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<?php
/**
* Abstract special page class with scaffolding for caching HTML and other values
* in a single blob.
*
* Before using any of the caching functionality, call startCache.
* After the last call to either getCachedValue or addCachedHTML, call saveCache.
*
* To get a cached value or compute it, use getCachedValue like this:
* $this->getCachedValue( $callback );
*
* To add HTML that should be cached, use addCachedHTML like this:
* $this->addCachedHTML( $callback );
*
* The callback function is only called when needed, so do all your expensive
* computations here. This function should returns the HTML to be cached.
* It should not add anything to the PageOutput object!
*
* 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
* @ingroup SpecialPage
* @author Jeroen De Dauw < jeroendedauw@gmail.com >
* @since 1.20
*/
abstract class SpecialCachedPage extends SpecialPage implements ICacheHelper {
/**
* CacheHelper object to which we forward the non-SpecialPage specific caching work.
* Initialized in startCache.
*
* @since 1.20
* @var CacheHelper
*/
protected $cacheHelper;
/**
* If the cache is enabled or not.
*
* @since 1.20
* @var bool
*/
protected $cacheEnabled = true;
/**
* Gets called after @see SpecialPage::execute.
*
* @since 1.20
*
* @param string|null $subPage
*/
protected function afterExecute( $subPage ) {
$this->saveCache();
parent::afterExecute( $subPage );
}
/**
* Sets if the cache should be enabled or not.
*
* @since 1.20
* @param bool $cacheEnabled
*/
public function setCacheEnabled( $cacheEnabled ) {
$this->cacheHelper->setCacheEnabled( $cacheEnabled );
}
/**
* Initializes the caching.
* Should be called before the first time anything is added via addCachedHTML.
*
* @since 1.20
*
* @param int|null $cacheExpiry Sets the cache expiry, either ttl in seconds or unix timestamp.
* @param bool|null $cacheEnabled Sets if the cache should be enabled or not.
*/
public function startCache( $cacheExpiry = null, $cacheEnabled = null ) {
if ( !isset( $this->cacheHelper ) ) {
$this->cacheHelper = new CacheHelper();
$this->cacheHelper->setCacheEnabled( $this->cacheEnabled );
$this->cacheHelper->setOnInitializedHandler( array( $this, 'onCacheInitialized' ) );
$keyArgs = $this->getCacheKey();
if ( array_key_exists( 'action', $keyArgs ) && $keyArgs['action'] === 'purge' ) {
unset( $keyArgs['action'] );
}
$this->cacheHelper->setCacheKey( $keyArgs );
if ( $this->getRequest()->getText( 'action' ) === 'purge' ) {
$this->cacheHelper->rebuildOnDemand();
}
}
$this->cacheHelper->startCache( $cacheExpiry, $cacheEnabled );
}
/**
* Get a cached value if available or compute it if not and then cache it if possible.
* The provided $computeFunction is only called when the computation needs to happen
* and should return a result value. $args are arguments that will be passed to the
* compute function when called.
*
* @since 1.20
*
* @param callable $computeFunction
* @param array|mixed $args
* @param string|null $key
*
* @return mixed
*/
public function getCachedValue( $computeFunction, $args = array(), $key = null ) {
return $this->cacheHelper->getCachedValue( $computeFunction, $args, $key );
}
/**
* Add some HTML to be cached.
* This is done by providing a callback function that should
* return the HTML to be added. It will only be called if the
* item is not in the cache yet or when the cache has been invalidated.
*
* @since 1.20
*
* @param callable $computeFunction
* @param array $args
* @param string|null $key
*/
public function addCachedHTML( $computeFunction, $args = array(), $key = null ) {
$this->getOutput()->addHTML( $this->cacheHelper->getCachedValue(
$computeFunction,
$args,
$key
) );
}
/**
* Saves the HTML to the cache in case it got recomputed.
* Should be called after the last time anything is added via addCachedHTML.
*
* @since 1.20
*/
public function saveCache() {
if ( isset( $this->cacheHelper ) ) {
$this->cacheHelper->saveCache();
}
}
/**
* Sets the time to live for the cache, in seconds or a unix timestamp
* indicating the point of expiry.
*
* @since 1.20
*
* @param int $cacheExpiry
*/
public function setExpiry( $cacheExpiry ) {
$this->cacheHelper->setExpiry( $cacheExpiry );
}
/**
* Returns the variables used to constructed the cache key in an array.
*
* @since 1.20
*
* @return array
*/
protected function getCacheKey() {
return array(
$this->mName,
$this->getLanguage()->getCode()
);
}
/**
* Gets called after the cache got initialized.
*
* @since 1.20
*
* @param bool $hasCached
*/
public function onCacheInitialized( $hasCached ) {
if ( $hasCached ) {
$this->getOutput()->setSubtitle( $this->cacheHelper->getCachedNotice( $this->getContext() ) );
}
}
}
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