MediaWikiGadgetsDefinitionRepo.php

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<?php
 
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\Database;
 
class MediaWikiGadgetsDefinitionRepo extends GadgetRepo {
    const CACHE_VERSION = 2;
 
    private $definitionCache;
 
    public function getGadget( $id ) {
        $gadgets = $this->loadGadgets();
        if ( !isset( $gadgets[$id] ) ) {
            throw new InvalidArgumentException( "No gadget registered for '$id'" );
        }
 
        return $gadgets[$id];
    }
 
    public function getGadgetIds() {
        $gadgets = $this->loadGadgets();
        if ( $gadgets ) {
            return array_keys( $gadgets );
        } else {
            return [];
        }
    }
 
    public function handlePageUpdate( LinkTarget $target ) {
        if ( $target->getNamespace() == NS_MEDIAWIKI && $target->getText() == 'Gadgets-definition' ) {
            $this->purgeDefinitionCache();
        }
    }
 
    private function purgeDefinitionCache() {
        $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
        $cache->touchCheckKey( $this->getDefinitionCacheKey() );
    }
 
    private function getDefinitionCacheKey() {
        $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
 
        return $cache->makeKey(
            'gadgets-definition',
            Gadget::GADGET_CLASS_VERSION,
            self::CACHE_VERSION
        );
    }
 
    protected function loadGadgets() {
        if ( $this->definitionCache !== null ) {
            return $this->definitionCache; // process cache hit
        }
 
        // Ideally $t1Cache is APC, and $wanCache is memcached
        $t1Cache = ObjectCache::getLocalServerInstance( 'hash' );
        $wanCache = MediaWikiServices::getInstance()->getMainWANObjectCache();
 
        $key = $this->getDefinitionCacheKey();
 
        // (a) Check the tier 1 cache
        $value = $t1Cache->get( $key );
        // Randomize logical APC expiry to avoid stampedes
        // somewhere between 7.0 and 15.0 (seconds)
        $cutoffAge = mt_rand( 7 * 1e6, 15 * 1e6 ) / 1e6;
        // Check if it passes a blind TTL check (avoids I/O)
        if ( $value && ( microtime( true ) - $value['time'] ) < $cutoffAge ) {
            $this->definitionCache = $value['gadgets']; // process cache
            return $this->definitionCache;
        }
        // Cache generated after the "check" time should be up-to-date
        $ckTime = $wanCache->getCheckKeyTime( $key ) + WANObjectCache::HOLDOFF_TTL;
        if ( $value && $value['time'] > $ckTime ) {
            $this->definitionCache = $value['gadgets']; // process cache
            return $this->definitionCache;
        }
 
        // (b) Fetch value from WAN cache or regenerate if needed.
        // This is hit occasionally and more so when the list changes.
        $us = $this;
        $value = $wanCache->getWithSetCallback(
            $key,
            Gadget::CACHE_TTL,
            function ( $old, &$ttl, &$setOpts ) use ( $us ) {
                $setOpts += Database::getCacheSetOptions( wfGetDB( DB_REPLICA ) );
 
                $now = microtime( true );
                $gadgets = $us->fetchStructuredList();
                if ( $gadgets === false ) {
                    $ttl = WANObjectCache::TTL_UNCACHEABLE;
                }
 
                return [ 'gadgets' => $gadgets, 'time' => $now ];
            },
            [ 'checkKeys' => [ $key ], 'lockTSE' => 300 ]
        );
 
        // Update the tier 1 cache as needed
        if ( $value['gadgets'] !== false && $value['time'] > $ckTime ) {
            // Set a modest TTL to keep the WAN key in cache
            $t1Cache->set( $key, $value, mt_rand( 300, 600 ) );
        }
 
        $this->definitionCache = $value['gadgets'];
 
        return $this->definitionCache;
    }
 
    public function fetchStructuredList( $forceNewText = null ) {
        if ( $forceNewText === null ) {
            // T157210: avoid using wfMessage() to avoid staleness due to cache layering
            $title = Title::makeTitle( NS_MEDIAWIKI, 'Gadgets-definition' );
            $rev = Revision::newFromTitle( $title );
            if ( !$rev || !$rev->getContent() || $rev->getContent()->isEmpty() ) {
                return false; // don't cache
            }
 
            $g = $rev->getContent()->getNativeData();
        } else {
            $g = $forceNewText;
        }
 
        $gadgets = $this->listFromDefinition( $g );
        if ( !count( $gadgets ) ) {
            return false; // don't cache; Bug 37228
        }
 
        $source = $forceNewText !== null ? 'input text' : 'MediaWiki:Gadgets-definition';
        wfDebug( __METHOD__ . ": $source parsed, cache entry should be updated\n" );
 
        return $gadgets;
    }
 
    private function listFromDefinition( $definition ) {
        $definition = preg_replace( '/<!--.*?-->/s', '', $definition );
        $lines = preg_split( '/(\r\n|\r|\n)+/', $definition );
 
        $gadgets = [];
        $section = '';
 
        foreach ( $lines as $line ) {
            $m = [];
            if ( preg_match( '/^==+ *([^*:\s|]+?)\s*==+\s*$/', $line, $m ) ) {
                $section = $m[1];
            } else {
                $gadget = $this->newFromDefinition( $line, $section );
                if ( $gadget ) {
                    $gadgets[$gadget->getName()] = $gadget;
                }
            }
        }
 
        return $gadgets;
    }
 
    public function newFromDefinition( $definition, $category ) {
        $m = [];
        if ( !preg_match(
            '/^\*+ *([a-zA-Z](?:[-_:.\w\d ]*[a-zA-Z0-9])?)(\s*\[.*?\])?\s*((\|[^|]*)+)\s*$/',
            $definition,
            $m
        ) ) {
            return false;
        }
        // NOTE: the gadget name is used as part of the name of a form field,
        // and must follow the rules defined in https://www.w3.org/TR/html4/types.html#type-cdata
        // Also, title-normalization applies.
        $info = [ 'category' => $category ];
        $info['name'] = trim( str_replace( ' ', '_', $m[1] ) );
        // If the name is too long, then RL will throw an MWException when
        // we try to register the module
        if ( !Gadget::isValidGadgetID( $info['name'] ) ) {
            return false;
        }
        $info['definition'] = $definition;
        $options = trim( $m[2], ' []' );
 
        foreach ( preg_split( '/\s*\|\s*/', $options, -1, PREG_SPLIT_NO_EMPTY ) as $option ) {
            $arr = preg_split( '/\s*=\s*/', $option, 2 );
            $option = $arr[0];
            if ( isset( $arr[1] ) ) {
                $params = explode( ',', $arr[1] );
                $params = array_map( 'trim', $params );
            } else {
                $params = [];
            }
 
            switch ( $option ) {
                case 'ResourceLoader':
                    $info['resourceLoaded'] = true;
                    break;
                case 'dependencies':
                    $info['dependencies'] = $params;
                    break;
                case 'peers':
                    $info['peers'] = $params;
                    break;
                case 'rights':
                    $info['requiredRights'] = $params;
                    break;
                case 'hidden':
                    $info['hidden'] = true;
                    break;
                case 'skins':
                    $info['requiredSkins'] = $params;
                    break;
                case 'default':
                    $info['onByDefault'] = true;
                    break;
                case 'targets':
                    $info['targets'] = $params;
                    break;
                case 'type':
                    // Single value, not a list
                    $info['type'] = $params[0] ?? '';
                    break;
            }
        }
 
        foreach ( preg_split( '/\s*\|\s*/', $m[3], -1, PREG_SPLIT_NO_EMPTY ) as $page ) {
            $page = "MediaWiki:Gadget-$page";
 
            if ( preg_match( '/\.js/', $page ) ) {
                $info['scripts'][] = $page;
            } elseif ( preg_match( '/\.css/', $page ) ) {
                $info['styles'][] = $page;
            }
        }
 
        return new Gadget( $info );
    }
}