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+<?php
+/**
+ * Cache of various elements in a single cache entry.
+ *
+ * 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
+ * @license GNU GPL v2 or later
+ * @author Jeroen De Dauw < jeroendedauw@gmail.com >
+ */
+
+/**
+ * Interface for all classes implementing CacheHelper functionality.
+ *
+ * @since 1.20
+ */
+interface ICacheHelper {
+ /**
+ * Sets if the cache should be enabled or not.
+ *
+ * @since 1.20
+ * @param bool $cacheEnabled
+ */
+ function 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.
+ */
+ function startCache( $cacheExpiry = null, $cacheEnabled = null );
+
+ /**
+ * 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
+ */
+ function getCachedValue( $computeFunction, $args = array(), $key = null );
+
+ /**
+ * 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
+ */
+ function 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
+ */
+ function setExpiry( $cacheExpiry );
+}
+
+/**
+ * Helper class for caching various elements in a single cache entry.
+ *
+ * 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!
+ *
+ * Before the first addCachedHTML call, you should call $this->startCache();
+ * After adding the last HTML that should be cached, call $this->saveCache();
+ *
+ * @since 1.20
+ */
+class CacheHelper implements ICacheHelper {
+ /**
+ * The time to live for the cache, in seconds or a unix timestamp indicating the point of expiry.
+ *
+ * @since 1.20
+ * @var int
+ */
+ protected $cacheExpiry = 3600;
+
+ /**
+ * List of HTML chunks to be cached (if !hasCached) or that where cached (of hasCached).
+ * If not cached already, then the newly computed chunks are added here,
+ * if it as cached already, chunks are removed from this list as they are needed.
+ *
+ * @since 1.20
+ * @var array
+ */
+ protected $cachedChunks;
+
+ /**
+ * Indicates if the to be cached content was already cached.
+ * Null if this information is not available yet.
+ *
+ * @since 1.20
+ * @var bool|null
+ */
+ protected $hasCached = null;
+
+ /**
+ * If the cache is enabled or not.
+ *
+ * @since 1.20
+ * @var bool
+ */
+ protected $cacheEnabled = true;
+
+ /**
+ * Function that gets called when initialization is done.
+ *
+ * @since 1.20
+ * @var callable
+ */
+ protected $onInitHandler = false;
+
+ /**
+ * Elements to build a cache key with.
+ *
+ * @since 1.20
+ * @var array
+ */
+ protected $cacheKey = array();
+
+ /**
+ * Sets if the cache should be enabled or not.
+ *
+ * @since 1.20
+ * @param bool $cacheEnabled
+ */
+ public function setCacheEnabled( $cacheEnabled ) {
+ $this->cacheEnabled = $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 ( is_null( $this->hasCached ) ) {
+ if ( !is_null( $cacheExpiry ) ) {
+ $this->cacheExpiry = $cacheExpiry;
+ }
+
+ if ( !is_null( $cacheEnabled ) ) {
+ $this->setCacheEnabled( $cacheEnabled );
+ }
+
+ $this->initCaching();
+ }
+ }
+
+ /**
+ * Returns a message that notifies the user he/she is looking at
+ * a cached version of the page, including a refresh link.
+ *
+ * @since 1.20
+ *
+ * @param IContextSource $context
+ * @param bool $includePurgeLink
+ *
+ * @return string
+ */
+ public function getCachedNotice( IContextSource $context, $includePurgeLink = true ) {
+ if ( $this->cacheExpiry < 86400 * 3650 ) {
+ $message = $context->msg(
+ 'cachedspecial-viewing-cached-ttl',
+ $context->getLanguage()->formatDuration( $this->cacheExpiry )
+ )->escaped();
+ } else {
+ $message = $context->msg(
+ 'cachedspecial-viewing-cached-ts'
+ )->escaped();
+ }
+
+ if ( $includePurgeLink ) {
+ $refreshArgs = $context->getRequest()->getQueryValues();
+ unset( $refreshArgs['title'] );
+ $refreshArgs['action'] = 'purge';
+
+ $subPage = $context->getTitle()->getFullText();
+ $subPage = explode( '/', $subPage, 2 );
+ $subPage = count( $subPage ) > 1 ? $subPage[1] : false;
+
+ $message .= ' ' . Linker::link(
+ $context->getTitle( $subPage ),
+ $context->msg( 'cachedspecial-refresh-now' )->escaped(),
+ array(),
+ $refreshArgs
+ );
+ }
+
+ return $message;
+ }
+
+ /**
+ * Initializes the caching if not already done so.
+ * Should be called before any of the caching functionality is used.
+ *
+ * @since 1.20
+ */
+ protected function initCaching() {
+ if ( $this->cacheEnabled && is_null( $this->hasCached ) ) {
+ $cachedChunks = wfGetCache( CACHE_ANYTHING )->get( $this->getCacheKeyString() );
+
+ $this->hasCached = is_array( $cachedChunks );
+ $this->cachedChunks = $this->hasCached ? $cachedChunks : array();
+
+ if ( $this->onInitHandler !== false ) {
+ call_user_func( $this->onInitHandler, $this->hasCached );
+ }
+ }
+ }
+
+ /**
+ * 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 ) {
+ $this->initCaching();
+
+ if ( $this->cacheEnabled && $this->hasCached ) {
+ $value = null;
+
+ if ( is_null( $key ) ) {
+ $itemKey = array_keys( array_slice( $this->cachedChunks, 0, 1 ) );
+ $itemKey = array_shift( $itemKey );
+
+ if ( !is_integer( $itemKey ) ) {
+ wfWarn( "Attempted to get item with non-numeric key while " .
+ "the next item in the queue has a key ($itemKey) in " . __METHOD__ );
+ } elseif ( is_null( $itemKey ) ) {
+ wfWarn( "Attempted to get an item while the queue is empty in " . __METHOD__ );
+ } else {
+ $value = array_shift( $this->cachedChunks );
+ }
+ } else {
+ if ( array_key_exists( $key, $this->cachedChunks ) ) {
+ $value = $this->cachedChunks[$key];
+ unset( $this->cachedChunks[$key] );
+ } else {
+ wfWarn( "There is no item with key '$key' in this->cachedChunks in " . __METHOD__ );
+ }
+ }
+ } else {
+ if ( !is_array( $args ) ) {
+ $args = array( $args );
+ }
+
+ $value = call_user_func_array( $computeFunction, $args );
+
+ if ( $this->cacheEnabled ) {
+ if ( is_null( $key ) ) {
+ $this->cachedChunks[] = $value;
+ } else {
+ $this->cachedChunks[$key] = $value;
+ }
+ }
+ }
+
+ return $value;
+ }
+
+ /**
+ * 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 ( $this->cacheEnabled && $this->hasCached === false && !empty( $this->cachedChunks ) ) {
+ wfGetCache( CACHE_ANYTHING )->set(
+ $this->getCacheKeyString(),
+ $this->cachedChunks,
+ $this->cacheExpiry
+ );
+ }
+ }
+
+ /**
+ * 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->cacheExpiry = $cacheExpiry;
+ }
+
+ /**
+ * Returns the cache key to use to cache this page's HTML output.
+ * Is constructed from the special page name and language code.
+ *
+ * @since 1.20
+ *
+ * @return string
+ * @throws MWException
+ */
+ protected function getCacheKeyString() {
+ if ( $this->cacheKey === array() ) {
+ throw new MWException( 'No cache key set, so cannot obtain or save the CacheHelper values.' );
+ }
+
+ return call_user_func_array( 'wfMemcKey', $this->cacheKey );
+ }
+
+ /**
+ * Sets the cache key that should be used.
+ *
+ * @since 1.20
+ *
+ * @param array $cacheKey
+ */
+ public function setCacheKey( array $cacheKey ) {
+ $this->cacheKey = $cacheKey;
+ }
+
+ /**
+ * Rebuild the content, even if it's already cached.
+ * This effectively has the same effect as purging the cache,
+ * since it will be overridden with the new value on the next request.
+ *
+ * @since 1.20
+ */
+ public function rebuildOnDemand() {
+ $this->hasCached = false;
+ }
+
+ /**
+ * Sets a function that gets called when initialization of the cache is done.
+ *
+ * @since 1.20
+ *
+ * @param callable $handlerFunction
+ */
+ public function setOnInitializedHandler( $handlerFunction ) {
+ $this->onInitHandler = $handlerFunction;
+ }
+}
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