MediaWiki  REL1_31
ChronologyProtector.php
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1 <?php
24 namespace Wikimedia\Rdbms;
25 
26 use Psr\Log\LoggerAwareInterface;
27 use Psr\Log\LoggerInterface;
28 use Psr\Log\NullLogger;
29 use Wikimedia\WaitConditionLoop;
31 
36 class ChronologyProtector implements LoggerAwareInterface {
38  protected $store;
40  protected $logger;
41 
43  protected $key;
45  protected $clientId;
47  protected $waitForPosIndex;
49  protected $waitForPosStoreTimeout = self::POS_STORE_WAIT_TIMEOUT;
51  protected $enabled = true;
53  protected $wait = true;
54 
56  protected $initialized = false;
58  protected $startupPositions = [];
60  protected $shutdownPositions = [];
62  protected $shutdownTouchDBs = [];
63 
65  const POSITION_TTL = 60;
67  const POS_STORE_WAIT_TIMEOUT = 5;
68 
75  public function __construct( BagOStuff $store, array $client, $posIndex = null ) {
76  $this->store = $store;
77  $this->clientId = md5( $client['ip'] . "\n" . $client['agent'] );
78  $this->key = $store->makeGlobalKey( __CLASS__, $this->clientId, 'v2' );
79  $this->waitForPosIndex = $posIndex;
80  $this->logger = new NullLogger();
81  }
82 
83  public function setLogger( LoggerInterface $logger ) {
84  $this->logger = $logger;
85  }
86 
91  public function setEnabled( $enabled ) {
92  $this->enabled = $enabled;
93  }
94 
99  public function setWaitEnabled( $enabled ) {
100  $this->wait = $enabled;
101  }
102 
114  public function initLB( ILoadBalancer $lb ) {
115  if ( !$this->enabled || $lb->getServerCount() <= 1 ) {
116  return; // non-replicated setup or disabled
117  }
118 
119  $this->initPositions();
120 
121  $masterName = $lb->getServerName( $lb->getWriterIndex() );
122  if (
123  isset( $this->startupPositions[$masterName] ) &&
124  $this->startupPositions[$masterName] instanceof DBMasterPos
125  ) {
126  $pos = $this->startupPositions[$masterName];
127  $this->logger->debug( __METHOD__ . ": LB for '$masterName' set to pos $pos\n" );
128  $lb->waitFor( $pos );
129  }
130  }
131 
139  public function shutdownLB( ILoadBalancer $lb ) {
140  if ( !$this->enabled ) {
141  return; // not enabled
142  } elseif ( !$lb->hasOrMadeRecentMasterChanges( INF ) ) {
143  // Only save the position if writes have been done on the connection
144  return;
145  }
146 
147  $masterName = $lb->getServerName( $lb->getWriterIndex() );
148  if ( $lb->getServerCount() > 1 ) {
149  $pos = $lb->getMasterPos();
150  if ( $pos ) {
151  $this->logger->debug( __METHOD__ . ": LB for '$masterName' has pos $pos\n" );
152  $this->shutdownPositions[$masterName] = $pos;
153  }
154  } else {
155  $this->logger->debug( __METHOD__ . ": DB '$masterName' touched\n" );
156  }
157  $this->shutdownTouchDBs[$masterName] = 1;
158  }
159 
169  public function shutdown( callable $workCallback = null, $mode = 'sync', &$cpIndex = null ) {
170  if ( !$this->enabled ) {
171  return [];
172  }
173 
175  // Some callers might want to know if a user recently touched a DB.
176  // These writes do not need to block on all datacenters receiving them.
177  foreach ( $this->shutdownTouchDBs as $dbName => $unused ) {
178  $store->set(
179  $this->getTouchedKey( $this->store, $dbName ),
180  microtime( true ),
181  $store::TTL_DAY
182  );
183  }
184 
185  if ( !count( $this->shutdownPositions ) ) {
186  return []; // nothing to save
187  }
188 
189  $this->logger->debug( __METHOD__ . ": saving master pos for " .
190  implode( ', ', array_keys( $this->shutdownPositions ) ) . "\n"
191  );
192 
193  // CP-protected writes should overwhemingly go to the master datacenter, so get DC-local
194  // lock to merge the values. Use a DC-local get() and a synchronous all-DC set(). This
195  // makes it possible for the BagOStuff class to write in parallel to all DCs with one RTT.
196  if ( $store->lock( $this->key, 3 ) ) {
197  if ( $workCallback ) {
198  // Let the store run the work before blocking on a replication sync barrier. By the
199  // time it's done with the work, the barrier should be fast if replication caught up.
200  $store->addBusyCallback( $workCallback );
201  }
202  $ok = $store->set(
203  $this->key,
204  $this->mergePositions(
205  $store->get( $this->key ),
206  $this->shutdownPositions,
207  $cpIndex
208  ),
209  self::POSITION_TTL,
210  ( $mode === 'sync' ) ? $store::WRITE_SYNC : 0
211  );
212  $store->unlock( $this->key );
213  } else {
214  $ok = false;
215  $cpIndex = null; // nothing saved
216  }
217 
218  if ( !$ok ) {
219  $bouncedPositions = $this->shutdownPositions;
220  // Raced out too many times or stash is down
221  $this->logger->warning( __METHOD__ . ": failed to save master pos for " .
222  implode( ', ', array_keys( $this->shutdownPositions ) ) . "\n"
223  );
224  } elseif ( $mode === 'sync' &&
225  $store->getQoS( $store::ATTR_SYNCWRITES ) < $store::QOS_SYNCWRITES_BE
226  ) {
227  // Positions may not be in all datacenters, force LBFactory to play it safe
228  $this->logger->info( __METHOD__ . ": store may not support synchronous writes." );
229  $bouncedPositions = $this->shutdownPositions;
230  } else {
231  $bouncedPositions = [];
232  }
233 
234  return $bouncedPositions;
235  }
236 
242  public function getTouched( $dbName ) {
243  return $this->store->get( $this->getTouchedKey( $this->store, $dbName ) );
244  }
245 
251  private function getTouchedKey( BagOStuff $store, $dbName ) {
252  return $store->makeGlobalKey( __CLASS__, 'mtime', $this->clientId, $dbName );
253  }
254 
258  protected function initPositions() {
259  if ( $this->initialized ) {
260  return;
261  }
262 
263  $this->initialized = true;
264  if ( $this->wait ) {
265  // If there is an expectation to see master positions from a certain write
266  // index or higher, then block until it appears, or until a timeout is reached.
267  // Since the write index restarts each time the key is created, it is possible that
268  // a lagged store has a matching key write index. However, in that case, it should
269  // already be expired and thus treated as non-existing, maintaining correctness.
270  if ( $this->waitForPosIndex > 0 ) {
271  $data = null;
272  $loop = new WaitConditionLoop(
273  function () use ( &$data ) {
274  $data = $this->store->get( $this->key );
275  if ( !is_array( $data ) ) {
276  return WaitConditionLoop::CONDITION_CONTINUE; // not found yet
277  } elseif ( !isset( $data['writeIndex'] ) ) {
278  return WaitConditionLoop::CONDITION_REACHED; // b/c
279  }
280 
281  return ( $data['writeIndex'] >= $this->waitForPosIndex )
282  ? WaitConditionLoop::CONDITION_REACHED
283  : WaitConditionLoop::CONDITION_CONTINUE;
284  },
286  );
287  $result = $loop->invoke();
288  $waitedMs = $loop->getLastWaitTime() * 1e3;
289 
290  if ( $result == $loop::CONDITION_REACHED ) {
291  $msg = "expected and found pos index {$this->waitForPosIndex} ({$waitedMs}ms)";
292  $this->logger->debug( $msg );
293  } else {
294  $msg = "expected but missed pos index {$this->waitForPosIndex} ({$waitedMs}ms)";
295  $this->logger->info( $msg );
296  }
297  } else {
298  $data = $this->store->get( $this->key );
299  }
300 
301  $this->startupPositions = $data ? $data['positions'] : [];
302  $this->logger->debug( __METHOD__ . ": key is {$this->key} (read)\n" );
303  } else {
304  $this->startupPositions = [];
305  $this->logger->debug( __METHOD__ . ": key is {$this->key} (unread)\n" );
306  }
307  }
308 
315  protected function mergePositions( $curValue, array $shutdownPositions, &$cpIndex = null ) {
317  $curPositions = isset( $curValue['positions'] ) ? $curValue['positions'] : [];
318  // Use the newest positions for each DB master
319  foreach ( $shutdownPositions as $db => $pos ) {
320  if (
321  !isset( $curPositions[$db] ) ||
322  !( $curPositions[$db] instanceof DBMasterPos ) ||
323  $pos->asOfTime() > $curPositions[$db]->asOfTime()
324  ) {
325  $curPositions[$db] = $pos;
326  }
327  }
328 
329  $cpIndex = isset( $curValue['writeIndex'] ) ? $curValue['writeIndex'] : 0;
330 
331  return [
332  'positions' => $curPositions,
333  'writeIndex' => ++$cpIndex
334  ];
335  }
336 }
Wikimedia\Rdbms\ChronologyProtector\$startupPositions
DBMasterPos[] $startupPositions
Map of (DB master name => position)
Definition: ChronologyProtector.php:58
use
Apache License January AND DISTRIBUTION Definitions License shall mean the terms and conditions for use
Definition: APACHE-LICENSE-2.0.txt:10
BagOStuff\getQoS
getQoS( $flag)
Definition: BagOStuff.php:778
array
the array() calling protocol came about after MediaWiki 1.4rc1.
Wikimedia\Rdbms\ChronologyProtector\$store
BagOStuff $store
Definition: ChronologyProtector.php:38
Wikimedia\Rdbms\ChronologyProtector\$wait
bool $wait
Whether to check and wait on positions.
Definition: ChronologyProtector.php:53
Wikimedia\Rdbms\ChronologyProtector\shutdown
shutdown(callable $workCallback=null, $mode='sync', &$cpIndex=null)
Notify the ChronologyProtector that the LBFactory is done calling shutdownLB() for now.
Definition: ChronologyProtector.php:169
Wikimedia\Rdbms\ChronologyProtector\$waitForPosStoreTimeout
int $waitForPosStoreTimeout
Max seconds to wait on positions to appear.
Definition: ChronologyProtector.php:49
Wikimedia\Rdbms\ChronologyProtector\$shutdownTouchDBs
float[] $shutdownTouchDBs
Map of (DB master name => 1)
Definition: ChronologyProtector.php:62
Wikimedia\Rdbms
Definition: ChronologyProtector.php:24
Wikimedia\Rdbms\ChronologyProtector\$initialized
bool $initialized
Whether the client data was loaded.
Definition: ChronologyProtector.php:56
Wikimedia\Rdbms\DBMasterPos
An object representing a master or replica DB position in a replicated setup.
Definition: DBMasterPos.php:12
Wikimedia\Rdbms\ChronologyProtector\__construct
__construct(BagOStuff $store, array $client, $posIndex=null)
Definition: ChronologyProtector.php:75
BagOStuff
interface is intended to be more or less compatible with the PHP memcached client.
Definition: BagOStuff.php:47
Wikimedia\Rdbms\ILoadBalancer\getServerCount
getServerCount()
Get the number of defined servers (not the number of open connections)
$result
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. 'ImgAuthModifyHeaders':Executed just before a file is streamed to a user via img_auth.php, allowing headers to be modified beforehand. $title:LinkTarget object & $headers:HTTP headers(name=> value, names are case insensitive). Two headers get special handling:If-Modified-Since(value must be a valid HTTP date) and Range(must be of the form "bytes=(\d*-\d*)") will be honored when streaming the file. '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 'ImportHandleUnknownUser':When a user doesn 't exist locally, this hook is called to give extensions an opportunity to auto-create it. If the auto-creation is successful, return false. $name:User name '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:Array with elements of the form "language:title" in the order that they will be output. & $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:1993
Wikimedia\Rdbms\ChronologyProtector\$logger
LoggerInterface $logger
Definition: ChronologyProtector.php:40
Wikimedia\Rdbms\ChronologyProtector\getTouched
getTouched( $dbName)
Definition: ChronologyProtector.php:242
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
Wikimedia\Rdbms\ChronologyProtector\setLogger
setLogger(LoggerInterface $logger)
Definition: ChronologyProtector.php:83
BagOStuff\unlock
unlock( $key)
Release an advisory lock on a key string.
Definition: BagOStuff.php:446
key
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:26
Wikimedia\Rdbms\ChronologyProtector\initPositions
initPositions()
Load in previous master positions for the client.
Definition: ChronologyProtector.php:258
Wikimedia\Rdbms\ILoadBalancer\getServerName
getServerName( $i)
Get the host name or IP address of the server with the specified index.
Wikimedia\Rdbms\ChronologyProtector\$waitForPosIndex
int null $waitForPosIndex
Expected minimum index of the last write to the position store.
Definition: ChronologyProtector.php:47
Wikimedia\Rdbms\ChronologyProtector\setWaitEnabled
setWaitEnabled( $enabled)
Definition: ChronologyProtector.php:99
store
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:4
Wikimedia\Rdbms\ILoadBalancer\getMasterPos
getMasterPos()
Get the current master position for chronology control purposes.
Wikimedia\Rdbms\ILoadBalancer\getWriterIndex
getWriterIndex()
BagOStuff\addBusyCallback
addBusyCallback(callable $workCallback)
Let a callback be run to avoid wasting time on special blocking calls.
Definition: BagOStuff.php:657
Wikimedia\Rdbms\ILoadBalancer\waitFor
waitFor( $pos)
Set the master wait position.
Wikimedia\Rdbms\ChronologyProtector\$key
string $key
Storage key name.
Definition: ChronologyProtector.php:43
Wikimedia\Rdbms\ChronologyProtector\$enabled
bool $enabled
Whether to no-op all method calls.
Definition: ChronologyProtector.php:51
Wikimedia\Rdbms\ChronologyProtector\initLB
initLB(ILoadBalancer $lb)
Initialise a ILoadBalancer to give it appropriate chronology protection.
Definition: ChronologyProtector.php:114
BagOStuff\makeGlobalKey
makeGlobalKey( $class, $component=null)
Make a global cache key.
Definition: BagOStuff.php:757
Wikimedia\Rdbms\ILoadBalancer\hasOrMadeRecentMasterChanges
hasOrMadeRecentMasterChanges( $age=null)
Check if this load balancer object had any recent or still pending writes issued against it by this P...
Wikimedia\Rdbms\ChronologyProtector\shutdownLB
shutdownLB(ILoadBalancer $lb)
Notify the ChronologyProtector that the ILoadBalancer is about to shut down.
Definition: ChronologyProtector.php:139
BagOStuff\get
get( $key, $flags=0, $oldFlags=null)
Get an item with the given key.
Definition: BagOStuff.php:182
Wikimedia\Rdbms\ChronologyProtector\mergePositions
mergePositions( $curValue, array $shutdownPositions, &$cpIndex=null)
Definition: ChronologyProtector.php:315
Wikimedia\Rdbms\ChronologyProtector
Class for ensuring a consistent ordering of events as seen by the user, despite replication.
Definition: ChronologyProtector.php:36
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
Wikimedia\Rdbms\ChronologyProtector\$clientId
string $clientId
Hash of client parameters.
Definition: ChronologyProtector.php:45
BagOStuff\lock
lock( $key, $timeout=6, $expiry=6, $rclass='')
Acquire an advisory lock on a key string.
Definition: BagOStuff.php:406
Wikimedia\Rdbms\ChronologyProtector\$shutdownPositions
DBMasterPos[] $shutdownPositions
Map of (DB master name => position)
Definition: ChronologyProtector.php:60
BagOStuff\set
set( $key, $value, $exptime=0, $flags=0)
Set an item.
Wikimedia\Rdbms\ChronologyProtector\getTouchedKey
getTouchedKey(BagOStuff $store, $dbName)
Definition: ChronologyProtector.php:251
Wikimedia\Rdbms\ChronologyProtector\setEnabled
setEnabled( $enabled)
Definition: ChronologyProtector.php:91
Wikimedia\Rdbms\ILoadBalancer
Database cluster connection, tracking, load balancing, and transaction manager interface.
Definition: ILoadBalancer.php:78