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<?php
/**
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
use Wikimedia\ObjectCache\BagOStuff;
/**
* Store an arbitrary value whilst representing several CacheDependency objects as one.
*
* You should typically only use DependencyWrapper::getValueFromCache(),
* rather than instantiating one of these objects directly.
*
* @ingroup Language
*/
class DependencyWrapper {
/** @var mixed */
private $value;
/** @var CacheDependency[] */
private $deps;
/**
* @param mixed $value The user-supplied value
* @param CacheDependency|CacheDependency[] $deps A dependency or dependency
* array. All dependencies must be objects implementing CacheDependency.
*/
public function __construct( $value = false, $deps = [] ) {
$this->value = $value;
if ( !is_array( $deps ) ) {
$deps = [ $deps ];
}
$this->deps = $deps;
}
/**
* Returns true if any of the dependencies have expired
*
* @return bool
*/
public function isExpired() {
foreach ( $this->deps as $dep ) {
if ( $dep->isExpired() ) {
return true;
}
}
return false;
}
/**
* Initialise dependency values in preparation for storing. This must be
* called before serialization.
*/
public function initialiseDeps() {
foreach ( $this->deps as $dep ) {
$dep->loadDependencyValues();
}
}
/**
* Get the user-defined value
* @return bool|mixed
*/
public function getValue() {
return $this->value;
}
/**
* Store the wrapper to a cache
*
* @param BagOStuff $cache
* @param string $key
* @param int $expiry
*/
public function storeToCache( $cache, $key, $expiry = 0 ) {
$this->initialiseDeps();
$cache->set( $key, $this, $expiry );
}
/**
* Attempt to get a value from the cache. If the value is expired or missing,
* it will be generated with the callback function (if present), and the newly
* calculated value will be stored to the cache in a wrapper.
*
* @param BagOStuff $cache
* @param string $key The cache key
* @param int $expiry The expiry timestamp or interval in seconds
* @param callable|false $callback The callback for generating the value, or false
* @param array $callbackParams The function parameters for the callback
* @param array $deps The dependencies to store on a cache miss. Note: these
* are not the dependencies used on a cache hit! Cache hits use the stored
* dependency array.
*
* @return mixed The value, or null if it was not present in the cache and no
* callback was defined.
*/
public static function getValueFromCache( $cache, $key, $expiry = 0, $callback = false,
$callbackParams = [], $deps = []
) {
$obj = $cache->get( $key );
if ( is_object( $obj ) && $obj instanceof DependencyWrapper && !$obj->isExpired() ) {
$value = $obj->value;
} elseif ( $callback ) {
$value = $callback( ...$callbackParams );
# Cache the newly-generated value
$wrapper = new DependencyWrapper( $value, $deps );
$wrapper->storeToCache( $cache, $key, $expiry );
} else {
$value = null;
}
return $value;
}
}