Current File : /www/varak.net/wiki.varak.net/includes/api/ApiStashEdit.php
<?php
/**
* 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
*/
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
use Wikimedia\ScopedCallback;
/**
* Prepare an edit in shared cache so that it can be reused on edit
*
* This endpoint can be called via AJAX as the user focuses on the edit
* summary box. By the time of submission, the parse may have already
* finished, and can be immediately used on page save. Certain parser
* functions like {{REVISIONID}} or {{CURRENTTIME}} may cause the cache
* to not be used on edit. Template and files used are check for changes
* since the output was generated. The cache TTL is also kept low for sanity.
*
* @ingroup API
* @since 1.25
*/
class ApiStashEdit extends ApiBase {
const ERROR_NONE = 'stashed';
const ERROR_PARSE = 'error_parse';
const ERROR_CACHE = 'error_cache';
const ERROR_UNCACHEABLE = 'uncacheable';
const ERROR_BUSY = 'busy';
const PRESUME_FRESH_TTL_SEC = 30;
const MAX_CACHE_TTL = 300; // 5 minutes
const MAX_SIGNATURE_TTL = 60;
public function execute() {
$user = $this->getUser();
$params = $this->extractRequestParams();
if ( $user->isBot() ) { // sanity
$this->dieWithError( 'apierror-botsnotsupported' );
}
$cache = ObjectCache::getLocalClusterInstance();
$page = $this->getTitleOrPageId( $params );
$title = $page->getTitle();
if ( !ContentHandler::getForModelID( $params['contentmodel'] )
->isSupportedFormat( $params['contentformat'] )
) {
$this->dieWithError(
[ 'apierror-badformat-generic', $params['contentformat'], $params['contentmodel'] ],
'badmodelformat'
);
}
$this->requireOnlyOneParameter( $params, 'stashedtexthash', 'text' );
$text = null;
$textHash = null;
if ( $params['stashedtexthash'] !== null ) {
// Load from cache since the client indicates the text is the same as last stash
$textHash = $params['stashedtexthash'];
if ( !preg_match( '/^[0-9a-f]{40}$/', $textHash ) ) {
$this->dieWithError( 'apierror-stashedit-missingtext', 'missingtext' );
}
$textKey = $cache->makeKey( 'stashedit', 'text', $textHash );
$text = $cache->get( $textKey );
if ( !is_string( $text ) ) {
$this->dieWithError( 'apierror-stashedit-missingtext', 'missingtext' );
}
} else {
// 'text' was passed. Trim and fix newlines so the key SHA1's
// match (see WebRequest::getText())
$text = rtrim( str_replace( "\r\n", "\n", $params['text'] ) );
$textHash = sha1( $text );
}
$textContent = ContentHandler::makeContent(
$text, $title, $params['contentmodel'], $params['contentformat'] );
$page = WikiPage::factory( $title );
if ( $page->exists() ) {
// Page exists: get the merged content with the proposed change
$baseRev = Revision::newFromPageId( $page->getId(), $params['baserevid'] );
if ( !$baseRev ) {
$this->dieWithError( [ 'apierror-nosuchrevid', $params['baserevid'] ] );
}
$currentRev = $page->getRevision();
if ( !$currentRev ) {
$this->dieWithError( [ 'apierror-missingrev-pageid', $page->getId() ], 'missingrev' );
}
// Merge in the new version of the section to get the proposed version
$editContent = $page->replaceSectionAtRev(
$params['section'],
$textContent,
$params['sectiontitle'],
$baseRev->getId()
);
if ( !$editContent ) {
$this->dieWithError( 'apierror-sectionreplacefailed', 'replacefailed' );
}
if ( $currentRev->getId() == $baseRev->getId() ) {
// Base revision was still the latest; nothing to merge
$content = $editContent;
} else {
// Merge the edit into the current version
$baseContent = $baseRev->getContent();
$currentContent = $currentRev->getContent();
if ( !$baseContent || !$currentContent ) {
$this->dieWithError( [ 'apierror-missingcontent-pageid', $page->getId() ], 'missingrev' );
}
$handler = ContentHandler::getForModelID( $baseContent->getModel() );
$content = $handler->merge3( $baseContent, $editContent, $currentContent );
}
} else {
// New pages: use the user-provided content model
$content = $textContent;
}
if ( !$content ) { // merge3() failed
$this->getResult()->addValue( null,
$this->getModuleName(), [ 'status' => 'editconflict' ] );
return;
}
// The user will abort the AJAX request by pressing "save", so ignore that
ignore_user_abort( true );
if ( $user->pingLimiter( 'stashedit' ) ) {
$status = 'ratelimited';
} else {
$status = self::parseAndStash( $page, $content, $user, $params['summary'] );
$textKey = $cache->makeKey( 'stashedit', 'text', $textHash );
$cache->set( $textKey, $text, self::MAX_CACHE_TTL );
}
$stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
$stats->increment( "editstash.cache_stores.$status" );
$ret = [ 'status' => $status ];
// If we were rate-limited, we still return the pre-existing valid hash if one was passed
if ( $status !== 'ratelimited' || $params['stashedtexthash'] !== null ) {
$ret['texthash'] = $textHash;
}
$this->getResult()->addValue( null, $this->getModuleName(), $ret );
}
/**
* @param WikiPage $page
* @param Content $content Edit content
* @param User $user
* @param string $summary Edit summary
* @return string ApiStashEdit::ERROR_* constant
* @since 1.25
*/
public static function parseAndStash( WikiPage $page, Content $content, User $user, $summary ) {
$cache = ObjectCache::getLocalClusterInstance();
$logger = LoggerFactory::getInstance( 'StashEdit' );
$title = $page->getTitle();
$key = self::getStashKey( $title, self::getContentHash( $content ), $user );
$fname = __METHOD__;
// Use the master DB to allow for fast blocking locks on the "save path" where this
// value might actually be used to complete a page edit. If the edit submission request
// happens before this edit stash requests finishes, then the submission will block until
// the stash request finishes parsing. For the lock acquisition below, there is not much
// need to duplicate parsing of the same content/user/summary bundle, so try to avoid
// blocking at all here.
$dbw = wfGetDB( DB_MASTER );
if ( !$dbw->lock( $key, $fname, 0 ) ) {
// De-duplicate requests on the same key
return self::ERROR_BUSY;
}
/** @noinspection PhpUnusedLocalVariableInspection */
$unlocker = new ScopedCallback( function () use ( $dbw, $key, $fname ) {
$dbw->unlock( $key, $fname );
} );
$cutoffTime = time() - self::PRESUME_FRESH_TTL_SEC;
// Reuse any freshly build matching edit stash cache
$editInfo = $cache->get( $key );
if ( $editInfo && wfTimestamp( TS_UNIX, $editInfo->timestamp ) >= $cutoffTime ) {
$alreadyCached = true;
} else {
$format = $content->getDefaultFormat();
$editInfo = $page->prepareContentForEdit( $content, null, $user, $format, false );
$alreadyCached = false;
}
if ( $editInfo && $editInfo->output ) {
// Let extensions add ParserOutput metadata or warm other caches
Hooks::run( 'ParserOutputStashForEdit',
[ $page, $content, $editInfo->output, $summary, $user ] );
$titleStr = (string)$title;
if ( $alreadyCached ) {
$logger->debug( "Already cached parser output for key '{cachekey}' ('{title}').",
[ 'cachekey' => $key, 'title' => $titleStr ] );
return self::ERROR_NONE;
}
list( $stashInfo, $ttl, $code ) = self::buildStashValue(
$editInfo->pstContent,
$editInfo->output,
$editInfo->timestamp,
$user
);
if ( $stashInfo ) {
$ok = $cache->set( $key, $stashInfo, $ttl );
if ( $ok ) {
$logger->debug( "Cached parser output for key '{cachekey}' ('{title}').",
[ 'cachekey' => $key, 'title' => $titleStr ] );
return self::ERROR_NONE;
} else {
$logger->error( "Failed to cache parser output for key '{cachekey}' ('{title}').",
[ 'cachekey' => $key, 'title' => $titleStr ] );
return self::ERROR_CACHE;
}
} else {
// @todo Doesn't seem reachable, see @todo in buildStashValue
$logger->info( "Uncacheable parser output for key '{cachekey}' ('{title}') [{code}].",
[ 'cachekey' => $key, 'title' => $titleStr, 'code' => $code ] );
return self::ERROR_UNCACHEABLE;
}
}
return self::ERROR_PARSE;
}
/**
* Check that a prepared edit is in cache and still up-to-date
*
* This method blocks if the prepared edit is already being rendered,
* waiting until rendering finishes before doing final validity checks.
*
* The cache is rejected if template or file changes are detected.
* Note that foreign template or file transclusions are not checked.
*
* The result is a map (pstContent,output,timestamp) with fields
* extracted directly from WikiPage::prepareContentForEdit().
*
* @param Title $title
* @param Content $content
* @param User $user User to get parser options from
* @return stdClass|bool Returns false on cache miss
*/
public static function checkCache( Title $title, Content $content, User $user ) {
if ( $user->isBot() ) {
return false; // bots never stash - don't pollute stats
}
$cache = ObjectCache::getLocalClusterInstance();
$logger = LoggerFactory::getInstance( 'StashEdit' );
$stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
$key = self::getStashKey( $title, self::getContentHash( $content ), $user );
$editInfo = $cache->get( $key );
if ( !is_object( $editInfo ) ) {
$start = microtime( true );
// We ignore user aborts and keep parsing. Block on any prior parsing
// so as to use its results and make use of the time spent parsing.
// Skip this logic if there no master connection in case this method
// is called on an HTTP GET request for some reason.
$lb = MediaWikiServices::getInstance()->getDBLoadBalancer();
$dbw = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
if ( $dbw && $dbw->lock( $key, __METHOD__, 30 ) ) {
$editInfo = $cache->get( $key );
$dbw->unlock( $key, __METHOD__ );
}
$timeMs = 1000 * max( 0, microtime( true ) - $start );
$stats->timing( 'editstash.lock_wait_time', $timeMs );
}
if ( !is_object( $editInfo ) || !$editInfo->output ) {
$stats->increment( 'editstash.cache_misses.no_stash' );
$logger->debug( "Empty cache for key '$key' ('$title'); user '{$user->getName()}'." );
return false;
}
$age = time() - wfTimestamp( TS_UNIX, $editInfo->output->getCacheTime() );
if ( $age <= self::PRESUME_FRESH_TTL_SEC ) {
// Assume nothing changed in this time
$stats->increment( 'editstash.cache_hits.presumed_fresh' );
$logger->debug( "Timestamp-based cache hit for key '$key' (age: $age sec)." );
} elseif ( isset( $editInfo->edits ) && $editInfo->edits === $user->getEditCount() ) {
// Logged-in user made no local upload/template edits in the meantime
$stats->increment( 'editstash.cache_hits.presumed_fresh' );
$logger->debug( "Edit count based cache hit for key '$key' (age: $age sec)." );
} elseif ( $user->isAnon()
&& self::lastEditTime( $user ) < $editInfo->output->getCacheTime()
) {
// Logged-out user made no local upload/template edits in the meantime
$stats->increment( 'editstash.cache_hits.presumed_fresh' );
$logger->debug( "Edit check based cache hit for key '$key' (age: $age sec)." );
} else {
// User may have changed included content
$editInfo = false;
}
if ( !$editInfo ) {
$stats->increment( 'editstash.cache_misses.proven_stale' );
$logger->info( "Stale cache for key '$key'; old key with outside edits. (age: $age sec)" );
} elseif ( $editInfo->output->getFlag( 'vary-revision' ) ) {
// This can be used for the initial parse, e.g. for filters or doEditContent(),
// but a second parse will be triggered in doEditUpdates(). This is not optimal.
$logger->info( "Cache for key '$key' ('$title') has vary_revision." );
} elseif ( $editInfo->output->getFlag( 'vary-revision-id' ) ) {
// Similar to the above if we didn't guess the ID correctly.
$logger->info( "Cache for key '$key' ('$title') has vary_revision_id." );
}
return $editInfo;
}
/**
* @param User $user
* @return string|null TS_MW timestamp or null
*/
private static function lastEditTime( User $user ) {
$db = wfGetDB( DB_REPLICA );
$actorQuery = ActorMigration::newMigration()->getWhere( $db, 'rc_user', $user, false );
$time = $db->selectField(
[ 'recentchanges' ] + $actorQuery['tables'],
'MAX(rc_timestamp)',
[ $actorQuery['conds'] ],
__METHOD__,
[],
$actorQuery['joins']
);
return wfTimestampOrNull( TS_MW, $time );
}
/**
* Get hash of the content, factoring in model/format
*
* @param Content $content
* @return string
*/
private static function getContentHash( Content $content ) {
return sha1( implode( "\n", [
$content->getModel(),
$content->getDefaultFormat(),
$content->serialize( $content->getDefaultFormat() )
] ) );
}
/**
* Get the temporary prepared edit stash key for a user
*
* This key can be used for caching prepared edits provided:
* - a) The $user was used for PST options
* - b) The parser output was made from the PST using cannonical matching options
*
* @param Title $title
* @param string $contentHash Result of getContentHash()
* @param User $user User to get parser options from
* @return string
*/
private static function getStashKey( Title $title, $contentHash, User $user ) {
return ObjectCache::getLocalClusterInstance()->makeKey(
'prepared-edit',
md5( $title->getPrefixedDBkey() ),
// Account for the edit model/text
$contentHash,
// Account for user name related variables like signatures
md5( $user->getId() . "\n" . $user->getName() )
);
}
/**
* Build a value to store in memcached based on the PST content and parser output
*
* This makes a simple version of WikiPage::prepareContentForEdit() as stash info
*
* @param Content $pstContent Pre-Save transformed content
* @param ParserOutput $parserOutput
* @param string $timestamp TS_MW
* @param User $user
* @return array (stash info array, TTL in seconds, info code) or (null, 0, info code)
*/
private static function buildStashValue(
Content $pstContent, ParserOutput $parserOutput, $timestamp, User $user
) {
// If an item is renewed, mind the cache TTL determined by config and parser functions.
// Put an upper limit on the TTL for sanity to avoid extreme template/file staleness.
$since = time() - wfTimestamp( TS_UNIX, $parserOutput->getCacheTime() );
$ttl = min( $parserOutput->getCacheExpiry() - $since, self::MAX_CACHE_TTL );
// Avoid extremely stale user signature timestamps (T84843)
if ( $parserOutput->getFlag( 'user-signature' ) ) {
$ttl = min( $ttl, self::MAX_SIGNATURE_TTL );
}
if ( $ttl <= 0 ) {
// @todo It doesn't seem like this can occur, because it would mean an entry older than
// getCacheExpiry() seconds, which is much longer than PRESUME_FRESH_TTL_SEC, and
// anything older than PRESUME_FRESH_TTL_SEC will have been thrown out already.
return [ null, 0, 'no_ttl' ];
}
// Only store what is actually needed
$stashInfo = (object)[
'pstContent' => $pstContent,
'output' => $parserOutput,
'timestamp' => $timestamp,
'edits' => $user->getEditCount()
];
return [ $stashInfo, $ttl, 'ok' ];
}
public function getAllowedParams() {
return [
'title' => [
ApiBase::PARAM_TYPE => 'string',
ApiBase::PARAM_REQUIRED => true
],
'section' => [
ApiBase::PARAM_TYPE => 'string',
],
'sectiontitle' => [
ApiBase::PARAM_TYPE => 'string'
],
'text' => [
ApiBase::PARAM_TYPE => 'text',
ApiBase::PARAM_DFLT => null
],
'stashedtexthash' => [
ApiBase::PARAM_TYPE => 'string',
ApiBase::PARAM_DFLT => null
],
'summary' => [
ApiBase::PARAM_TYPE => 'string',
],
'contentmodel' => [
ApiBase::PARAM_TYPE => ContentHandler::getContentModels(),
ApiBase::PARAM_REQUIRED => true
],
'contentformat' => [
ApiBase::PARAM_TYPE => ContentHandler::getAllContentFormats(),
ApiBase::PARAM_REQUIRED => true
],
'baserevid' => [
ApiBase::PARAM_TYPE => 'integer',
ApiBase::PARAM_REQUIRED => true
]
];
}
public function needsToken() {
return 'csrf';
}
public function mustBePosted() {
return true;
}
public function isWriteMode() {
return true;
}
public function isInternal() {
return true;
}
}
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