359 lines
10 KiB
PHP
359 lines
10 KiB
PHP
<?php
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/**
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* ~~summary~~
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*
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* ~~description~~
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*
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* PHP version 5
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*
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* @category Caching
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* @package PEAR2_Cache_SHM
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* @author Vasil Rangelov <boen.robot@gmail.com>
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* @copyright 2011 Vasil Rangelov
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* @license http://www.gnu.org/copyleft/lesser.html LGPL License 2.1
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* @version 0.1.3
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* @link http://pear2.php.net/PEAR2_Cache_SHM
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*/
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/**
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* The namespace declaration.
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*/
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namespace PEAR2\Cache\SHM\Adapter;
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/**
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* Throws exceptions from this namespace, and extends from this class.
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*/
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use PEAR2\Cache\SHM;
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/**
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* {@link Placebo::getIterator()} returns this object.
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*/
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use ArrayObject;
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/**
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* This adapter is not truly persistent. It is intended to emulate persistency
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* in non persistent environments, so that upper level applications can use a
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* single code path for persistent and non persistent code.
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*
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* @category Caching
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* @package PEAR2_Cache_SHM
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* @author Vasil Rangelov <boen.robot@gmail.com>
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* @license http://www.gnu.org/copyleft/lesser.html LGPL License 2.1
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* @link http://pear2.php.net/PEAR2_Cache_SHM
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*/
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class Placebo extends SHM
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{
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/**
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* @var string ID of the current storage.
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*/
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protected $persistentId;
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/**
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* List of persistent IDs.
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*
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* A list of persistent IDs within the current request (as keys) with an int
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* (as a value) specifying the number of instances in the current request.
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* Used as an attempt to ensure implicit lock releases on destruction.
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* @var array
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*/
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protected static $requestInstances = array();
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/**
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* @var array Array of lock names (as values) for each persistent ID (as
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* key) obtained during the current request.
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*/
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protected static $locksBackup = array();
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/**
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* The data storage.
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*
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* Each persistent ID is a key, and the value is an array.
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* Each such array has data keys as its keys, and an array as a value.
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* Each such array has as its elements the value, the timeout and the time
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* the data was set.
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* @var array
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*/
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protected static $data = array();
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/**
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* Creates a new shared memory storage.
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*
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* Estabilishes a separate persistent storage.
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*
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* @param string $persistentId The ID for the storage. The storage will be
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* reused if it exists, or created if it doesn't exist. Data and locks
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* are namespaced by this ID.
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*/
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public function __construct($persistentId)
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{
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if (isset(static::$requestInstances[$persistentId])) {
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++static::$requestInstances[$persistentId];
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} else {
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static::$requestInstances[$persistentId] = 1;
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static::$locksBackup[$persistentId] = array();
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static::$data[$persistentId] = array();
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}
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$this->persistentId = $persistentId;
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}
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/**
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* Releases any unreleased locks.
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*/
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public function __destruct()
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{
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if (0 === --static::$requestInstances[$this->persistentId]) {
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static::$locksBackup[$this->persistentId] = array();
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}
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}
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/**
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* Checks if the adapter meets its requirements.
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public static function isMeetingRequirements()
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{
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return 'cli' === PHP_SAPI;
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}
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/**
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* Pretends to obtain a lock.
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*
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* @param string $key Ignored.
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* @param double $timeout Ignored.
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public function lock($key, $timeout = null)
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{
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$key = (string) $key;
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if (in_array($key, static::$locksBackup[$this->persistentId], true)) {
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return false;
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}
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static::$locksBackup[$this->persistentId][] = $key;
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return true;
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}
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/**
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* Pretends to release a lock.
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*
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* @param string $key Ignored
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public function unlock($key)
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{
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$key = (string) $key;
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if (!in_array($key, static::$locksBackup[$this->persistentId], true)) {
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return false;
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}
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unset(static::$locksBackup[$this->persistentId][array_search(
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$key,
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static::$locksBackup[$this->persistentId],
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true
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)]);
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return true;
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}
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/**
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* Checks if a specified key is in the storage.
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*
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* @param string $key Name of key to check.
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*
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* @return bool TRUE if the key is in the storage, FALSE otherwise.
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*/
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public function exists($key)
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{
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return array_key_exists($key, static::$data[$this->persistentId]);
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}
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/**
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* Adds a value to the shared memory storage.
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*
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* Adds a value to the storage if it doesn't exist, or fails if it does.
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*
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* @param string $key Name of key to associate the value with.
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* @param mixed $value Value for the specified key.
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* @param int $ttl Because "true" adapters purge the cache at the next
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* request, this setting is ignored.
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public function add($key, $value, $ttl = 0)
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{
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if ($this->exists($key)) {
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return false;
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}
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return $this->set($key, $value, $ttl);
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}
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/**
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* Sets a value in the shared memory storage.
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*
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* Adds a value to the storage if it doesn't exist, overwrites it otherwise.
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*
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* @param string $key Name of key to associate the value with.
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* @param mixed $value Value for the specified key.
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* @param int $ttl Because "true" adapters purge the cache at the next
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* request, this setting is ignored.
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public function set($key, $value, $ttl = 0)
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{
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static::$data[$this->persistentId][$key] = $value;
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return true;
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}
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/**
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* Gets a value from the shared memory storage.
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*
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* Gets the current value, or throws an exception if it's not stored.
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*
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* @param string $key Name of key to get the value of.
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*
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* @return mixed The current value of the specified key.
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*/
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public function get($key)
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{
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if ($this->exists($key)) {
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return static::$data[$this->persistentId][$key];
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}
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throw new SHM\InvalidArgumentException(
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'Unable to fetch key. No such key.',
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200
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);
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}
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/**
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* Deletes a value from the shared memory storage.
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*
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* @param string $key Name of key to delete.
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public function delete($key)
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{
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if ($this->exists($key)) {
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unset(static::$data[$this->persistentId][$key]);
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return true;
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}
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return false;
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}
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/**
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* Increases a value from the shared memory storage.
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*
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* Increases a value from the shared memory storage. Unlike a plain
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* set($key, get($key)+$step) combination, this function also implicitly
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* performs locking.
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*
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* @param string $key Name of key to increase.
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* @param int $step Value to increase the key by.
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*
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* @return int The new value.
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*/
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public function inc($key, $step = 1)
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{
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if (!$this->exists($key) || !is_int($value = $this->get($key))
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|| !$this->set($key, $value + (int) $step)
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) {
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throw new SHM\InvalidArgumentException(
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'Unable to increase the value. Are you sure the value is int?',
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201
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);
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}
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return $this->get($key);
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}
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/**
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* Decreases a value from the shared memory storage.
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*
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* Decreases a value from the shared memory storage. Unlike a plain
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* set($key, get($key)-$step) combination, this function also implicitly
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* performs locking.
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*
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* @param string $key Name of key to decrease.
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* @param int $step Value to decrease the key by.
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*
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* @return int The new value.
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*/
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public function dec($key, $step = 1)
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{
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if (!$this->exists($key) || !is_int($value = $this->get($key))
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|| !$this->set($key, $value - (int) $step)
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) {
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throw new SHM\InvalidArgumentException(
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'Unable to increase the value. Are you sure the value is int?',
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202
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);
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}
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return $this->get($key);
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}
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/**
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* Sets a new value if a key has a certain value.
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*
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* Sets a new value if a key has a certain value. This function only works
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* when $old and $new are longs.
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*
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* @param string $key Key of the value to compare and set.
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* @param int $old The value to compare the key against.
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* @param int $new The value to set the key to.
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*
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* @return bool TRUE on success, FALSE on failure.
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*/
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public function cas($key, $old, $new)
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{
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return $this->exists($key) && ($this->get($key) === $old)
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&& is_int($new) && $this->set($key, $new);
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}
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/**
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* Clears the persistent storage.
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*
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* Clears the persistent storage, i.e. removes all keys. Locks are left
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* intact.
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*
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* @return void
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*/
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public function clear()
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{
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static::$data[$this->persistentId] = array();
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}
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/**
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* Retrieve an external iterator
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*
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* Returns an external iterator.
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*
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* @param string|null $filter A PCRE regular expression.
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* Only matching keys will be iterated over.
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* Setting this to NULL matches all keys of this instance.
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* @param bool $keysOnly Whether to return only the keys,
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* or return both the keys and values.
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*
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* @return ArrayObject An array with all matching keys as array keys,
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* and values as array values. If $keysOnly is TRUE, the array keys are
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* numeric, and the array values are key names.
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*/
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public function getIterator($filter = null, $keysOnly = false)
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{
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if (null === $filter) {
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return new ArrayObject(
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$keysOnly
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? array_keys(static::$data[$this->persistentId])
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: static::$data[$this->persistentId]
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);
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}
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$result = array();
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foreach (static::$data[$this->persistentId] as $key => $value) {
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if (preg_match($filter, $key)) {
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$result[$key] = $value;
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}
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}
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return new ArrayObject($keysOnly ? array_keys($result) : $result);
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}
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}
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