     * @param array $keys A list of keys that can obtained in a single operation.
     * @return array      An array of CacheItem classes. 
     *                    The resulting array must use the CacheItem's key as the associative key for the array.
     */
    public function getItems($keys);
    
    /**
     * Persistence or re-persistence of multiple CacheItem objects, 
     * this does not differ from the setItem() method except that it's setting multiple items at once
     * If the TTL is not null then the TTL value for the Item will be overwritten either by this new TTL value
     * 
     * @param array         $items An array of CacheItem objects, this is for a multiple-set operation.
     * @param null|integer  $ttl   Optional. If the implementing library has expiration support then the TTL timestamp value is passed in here. 
     * @return boolean The result of the multiple-set operation
     */
    public function setItems($items, $ttl = null);
    
    
}

CacheItem.php

<?php
namespace Psr\Cache;

interface CacheItem
{
    
    /**
     * Get the key associated with this CacheItem
     * 
     * @return string
     */
    public function getKey();
    
    /**
     * Obtain the value of this cache item
     * 
     * @return mixed
     */
    public function getValue();
    
    /**
     * This boolean value tells us if our cache item is currently in the cache or not
     * 
     * @return boolean
     */
    public function isHit();

    /**
     * @param mixed $value
     */
    public function setValue($value);
    
}