CacheHelper.php

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<?php
interface ICacheHelper {

        function setCacheEnabled( $cacheEnabled );

        function startCache( $cacheExpiry = null, $cacheEnabled = null );

        function getCachedValue( $computeFunction, $args = array(), $key = null );

        function saveCache();

        function setExpiry( $cacheExpiry );

}

class CacheHelper implements ICacheHelper {

        protected $cacheExpiry = 3600;

        protected $cachedChunks;

        protected $hasCached = null;

        protected $cacheEnabled = true;

        protected $onInitHandler = false;

        protected $cacheKey = array();

        public function setCacheEnabled( $cacheEnabled ) {
                $this->cacheEnabled = $cacheEnabled;
        }

        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();
                }
        }

        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;
        }

        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 );
                        }
                }
        }

        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;
        }

        public function saveCache() {
                if ( $this->cacheEnabled && $this->hasCached === false && !empty( $this->cachedChunks ) ) {
                        wfGetCache( CACHE_ANYTHING )->set( $this->getCacheKeyString(), $this->cachedChunks, $this->cacheExpiry );
                }
        }

        public function setExpiry( $cacheExpiry ) {
                $this->cacheExpiry = $cacheExpiry;
        }

        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 );
        }

        public function setCacheKey( array $cacheKey ) {
                $this->cacheKey = $cacheKey;
        }

        public function rebuildOnDemand() {
                $this->hasCached = false;
        }

        public function setOnInitializedHandler( $handlerFunction ) {
                $this->onInitHandler = $handlerFunction;
        }

}