mediawiki-extensions-Gadgets/includes/MediaWikiGadgetsDefinitionRepo.php
Kunal Mehta a544c227f2 Avoid hardcoding specific GadgetRepo implementations for cache invalidations
Depending on GadgetRepo::singleton() to return a specific implementation
is fragile. Pass each created/updated/deleted page to
GadgetRepo::handlePageCreation/Update/Deletion() and let each specific
implementation deal with it.

Use LinkTarget to be TitleValue compatible for the future.

Change-Id: Ibe2e26d12369a897c53757adf621926f62af7f7b
2017-11-07 12:13:11 -08:00

256 lines
7.3 KiB
PHP

<?php
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\Database;
/**
* Gadgets repo powered by MediaWiki:Gadgets-definition
*/
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();
}
}
/**
* Purge the definitions cache, for example if MediaWiki:Gadgets-definition
* was edited.
*/
private function purgeDefinitionCache() {
$cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
$cache->touchCheckKey( $this->getCheckKey() );
}
private function getCheckKey() {
return wfMemcKey( 'gadgets-definition', Gadget::GADGET_CLASS_VERSION, self::CACHE_VERSION );
}
/**
* Loads list of gadgets and returns it as associative array of sections with gadgets
* e.g. [ 'sectionnname1' => [ $gadget1, $gadget2 ],
* 'sectionnname2' => [ $gadget3 ] ];
* @return array|bool Gadget array or false on failure
*/
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->getCheckKey();
// (a) Check the tier 1 cache
$value = $t1Cache->get( $key );
// Check if it passes a blind TTL check (avoids I/O)
if ( $value && ( microtime( true ) - $value['time'] ) < 10 ) {
$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;
}
/**
* Fetch list of gadgets and returns it as associative array of sections with gadgets
* e.g. [ $name => $gadget1, etc. ]
* @param string $forceNewText Injected text of MediaWiki:gadgets-definition [optional]
* @return array|bool
*/
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;
}
/**
* Generates a structured list of Gadget objects from a definition
*
* @param string $definition
* @return Gadget[] List of Gadget objects indexed by the gadget's name.
*/
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;
}
/**
* Creates an instance of this class from definition in MediaWiki:Gadgets-definition
* @param string $definition Gadget definition
* @param string $category
* @return Gadget|bool Instance of Gadget class or false if $definition is invalid
*/
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'] = isset( $params[0] ) ? $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 );
}
}