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Item.php
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Item.php
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<?php
/*
* This file is part of the Stash package.
*
* (c) Robert Hafner <tedivm@tedivm.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Stash;
use Stash\Exception\Exception;
use Stash\Interfaces\DriverInterface;
use Stash\Interfaces\ItemInterface;
use Stash\Interfaces\PoolInterface;
/**
* Stash caches data that has a high generation cost, such as template preprocessing or code that requires a database
* connection. This class can store any native php datatype, as long as it can be serialized (so when creating classes
* that you wish to store instances of, remember the __sleep and __wake magic functions).
*
* @package Stash
* @author Robert Hafner <tedivm@tedivm.com>
*/
class Item implements ItemInterface
{
/**
* @deprecated
*/
const SP_NONE = 0;
/**
* @deprecated
*/
const SP_OLD = 1;
/**
* @deprecated
*/
const SP_VALUE = 2;
/**
* @deprecated
*/
const SP_SLEEP = 3;
/**
* @deprecated
*/
const SP_PRECOMPUTE = 4;
/**
* This is the default time, in seconds, that objects are cached for.
*
* @var int seconds
*/
public static $cacheTime = 432000; // five days
/**
* Disables the cache system wide. It is used internally when the storage engine fails or if the cache is being
* cleared. This differs from the cacheEnabled property in that it affects all instances of the cache, not just one.
*
* @var bool
*/
public static $runtimeDisable = false;
/**
* Used internally to mark the class as disabled. Unlike the static runtimeDisable flag this is effective only for
* the current instance.
*
* @var bool
*/
protected $cacheEnabled = true;
/**
* Contains a list of default arguments for when users do not supply them.
*
* @var array
*/
protected $defaults = array('precompute_time' => 40, // time, in seconds, before expiration
'sleep_time' => 500, // time, in microseconds, to sleep
'sleep_attempts' => 1, // number of times to sleep, wake up, and recheck cache
'stampede_ttl' => 30, // How long a stampede flag will be acknowledged
);
/**
* The identifier for the item being cached. It is set through the setupKey function.
*
* @var array One dimensional array representing the location of a cached object.
*/
protected $key;
/**
* A serialized version of the key, used primarily used as the index in various arrays.
*
* @var string
*/
protected $keyString;
/**
* Marks whether or not stampede protection is enabled for this instance of Stash.
*
* @var bool
*/
protected $stampedeRunning = false;
/**
* The Pool that spawned this instance of the Item..
*
* @var \Stash\Interfaces\PoolInterface
*/
protected $pool;
/**
* The cacheDriver being used by the system. While this class handles all of the higher functions, it's the cache
* driver here that handles all of the storage/retrieval functionality. This value is set by the constructor.
*
* @var \Stash\Interfaces\DriverInterface
*/
protected $driver;
/**
* If set various then errors and exceptions will get passed to the PSR Compliant logging library. This
* can be set using the setLogger() function in this class.
*
* @var \Psr\Log\LoggerInterface
*/
protected $logger;
/**
* Defines the namespace the item lives in.
*
* @var string|null
*/
protected $namespace = null;
/**
* This is a flag to see if a valid response is returned. It is set by the getData function and is used by the
* isMiss function.
*
* @var bool
*/
private $isHit = null;
/**
* {@inheritdoc}
*/
public function setPool(PoolInterface $pool)
{
$this->pool = $pool;
$this->setDriver($pool->getDriver());
}
/**
* {@inheritdoc}
*/
public function setKey($key, $namespace = null)
{
$this->namespace = $namespace;
$this->setupKey($key);
}
/**
* {@inheritdoc}
*/
public function disable()
{
$this->cacheEnabled = false;
return true;
}
/**
* {@inheritdoc}
*/
public function getKey()
{
return isset($this->keyString) ? $this->keyString : false;
}
/**
* {@inheritdoc}
*/
public function clear()
{
try {
return $this->executeClear();
} catch (Exception $e) {
$this->logException('Clearing cache caused exception.', $e);
$this->disable();
return false;
}
}
private function executeClear()
{
if ($this->isDisabled()) {
return false;
}
return $this->driver->clear(isset($this->key) ? $this->key : null);
}
/**
* {@inheritdoc}
*/
public function get($invalidation = 0, $arg = null, $arg2 = null)
{
try {
return $this->executeGet($invalidation, $arg, $arg2);
} catch (Exception $e) {
$this->logException('Retrieving from cache caused exception.', $e);
$this->disable();
return null;
}
}
private function executeGet($invalidation, $arg, $arg2)
{
$this->isHit = false;
if ($this->isDisabled()) {
return null;
}
if (!isset($this->key)) {
return null;
}
if (!is_array($invalidation)) {
$vArray = array();
if (isset($invalidation)) {
$vArray[] = $invalidation;
}
if (isset($arg)) {
$vArray[] = $arg;
}
if (isset($arg2)) {
$vArray[] = $arg2;
}
$invalidation = $vArray;
}
$record = $this->getRecord();
$this->validateRecord($invalidation, $record);
return isset($record['data']['return']) ? $record['data']['return'] : null;
}
/**
* {@inheritdoc}
*/
public function isMiss()
{
if (!isset($this->isHit)) {
$this->get();
}
if ($this->isDisabled()) {
return true;
}
return !$this->isHit;
}
/**
* {@inheritdoc}
*/
public function lock($ttl = null)
{
if ($this->isDisabled()) {
return true;
}
if (!isset($this->key)) {
return false;
}
$this->stampedeRunning = true;
$expiration = isset($ttl) && is_numeric($ttl) ? (int) $ttl : $this->defaults['stampede_ttl'];
$spkey = $this->key;
$spkey[0] = 'sp';
return $this->driver->storeData($spkey, true, time() + $expiration);
}
/**
* {@inheritdoc}
*/
public function set($data, $ttl = null)
{
try {
return $this->executeSet($data, $ttl);
} catch (Exception $e) {
$this->logException('Setting value in cache caused exception.', $e);
$this->disable();
return false;
}
}
private function executeSet($data, $time)
{
if ($this->isDisabled()) {
return false;
}
if (!isset($this->key)) {
return false;
}
$store = array();
$store['return'] = $data;
$store['createdOn'] = time();
if (isset($time)) {
if ($time instanceof \DateTime) {
$expiration = $time->getTimestamp();
$cacheTime = $expiration - $store['createdOn'];
} else {
$cacheTime = isset($time) && is_numeric($time) ? $time : self::$cacheTime;
}
} else {
$cacheTime = self::$cacheTime;
}
$expiration = $store['createdOn'] + $cacheTime;
if ($cacheTime > 0) {
$expirationDiff = rand(0, floor($cacheTime * .15));
$expiration -= $expirationDiff;
}
if ($this->stampedeRunning === true) {
$spkey = $this->key;
$spkey[0] = 'sp'; // change "cache" data namespace to stampede namespace
$this->driver->clear($spkey);
$this->stampedeRunning = false;
}
return $this->driver->storeData($this->key, $store, $expiration);
}
/**
* {@inheritdoc}
*/
public function extend($ttl = null)
{
if ($this->isDisabled()) {
return false;
}
return $this->set($this->get(), $ttl);
}
/**
* {@inheritdoc}
*/
public function isDisabled()
{
return self::$runtimeDisable
|| !$this->cacheEnabled
|| (defined('STASH_DISABLE_CACHE') && STASH_DISABLE_CACHE);
}
/**
* {@inheritdoc}
*/
public function setLogger($logger)
{
$this->logger = $logger;
}
/**
* Sets the driver this object uses to interact with the caching system.
*
* @param DriverInterface $driver
*/
protected function setDriver(DriverInterface $driver)
{
$this->driver = $driver;
}
/**
* Logs an exception with the Logger class, if it exists.
*
* @param string $message
* @param \Exception $exception
* @return bool
*/
protected function logException($message, $exception)
{
if (!isset($this->logger)) {
return false;
}
$this->logger->critical($message,
array('exception' => $exception,
'key' => $this->keyString));
return true;
}
/**
* Returns true if another Item is currently recalculating the cache.
*
* @param array $key
* @return bool
*/
protected function getStampedeFlag($key)
{
$key[0] = 'sp'; // change "cache" data namespace to stampede namespace
$spReturn = $this->driver->getData($key);
$sp = isset($spReturn['data']) ? $spReturn['data'] : false;
if (isset($spReturn['expiration'])) {
if ($spReturn['expiration'] < time()) {
$sp = false;
}
}
return $sp;
}
/**
* Returns the record for the current key. If there is no record than an empty array is returned.
*
* @return array
*/
protected function getRecord()
{
$record = $this->driver->getData($this->key);
if (!is_array($record)) {
return array();
}
return $record;
}
/**
* Decides whether the current data is fresh according to the supplied validation technique. As some techniques
* actively change the record this function takes that in as a reference.
*
* This function has the ability to change the isHit property as well as the record passed.
*
* @internal
* @param array $validation
* @param array &$record
*/
protected function validateRecord($validation, &$record)
{
if (is_array($validation)) {
$argArray = $validation;
$invalidation = isset($argArray[0]) ? $argArray[0] : Invalidation::PRECOMPUTE;
if (isset($argArray[1])) {
$arg = $argArray[1];
}
if (isset($argArray[2])) {
$arg2 = $argArray[2];
}
} else {
$invalidation = Invalidation::PRECOMPUTE;
}
$curTime = microtime(true);
if (isset($record['expiration']) && ($ttl = $record['expiration'] - $curTime) > 0) {
$this->isHit = true;
if ($invalidation == Invalidation::PRECOMPUTE) {
$time = isset($arg) && is_numeric($arg) ? $arg : $this->defaults['precompute_time'];
// If stampede control is on it means another cache is already processing, so we return
// true for the hit.
if ($ttl < $time) {
$this->isHit = (bool) $this->getStampedeFlag($this->key);
}
}
return;
}
if (!isset($invalidation) || $invalidation == Invalidation::NONE) {
$this->isHit = false;
return;
}
if (!$this->getStampedeFlag($this->key)) {
$this->isHit = false;
return;
}
switch ($invalidation) {
case Invalidation::VALUE:
if (!isset($arg)) {
$this->isHit = false;
return;
} else {
$record['data']['return'] = $arg;
$this->isHit = true;
}
break;
case Invalidation::SLEEP:
$time = isset($arg) && is_numeric($arg) ? $arg : $this->defaults['sleep_time'];
$attempts = isset($arg2) && is_numeric($arg2) ? $arg2 : $this->defaults['sleep_attempts'];
$ptime = $time * 1000;
if ($attempts <= 0) {
$this->isHit = false;
$record['data']['return'] = null;
break;
}
usleep($ptime);
$record['data']['return'] = $this->get(Invalidation::SLEEP, $time, $attempts - 1);
break;
case Invalidation::OLD:
$this->isHit = true;
break;
default:
$this->isHit = false;
break;
} // switch($invalidate)
}
/**
* {@inheritdoc}
*/
public function getCreation()
{
$record = $this->getRecord();
if (!isset($record['data']['createdOn'])) {
return false;
}
$dateTime = new \DateTime();
$dateTime->setTimestamp($record['data']['createdOn']);
return $dateTime;
}
/**
* {@inheritdoc}
*/
public function getExpiration()
{
$record = $this->getRecord();
if (!isset($record['expiration'])) {
return false;
}
$dateTime = new \DateTime();
$dateTime->setTimestamp($record['expiration']);
return $dateTime;
}
/**
* This clears out any locks that are present if this Item is prematurely destructed.
*/
public function __destruct()
{
if (isset($this->stampedeRunning) && $this->stampedeRunning === true) {
$spkey = $this->key;
$spkey[0] = 'sp';
$this->driver->clear($spkey);
}
}
/**
* This function is used by the Pool object while creating this object. It
* is an internal function an should not be called directly.
*
* @param array $key
* @throws \InvalidArgumentException
*/
protected function setupKey($key)
{
if (!is_array($key)) {
throw new \InvalidArgumentException('Item requires keys as arrays.');
}
$keyStringTmp = $key;
if (isset($this->namespace)) {
array_shift($keyStringTmp);
}
$this->keyString = implode('/', $keyStringTmp);
// We implant the namespace "cache" to the front of every stash object's key. This allows us to segment
// off the user data, and use other 'namespaces' for internal purposes.
array_unshift($key, 'cache');
$this->key = array_map('strtolower', $key);
}
}