MediaWiki  1.28.0
ChronologyProtector.php
Go to the documentation of this file.
1 <?php
26 
31 class ChronologyProtector implements LoggerAwareInterface {
33  protected $store;
35  protected $logger;
36 
38  protected $key;
40  protected $clientId;
42  protected $waitForPosTime;
44  protected $waitForPosTimeout = self::POS_WAIT_TIMEOUT;
46  protected $enabled = true;
48  protected $wait = true;
49 
51  protected $initialized = false;
53  protected $startupPositions = [];
55  protected $shutdownPositions = [];
57  protected $shutdownTouchDBs = [];
58 
60  const POSITION_TTL = 60;
62  const POS_WAIT_TIMEOUT = 5;
63 
70  public function __construct( BagOStuff $store, array $client, $posTime = null ) {
71  $this->store = $store;
72  $this->clientId = md5( $client['ip'] . "\n" . $client['agent'] );
73  $this->key = $store->makeGlobalKey( __CLASS__, $this->clientId );
74  $this->waitForPosTime = $posTime;
75  $this->logger = new \Psr\Log\NullLogger();
76  }
77 
78  public function setLogger( LoggerInterface $logger ) {
79  $this->logger = $logger;
80  }
81 
86  public function setEnabled( $enabled ) {
87  $this->enabled = $enabled;
88  }
89 
94  public function setWaitEnabled( $enabled ) {
95  $this->wait = $enabled;
96  }
97 
109  public function initLB( ILoadBalancer $lb ) {
110  if ( !$this->enabled || $lb->getServerCount() <= 1 ) {
111  return; // non-replicated setup or disabled
112  }
113 
114  $this->initPositions();
115 
116  $masterName = $lb->getServerName( $lb->getWriterIndex() );
117  if ( !empty( $this->startupPositions[$masterName] ) ) {
118  $pos = $this->startupPositions[$masterName];
119  $this->logger->info( __METHOD__ . ": LB for '$masterName' set to pos $pos\n" );
120  $lb->waitFor( $pos );
121  }
122  }
123 
131  public function shutdownLB( ILoadBalancer $lb ) {
132  if ( !$this->enabled ) {
133  return; // not enabled
134  } elseif ( !$lb->hasOrMadeRecentMasterChanges( INF ) ) {
135  // Only save the position if writes have been done on the connection
136  return;
137  }
138 
139  $masterName = $lb->getServerName( $lb->getWriterIndex() );
140  if ( $lb->getServerCount() > 1 ) {
141  $pos = $lb->getMasterPos();
142  $this->logger->info( __METHOD__ . ": LB for '$masterName' has pos $pos\n" );
143  $this->shutdownPositions[$masterName] = $pos;
144  } else {
145  $this->logger->info( __METHOD__ . ": DB '$masterName' touched\n" );
146  }
147  $this->shutdownTouchDBs[$masterName] = 1;
148  }
149 
158  public function shutdown( callable $workCallback = null, $mode = 'sync' ) {
159  if ( !$this->enabled ) {
160  return [];
161  }
162 
164  // Some callers might want to know if a user recently touched a DB.
165  // These writes do not need to block on all datacenters receiving them.
166  foreach ( $this->shutdownTouchDBs as $dbName => $unused ) {
167  $store->set(
168  $this->getTouchedKey( $this->store, $dbName ),
169  microtime( true ),
170  $store::TTL_DAY
171  );
172  }
173 
174  if ( !count( $this->shutdownPositions ) ) {
175  return []; // nothing to save
176  }
177 
178  $this->logger->info( __METHOD__ . ": saving master pos for " .
179  implode( ', ', array_keys( $this->shutdownPositions ) ) . "\n"
180  );
181 
182  // CP-protected writes should overwhemingly go to the master datacenter, so get DC-local
183  // lock to merge the values. Use a DC-local get() and a synchronous all-DC set(). This
184  // makes it possible for the BagOStuff class to write in parallel to all DCs with one RTT.
185  if ( $store->lock( $this->key, 3 ) ) {
186  if ( $workCallback ) {
187  // Let the store run the work before blocking on a replication sync barrier. By the
188  // time it's done with the work, the barrier should be fast if replication caught up.
189  $store->addBusyCallback( $workCallback );
190  }
191  $ok = $store->set(
192  $this->key,
193  self::mergePositions( $store->get( $this->key ), $this->shutdownPositions ),
194  self::POSITION_TTL,
195  ( $mode === 'sync' ) ? $store::WRITE_SYNC : 0
196  );
197  $store->unlock( $this->key );
198  } else {
199  $ok = false;
200  }
201 
202  if ( !$ok ) {
203  $bouncedPositions = $this->shutdownPositions;
204  // Raced out too many times or stash is down
205  $this->logger->warning( __METHOD__ . ": failed to save master pos for " .
206  implode( ', ', array_keys( $this->shutdownPositions ) ) . "\n"
207  );
208  } elseif ( $mode === 'sync' &&
209  $store->getQoS( $store::ATTR_SYNCWRITES ) < $store::QOS_SYNCWRITES_BE
210  ) {
211  // Positions may not be in all datacenters, force LBFactory to play it safe
212  $this->logger->info( __METHOD__ . ": store may not support synchronous writes." );
213  $bouncedPositions = $this->shutdownPositions;
214  } else {
215  $bouncedPositions = [];
216  }
217 
218  return $bouncedPositions;
219  }
220 
226  public function getTouched( $dbName ) {
227  return $this->store->get( $this->getTouchedKey( $this->store, $dbName ) );
228  }
229 
235  private function getTouchedKey( BagOStuff $store, $dbName ) {
236  return $store->makeGlobalKey( __CLASS__, 'mtime', $this->clientId, $dbName );
237  }
238 
242  protected function initPositions() {
243  if ( $this->initialized ) {
244  return;
245  }
246 
247  $this->initialized = true;
248  if ( $this->wait ) {
249  // If there is an expectation to see master positions with a certain min
250  // timestamp, then block until they appear, or until a timeout is reached.
251  if ( $this->waitForPosTime > 0.0 ) {
252  $data = null;
253  $loop = new WaitConditionLoop(
254  function () use ( &$data ) {
255  $data = $this->store->get( $this->key );
256 
257  return ( self::minPosTime( $data ) >= $this->waitForPosTime )
258  ? WaitConditionLoop::CONDITION_REACHED
259  : WaitConditionLoop::CONDITION_CONTINUE;
260  },
262  );
263  $result = $loop->invoke();
264  $waitedMs = $loop->getLastWaitTime() * 1e3;
265 
266  if ( $result == $loop::CONDITION_REACHED ) {
267  $msg = "expected and found pos time {$this->waitForPosTime} ({$waitedMs}ms)";
268  $this->logger->debug( $msg );
269  } else {
270  $msg = "expected but missed pos time {$this->waitForPosTime} ({$waitedMs}ms)";
271  $this->logger->info( $msg );
272  }
273  } else {
274  $data = $this->store->get( $this->key );
275  }
276 
277  $this->startupPositions = $data ? $data['positions'] : [];
278  $this->logger->info( __METHOD__ . ": key is {$this->key} (read)\n" );
279  } else {
280  $this->startupPositions = [];
281  $this->logger->info( __METHOD__ . ": key is {$this->key} (unread)\n" );
282  }
283  }
284 
289  private static function minPosTime( $data ) {
290  if ( !isset( $data['positions'] ) ) {
291  return null;
292  }
293 
294  $min = null;
295  foreach ( $data['positions'] as $pos ) {
297  $min = $min ? min( $pos->asOfTime(), $min ) : $pos->asOfTime();
298  }
299 
300  return $min;
301  }
302 
308  private static function mergePositions( $curValue, array $shutdownPositions ) {
310  if ( $curValue === false ) {
311  $curPositions = $shutdownPositions;
312  } else {
313  $curPositions = $curValue['positions'];
314  // Use the newest positions for each DB master
315  foreach ( $shutdownPositions as $db => $pos ) {
316  if ( !isset( $curPositions[$db] )
317  || $pos->asOfTime() > $curPositions[$db]->asOfTime()
318  ) {
319  $curPositions[$db] = $pos;
320  }
321  }
322  }
323 
324  return [ 'positions' => $curPositions ];
325  }
326 }
bool $initialized
Whether the client data was loaded.
the array() calling protocol came about after MediaWiki 1.4rc1.
bool $enabled
Whether to no-op all method calls.
getMasterPos()
Get the current master position for chronology control purposes.
initLB(ILoadBalancer $lb)
Initialise a ILoadBalancer to give it appropriate chronology protection.
DBMasterPos[] $shutdownPositions
Map of (DB master name => position)
Apache License January AND DISTRIBUTION Definitions License shall mean the terms and conditions for use
lock($key, $timeout=6, $expiry=6, $rclass= '')
Acquire an advisory lock on a key string.
Definition: BagOStuff.php:403
getQoS($flag)
Definition: BagOStuff.php:773
getTouchedKey(BagOStuff $store, $dbName)
shutdownLB(ILoadBalancer $lb)
Notify the ChronologyProtector that the ILoadBalancer is about to shut down.
static mergePositions($curValue, array $shutdownPositions)
set($key, $value, $exptime=0, $flags=0)
Set an item.
initPositions()
Load in previous master positions for the client.
MediaWiki s SiteStore can be cached and stored in a flat in a json format If the SiteStore is frequently the file cache may provide a performance benefit over a database store
Definition: sitescache.txt:1
waitFor($pos)
Set the master wait position If a DB_REPLICA connection has been opened already, waits Otherwise sets...
The index of the header message $result[1]=The index of the body text message $result[2 through n]=Parameters passed to body text message.Please note the header message cannot receive/use parameters. 'ImportHandleLogItemXMLTag':When parsing a XML tag in a log item.Return false to stop further processing of the tag $reader:XMLReader object $logInfo:Array of information 'ImportHandlePageXMLTag':When parsing a XML tag in a page.Return false to stop further processing of the tag $reader:XMLReader object &$pageInfo:Array of information 'ImportHandleRevisionXMLTag':When parsing a XML tag in a page revision.Return false to stop further processing of the tag $reader:XMLReader object $pageInfo:Array of page information $revisionInfo:Array of revision information 'ImportHandleToplevelXMLTag':When parsing a top level XML tag.Return false to stop further processing of the tag $reader:XMLReader object 'ImportHandleUploadXMLTag':When parsing a XML tag in a file upload.Return false to stop further processing of the tag $reader:XMLReader object $revisionInfo:Array of information 'ImportLogInterwikiLink':Hook to change the interwiki link used in log entries and edit summaries for transwiki imports.&$fullInterwikiPrefix:Interwiki prefix, may contain colons.&$pageTitle:String that contains page title. 'ImportSources':Called when reading from the $wgImportSources configuration variable.Can be used to lazy-load the import sources list.&$importSources:The value of $wgImportSources.Modify as necessary.See the comment in DefaultSettings.php for the detail of how to structure this array. 'InfoAction':When building information to display on the action=info page.$context:IContextSource object &$pageInfo:Array of information 'InitializeArticleMaybeRedirect':MediaWiki check to see if title is a redirect.&$title:Title object for the current page &$request:WebRequest &$ignoreRedirect:boolean to skip redirect check &$target:Title/string of redirect target &$article:Article object 'InternalParseBeforeLinks':during Parser's internalParse method before links but after nowiki/noinclude/includeonly/onlyinclude and other processings.&$parser:Parser object &$text:string containing partially parsed text &$stripState:Parser's internal StripState object 'InternalParseBeforeSanitize':during Parser's internalParse method just before the parser removes unwanted/dangerous HTML tags and after nowiki/noinclude/includeonly/onlyinclude and other processings.Ideal for syntax-extensions after template/parser function execution which respect nowiki and HTML-comments.&$parser:Parser object &$text:string containing partially parsed text &$stripState:Parser's internal StripState object 'InterwikiLoadPrefix':When resolving if a given prefix is an interwiki or not.Return true without providing an interwiki to continue interwiki search.$prefix:interwiki prefix we are looking for.&$iwData:output array describing the interwiki with keys iw_url, iw_local, iw_trans and optionally iw_api and iw_wikiid. 'InvalidateEmailComplete':Called after a user's email has been invalidated successfully.$user:user(object) whose email is being invalidated 'IRCLineURL':When constructing the URL to use in an IRC notification.Callee may modify $url and $query, URL will be constructed as $url.$query &$url:URL to index.php &$query:Query string $rc:RecentChange object that triggered url generation 'IsFileCacheable':Override the result of Article::isFileCacheable()(if true) &$article:article(object) being checked 'IsTrustedProxy':Override the result of IP::isTrustedProxy() &$ip:IP being check &$result:Change this value to override the result of IP::isTrustedProxy() 'IsUploadAllowedFromUrl':Override the result of UploadFromUrl::isAllowedUrl() $url:URL used to upload from &$allowed:Boolean indicating if uploading is allowed for given URL 'isValidEmailAddr':Override the result of Sanitizer::validateEmail(), for instance to return false if the domain name doesn't match your organization.$addr:The e-mail address entered by the user &$result:Set this and return false to override the internal checks 'isValidPassword':Override the result of User::isValidPassword() $password:The password entered by the user &$result:Set this and return false to override the internal checks $user:User the password is being validated for 'Language::getMessagesFileName':$code:The language code or the language we're looking for a messages file for &$file:The messages file path, you can override this to change the location. 'LanguageGetMagic':DEPRECATED!Use $magicWords in a file listed in $wgExtensionMessagesFiles instead.Use this to define synonyms of magic words depending of the language &$magicExtensions:associative array of magic words synonyms $lang:language code(string) 'LanguageGetNamespaces':Provide custom ordering for namespaces or remove namespaces.Do not use this hook to add namespaces.Use CanonicalNamespaces for that.&$namespaces:Array of namespaces indexed by their numbers 'LanguageGetSpecialPageAliases':DEPRECATED!Use $specialPageAliases in a file listed in $wgExtensionMessagesFiles instead.Use to define aliases of special pages names depending of the language &$specialPageAliases:associative array of magic words synonyms $lang:language code(string) 'LanguageGetTranslatedLanguageNames':Provide translated language names.&$names:array of language code=> language name $code:language of the preferred translations 'LanguageLinks':Manipulate a page's language links.This is called in various places to allow extensions to define the effective language links for a page.$title:The page's Title.&$links:Associative array mapping language codes to prefixed links of the form"language:title".&$linkFlags:Associative array mapping prefixed links to arrays of flags.Currently unused, but planned to provide support for marking individual language links in the UI, e.g.for featured articles. 'LanguageSelector':Hook to change the language selector available on a page.$out:The output page.$cssClassName:CSS class name of the language selector. 'LinkBegin':DEPRECATED!Use HtmlPageLinkRendererBegin instead.Used when generating internal and interwiki links in Linker::link(), before processing starts.Return false to skip default processing and return $ret.See documentation for Linker::link() for details on the expected meanings of parameters.$skin:the Skin object $target:the Title that the link is pointing to &$html:the contents that the< a > tag should have(raw HTML) $result
Definition: hooks.txt:1934
float null $waitForPosTime
Minimum UNIX timestamp of 1+ expected startup positions.
bool $wait
Whether to check and wait on positions.
shutdown(callable $workCallback=null, $mode= 'sync')
Notify the ChronologyProtector that the LBFactory is done calling shutdownLB() for now...
design txt This is a brief overview of the new design More thorough and up to date information is available on the documentation wiki at etc Handles the details of getting and saving to the user table of the and dealing with sessions and cookies OutputPage Encapsulates the entire HTML page that will be sent in response to any server request It is used by calling its functions to add in any and then calling but I prefer the flexibility This should also do the output encoding The system allocates a global one in $wgOut Title Represents the title of an and does all the work of translating among various forms such as plain database key
Definition: design.txt:25
Database cluster connection, tracking, load balancing, and transaction manager interface.
int $waitForPosTimeout
Max seconds to wait on positions to appear.
__construct(BagOStuff $store, array $client, $posTime=null)
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:9
getServerCount()
Get the number of defined servers (not the number of open connections)
string $key
Storage key name.
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:35
Class for ensuring a consistent ordering of events as seen by the user, despite replication.
setLogger(LoggerInterface $logger)
hasOrMadeRecentMasterChanges($age=null)
Check if this load balancer object had any recent or still pending writes issued against it by this P...
get($key, $flags=0, $oldFlags=null)
Get an item with the given key.
Definition: BagOStuff.php:179
addBusyCallback(callable $workCallback)
Let a callback be run to avoid wasting time on special blocking calls.
Definition: BagOStuff.php:654
float[] $shutdownTouchDBs
Map of (DB master name => 1)
getServerName($i)
Get the host name or IP address of the server with the specified index Prefer a readable name if avai...
DBMasterPos[] $startupPositions
Map of (DB master name => position)
unlock($key)
Release an advisory lock on a key string.
Definition: BagOStuff.php:443
string $clientId
Hash of client parameters.
makeGlobalKey()
Make a global cache key.
Definition: BagOStuff.php:753