REL1_29/php/MessageCache_8php_source.html

<?php

use MediaWiki\MediaWikiServices;

use Wikimedia\ScopedCallback;

use MediaWiki\Logger\LoggerFactory;

use Wikimedia\Rdbms\Database;


define( 'MSG_CACHE_VERSION', 2 );


class MessageCache {

    const FOR_UPDATE = 1; // force message reload


    const WAIT_SEC = 15;

    const LOCK_TTL = 30;


    protected $mCache;


    protected $mCacheVolatile = [];


    protected $mDisable;


    protected $mExpiry;


    protected $mParserOptions;

    protected $mParser;


    protected $mLoadedLanguages = [];


    protected $mInParser = false;


    protected $wanCache;

    protected $clusterCache;

    protected $srvCache;


    private static $instance;


    public static function singleton() {

        if ( self::$instance === null ) {

            global $wgUseDatabaseMessages, $wgMsgCacheExpiry, $wgUseLocalMessageCache;

            self::$instance = new self(

                MediaWikiServices::getInstance()->getMainWANObjectCache(),

                wfGetMessageCacheStorage(),

                $wgUseLocalMessageCache

                    ? MediaWikiServices::getInstance()->getLocalServerObjectCache()

                    : new EmptyBagOStuff(),

                $wgUseDatabaseMessages,

                $wgMsgCacheExpiry

            );

        }


        return self::$instance;

    }


    public static function destroyInstance() {

        self::$instance = null;

    }


    public static function normalizeKey( $key ) {

        global $wgContLang;


        $lckey = strtr( $key, ' ', '_' );

        if ( ord( $lckey ) < 128 ) {

            $lckey[0] = strtolower( $lckey[0] );

        } else {

            $lckey = $wgContLang->lcfirst( $lckey );

        }


        return $lckey;

    }


    public function __construct(

        WANObjectCache $wanCache,

        BagOStuff $clusterCache,

        BagOStuff $srvCache,

        $useDB,

        $expiry

    ) {

        $this->wanCache = $wanCache;

        $this->clusterCache = $clusterCache;

        $this->srvCache = $srvCache;


        $this->mDisable = !$useDB;

        $this->mExpiry = $expiry;

    }


    function getParserOptions() {

        global $wgUser;


        if ( !$this->mParserOptions ) {

            if ( !$wgUser->isSafeToLoad() ) {

                // $wgUser isn't unstubbable yet, so don't try to get a

                // ParserOptions for it. And don't cache this ParserOptions

                // either.

                $po = ParserOptions::newFromAnon();

                $po->setEditSection( false );

                $po->setAllowUnsafeRawHtml( false );

                return $po;

            }


            $this->mParserOptions = new ParserOptions;

            $this->mParserOptions->setEditSection( false );

            // Messages may take parameters that could come

            // from malicious sources. As a precaution, disable

            // the <html> parser tag when parsing messages.

            $this->mParserOptions->setAllowUnsafeRawHtml( false );

        }


        return $this->mParserOptions;

    }


    protected function getLocalCache( $code ) {

        $cacheKey = wfMemcKey( __CLASS__, $code );


        return $this->srvCache->get( $cacheKey );

    }


    protected function saveToLocalCache( $code, $cache ) {

        $cacheKey = wfMemcKey( __CLASS__, $code );

        $this->srvCache->set( $cacheKey, $cache );

    }


    protected function load( $code, $mode = null ) {

        if ( !is_string( $code ) ) {

            throw new InvalidArgumentException( "Missing language code" );

        }


        # Don't do double loading...

        if ( isset( $this->mLoadedLanguages[$code] ) && $mode != self::FOR_UPDATE ) {

            return true;

        }


        # 8 lines of code just to say (once) that message cache is disabled

        if ( $this->mDisable ) {

            static $shownDisabled = false;

            if ( !$shownDisabled ) {

                wfDebug( __METHOD__ . ": disabled\n" );

                $shownDisabled = true;

            }


            return true;

        }


        # Loading code starts

        $success = false; # Keep track of success

        $staleCache = false; # a cache array with expired data, or false if none has been loaded

        $where = []; # Debug info, delayed to avoid spamming debug log too much


        # Hash of the contents is stored in memcache, to detect if data-center cache

        # or local cache goes out of date (e.g. due to replace() on some other server)

        list( $hash, $hashVolatile ) = $this->getValidationHash( $code );

        $this->mCacheVolatile[$code] = $hashVolatile;


        # Try the local cache and check against the cluster hash key...

        $cache = $this->getLocalCache( $code );

        if ( !$cache ) {

            $where[] = 'local cache is empty';

        } elseif ( !isset( $cache['HASH'] ) || $cache['HASH'] !== $hash ) {

            $where[] = 'local cache has the wrong hash';

            $staleCache = $cache;

        } elseif ( $this->isCacheExpired( $cache ) ) {

            $where[] = 'local cache is expired';

            $staleCache = $cache;

        } elseif ( $hashVolatile ) {

            $where[] = 'local cache validation key is expired/volatile';

            $staleCache = $cache;

        } else {

            $where[] = 'got from local cache';

            $success = true;

            $this->mCache[$code] = $cache;

        }


        if ( !$success ) {

            $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages

            # Try the global cache. If it is empty, try to acquire a lock. If

            # the lock can't be acquired, wait for the other thread to finish

            # and then try the global cache a second time.

            for ( $failedAttempts = 0; $failedAttempts <= 1; $failedAttempts++ ) {

                if ( $hashVolatile && $staleCache ) {

                    # Do not bother fetching the whole cache blob to avoid I/O.

                    # Instead, just try to get the non-blocking $statusKey lock

                    # below, and use the local stale value if it was not acquired.

                    $where[] = 'global cache is presumed expired';

                } else {

                    $cache = $this->clusterCache->get( $cacheKey );

                    if ( !$cache ) {

                        $where[] = 'global cache is empty';

                    } elseif ( $this->isCacheExpired( $cache ) ) {

                        $where[] = 'global cache is expired';

                        $staleCache = $cache;

                    } elseif ( $hashVolatile ) {

                        # DB results are replica DB lag prone until the holdoff TTL passes.

                        # By then, updates should be reflected in loadFromDBWithLock().

                        # One thread renerates the cache while others use old values.

                        $where[] = 'global cache is expired/volatile';

                        $staleCache = $cache;

                    } else {

                        $where[] = 'got from global cache';

                        $this->mCache[$code] = $cache;

                        $this->saveToCaches( $cache, 'local-only', $code );

                        $success = true;

                    }

                }


                if ( $success ) {

                    # Done, no need to retry

                    break;

                }


                # We need to call loadFromDB. Limit the concurrency to one process.

                # This prevents the site from going down when the cache expires.

                # Note that the DB slam protection lock here is non-blocking.

                $loadStatus = $this->loadFromDBWithLock( $code, $where, $mode );

                if ( $loadStatus === true ) {

                    $success = true;

                    break;

                } elseif ( $staleCache ) {

                    # Use the stale cache while some other thread constructs the new one

                    $where[] = 'using stale cache';

                    $this->mCache[$code] = $staleCache;

                    $success = true;

                    break;

                } elseif ( $failedAttempts > 0 ) {

                    # Already blocked once, so avoid another lock/unlock cycle.

                    # This case will typically be hit if memcached is down, or if

                    # loadFromDB() takes longer than LOCK_WAIT.

                    $where[] = "could not acquire status key.";

                    break;

                } elseif ( $loadStatus === 'cantacquire' ) {

                    # Wait for the other thread to finish, then retry. Normally,

                    # the memcached get() will then yeild the other thread's result.

                    $where[] = 'waited for other thread to complete';

                    $this->getReentrantScopedLock( $cacheKey );

                } else {

                    # Disable cache; $loadStatus is 'disabled'

                    break;

                }

            }

        }


        if ( !$success ) {

            $where[] = 'loading FAILED - cache is disabled';

            $this->mDisable = true;

            $this->mCache = false;

            wfDebugLog( 'MessageCacheError', __METHOD__ . ": Failed to load $code\n" );

            # This used to throw an exception, but that led to nasty side effects like

            # the whole wiki being instantly down if the memcached server died

        } else {

            # All good, just record the success

            $this->mLoadedLanguages[$code] = true;

        }


        $info = implode( ', ', $where );

        wfDebugLog( 'MessageCache', __METHOD__ . ": Loading $code... $info\n" );


        return $success;

    }


    protected function loadFromDBWithLock( $code, array &$where, $mode = null ) {

        # If cache updates on all levels fail, give up on message overrides.

        # This is to avoid easy site outages; see $saveSuccess comments below.

        $statusKey = wfMemcKey( 'messages', $code, 'status' );

        $status = $this->clusterCache->get( $statusKey );

        if ( $status === 'error' ) {

            $where[] = "could not load; method is still globally disabled";

            return 'disabled';

        }


        # Now let's regenerate

        $where[] = 'loading from database';


        # Lock the cache to prevent conflicting writes.

        # This lock is non-blocking so stale cache can quickly be used.

        # Note that load() will call a blocking getReentrantScopedLock()

        # after this if it really need to wait for any current thread.

        $cacheKey = wfMemcKey( 'messages', $code );

        $scopedLock = $this->getReentrantScopedLock( $cacheKey, 0 );

        if ( !$scopedLock ) {

            $where[] = 'could not acquire main lock';

            return 'cantacquire';

        }


        $cache = $this->loadFromDB( $code, $mode );

        $this->mCache[$code] = $cache;

        $saveSuccess = $this->saveToCaches( $cache, 'all', $code );


        if ( !$saveSuccess ) {

            if ( $this->srvCache instanceof EmptyBagOStuff ) {

                $this->clusterCache->set( $statusKey, 'error', 60 * 5 );

                $where[] = 'could not save cache, disabled globally for 5 minutes';

            } else {

                $where[] = "could not save global cache";

            }

        }


        return true;

    }


    protected function loadFromDB( $code, $mode = null ) {

        global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;


        $dbr = wfGetDB( ( $mode == self::FOR_UPDATE ) ? DB_MASTER : DB_REPLICA );


        $cache = [];


        # Common conditions

        $conds = [

            'page_is_redirect' => 0,

            'page_namespace' => NS_MEDIAWIKI,

        ];


        $mostused = [];

        if ( $wgAdaptiveMessageCache && $code !== $wgLanguageCode ) {

            if ( !isset( $this->mCache[$wgLanguageCode] ) ) {

                $this->load( $wgLanguageCode );

            }

            $mostused = array_keys( $this->mCache[$wgLanguageCode] );

            foreach ( $mostused as $key => $value ) {

                $mostused[$key] = "$value/$code";

            }

        }


        if ( count( $mostused ) ) {

            $conds['page_title'] = $mostused;

        } elseif ( $code !== $wgLanguageCode ) {

            $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), '/', $code );

        } else {

            # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses

            # other than language code.

            $conds[] = 'page_title NOT' .

                $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );

        }


        # Conditions to fetch oversized pages to ignore them

        $bigConds = $conds;

        $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );


        # Load titles for all oversized pages in the MediaWiki namespace

        $res = $dbr->select(

            'page',

            [ 'page_title', 'page_latest' ],

            $bigConds,

            __METHOD__ . "($code)-big"

        );

        foreach ( $res as $row ) {

            $cache[$row->page_title] = '!TOO BIG';

            // At least include revision ID so page changes are reflected in the hash

            $cache['EXCESSIVE'][$row->page_title] = $row->page_latest;

        }


        # Conditions to load the remaining pages with their contents

        $smallConds = $conds;

        $smallConds[] = 'page_latest=rev_id';

        $smallConds[] = 'rev_text_id=old_id';

        $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );


        $res = $dbr->select(

            [ 'page', 'revision', 'text' ],

            [ 'page_title', 'old_id', 'old_text', 'old_flags' ],

            $smallConds,

            __METHOD__ . "($code)-small"

        );


        foreach ( $res as $row ) {

            $text = Revision::getRevisionText( $row );

            if ( $text === false ) {

                // Failed to fetch data; possible ES errors?

                // Store a marker to fetch on-demand as a workaround...

                // TODO Use a differnt marker

                $entry = '!TOO BIG';

                wfDebugLog(

                    'MessageCache',

                    __METHOD__

                    . ": failed to load message page text for {$row->page_title} ($code)"

                );

            } else {

                $entry = ' ' . $text;

            }

            $cache[$row->page_title] = $entry;

        }


        $cache['VERSION'] = MSG_CACHE_VERSION;

        ksort( $cache );


        # Hash for validating local cache (APC). No need to take into account

        # messages larger than $wgMaxMsgCacheEntrySize, since those are only

        # stored and fetched from memcache.

        $cache['HASH'] = md5( serialize( $cache ) );

        $cache['EXPIRY'] = wfTimestamp( TS_MW, time() + $this->mExpiry );


        return $cache;

    }


    public function replace( $title, $text ) {

        global $wgLanguageCode;


        if ( $this->mDisable ) {

            return;

        }


        list( $msg, $code ) = $this->figureMessage( $title );

        if ( strpos( $title, '/' ) !== false && $code === $wgLanguageCode ) {

            // Content language overrides do not use the /<code> suffix

            return;

        }


        // (a) Update the process cache with the new message text

        if ( $text === false ) {

            // Page deleted

            $this->mCache[$code][$title] = '!NONEXISTENT';

        } else {

            // Ignore $wgMaxMsgCacheEntrySize so the process cache is up to date

            $this->mCache[$code][$title] = ' ' . $text;

        }


        // (b) Update the shared caches in a deferred update with a fresh DB snapshot

        DeferredUpdates::addCallableUpdate(

            function () use ( $title, $msg, $code ) {

                global $wgContLang, $wgMaxMsgCacheEntrySize;

                // Allow one caller at a time to avoid race conditions

                $scopedLock = $this->getReentrantScopedLock( wfMemcKey( 'messages', $code ) );

                if ( !$scopedLock ) {

                    LoggerFactory::getInstance( 'MessageCache' )->error(

                        __METHOD__ . ': could not acquire lock to update {title} ({code})',

                        [ 'title' => $title, 'code' => $code ] );

                    return;

                }

                // Load the messages from the master DB to avoid race conditions

                $cache = $this->loadFromDB( $code, self::FOR_UPDATE );

                $this->mCache[$code] = $cache;

                // Load the process cache values and set the per-title cache keys

                $page = WikiPage::factory( Title::makeTitle( NS_MEDIAWIKI, $title ) );

                $page->loadPageData( $page::READ_LATEST );

                $text = $this->getMessageTextFromContent( $page->getContent() );

                // Check if an individual cache key should exist and update cache accordingly

                if ( is_string( $text ) && strlen( $text ) > $wgMaxMsgCacheEntrySize ) {

                    $titleKey = $this->bigMessageCacheKey( $this->mCache[$code]['HASH'], $title );

                    $this->wanCache->set( $titleKey, ' ' . $text, $this->mExpiry );

                }

                // Mark this cache as definitely being "latest" (non-volatile) so

                // load() calls do try to refresh the cache with replica DB data

                $this->mCache[$code]['LATEST'] = time();

                // Pre-emptively update the local datacenter cache so things like edit filter and

                // blacklist changes are reflect immediately, as these often use MediaWiki: pages.

                // The datacenter handling replace() calls should be the same one handling edits

                // as they require HTTP POST.

                $this->saveToCaches( $this->mCache[$code], 'all', $code );

                // Release the lock now that the cache is saved

                ScopedCallback::consume( $scopedLock );


                // Relay the purge. Touching this check key expires cache contents

                // and local cache (APC) validation hash across all datacenters.

                $this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );

                // Also delete cached sidebar... just in case it is affected

                // @TODO: shouldn't this be $code === $wgLanguageCode?

                if ( $code === 'en' ) {

                    // Purge all language sidebars, e.g. on ?action=purge to the sidebar messages

                    $codes = array_keys( Language::fetchLanguageNames() );

                } else {

                    // Purge only the sidebar for this language

                    $codes = [ $code ];

                }

                foreach ( $codes as $code ) {

                    $this->wanCache->delete( wfMemcKey( 'sidebar', $code ) );

                }


                // Purge the message in the message blob store

                $resourceloader = RequestContext::getMain()->getOutput()->getResourceLoader();

                $blobStore = $resourceloader->getMessageBlobStore();

                $blobStore->updateMessage( $wgContLang->lcfirst( $msg ) );


                Hooks::run( 'MessageCacheReplace', [ $title, $text ] );

            },

            DeferredUpdates::PRESEND

        );

    }


    protected function isCacheExpired( $cache ) {

        if ( !isset( $cache['VERSION'] ) || !isset( $cache['EXPIRY'] ) ) {

            return true;

        }

        if ( $cache['VERSION'] != MSG_CACHE_VERSION ) {

            return true;

        }

        if ( wfTimestampNow() >= $cache['EXPIRY'] ) {

            return true;

        }


        return false;

    }


    protected function saveToCaches( array $cache, $dest, $code = false ) {

        if ( $dest === 'all' ) {

            $cacheKey = wfMemcKey( 'messages', $code );

            $success = $this->clusterCache->set( $cacheKey, $cache );

            $this->setValidationHash( $code, $cache );

        } else {

            $success = true;

        }


        $this->saveToLocalCache( $code, $cache );


        return $success;

    }


    protected function getValidationHash( $code ) {

        $curTTL = null;

        $value = $this->wanCache->get(

            $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),

            $curTTL,

            [ wfMemcKey( 'messages', $code ) ]

        );


        if ( $value ) {

            $hash = $value['hash'];

            if ( ( time() - $value['latest'] ) < WANObjectCache::TTL_MINUTE ) {

                // Cache was recently updated via replace() and should be up-to-date.

                // That method is only called in the primary datacenter and uses FOR_UPDATE.

                // Also, it is unlikely that the current datacenter is *now* secondary one.

                $expired = false;

            } else {

                // See if the "check" key was bumped after the hash was generated

                $expired = ( $curTTL < 0 );

            }

        } else {

            // No hash found at all; cache must regenerate to be safe

            $hash = false;

            $expired = true;

        }


        return [ $hash, $expired ];

    }


    protected function setValidationHash( $code, array $cache ) {

        $this->wanCache->set(

            $this->wanCache->makeKey( 'messages', $code, 'hash', 'v1' ),

            [

                'hash' => $cache['HASH'],

                'latest' => isset( $cache['LATEST'] ) ? $cache['LATEST'] : 0

            ],

            WANObjectCache::TTL_INDEFINITE

        );

    }


    protected function getReentrantScopedLock( $key, $timeout = self::WAIT_SEC ) {

        return $this->clusterCache->getScopedLock( $key, $timeout, self::LOCK_TTL, __METHOD__ );

    }


    function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {

        if ( is_int( $key ) ) {

            // Fix numerical strings that somehow become ints

            // on their way here

            $key = (string)$key;

        } elseif ( !is_string( $key ) ) {

            throw new MWException( 'Non-string key given' );

        } elseif ( $key === '' ) {

            // Shortcut: the empty key is always missing

            return false;

        }


        // For full keys, get the language code from the key

        $pos = strrpos( $key, '/' );

        if ( $isFullKey && $pos !== false ) {

            $langcode = substr( $key, $pos + 1 );

            $key = substr( $key, 0, $pos );

        }


        // Normalise title-case input (with some inlining)

        $lckey = MessageCache::normalizeKey( $key );


        Hooks::run( 'MessageCache::get', [ &$lckey ] );


        // Loop through each language in the fallback list until we find something useful

        $lang = wfGetLangObj( $langcode );

        $message = $this->getMessageFromFallbackChain(

            $lang,

            $lckey,

            !$this->mDisable && $useDB

        );


        // If we still have no message, maybe the key was in fact a full key so try that

        if ( $message === false ) {

            $parts = explode( '/', $lckey );

            // We may get calls for things that are http-urls from sidebar

            // Let's not load nonexistent languages for those

            // They usually have more than one slash.

            if ( count( $parts ) == 2 && $parts[1] !== '' ) {

                $message = Language::getMessageFor( $parts[0], $parts[1] );

                if ( $message === null ) {

                    $message = false;

                }

            }

        }


        // Post-processing if the message exists

        if ( $message !== false ) {

            // Fix whitespace

            $message = str_replace(

                [

                    # Fix for trailing whitespace, removed by textarea

                    '&#32;',

                    # Fix for NBSP, converted to space by firefox

                    '&nbsp;',

                    '&#160;',

                    '&shy;'

                ],

                [

                    ' ',

                    "\xc2\xa0",

                    "\xc2\xa0",

                    "\xc2\xad"

                ],

                $message

            );

        }


        return $message;

    }


    protected function getMessageFromFallbackChain( $lang, $lckey, $useDB ) {

        global $wgContLang;


        $alreadyTried = [];


        // First try the requested language.

        $message = $this->getMessageForLang( $lang, $lckey, $useDB, $alreadyTried );

        if ( $message !== false ) {

            return $message;

        }


        // Now try checking the site language.

        $message = $this->getMessageForLang( $wgContLang, $lckey, $useDB, $alreadyTried );

        return $message;

    }


    private function getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried ) {

        global $wgContLang;


        $langcode = $lang->getCode();


        // Try checking the database for the requested language

        if ( $useDB ) {

            $uckey = $wgContLang->ucfirst( $lckey );


            if ( !isset( $alreadyTried[ $langcode ] ) ) {

                $message = $this->getMsgFromNamespace(

                    $this->getMessagePageName( $langcode, $uckey ),

                    $langcode

                );


                if ( $message !== false ) {

                    return $message;

                }

                $alreadyTried[ $langcode ] = true;

            }

        } else {

            $uckey = null;

        }


        // Check the CDB cache

        $message = $lang->getMessage( $lckey );

        if ( $message !== null ) {

            return $message;

        }


        // Try checking the database for all of the fallback languages

        if ( $useDB ) {

            $fallbackChain = Language::getFallbacksFor( $langcode );


            foreach ( $fallbackChain as $code ) {

                if ( isset( $alreadyTried[ $code ] ) ) {

                    continue;

                }


                $message = $this->getMsgFromNamespace(

                    $this->getMessagePageName( $code, $uckey ), $code );


                if ( $message !== false ) {

                    return $message;

                }

                $alreadyTried[ $code ] = true;

            }

        }


        return false;

    }


    private function getMessagePageName( $langcode, $uckey ) {

        global $wgLanguageCode;


        if ( $langcode === $wgLanguageCode ) {

            // Messages created in the content language will not have the /lang extension

            return $uckey;

        } else {

            return "$uckey/$langcode";

        }

    }


    public function getMsgFromNamespace( $title, $code ) {

        $this->load( $code );


        if ( isset( $this->mCache[$code][$title] ) ) {

            $entry = $this->mCache[$code][$title];

            if ( substr( $entry, 0, 1 ) === ' ' ) {

                // The message exists, so make sure a string is returned.

                return (string)substr( $entry, 1 );

            } elseif ( $entry === '!NONEXISTENT' ) {

                return false;

            } elseif ( $entry === '!TOO BIG' ) {

                // Fall through and try invididual message cache below

            }

        } else {

            // XXX: This is not cached in process cache, should it?

            $message = false;

            Hooks::run( 'MessagesPreLoad', [ $title, &$message, $code ] );

            if ( $message !== false ) {

                return $message;

            }


            return false;

        }


        // Individual message cache key

        $titleKey = $this->bigMessageCacheKey( $this->mCache[$code]['HASH'], $title );


        if ( $this->mCacheVolatile[$code] ) {

            $entry = false;

            // Make sure that individual keys respect the WAN cache holdoff period too

            LoggerFactory::getInstance( 'MessageCache' )->debug(

                __METHOD__ . ': loading volatile key \'{titleKey}\'',

                [ 'titleKey' => $titleKey, 'code' => $code ] );

        } else {

            // Try the individual message cache

            $entry = $this->wanCache->get( $titleKey );

        }


        if ( $entry !== false ) {

            if ( substr( $entry, 0, 1 ) === ' ' ) {

                $this->mCache[$code][$title] = $entry;

                // The message exists, so make sure a string is returned

                return (string)substr( $entry, 1 );

            } elseif ( $entry === '!NONEXISTENT' ) {

                $this->mCache[$code][$title] = '!NONEXISTENT';


                return false;

            } else {

                // Corrupt/obsolete entry, delete it

                $this->wanCache->delete( $titleKey );

            }

        }


        // Try loading the message from the database

        $dbr = wfGetDB( DB_REPLICA );

        $cacheOpts = Database::getCacheSetOptions( $dbr );

        // Use newKnownCurrent() to avoid querying revision/user tables

        $titleObj = Title::makeTitle( NS_MEDIAWIKI, $title );

        if ( $titleObj->getLatestRevID() ) {

            $revision = Revision::newKnownCurrent(

                $dbr,

                $titleObj->getArticleID(),

                $titleObj->getLatestRevID()

            );

        } else {

            $revision = false;

        }


        if ( $revision ) {

            $content = $revision->getContent();

            if ( $content ) {

                $message = $this->getMessageTextFromContent( $content );

                if ( is_string( $message ) ) {

                    $this->mCache[$code][$title] = ' ' . $message;

                    $this->wanCache->set( $titleKey, ' ' . $message, $this->mExpiry, $cacheOpts );

                }

            } else {

                // A possibly temporary loading failure

                LoggerFactory::getInstance( 'MessageCache' )->warning(

                    __METHOD__ . ': failed to load message page text for \'{titleKey}\'',

                    [ 'titleKey' => $titleKey, 'code' => $code ] );

                $message = null; // no negative caching

            }

        } else {

            $message = false; // negative caching

        }


        if ( $message === false ) {

            // Negative caching in case a "too big" message is no longer available (deleted)

            $this->mCache[$code][$title] = '!NONEXISTENT';

            $this->wanCache->set( $titleKey, '!NONEXISTENT', $this->mExpiry, $cacheOpts );

        }


        return $message;

    }


    function transform( $message, $interface = false, $language = null, $title = null ) {

        // Avoid creating parser if nothing to transform

        if ( strpos( $message, '{{' ) === false ) {

            return $message;

        }


        if ( $this->mInParser ) {

            return $message;

        }


        $parser = $this->getParser();

        if ( $parser ) {

            $popts = $this->getParserOptions();

            $popts->setInterfaceMessage( $interface );

            $popts->setTargetLanguage( $language );


            $userlang = $popts->setUserLang( $language );

            $this->mInParser = true;

            $message = $parser->transformMsg( $message, $popts, $title );

            $this->mInParser = false;

            $popts->setUserLang( $userlang );

        }


        return $message;

    }


    function getParser() {

        global $wgParser, $wgParserConf;


        if ( !$this->mParser && isset( $wgParser ) ) {

            # Do some initialisation so that we don't have to do it twice

            $wgParser->firstCallInit();

            # Clone it and store it

            $class = $wgParserConf['class'];

            if ( $class == 'ParserDiffTest' ) {

                # Uncloneable

                $this->mParser = new $class( $wgParserConf );

            } else {

                $this->mParser = clone $wgParser;

            }

        }


        return $this->mParser;

    }


    public function parse( $text, $title = null, $linestart = true,

        $interface = false, $language = null

    ) {

        global $wgTitle;


        if ( $this->mInParser ) {

            return htmlspecialchars( $text );

        }


        $parser = $this->getParser();

        $popts = $this->getParserOptions();

        $popts->setInterfaceMessage( $interface );


        if ( is_string( $language ) ) {

            $language = Language::factory( $language );

        }

        $popts->setTargetLanguage( $language );


        if ( !$title || !$title instanceof Title ) {

            wfDebugLog( 'GlobalTitleFail', __METHOD__ . ' called by ' .

                wfGetAllCallers( 6 ) . ' with no title set.' );

            $title = $wgTitle;

        }

        // Sometimes $wgTitle isn't set either...

        if ( !$title ) {

            # It's not uncommon having a null $wgTitle in scripts. See r80898

            # Create a ghost title in such case

            $title = Title::makeTitle( NS_SPECIAL, 'Badtitle/title not set in ' . __METHOD__ );

        }


        $this->mInParser = true;

        $res = $parser->parse( $text, $title, $popts, $linestart );

        $this->mInParser = false;


        return $res;

    }


    function disable() {

        $this->mDisable = true;

    }


    function enable() {

        $this->mDisable = false;

    }


    public function isDisabled() {

        return $this->mDisable;

    }


    function clear() {

        $langs = Language::fetchLanguageNames( null, 'mw' );

        foreach ( array_keys( $langs ) as $code ) {

            # Global and local caches

            $this->wanCache->touchCheckKey( wfMemcKey( 'messages', $code ) );

        }


        $this->mLoadedLanguages = [];

    }


    public function figureMessage( $key ) {

        global $wgLanguageCode;


        $pieces = explode( '/', $key );

        if ( count( $pieces ) < 2 ) {

            return [ $key, $wgLanguageCode ];

        }


        $lang = array_pop( $pieces );

        if ( !Language::fetchLanguageName( $lang, null, 'mw' ) ) {

            return [ $key, $wgLanguageCode ];

        }


        $message = implode( '/', $pieces );


        return [ $message, $lang ];

    }


    public function getAllMessageKeys( $code ) {

        global $wgContLang;


        $this->load( $code );

        if ( !isset( $this->mCache[$code] ) ) {

            // Apparently load() failed

            return null;

        }

        // Remove administrative keys

        $cache = $this->mCache[$code];

        unset( $cache['VERSION'] );

        unset( $cache['EXPIRY'] );

        unset( $cache['EXCESSIVE'] );

        // Remove any !NONEXISTENT keys

        $cache = array_diff( $cache, [ '!NONEXISTENT' ] );


        // Keys may appear with a capital first letter. lcfirst them.

        return array_map( [ $wgContLang, 'lcfirst' ], array_keys( $cache ) );

    }


    public function updateMessageOverride( Title $title, Content $content = null ) {

        global $wgContLang;


        $msgText = $this->getMessageTextFromContent( $content );

        if ( $msgText === null ) {

            $msgText = false; // treat as not existing

        }


        $this->replace( $title->getDBkey(), $msgText );


        if ( $wgContLang->hasVariants() ) {

            $wgContLang->updateConversionTable( $title );

        }

    }


    private function getMessageTextFromContent( Content $content = null ) {

        // @TODO: could skip pseudo-messages like js/css here, based on content model

        if ( $content ) {

            // Message page exists...

            // XXX: Is this the right way to turn a Content object into a message?

            // NOTE: $content is typically either WikitextContent, JavaScriptContent or

            //       CssContent. MessageContent is *not* used for storing messages, it's

            //       only used for wrapping them when needed.

            $msgText = $content->getWikitextForTransclusion();

            if ( $msgText === false || $msgText === null ) {

                // This might be due to some kind of misconfiguration...

                $msgText = null;

                LoggerFactory::getInstance( 'MessageCache' )->warning(

                    __METHOD__ . ": message content doesn't provide wikitext "

                    . "(content model: " . $content->getModel() . ")" );

            }

        } else {

            // Message page does not exist...

            $msgText = false;

        }


        return $msgText;

    }


    private function bigMessageCacheKey( $hash, $title ) {

        return $this->wanCache->makeKey( 'messages-big', $hash, $title );

    }


}


or
or
Definition APACHE-LICENSE-2.0.txt:114

use
Apache License January AND DISTRIBUTION Definitions License shall mean the terms and conditions for use
Definition APACHE-LICENSE-2.0.txt:10

by
Apache License January AND DISTRIBUTION Definitions License shall mean the terms and conditions for and distribution as defined by Sections through of this document Licensor shall mean the copyright owner or entity authorized by the copyright owner that is granting the License Legal Entity shall mean the union of the acting entity and all other entities that control are controlled by or are under common control with that entity For the purposes of this definition control direct or to cause the direction or management of such whether by contract or including but not limited to software source documentation and configuration files Object form shall mean any form resulting from mechanical transformation or translation of a Source including but not limited to compiled object generated and conversions to other media types Work shall mean the work of whether in Source or Object made available under the as indicated by a copyright notice that is included in or attached to the whether in Source or Object that is based or other modifications as a an original work of authorship For the purposes of this Derivative Works shall not include works that remain separable or merely the Work and Derivative Works thereof Contribution shall mean any work of including the original version of the Work and any modifications or additions to that Work or Derivative Works that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner For the purposes of this submitted means any form of or written communication sent to the Licensor or its including but not limited to communication on electronic mailing source code control and issue tracking systems that are managed by
Definition APACHE-LICENSE-2.0.txt:58

serialize
serialize()
Definition ApiMessage.php:177

$wgLanguageCode
$wgLanguageCode
Site language code.
Definition DefaultSettings.php:2839

$wgUseLocalMessageCache
$wgUseLocalMessageCache
Set this to true to maintain a copy of the message cache on the local server.
Definition DefaultSettings.php:2457

$wgAdaptiveMessageCache
$wgAdaptiveMessageCache
Instead of caching everything, only cache those messages which have been customised in the site conte...
Definition DefaultSettings.php:2465

$wgUseDatabaseMessages
$wgUseDatabaseMessages
Translation using MediaWiki: namespace.
Definition DefaultSettings.php:3032

$wgMaxMsgCacheEntrySize
$wgMaxMsgCacheEntrySize
Maximum entry size in the message cache, in bytes.
Definition DefaultSettings.php:3042

$wgParserConf
$wgParserConf
Parser configuration.
Definition DefaultSettings.php:4149

$wgMsgCacheExpiry
$wgMsgCacheExpiry
Expiry time for the message cache key.
Definition DefaultSettings.php:3037

wfGetLangObj
wfGetLangObj( $langcode=false)
Return a Language object from $langcode.
Definition GlobalFunctions.php:1322

wfDebug
wfDebug( $text, $dest='all', array $context=[])
Sends a line to the debug log if enabled or, optionally, to a comment in output.
Definition GlobalFunctions.php:1000

wfTimestampNow
wfTimestampNow()
Convenience function; returns MediaWiki timestamp for the present time.
Definition GlobalFunctions.php:2024

wfGetDB
wfGetDB( $db, $groups=[], $wiki=false)
Get a Database object.
Definition GlobalFunctions.php:3063

wfGetMessageCacheStorage
wfGetMessageCacheStorage()
Get the cache object used by the message cache.
Definition GlobalFunctions.php:3420

wfMemcKey
wfMemcKey()
Make a cache key for the local wiki.
Definition GlobalFunctions.php:2964

wfGetAllCallers
wfGetAllCallers( $limit=3)
Return a string consisting of callers in the stack.
Definition GlobalFunctions.php:1578

wfDebugLog
wfDebugLog( $logGroup, $text, $dest='all', array $context=[])
Send a line to a supplementary debug log file, if configured, or main debug log if not.
Definition GlobalFunctions.php:1093

wfTimestamp
wfTimestamp( $outputtype=TS_UNIX, $ts=0)
Get a timestamp string in one of various formats.
Definition GlobalFunctions.php:1995

MSG_CACHE_VERSION
const MSG_CACHE_VERSION
MediaWiki message cache structure version.
Definition MessageCache.php:32

$success
$success
Definition NoLocalSettings.php:44

$wgUser
$wgUser
Definition Setup.php:781

$wgParser
$wgParser
Definition Setup.php:796

$wgTitle
if(! $wgRequest->checkUrlExtension()) if(isset($_SERVER[ 'PATH_INFO']) &&$_SERVER[ 'PATH_INFO'] !='') if(! $wgEnableAPI) $wgTitle
Definition api.php:68

BagOStuff
interface is intended to be more or less compatible with the PHP memcached client.
Definition BagOStuff.php:47

EmptyBagOStuff
A BagOStuff object with no objects in it.
Definition EmptyBagOStuff.php:29

MWException
MediaWiki exception.
Definition MWException.php:26

MediaWiki\Logger\LoggerFactory
PSR-3 logger instance factory.
Definition LoggerFactory.php:46

MediaWiki\MediaWikiServices
MediaWikiServices is the service locator for the application scope of MediaWiki.
Definition MediaWikiServices.php:76

MessageCache
Message cache Performs various MediaWiki namespace-related functions.
Definition MessageCache.php:39

MessageCache\getValidationHash
getValidationHash( $code)
Get the md5 used to validate the local APC cache.
Definition MessageCache.php:692

MessageCache\loadFromDBWithLock
loadFromDBWithLock( $code, array &$where, $mode=null)
Definition MessageCache.php:396

MessageCache\LOCK_TTL
const LOCK_TTL
How long memcached locks last.
Definition MessageCache.php:45

MessageCache\loadFromDB
loadFromDB( $code, $mode=null)
Loads cacheable messages from the database.
Definition MessageCache.php:458

MessageCache\getMessageForLang
getMessageForLang( $lang, $lckey, $useDB, &$alreadyTried)
Given a language, try and fetch messages from that language and its fallbacks.
Definition MessageCache.php:893

MessageCache\$mExpiry
$mExpiry
Lifetime for cache, used by object caching.
Definition MessageCache.php:72

MessageCache\saveToLocalCache
saveToLocalCache( $code, $cache)
Save the cache to APC.
Definition MessageCache.php:228

MessageCache\getMessagePageName
getMessagePageName( $langcode, $uckey)
Get the message page name for a given language.
Definition MessageCache.php:952

MessageCache\$instance
static $instance
Singleton instance.
Definition MessageCache.php:105

MessageCache\$mParser
Parser $mParser
Definition MessageCache.php:80

MessageCache\saveToCaches
saveToCaches(array $cache, $dest, $code=false)
Shortcut to update caches.
Definition MessageCache.php:672

MessageCache\$mInParser
$mInParser
Definition MessageCache.php:91

MessageCache\setValidationHash
setValidationHash( $code, array $cache)
Set the md5 used to validate the local disk cache.
Definition MessageCache.php:730

MessageCache\$mCacheVolatile
bool[] $mCacheVolatile
Map of (language code => boolean)
Definition MessageCache.php:60

MessageCache\isCacheExpired
isCacheExpired( $cache)
Is the given cache array expired due to time passing or a version change?
Definition MessageCache.php:649

MessageCache\getMsgFromNamespace
getMsgFromNamespace( $title, $code)
Get a message from the MediaWiki namespace, with caching.
Definition MessageCache.php:975

MessageCache\getReentrantScopedLock
getReentrantScopedLock( $key, $timeout=self::WAIT_SEC)
Definition MessageCache.php:746

MessageCache\WAIT_SEC
const WAIT_SEC
How long to wait for memcached locks.
Definition MessageCache.php:43

MessageCache\$mDisable
$mDisable
Should mean that database cannot be used, but check.
Definition MessageCache.php:66

MessageCache\getLocalCache
getLocalCache( $code)
Try to load the cache from APC.
Definition MessageCache.php:216

MessageCache\destroyInstance
static destroyInstance()
Destroy the singleton instance.
Definition MessageCache.php:135

MessageCache\load
load( $code, $mode=null)
Loads messages from caches or from database in this order: (1) local message cache (if $wgUseLocalMes...
Definition MessageCache.php:254

MessageCache\$srvCache
BagOStuff $srvCache
Definition MessageCache.php:98

MessageCache\transform
transform( $message, $interface=false, $language=null, $title=null)
Definition MessageCache.php:1078

MessageCache\updateMessageOverride
updateMessageOverride(Title $title, Content $content=null)
Purge message caches when a MediaWiki: page is created, updated, or deleted.
Definition MessageCache.php:1265

MessageCache\getMessageFromFallbackChain
getMessageFromFallbackChain( $lang, $lckey, $useDB)
Given a language, try and fetch messages from that language.
Definition MessageCache.php:867

MessageCache\$mLoadedLanguages
$mLoadedLanguages
Variable for tracking which variables are already loaded.
Definition MessageCache.php:86

MessageCache\isDisabled
isDisabled()
Whether DB/cache usage is disabled for determining messages.
Definition MessageCache.php:1191

MessageCache\disable
disable()
Definition MessageCache.php:1171

MessageCache\$clusterCache
BagOStuff $clusterCache
Definition MessageCache.php:96

MessageCache\getParser
getParser()
Definition MessageCache.php:1107

MessageCache\getMessageTextFromContent
getMessageTextFromContent(Content $content=null)
Definition MessageCache.php:1284

MessageCache\__construct
__construct(WANObjectCache $wanCache, BagOStuff $clusterCache, BagOStuff $srvCache, $useDB, $expiry)
Definition MessageCache.php:165

MessageCache\clear
clear()
Clear all stored messages.
Definition MessageCache.php:1198

MessageCache\singleton
static singleton()
Get the signleton instance of this class.
Definition MessageCache.php:113

MessageCache\getAllMessageKeys
getAllMessageKeys( $code)
Get all message keys stored in the message cache for a given language.
Definition MessageCache.php:1238

MessageCache\$mCache
$mCache
Process local cache of loaded messages that are defined in MediaWiki namespace.
Definition MessageCache.php:55

MessageCache\$wanCache
WANObjectCache $wanCache
Definition MessageCache.php:94

MessageCache\normalizeKey
static normalizeKey( $key)
Normalize message key input.
Definition MessageCache.php:145

MessageCache\FOR_UPDATE
const FOR_UPDATE
Definition MessageCache.php:40

MessageCache\enable
enable()
Definition MessageCache.php:1175

MessageCache\figureMessage
figureMessage( $key)
Definition MessageCache.php:1212

MessageCache\parse
parse( $text, $title=null, $linestart=true, $interface=false, $language=null)
Definition MessageCache.php:1134

MessageCache\$mParserOptions
ParserOptions $mParserOptions
Message cache has its own parser which it uses to transform messages.
Definition MessageCache.php:78

MessageCache\replace
replace( $title, $text)
Updates cache as necessary when message page is changed.
Definition MessageCache.php:559

MessageCache\getParserOptions
getParserOptions()
ParserOptions is lazy initialised.
Definition MessageCache.php:185

MessageCache\bigMessageCacheKey
bigMessageCacheKey( $hash, $title)
Definition MessageCache.php:1313

ParserOptions
Set options of the Parser.
Definition ParserOptions.php:33

ParserOptions\newFromAnon
static newFromAnon()
Get a ParserOptions object for an anonymous user.
Definition ParserOptions.php:693

ParserOptions\setEditSection
setEditSection( $x)
Definition ParserOptions.php:504

Parser
PHP Parser - Processes wiki markup (which uses a more user-friendly syntax, such as "[[link]]" for ma...
Definition Parser.php:70

RequestContext\getMain
static getMain()
Static methods.
Definition RequestContext.php:468

Revision\newKnownCurrent
static newKnownCurrent(IDatabase $db, $pageId, $revId)
Load a revision based on a known page ID and current revision ID from the DB.
Definition Revision.php:1921

Revision\getRevisionText
static getRevisionText( $row, $prefix='old_', $wiki=false)
Get revision text associated with an old or archive row.
Definition Revision.php:1258

Title
Represents a title within MediaWiki.
Definition Title.php:39

Title\getDBkey
getDBkey()
Get the main part with underscores.
Definition Title.php:901

WANObjectCache
Multi-datacenter aware caching interface.
Definition WANObjectCache.php:81

WikiPage\factory
static factory(Title $title)
Create a WikiPage object of the appropriate class for the given title.
Definition WikiPage.php:120

Wikimedia\Rdbms\Database
Relational database abstraction object.
Definition Database.php:45

$res
$res
Definition database.txt:21

list
deferred txt A few of the database updates required by various functions here can be deferred until after the result page is displayed to the user For updating the view updating the linked to tables after a etc PHP does not yet have any way to tell the server to actually return and disconnect while still running these but it might have such a feature in the future We handle these by creating a deferred update object and putting those objects on a global list
Definition deferred.txt:11

$wgContLang
this class mediates it Skin Encapsulates a look and feel for the wiki All of the functions that render HTML and make choices about how to render it are here and are called from various other places when and is meant to be subclassed with other skins that may override some of its functions The User object contains a reference to a and so rather than having a global skin object we just rely on the global User and get the skin with $wgUser and also has some character encoding functions and other locale stuff The current user interface language is instantiated as and the local content language as $wgContLang
Definition design.txt:57

too
I won t presume to tell you how to I m just describing the methods I chose to use for myself If you do choose to follow these it will probably be easier for you to collaborate with others on the but if you want to contribute without by all means do which work well I also use K &R brace matching style I know that s a religious issue for so if you want to use a style that puts opening braces on the next that s OK too
Definition design.txt:80

global
when a variable name is used in a it is silently declared as a new local masking the global
Definition design.txt:95

as
This document is intended to provide useful advice for parties seeking to redistribute MediaWiki to end users It s targeted particularly at maintainers for Linux since it s been observed that distribution packages of MediaWiki often break We ve consistently had to recommend that users seeking support use official tarballs instead of their distribution s and this often solves whatever problem the user is having It would be nice if this could such as
Definition distributors.txt:22

of
globals txt Globals are evil The original MediaWiki code relied on globals for processing context far too often MediaWiki development since then has been a story of slowly moving context out of global variables and into objects Storing processing context in object member variables allows those objects to be reused in a much more flexible way Consider the elegance of
database rows
Definition globals.txt:10

NS_MEDIAWIKI
const NS_MEDIAWIKI
Definition Defines.php:70

NS_SPECIAL
const NS_SPECIAL
Definition Defines.php:51

array
the array() calling protocol came about after MediaWiki 1.4rc1.

$parser
do that in ParserLimitReportFormat instead $parser
Definition hooks.txt:2536

$page
do that in ParserLimitReportFormat instead use this to modify the parameters of the image and a DIV can begin in one section and end in another Make sure your code can handle that case gracefully See the EditSectionClearerLink extension for an example zero but section is usually empty its values are the globals values before the output is cached $page
Definition hooks.txt:2578

string
This code would result in ircNotify being run twice when an article is and once for brion Hooks can return three possible true was required This is the default since MediaWiki *some string
Definition hooks.txt:183

$content
this hook is for auditing only RecentChangesLinked and Watchlist RecentChangesLinked and Watchlist Do not use this to implement individual filters if they are compatible with the ChangesListFilter and ChangesListFilterGroup structure use sub classes of those in conjunction with the ChangesListSpecialPageStructuredFilters hook This hook can be used to implement filters that do not implement that or custom behavior that is not an individual filter e g Watchlist and Watchlist you will want to construct new ChangesListBooleanFilter or ChangesListStringOptionsFilter objects When constructing you specify which group they belong to You can reuse existing or create your you must register them with $special registerFilterGroup removed from all revisions and log entries to which it was applied This gives extensions a chance to take it off their books as the deletion has already been partly carried out by this point or something similar the user will be unable to create the tag set and then return false from the hook function Ensure you consume the ChangeTagAfterDelete hook to carry out custom deletion actions as context called by AbstractContent::getParserOutput May be used to override the normal model specific rendering of page content $content
Definition hooks.txt:1100

$code
this hook is for auditing only or null if authentication failed before getting that far or null if we can t even determine that probably a stub it is not rendered in wiki pages or galleries in category pages allow injecting custom HTML after the section Any uses of the hook need to handle escaping see BaseTemplate::getToolbox and BaseTemplate::makeListItem for details on the format of individual items inside of this array or by returning and letting standard HTTP rendering take place modifiable or by returning false and taking over the output modifiable & $code
Definition hooks.txt:865

$title
namespace and then decline to actually register it file or subcat img or subcat $title
Definition hooks.txt:964

in
null for the local wiki Added in
Definition hooks.txt:1572

$status
this hook is for auditing only RecentChangesLinked and Watchlist RecentChangesLinked and Watchlist Do not use this to implement individual filters if they are compatible with the ChangesListFilter and ChangesListFilterGroup structure use sub classes of those in conjunction with the ChangesListSpecialPageStructuredFilters hook This hook can be used to implement filters that do not implement that or custom behavior that is not an individual filter e g Watchlist and Watchlist you will want to construct new ChangesListBooleanFilter or ChangesListStringOptionsFilter objects When constructing you specify which group they belong to You can reuse existing or create your you must register them with $special registerFilterGroup removed from all revisions and log entries to which it was applied This gives extensions a chance to take it off their books as the deletion has already been partly carried out by this point or something similar the user will be unable to create the tag set $status
Definition hooks.txt:1049

replace
static configuration should be added through ResourceLoaderGetConfigVars instead can be used to get the real title after the basic globals have been set but before ordinary actions take place replace
Definition hooks.txt:2206

false
processing should stop and the error should be shown to the user * false
Definition hooks.txt:189

messages
passed in as a query string parameter to the various URLs constructed here(i.e. $prevlink) $ldel you ll need to handle error messages
Definition hooks.txt:1252

php
injection txt This is an overview of how MediaWiki makes use of dependency injection The design described here grew from the discussion of RFC T384 The term dependency this means that anything an object needs to operate should be injected from the the object itself should only know narrow no concrete implementation of the logic it relies on The requirement to inject everything typically results in an architecture that based on two main types of and essentially stateless service objects that use other service objects to operate on the value objects As of the beginning MediaWiki is only starting to use the DI approach Much of the code still relies on global state or direct resulting in a highly cyclical dependency which acts as the top level factory for services in MediaWiki which can be used to gain access to default instances of various services MediaWikiServices however also allows new services to be defined and default services to be redefined Services are defined or redefined by providing a callback the instantiator that will return a new instance of the service When it will create an instance of MediaWikiServices and populate it with the services defined in the files listed by thereby bootstrapping the DI framework Per $wgServiceWiringFiles lists includes ServiceWiring php
Definition injection.txt:37

Content
Base interface for content objects.
Definition Content.php:34

cache
you have access to all of the normal MediaWiki so you can get a DB use the cache
Definition maintenance.txt:55

$cache
$cache
Definition mcc.php:33

load
MediaWiki has optional support for a high distributed memory object caching system For general information on but for a larger site with heavy load
Definition memcached.txt:6

data
This document describes the state of Postgres support in and is fairly well maintained The main code is very well while extensions are very hit and miss it is probably the most supported database after MySQL Much of the work in making MediaWiki database agnostic came about through the work of creating Postgres as and are nearing end of but without copying over all the usage comments General notes on the but these can almost always be programmed around *Although Postgres has a true BOOLEAN boolean columns are always mapped to as the code does not always treat the column as a and VARBINARY columns should simply be TEXT The only exception is when VARBINARY is used to store true binary data
Definition postgres.txt:43

DB_REPLICA
const DB_REPLICA
Definition defines.php:25

DB_MASTER
const DB_MASTER
Definition defines.php:26

$value
$value
Definition styleTest.css.php:45

$lang
if(!isset( $args[0])) $lang
Definition testCompression.php:33

$dbr
$dbr
Definition testCompression.php:50