<?php
 
 namespace Psr\SimpleCache;
 
 interface CacheInterface
 {
     /**
      * Fetches a value from the cache.
      *
      * @param string $key     The unique key of this item in the cache.
      * @param mixed  $default Default value to return if the key does not exist.
      *
      * @return mixed The value of the item from the cache, or $default in case of cache miss.
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if the $key string is not a legal value.
      */
     public function get($key, $default = null);
 
     /**
      * Persists 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                  $value The value of the item to store, must be serializable.
      * @param null|int|\DateInterval $ttl   Optional. The TTL value of this item. If no value is sent and
      *                                      the driver supports TTL then the library may set a default value
      *                                      for it or let the driver take care of that.
      *
      * @return bool True on success and false on failure.
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if the $key string is not a legal value.
      */
     public function set($key, $value, $ttl = null);
 
     /**
      * Delete an item from the cache by its unique key.
      *
      * @param string $key The unique cache key of the item to delete.
      *
      * @return bool True if the item was successfully removed. False if there was an error.
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if the $key string is not a legal value.
      */
     public function delete($key);
 
     /**
      * Wipes clean the entire cache's keys.
      *
      * @return bool True on success and false on failure.
      */
     public function clear();
 
     /**
      * Obtains multiple cache items by their unique keys.
      *
      * @param iterable $keys    A list of keys that can obtained in a single operation.
      * @param mixed    $default Default value to return for keys that do not exist.
      *
      * @return iterable A list of key => value pairs. Cache keys that do not exist or are stale will have $default as value.
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if $keys is neither an array nor a Traversable,
      *   or if any of the $keys are not a legal value.
      */
     public function getMultiple($keys, $default = null);
 
     /**
      * Persists a set of key => value pairs in the cache, with an optional TTL.
      *
      * @param iterable               $values A list of key => value pairs for a multiple-set operation.
      * @param null|int|\DateInterval $ttl    Optional. The TTL value of this item. If no value is sent and
      *                                       the driver supports TTL then the library may set a default value
      *                                       for it or let the driver take care of that.
      *
      * @return bool True on success and false on failure.
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if $values is neither an array nor a Traversable,
      *   or if any of the $values are not a legal value.
      */
     public function setMultiple($values, $ttl = null);
 
     /**
      * Deletes multiple cache items in a single operation.
      *
      * @param iterable $keys A list of string-based keys to be deleted.
      *
      * @return bool True if the items were successfully removed. False if there was an error.
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if $keys is neither an array nor a Traversable,
      *   or if any of the $keys are not a legal value.
      */
     public function deleteMultiple($keys);
 
     /**
      * Determines whether an item is present in the cache.
      *
      * NOTE: It is recommended that has() is only to be used for cache warming type purposes
      * and not to be used within your live applications operations for get/set, as this method
      * is subject to a race condition where your has() will return true and immediately after,
      * another script can remove it making the state of your app out of date.
      *
      * @param string $key The cache item key.
      *
      * @return bool
      *
      * @throws \Psr\SimpleCache\InvalidArgumentException
      *   MUST be thrown if the $key string is not a legal value.
      */
     public function has($key);
 }