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[lhc/web/wiklou.git] / includes / libs / rdbms / loadbalancer / LoadBalancer.php
1 <?php
2 /**
3 * Database load balancing manager
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
19 *
20 * @file
21 * @ingroup Database
22 */
23 use Psr\Log\LoggerInterface;
24
25 /**
26 * Database connection, tracking, load balancing, and transaction manager for a cluster
27 *
28 * @ingroup Database
29 */
30 class LoadBalancer implements ILoadBalancer {
31 /** @var array[] Map of (server index => server config array) */
32 private $mServers;
33 /** @var array[] Map of (local/foreignUsed/foreignFree => server index => IDatabase array) */
34 private $mConns;
35 /** @var array Map of (server index => weight) */
36 private $mLoads;
37 /** @var array[] Map of (group => server index => weight) */
38 private $mGroupLoads;
39 /** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */
40 private $mAllowLagged;
41 /** @var integer Seconds to spend waiting on replica DB lag to resolve */
42 private $mWaitTimeout;
43 /** @var string The LoadMonitor subclass name */
44 private $mLoadMonitorClass;
45 /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
46 private $tableAliases = [];
47
48 /** @var ILoadMonitor */
49 private $mLoadMonitor;
50 /** @var BagOStuff */
51 private $srvCache;
52 /** @var BagOStuff */
53 private $memCache;
54 /** @var WANObjectCache */
55 private $wanCache;
56 /** @var object|string Class name or object With profileIn/profileOut methods */
57 protected $profiler;
58 /** @var TransactionProfiler */
59 protected $trxProfiler;
60 /** @var LoggerInterface */
61 protected $replLogger;
62 /** @var LoggerInterface */
63 protected $connLogger;
64 /** @var LoggerInterface */
65 protected $queryLogger;
66 /** @var LoggerInterface */
67 protected $perfLogger;
68
69 /** @var bool|IDatabase Database connection that caused a problem */
70 private $mErrorConnection;
71 /** @var integer The generic (not query grouped) replica DB index (of $mServers) */
72 private $mReadIndex;
73 /** @var bool|DBMasterPos False if not set */
74 private $mWaitForPos;
75 /** @var bool Whether the generic reader fell back to a lagged replica DB */
76 private $laggedReplicaMode = false;
77 /** @var bool Whether the generic reader fell back to a lagged replica DB */
78 private $allReplicasDownMode = false;
79 /** @var string The last DB selection or connection error */
80 private $mLastError = 'Unknown error';
81 /** @var string|bool Reason the LB is read-only or false if not */
82 private $readOnlyReason = false;
83 /** @var integer Total connections opened */
84 private $connsOpened = 0;
85 /** @var string|bool String if a requested DBO_TRX transaction round is active */
86 private $trxRoundId = false;
87 /** @var array[] Map of (name => callable) */
88 private $trxRecurringCallbacks = [];
89 /** @var DatabaseDomain Local Domain ID and default for selectDB() calls */
90 private $localDomain;
91 /** @var string Alternate ID string for the domain instead of DatabaseDomain::getId() */
92 private $localDomainIdAlias;
93 /** @var string Current server name */
94 private $host;
95 /** @var bool Whether this PHP instance is for a CLI script */
96 protected $cliMode;
97 /** @var string Agent name for query profiling */
98 protected $agent;
99
100 /** @var callable Exception logger */
101 private $errorLogger;
102
103 /** @var boolean */
104 private $disabled = false;
105
106 /** @var integer Warn when this many connection are held */
107 const CONN_HELD_WARN_THRESHOLD = 10;
108 /** @var integer Default 'max lag' when unspecified */
109 const MAX_LAG_DEFAULT = 10;
110 /** @var integer Max time to wait for a replica DB to catch up (e.g. ChronologyProtector) */
111 const POS_WAIT_TIMEOUT = 10;
112 /** @var integer Seconds to cache master server read-only status */
113 const TTL_CACHE_READONLY = 5;
114
115 public function __construct( array $params ) {
116 if ( !isset( $params['servers'] ) ) {
117 throw new InvalidArgumentException( __CLASS__ . ': missing servers parameter' );
118 }
119 $this->mServers = $params['servers'];
120
121 $this->localDomain = isset( $params['localDomain'] )
122 ? DatabaseDomain::newFromId( $params['localDomain'] )
123 : DatabaseDomain::newUnspecified();
124 // In case a caller assumes that the domain ID is simply <db>-<prefix>, which is almost
125 // always true, gracefully handle the case when they fail to account for escaping.
126 if ( $this->localDomain->getTablePrefix() != '' ) {
127 $this->localDomainIdAlias =
128 $this->localDomain->getDatabase() . '-' . $this->localDomain->getTablePrefix();
129 } else {
130 $this->localDomainIdAlias = $this->localDomain->getDatabase();
131 }
132
133 $this->mWaitTimeout = isset( $params['waitTimeout'] )
134 ? $params['waitTimeout']
135 : self::POS_WAIT_TIMEOUT;
136
137 $this->mReadIndex = -1;
138 $this->mConns = [
139 'local' => [],
140 'foreignUsed' => [],
141 'foreignFree' => []
142 ];
143 $this->mLoads = [];
144 $this->mWaitForPos = false;
145 $this->mErrorConnection = false;
146 $this->mAllowLagged = false;
147
148 if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
149 $this->readOnlyReason = $params['readOnlyReason'];
150 }
151
152 if ( isset( $params['loadMonitor'] ) ) {
153 $this->mLoadMonitorClass = $params['loadMonitor'];
154 } else {
155 $master = reset( $params['servers'] );
156 if ( isset( $master['type'] ) && $master['type'] === 'mysql' ) {
157 $this->mLoadMonitorClass = 'LoadMonitorMySQL';
158 } else {
159 $this->mLoadMonitorClass = 'LoadMonitorNull';
160 }
161 }
162
163 foreach ( $params['servers'] as $i => $server ) {
164 $this->mLoads[$i] = $server['load'];
165 if ( isset( $server['groupLoads'] ) ) {
166 foreach ( $server['groupLoads'] as $group => $ratio ) {
167 if ( !isset( $this->mGroupLoads[$group] ) ) {
168 $this->mGroupLoads[$group] = [];
169 }
170 $this->mGroupLoads[$group][$i] = $ratio;
171 }
172 }
173 }
174
175 if ( isset( $params['srvCache'] ) ) {
176 $this->srvCache = $params['srvCache'];
177 } else {
178 $this->srvCache = new EmptyBagOStuff();
179 }
180 if ( isset( $params['memCache'] ) ) {
181 $this->memCache = $params['memCache'];
182 } else {
183 $this->memCache = new EmptyBagOStuff();
184 }
185 if ( isset( $params['wanCache'] ) ) {
186 $this->wanCache = $params['wanCache'];
187 } else {
188 $this->wanCache = WANObjectCache::newEmpty();
189 }
190 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
191 if ( isset( $params['trxProfiler'] ) ) {
192 $this->trxProfiler = $params['trxProfiler'];
193 } else {
194 $this->trxProfiler = new TransactionProfiler();
195 }
196
197 $this->errorLogger = isset( $params['errorLogger'] )
198 ? $params['errorLogger']
199 : function ( Exception $e ) {
200 trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
201 };
202
203 foreach ( [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ] as $key ) {
204 $this->$key = isset( $params[$key] ) ? $params[$key] : new \Psr\Log\NullLogger();
205 }
206
207 $this->host = isset( $params['hostname'] )
208 ? $params['hostname']
209 : ( gethostname() ?: 'unknown' );
210 $this->cliMode = isset( $params['cliMode'] ) ? $params['cliMode'] : PHP_SAPI === 'cli';
211 $this->agent = isset( $params['agent'] ) ? $params['agent'] : '';
212 }
213
214 /**
215 * Get a LoadMonitor instance
216 *
217 * @return ILoadMonitor
218 */
219 private function getLoadMonitor() {
220 if ( !isset( $this->mLoadMonitor ) ) {
221 $class = $this->mLoadMonitorClass;
222 $this->mLoadMonitor = new $class( $this, $this->srvCache, $this->memCache );
223 $this->mLoadMonitor->setLogger( $this->replLogger );
224 }
225
226 return $this->mLoadMonitor;
227 }
228
229 /**
230 * @param array $loads
231 * @param bool|string $domain Domain to get non-lagged for
232 * @param int $maxLag Restrict the maximum allowed lag to this many seconds
233 * @return bool|int|string
234 */
235 private function getRandomNonLagged( array $loads, $domain = false, $maxLag = INF ) {
236 $lags = $this->getLagTimes( $domain );
237
238 # Unset excessively lagged servers
239 foreach ( $lags as $i => $lag ) {
240 if ( $i != 0 ) {
241 # How much lag this server nominally is allowed to have
242 $maxServerLag = isset( $this->mServers[$i]['max lag'] )
243 ? $this->mServers[$i]['max lag']
244 : self::MAX_LAG_DEFAULT; // default
245 # Constrain that futher by $maxLag argument
246 $maxServerLag = min( $maxServerLag, $maxLag );
247
248 $host = $this->getServerName( $i );
249 if ( $lag === false && !is_infinite( $maxServerLag ) ) {
250 $this->replLogger->error( "Server $host (#$i) is not replicating?" );
251 unset( $loads[$i] );
252 } elseif ( $lag > $maxServerLag ) {
253 $this->replLogger->warning( "Server $host (#$i) has >= $lag seconds of lag" );
254 unset( $loads[$i] );
255 }
256 }
257 }
258
259 # Find out if all the replica DBs with non-zero load are lagged
260 $sum = 0;
261 foreach ( $loads as $load ) {
262 $sum += $load;
263 }
264 if ( $sum == 0 ) {
265 # No appropriate DB servers except maybe the master and some replica DBs with zero load
266 # Do NOT use the master
267 # Instead, this function will return false, triggering read-only mode,
268 # and a lagged replica DB will be used instead.
269 return false;
270 }
271
272 if ( count( $loads ) == 0 ) {
273 return false;
274 }
275
276 # Return a random representative of the remainder
277 return ArrayUtils::pickRandom( $loads );
278 }
279
280 public function getReaderIndex( $group = false, $domain = false ) {
281 if ( count( $this->mServers ) == 1 ) {
282 # Skip the load balancing if there's only one server
283 return $this->getWriterIndex();
284 } elseif ( $group === false && $this->mReadIndex >= 0 ) {
285 # Shortcut if generic reader exists already
286 return $this->mReadIndex;
287 }
288
289 # Find the relevant load array
290 if ( $group !== false ) {
291 if ( isset( $this->mGroupLoads[$group] ) ) {
292 $nonErrorLoads = $this->mGroupLoads[$group];
293 } else {
294 # No loads for this group, return false and the caller can use some other group
295 $this->connLogger->info( __METHOD__ . ": no loads for group $group" );
296
297 return false;
298 }
299 } else {
300 $nonErrorLoads = $this->mLoads;
301 }
302
303 if ( !count( $nonErrorLoads ) ) {
304 throw new InvalidArgumentException( "Empty server array given to LoadBalancer" );
305 }
306
307 # Scale the configured load ratios according to the dynamic load if supported
308 $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group, $domain );
309
310 $laggedReplicaMode = false;
311
312 # No server found yet
313 $i = false;
314 # First try quickly looking through the available servers for a server that
315 # meets our criteria
316 $currentLoads = $nonErrorLoads;
317 while ( count( $currentLoads ) ) {
318 if ( $this->mAllowLagged || $laggedReplicaMode ) {
319 $i = ArrayUtils::pickRandom( $currentLoads );
320 } else {
321 $i = false;
322 if ( $this->mWaitForPos && $this->mWaitForPos->asOfTime() ) {
323 # ChronologyProtecter causes mWaitForPos to be set via sessions.
324 # This triggers doWait() after connect, so it's especially good to
325 # avoid lagged servers so as to avoid just blocking in that method.
326 $ago = microtime( true ) - $this->mWaitForPos->asOfTime();
327 # Aim for <= 1 second of waiting (being too picky can backfire)
328 $i = $this->getRandomNonLagged( $currentLoads, $domain, $ago + 1 );
329 }
330 if ( $i === false ) {
331 # Any server with less lag than it's 'max lag' param is preferable
332 $i = $this->getRandomNonLagged( $currentLoads, $domain );
333 }
334 if ( $i === false && count( $currentLoads ) != 0 ) {
335 # All replica DBs lagged. Switch to read-only mode
336 $this->replLogger->error( "All replica DBs lagged. Switch to read-only mode" );
337 $i = ArrayUtils::pickRandom( $currentLoads );
338 $laggedReplicaMode = true;
339 }
340 }
341
342 if ( $i === false ) {
343 # pickRandom() returned false
344 # This is permanent and means the configuration or the load monitor
345 # wants us to return false.
346 $this->connLogger->debug( __METHOD__ . ": pickRandom() returned false" );
347
348 return false;
349 }
350
351 $serverName = $this->getServerName( $i );
352 $this->connLogger->debug( __METHOD__ . ": Using reader #$i: $serverName..." );
353
354 $conn = $this->openConnection( $i, $domain );
355 if ( !$conn ) {
356 $this->connLogger->warning( __METHOD__ . ": Failed connecting to $i/$domain" );
357 unset( $nonErrorLoads[$i] );
358 unset( $currentLoads[$i] );
359 $i = false;
360 continue;
361 }
362
363 // Decrement reference counter, we are finished with this connection.
364 // It will be incremented for the caller later.
365 if ( $domain !== false ) {
366 $this->reuseConnection( $conn );
367 }
368
369 # Return this server
370 break;
371 }
372
373 # If all servers were down, quit now
374 if ( !count( $nonErrorLoads ) ) {
375 $this->connLogger->error( "All servers down" );
376 }
377
378 if ( $i !== false ) {
379 # Replica DB connection successful.
380 # Wait for the session master pos for a short time.
381 if ( $this->mWaitForPos && $i > 0 ) {
382 $this->doWait( $i );
383 }
384 if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) {
385 $this->mReadIndex = $i;
386 # Record if the generic reader index is in "lagged replica DB" mode
387 if ( $laggedReplicaMode ) {
388 $this->laggedReplicaMode = true;
389 }
390 }
391 $serverName = $this->getServerName( $i );
392 $this->connLogger->debug(
393 __METHOD__ . ": using server $serverName for group '$group'" );
394 }
395
396 return $i;
397 }
398
399 public function waitFor( $pos ) {
400 $this->mWaitForPos = $pos;
401 $i = $this->mReadIndex;
402
403 if ( $i > 0 ) {
404 if ( !$this->doWait( $i ) ) {
405 $this->laggedReplicaMode = true;
406 }
407 }
408 }
409
410 public function waitForOne( $pos, $timeout = null ) {
411 $this->mWaitForPos = $pos;
412
413 $i = $this->mReadIndex;
414 if ( $i <= 0 ) {
415 // Pick a generic replica DB if there isn't one yet
416 $readLoads = $this->mLoads;
417 unset( $readLoads[$this->getWriterIndex()] ); // replica DBs only
418 $readLoads = array_filter( $readLoads ); // with non-zero load
419 $i = ArrayUtils::pickRandom( $readLoads );
420 }
421
422 if ( $i > 0 ) {
423 $ok = $this->doWait( $i, true, $timeout );
424 } else {
425 $ok = true; // no applicable loads
426 }
427
428 return $ok;
429 }
430
431 public function waitForAll( $pos, $timeout = null ) {
432 $this->mWaitForPos = $pos;
433 $serverCount = count( $this->mServers );
434
435 $ok = true;
436 for ( $i = 1; $i < $serverCount; $i++ ) {
437 if ( $this->mLoads[$i] > 0 ) {
438 $ok = $this->doWait( $i, true, $timeout ) && $ok;
439 }
440 }
441
442 return $ok;
443 }
444
445 public function getAnyOpenConnection( $i ) {
446 foreach ( $this->mConns as $connsByServer ) {
447 if ( !empty( $connsByServer[$i] ) ) {
448 return reset( $connsByServer[$i] );
449 }
450 }
451
452 return false;
453 }
454
455 /**
456 * Wait for a given replica DB to catch up to the master pos stored in $this
457 * @param int $index Server index
458 * @param bool $open Check the server even if a new connection has to be made
459 * @param int $timeout Max seconds to wait; default is mWaitTimeout
460 * @return bool
461 */
462 protected function doWait( $index, $open = false, $timeout = null ) {
463 $close = false; // close the connection afterwards
464
465 // Check if we already know that the DB has reached this point
466 $server = $this->getServerName( $index );
467 $key = $this->srvCache->makeGlobalKey( __CLASS__, 'last-known-pos', $server );
468 /** @var DBMasterPos $knownReachedPos */
469 $knownReachedPos = $this->srvCache->get( $key );
470 if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos ) ) {
471 $this->replLogger->debug( __METHOD__ .
472 ": replica DB $server known to be caught up (pos >= $knownReachedPos)." );
473 return true;
474 }
475
476 // Find a connection to wait on, creating one if needed and allowed
477 $conn = $this->getAnyOpenConnection( $index );
478 if ( !$conn ) {
479 if ( !$open ) {
480 $this->replLogger->debug( __METHOD__ . ": no connection open for $server" );
481
482 return false;
483 } else {
484 $conn = $this->openConnection( $index, '' );
485 if ( !$conn ) {
486 $this->replLogger->warning( __METHOD__ . ": failed to connect to $server" );
487
488 return false;
489 }
490 // Avoid connection spam in waitForAll() when connections
491 // are made just for the sake of doing this lag check.
492 $close = true;
493 }
494 }
495
496 $this->replLogger->info( __METHOD__ . ": Waiting for replica DB $server to catch up..." );
497 $timeout = $timeout ?: $this->mWaitTimeout;
498 $result = $conn->masterPosWait( $this->mWaitForPos, $timeout );
499
500 if ( $result == -1 || is_null( $result ) ) {
501 // Timed out waiting for replica DB, use master instead
502 $msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
503 $this->replLogger->warning( "$msg" );
504 $ok = false;
505 } else {
506 $this->replLogger->info( __METHOD__ . ": Done" );
507 $ok = true;
508 // Remember that the DB reached this point
509 $this->srvCache->set( $key, $this->mWaitForPos, BagOStuff::TTL_DAY );
510 }
511
512 if ( $close ) {
513 $this->closeConnection( $conn );
514 }
515
516 return $ok;
517 }
518
519 /**
520 * @see ILoadBalancer::getConnection()
521 *
522 * @param int $i
523 * @param array $groups
524 * @param bool $domain
525 * @return Database
526 * @throws DBConnectionError
527 */
528 public function getConnection( $i, $groups = [], $domain = false ) {
529 if ( $i === null || $i === false ) {
530 throw new InvalidArgumentException( 'Attempt to call ' . __METHOD__ .
531 ' with invalid server index' );
532 }
533
534 if ( $this->localDomain->equals( $domain ) || $domain === $this->localDomainIdAlias ) {
535 $domain = false; // local connection requested
536 }
537
538 $groups = ( $groups === false || $groups === [] )
539 ? [ false ] // check one "group": the generic pool
540 : (array)$groups;
541
542 $masterOnly = ( $i == self::DB_MASTER || $i == $this->getWriterIndex() );
543 $oldConnsOpened = $this->connsOpened; // connections open now
544
545 if ( $i == self::DB_MASTER ) {
546 $i = $this->getWriterIndex();
547 } else {
548 # Try to find an available server in any the query groups (in order)
549 foreach ( $groups as $group ) {
550 $groupIndex = $this->getReaderIndex( $group, $domain );
551 if ( $groupIndex !== false ) {
552 $i = $groupIndex;
553 break;
554 }
555 }
556 }
557
558 # Operation-based index
559 if ( $i == self::DB_REPLICA ) {
560 $this->mLastError = 'Unknown error'; // reset error string
561 # Try the general server pool if $groups are unavailable.
562 $i = in_array( false, $groups, true )
563 ? false // don't bother with this if that is what was tried above
564 : $this->getReaderIndex( false, $domain );
565 # Couldn't find a working server in getReaderIndex()?
566 if ( $i === false ) {
567 $this->mLastError = 'No working replica DB server: ' . $this->mLastError;
568 // Throw an exception
569 $this->reportConnectionError();
570 return null; // not reached
571 }
572 }
573
574 # Now we have an explicit index into the servers array
575 $conn = $this->openConnection( $i, $domain );
576 if ( !$conn ) {
577 // Throw an exception
578 $this->reportConnectionError();
579 return null; // not reached
580 }
581
582 # Profile any new connections that happen
583 if ( $this->connsOpened > $oldConnsOpened ) {
584 $host = $conn->getServer();
585 $dbname = $conn->getDBname();
586 $this->trxProfiler->recordConnection( $host, $dbname, $masterOnly );
587 }
588
589 if ( $masterOnly ) {
590 # Make master-requested DB handles inherit any read-only mode setting
591 $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $domain, $conn ) );
592 }
593
594 return $conn;
595 }
596
597 public function reuseConnection( $conn ) {
598 $serverIndex = $conn->getLBInfo( 'serverIndex' );
599 $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
600 if ( $serverIndex === null || $refCount === null ) {
601 /**
602 * This can happen in code like:
603 * foreach ( $dbs as $db ) {
604 * $conn = $lb->getConnection( $lb::DB_REPLICA, [], $db );
605 * ...
606 * $lb->reuseConnection( $conn );
607 * }
608 * When a connection to the local DB is opened in this way, reuseConnection()
609 * should be ignored
610 */
611 return;
612 } elseif ( $conn instanceof DBConnRef ) {
613 // DBConnRef already handles calling reuseConnection() and only passes the live
614 // Database instance to this method. Any caller passing in a DBConnRef is broken.
615 $this->connLogger->error( __METHOD__ . ": got DBConnRef instance.\n" .
616 ( new RuntimeException() )->getTraceAsString() );
617
618 return;
619 }
620
621 $domain = $conn->getDomainID();
622 if ( $this->mConns['foreignUsed'][$serverIndex][$domain] !== $conn ) {
623 throw new InvalidArgumentException( __METHOD__ .
624 ": connection not found, has the connection been freed already?" );
625 }
626 $conn->setLBInfo( 'foreignPoolRefCount', --$refCount );
627 if ( $refCount <= 0 ) {
628 $this->mConns['foreignFree'][$serverIndex][$domain] = $conn;
629 unset( $this->mConns['foreignUsed'][$serverIndex][$domain] );
630 if ( !$this->mConns['foreignUsed'][$serverIndex] ) {
631 unset( $this->mConns[ 'foreignUsed' ][$serverIndex] ); // clean up
632 }
633 $this->connLogger->debug( __METHOD__ . ": freed connection $serverIndex/$domain" );
634 } else {
635 $this->connLogger->debug( __METHOD__ .
636 ": reference count for $serverIndex/$domain reduced to $refCount" );
637 }
638 }
639
640 public function getConnectionRef( $db, $groups = [], $domain = false ) {
641 $domain = ( $domain !== false ) ? $domain : $this->localDomain;
642
643 return new DBConnRef( $this, $this->getConnection( $db, $groups, $domain ) );
644 }
645
646 public function getLazyConnectionRef( $db, $groups = [], $domain = false ) {
647 $domain = ( $domain !== false ) ? $domain : $this->localDomain;
648
649 return new DBConnRef( $this, [ $db, $groups, $domain ] );
650 }
651
652 /**
653 * @see ILoadBalancer::openConnection()
654 *
655 * @param int $i
656 * @param bool $domain
657 * @return bool|Database
658 * @throws DBAccessError
659 */
660 public function openConnection( $i, $domain = false ) {
661 if ( $this->localDomain->equals( $domain ) || $domain === $this->localDomainIdAlias ) {
662 $domain = false; // local connection requested
663 }
664
665 if ( $domain !== false ) {
666 $conn = $this->openForeignConnection( $i, $domain );
667 } elseif ( isset( $this->mConns['local'][$i][0] ) ) {
668 $conn = $this->mConns['local'][$i][0];
669 } else {
670 $server = $this->mServers[$i];
671 $server['serverIndex'] = $i;
672 $conn = $this->reallyOpenConnection( $server, false );
673 $serverName = $this->getServerName( $i );
674 if ( $conn->isOpen() ) {
675 $this->connLogger->debug( "Connected to database $i at '$serverName'." );
676 $this->mConns['local'][$i][0] = $conn;
677 } else {
678 $this->connLogger->warning( "Failed to connect to database $i at '$serverName'." );
679 $this->mErrorConnection = $conn;
680 $conn = false;
681 }
682 }
683
684 if ( $conn && !$conn->isOpen() ) {
685 // Connection was made but later unrecoverably lost for some reason.
686 // Do not return a handle that will just throw exceptions on use,
687 // but let the calling code (e.g. getReaderIndex) try another server.
688 // See DatabaseMyslBase::ping() for how this can happen.
689 $this->mErrorConnection = $conn;
690 $conn = false;
691 }
692
693 return $conn;
694 }
695
696 /**
697 * Open a connection to a foreign DB, or return one if it is already open.
698 *
699 * Increments a reference count on the returned connection which locks the
700 * connection to the requested domain. This reference count can be
701 * decremented by calling reuseConnection().
702 *
703 * If a connection is open to the appropriate server already, but with the wrong
704 * database, it will be switched to the right database and returned, as long as
705 * it has been freed first with reuseConnection().
706 *
707 * On error, returns false, and the connection which caused the
708 * error will be available via $this->mErrorConnection.
709 *
710 * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError.
711 *
712 * @param int $i Server index
713 * @param string $domain Domain ID to open
714 * @return Database
715 */
716 private function openForeignConnection( $i, $domain ) {
717 $domainInstance = DatabaseDomain::newFromId( $domain );
718 $dbName = $domainInstance->getDatabase();
719 $prefix = $domainInstance->getTablePrefix();
720
721 if ( isset( $this->mConns['foreignUsed'][$i][$domain] ) ) {
722 // Reuse an already-used connection
723 $conn = $this->mConns['foreignUsed'][$i][$domain];
724 $this->connLogger->debug( __METHOD__ . ": reusing connection $i/$domain" );
725 } elseif ( isset( $this->mConns['foreignFree'][$i][$domain] ) ) {
726 // Reuse a free connection for the same domain
727 $conn = $this->mConns['foreignFree'][$i][$domain];
728 unset( $this->mConns['foreignFree'][$i][$domain] );
729 $this->mConns['foreignUsed'][$i][$domain] = $conn;
730 $this->connLogger->debug( __METHOD__ . ": reusing free connection $i/$domain" );
731 } elseif ( !empty( $this->mConns['foreignFree'][$i] ) ) {
732 // Reuse a connection from another domain
733 $conn = reset( $this->mConns['foreignFree'][$i] );
734 $oldDomain = key( $this->mConns['foreignFree'][$i] );
735 // The empty string as a DB name means "don't care".
736 // DatabaseMysqlBase::open() already handle this on connection.
737 if ( strlen( $dbName ) && !$conn->selectDB( $dbName ) ) {
738 $this->mLastError = "Error selecting database '$dbName' on server " .
739 $conn->getServer() . " from client host {$this->host}";
740 $this->mErrorConnection = $conn;
741 $conn = false;
742 } else {
743 $conn->tablePrefix( $prefix );
744 unset( $this->mConns['foreignFree'][$i][$oldDomain] );
745 $this->mConns['foreignUsed'][$i][$domain] = $conn;
746 $this->connLogger->debug( __METHOD__ .
747 ": reusing free connection from $oldDomain for $domain" );
748 }
749 } else {
750 // Open a new connection
751 $server = $this->mServers[$i];
752 $server['serverIndex'] = $i;
753 $server['foreignPoolRefCount'] = 0;
754 $server['foreign'] = true;
755 $conn = $this->reallyOpenConnection( $server, $dbName );
756 if ( !$conn->isOpen() ) {
757 $this->connLogger->warning( __METHOD__ . ": connection error for $i/$domain" );
758 $this->mErrorConnection = $conn;
759 $conn = false;
760 } else {
761 $conn->tablePrefix( $prefix );
762 $this->mConns['foreignUsed'][$i][$domain] = $conn;
763 $this->connLogger->debug( __METHOD__ . ": opened new connection for $i/$domain" );
764 }
765 }
766
767 // Increment reference count
768 if ( $conn ) {
769 $refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
770 $conn->setLBInfo( 'foreignPoolRefCount', $refCount + 1 );
771 }
772
773 return $conn;
774 }
775
776 /**
777 * Test if the specified index represents an open connection
778 *
779 * @param int $index Server index
780 * @access private
781 * @return bool
782 */
783 private function isOpen( $index ) {
784 if ( !is_integer( $index ) ) {
785 return false;
786 }
787
788 return (bool)$this->getAnyOpenConnection( $index );
789 }
790
791 /**
792 * Really opens a connection. Uncached.
793 * Returns a Database object whether or not the connection was successful.
794 * @access private
795 *
796 * @param array $server
797 * @param string|bool $dbNameOverride Use "" to not select any database
798 * @return Database
799 * @throws DBAccessError
800 * @throws InvalidArgumentException
801 */
802 protected function reallyOpenConnection( $server, $dbNameOverride = false ) {
803 if ( $this->disabled ) {
804 throw new DBAccessError();
805 }
806
807 if ( !is_array( $server ) ) {
808 throw new InvalidArgumentException(
809 'You must update your load-balancing configuration. ' .
810 'See DefaultSettings.php entry for $wgDBservers.' );
811 }
812
813 if ( $dbNameOverride !== false ) {
814 $server['dbname'] = $dbNameOverride;
815 }
816
817 // Let the handle know what the cluster master is (e.g. "db1052")
818 $masterName = $this->getServerName( $this->getWriterIndex() );
819 $server['clusterMasterHost'] = $masterName;
820
821 // Log when many connection are made on requests
822 if ( ++$this->connsOpened >= self::CONN_HELD_WARN_THRESHOLD ) {
823 $this->perfLogger->warning( __METHOD__ . ": " .
824 "{$this->connsOpened}+ connections made (master=$masterName)" );
825 }
826
827 $server['srvCache'] = $this->srvCache;
828 // Set loggers and profilers
829 $server['connLogger'] = $this->connLogger;
830 $server['queryLogger'] = $this->queryLogger;
831 $server['errorLogger'] = $this->errorLogger;
832 $server['profiler'] = $this->profiler;
833 $server['trxProfiler'] = $this->trxProfiler;
834 // Use the same agent and PHP mode for all DB handles
835 $server['cliMode'] = $this->cliMode;
836 $server['agent'] = $this->agent;
837 // Use DBO_DEFAULT flags by default for LoadBalancer managed databases. Assume that the
838 // application calls LoadBalancer::commitMasterChanges() before the PHP script completes.
839 $server['flags'] = isset( $server['flags'] ) ? $server['flags'] : IDatabase::DBO_DEFAULT;
840
841 // Create a live connection object
842 try {
843 $db = Database::factory( $server['type'], $server );
844 } catch ( DBConnectionError $e ) {
845 // FIXME: This is probably the ugliest thing I have ever done to
846 // PHP. I'm half-expecting it to segfault, just out of disgust. -- TS
847 $db = $e->db;
848 }
849
850 $db->setLBInfo( $server );
851 $db->setLazyMasterHandle(
852 $this->getLazyConnectionRef( self::DB_MASTER, [], $db->getDomainID() )
853 );
854 $db->setTableAliases( $this->tableAliases );
855
856 if ( $server['serverIndex'] === $this->getWriterIndex() ) {
857 if ( $this->trxRoundId !== false ) {
858 $this->applyTransactionRoundFlags( $db );
859 }
860 foreach ( $this->trxRecurringCallbacks as $name => $callback ) {
861 $db->setTransactionListener( $name, $callback );
862 }
863 }
864
865 return $db;
866 }
867
868 /**
869 * @throws DBConnectionError
870 */
871 private function reportConnectionError() {
872 $conn = $this->mErrorConnection; // the connection which caused the error
873 $context = [
874 'method' => __METHOD__,
875 'last_error' => $this->mLastError,
876 ];
877
878 if ( !is_object( $conn ) ) {
879 // No last connection, probably due to all servers being too busy
880 $this->connLogger->error(
881 "LB failure with no last connection. Connection error: {last_error}",
882 $context
883 );
884
885 // If all servers were busy, mLastError will contain something sensible
886 throw new DBConnectionError( null, $this->mLastError );
887 } else {
888 $context['db_server'] = $conn->getProperty( 'mServer' );
889 $this->connLogger->warning(
890 "Connection error: {last_error} ({db_server})",
891 $context
892 );
893
894 // throws DBConnectionError
895 $conn->reportConnectionError( "{$this->mLastError} ({$context['db_server']})" );
896 }
897 }
898
899 public function getWriterIndex() {
900 return 0;
901 }
902
903 public function haveIndex( $i ) {
904 return array_key_exists( $i, $this->mServers );
905 }
906
907 public function isNonZeroLoad( $i ) {
908 return array_key_exists( $i, $this->mServers ) && $this->mLoads[$i] != 0;
909 }
910
911 public function getServerCount() {
912 return count( $this->mServers );
913 }
914
915 public function getServerName( $i ) {
916 if ( isset( $this->mServers[$i]['hostName'] ) ) {
917 $name = $this->mServers[$i]['hostName'];
918 } elseif ( isset( $this->mServers[$i]['host'] ) ) {
919 $name = $this->mServers[$i]['host'];
920 } else {
921 $name = '';
922 }
923
924 return ( $name != '' ) ? $name : 'localhost';
925 }
926
927 public function getServerInfo( $i ) {
928 if ( isset( $this->mServers[$i] ) ) {
929 return $this->mServers[$i];
930 } else {
931 return false;
932 }
933 }
934
935 public function setServerInfo( $i, array $serverInfo ) {
936 $this->mServers[$i] = $serverInfo;
937 }
938
939 public function getMasterPos() {
940 # If this entire request was served from a replica DB without opening a connection to the
941 # master (however unlikely that may be), then we can fetch the position from the replica DB.
942 $masterConn = $this->getAnyOpenConnection( $this->getWriterIndex() );
943 if ( !$masterConn ) {
944 $serverCount = count( $this->mServers );
945 for ( $i = 1; $i < $serverCount; $i++ ) {
946 $conn = $this->getAnyOpenConnection( $i );
947 if ( $conn ) {
948 return $conn->getSlavePos();
949 }
950 }
951 } else {
952 return $masterConn->getMasterPos();
953 }
954
955 return false;
956 }
957
958 public function disable() {
959 $this->closeAll();
960 $this->disabled = true;
961 }
962
963 public function closeAll() {
964 $this->forEachOpenConnection( function ( IDatabase $conn ) {
965 $host = $conn->getServer();
966 $this->connLogger->debug( "Closing connection to database '$host'." );
967 $conn->close();
968 } );
969
970 $this->mConns = [
971 'local' => [],
972 'foreignFree' => [],
973 'foreignUsed' => [],
974 ];
975 $this->connsOpened = 0;
976 }
977
978 public function closeConnection( IDatabase $conn ) {
979 $serverIndex = $conn->getLBInfo( 'serverIndex' ); // second index level of mConns
980 foreach ( $this->mConns as $type => $connsByServer ) {
981 if ( !isset( $connsByServer[$serverIndex] ) ) {
982 continue;
983 }
984
985 foreach ( $connsByServer[$serverIndex] as $i => $trackedConn ) {
986 if ( $conn === $trackedConn ) {
987 $host = $this->getServerName( $i );
988 $this->connLogger->debug( "Closing connection to database $i at '$host'." );
989 unset( $this->mConns[$type][$serverIndex][$i] );
990 --$this->connsOpened;
991 break 2;
992 }
993 }
994 }
995
996 $conn->close();
997 }
998
999 public function commitAll( $fname = __METHOD__ ) {
1000 $failures = [];
1001
1002 $restore = ( $this->trxRoundId !== false );
1003 $this->trxRoundId = false;
1004 $this->forEachOpenConnection(
1005 function ( IDatabase $conn ) use ( $fname, $restore, &$failures ) {
1006 try {
1007 $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS );
1008 } catch ( DBError $e ) {
1009 call_user_func( $this->errorLogger, $e );
1010 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1011 }
1012 if ( $restore && $conn->getLBInfo( 'master' ) ) {
1013 $this->undoTransactionRoundFlags( $conn );
1014 }
1015 }
1016 );
1017
1018 if ( $failures ) {
1019 throw new DBExpectedError(
1020 null,
1021 "Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
1022 );
1023 }
1024 }
1025
1026 public function finalizeMasterChanges() {
1027 $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) {
1028 // Any error should cause all DB transactions to be rolled back together
1029 $conn->setTrxEndCallbackSuppression( false );
1030 $conn->runOnTransactionPreCommitCallbacks();
1031 // Defer post-commit callbacks until COMMIT finishes for all DBs
1032 $conn->setTrxEndCallbackSuppression( true );
1033 } );
1034 }
1035
1036 public function approveMasterChanges( array $options ) {
1037 $limit = isset( $options['maxWriteDuration'] ) ? $options['maxWriteDuration'] : 0;
1038 $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( $limit ) {
1039 // If atomic sections or explicit transactions are still open, some caller must have
1040 // caught an exception but failed to properly rollback any changes. Detect that and
1041 // throw and error (causing rollback).
1042 if ( $conn->explicitTrxActive() ) {
1043 throw new DBTransactionError(
1044 $conn,
1045 "Explicit transaction still active. A caller may have caught an error."
1046 );
1047 }
1048 // Assert that the time to replicate the transaction will be sane.
1049 // If this fails, then all DB transactions will be rollback back together.
1050 $time = $conn->pendingWriteQueryDuration( $conn::ESTIMATE_DB_APPLY );
1051 if ( $limit > 0 && $time > $limit ) {
1052 throw new DBTransactionSizeError(
1053 $conn,
1054 "Transaction spent $time second(s) in writes, exceeding the $limit limit.",
1055 [ $time, $limit ]
1056 );
1057 }
1058 // If a connection sits idle while slow queries execute on another, that connection
1059 // may end up dropped before the commit round is reached. Ping servers to detect this.
1060 if ( $conn->writesOrCallbacksPending() && !$conn->ping() ) {
1061 throw new DBTransactionError(
1062 $conn,
1063 "A connection to the {$conn->getDBname()} database was lost before commit."
1064 );
1065 }
1066 } );
1067 }
1068
1069 public function beginMasterChanges( $fname = __METHOD__ ) {
1070 if ( $this->trxRoundId !== false ) {
1071 throw new DBTransactionError(
1072 null,
1073 "$fname: Transaction round '{$this->trxRoundId}' already started."
1074 );
1075 }
1076 $this->trxRoundId = $fname;
1077
1078 $failures = [];
1079 $this->forEachOpenMasterConnection(
1080 function ( DatabaseBase $conn ) use ( $fname, &$failures ) {
1081 $conn->setTrxEndCallbackSuppression( true );
1082 try {
1083 $conn->flushSnapshot( $fname );
1084 } catch ( DBError $e ) {
1085 call_user_func( $this->errorLogger, $e );
1086 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1087 }
1088 $conn->setTrxEndCallbackSuppression( false );
1089 $this->applyTransactionRoundFlags( $conn );
1090 }
1091 );
1092
1093 if ( $failures ) {
1094 throw new DBExpectedError(
1095 null,
1096 "$fname: Flush failed on server(s) " . implode( "\n", array_unique( $failures ) )
1097 );
1098 }
1099 }
1100
1101 public function commitMasterChanges( $fname = __METHOD__ ) {
1102 $failures = [];
1103
1104 $restore = ( $this->trxRoundId !== false );
1105 $this->trxRoundId = false;
1106 $this->forEachOpenMasterConnection(
1107 function ( IDatabase $conn ) use ( $fname, $restore, &$failures ) {
1108 try {
1109 if ( $conn->writesOrCallbacksPending() ) {
1110 $conn->commit( $fname, $conn::FLUSHING_ALL_PEERS );
1111 } elseif ( $restore ) {
1112 $conn->flushSnapshot( $fname );
1113 }
1114 } catch ( DBError $e ) {
1115 call_user_func( $this->errorLogger, $e );
1116 $failures[] = "{$conn->getServer()}: {$e->getMessage()}";
1117 }
1118 if ( $restore ) {
1119 $this->undoTransactionRoundFlags( $conn );
1120 }
1121 }
1122 );
1123
1124 if ( $failures ) {
1125 throw new DBExpectedError(
1126 null,
1127 "$fname: Commit failed on server(s) " . implode( "\n", array_unique( $failures ) )
1128 );
1129 }
1130 }
1131
1132 public function runMasterPostTrxCallbacks( $type ) {
1133 $e = null; // first exception
1134 $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) use ( $type, &$e ) {
1135 $conn->setTrxEndCallbackSuppression( false );
1136 if ( $conn->writesOrCallbacksPending() ) {
1137 // This happens if onTransactionIdle() callbacks leave callbacks on *another* DB
1138 // (which finished its callbacks already). Warn and recover in this case. Let the
1139 // callbacks run in the final commitMasterChanges() in LBFactory::shutdown().
1140 $this->queryLogger->error( __METHOD__ . ": found writes/callbacks pending." );
1141 return;
1142 } elseif ( $conn->trxLevel() ) {
1143 // This happens for single-DB setups where DB_REPLICA uses the master DB,
1144 // thus leaving an implicit read-only transaction open at this point. It
1145 // also happens if onTransactionIdle() callbacks leave implicit transactions
1146 // open on *other* DBs (which is slightly improper). Let these COMMIT on the
1147 // next call to commitMasterChanges(), possibly in LBFactory::shutdown().
1148 return;
1149 }
1150 try {
1151 $conn->runOnTransactionIdleCallbacks( $type );
1152 } catch ( Exception $ex ) {
1153 $e = $e ?: $ex;
1154 }
1155 try {
1156 $conn->runTransactionListenerCallbacks( $type );
1157 } catch ( Exception $ex ) {
1158 $e = $e ?: $ex;
1159 }
1160 } );
1161
1162 return $e;
1163 }
1164
1165 public function rollbackMasterChanges( $fname = __METHOD__ ) {
1166 $restore = ( $this->trxRoundId !== false );
1167 $this->trxRoundId = false;
1168 $this->forEachOpenMasterConnection(
1169 function ( IDatabase $conn ) use ( $fname, $restore ) {
1170 if ( $conn->writesOrCallbacksPending() ) {
1171 $conn->rollback( $fname, $conn::FLUSHING_ALL_PEERS );
1172 }
1173 if ( $restore ) {
1174 $this->undoTransactionRoundFlags( $conn );
1175 }
1176 }
1177 );
1178 }
1179
1180 public function suppressTransactionEndCallbacks() {
1181 $this->forEachOpenMasterConnection( function ( DatabaseBase $conn ) {
1182 $conn->setTrxEndCallbackSuppression( true );
1183 } );
1184 }
1185
1186 /**
1187 * @param IDatabase $conn
1188 */
1189 private function applyTransactionRoundFlags( IDatabase $conn ) {
1190 if ( $conn->getFlag( $conn::DBO_DEFAULT ) ) {
1191 // DBO_TRX is controlled entirely by CLI mode presence with DBO_DEFAULT.
1192 // Force DBO_TRX even in CLI mode since a commit round is expected soon.
1193 $conn->setFlag( $conn::DBO_TRX, $conn::REMEMBER_PRIOR );
1194 // If config has explicitly requested DBO_TRX be either on or off by not
1195 // setting DBO_DEFAULT, then respect that. Forcing no transactions is useful
1196 // for things like blob stores (ExternalStore) which want auto-commit mode.
1197 }
1198 }
1199
1200 /**
1201 * @param IDatabase $conn
1202 */
1203 private function undoTransactionRoundFlags( IDatabase $conn ) {
1204 if ( $conn->getFlag( $conn::DBO_DEFAULT ) ) {
1205 $conn->restoreFlags( $conn::RESTORE_PRIOR );
1206 }
1207 }
1208
1209 public function flushReplicaSnapshots( $fname = __METHOD__ ) {
1210 $this->forEachOpenReplicaConnection( function ( IDatabase $conn ) {
1211 $conn->flushSnapshot( __METHOD__ );
1212 } );
1213 }
1214
1215 public function hasMasterConnection() {
1216 return $this->isOpen( $this->getWriterIndex() );
1217 }
1218
1219 public function hasMasterChanges() {
1220 $pending = 0;
1221 $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$pending ) {
1222 $pending |= $conn->writesOrCallbacksPending();
1223 } );
1224
1225 return (bool)$pending;
1226 }
1227
1228 public function lastMasterChangeTimestamp() {
1229 $lastTime = false;
1230 $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$lastTime ) {
1231 $lastTime = max( $lastTime, $conn->lastDoneWrites() );
1232 } );
1233
1234 return $lastTime;
1235 }
1236
1237 public function hasOrMadeRecentMasterChanges( $age = null ) {
1238 $age = ( $age === null ) ? $this->mWaitTimeout : $age;
1239
1240 return ( $this->hasMasterChanges()
1241 || $this->lastMasterChangeTimestamp() > microtime( true ) - $age );
1242 }
1243
1244 public function pendingMasterChangeCallers() {
1245 $fnames = [];
1246 $this->forEachOpenMasterConnection( function ( IDatabase $conn ) use ( &$fnames ) {
1247 $fnames = array_merge( $fnames, $conn->pendingWriteCallers() );
1248 } );
1249
1250 return $fnames;
1251 }
1252
1253 public function getLaggedReplicaMode( $domain = false ) {
1254 // No-op if there is only one DB (also avoids recursion)
1255 if ( !$this->laggedReplicaMode && $this->getServerCount() > 1 ) {
1256 try {
1257 // See if laggedReplicaMode gets set
1258 $conn = $this->getConnection( self::DB_REPLICA, false, $domain );
1259 $this->reuseConnection( $conn );
1260 } catch ( DBConnectionError $e ) {
1261 // Avoid expensive re-connect attempts and failures
1262 $this->allReplicasDownMode = true;
1263 $this->laggedReplicaMode = true;
1264 }
1265 }
1266
1267 return $this->laggedReplicaMode;
1268 }
1269
1270 /**
1271 * @param bool $domain
1272 * @return bool
1273 * @deprecated 1.28; use getLaggedReplicaMode()
1274 */
1275 public function getLaggedSlaveMode( $domain = false ) {
1276 return $this->getLaggedReplicaMode( $domain );
1277 }
1278
1279 public function laggedReplicaUsed() {
1280 return $this->laggedReplicaMode;
1281 }
1282
1283 /**
1284 * @return bool
1285 * @since 1.27
1286 * @deprecated Since 1.28; use laggedReplicaUsed()
1287 */
1288 public function laggedSlaveUsed() {
1289 return $this->laggedReplicaUsed();
1290 }
1291
1292 public function getReadOnlyReason( $domain = false, IDatabase $conn = null ) {
1293 if ( $this->readOnlyReason !== false ) {
1294 return $this->readOnlyReason;
1295 } elseif ( $this->getLaggedReplicaMode( $domain ) ) {
1296 if ( $this->allReplicasDownMode ) {
1297 return 'The database has been automatically locked ' .
1298 'until the replica database servers become available';
1299 } else {
1300 return 'The database has been automatically locked ' .
1301 'while the replica database servers catch up to the master.';
1302 }
1303 } elseif ( $this->masterRunningReadOnly( $domain, $conn ) ) {
1304 return 'The database master is running in read-only mode.';
1305 }
1306
1307 return false;
1308 }
1309
1310 /**
1311 * @param string $domain Domain ID, or false for the current domain
1312 * @param IDatabase|null DB master connectionl used to avoid loops [optional]
1313 * @return bool
1314 */
1315 private function masterRunningReadOnly( $domain, IDatabase $conn = null ) {
1316 $cache = $this->wanCache;
1317 $masterServer = $this->getServerName( $this->getWriterIndex() );
1318
1319 return (bool)$cache->getWithSetCallback(
1320 $cache->makeGlobalKey( __CLASS__, 'server-read-only', $masterServer ),
1321 self::TTL_CACHE_READONLY,
1322 function () use ( $domain, $conn ) {
1323 $this->trxProfiler->setSilenced( true );
1324 try {
1325 $dbw = $conn ?: $this->getConnection( self::DB_MASTER, [], $domain );
1326 $readOnly = (int)$dbw->serverIsReadOnly();
1327 if ( !$conn ) {
1328 $this->reuseConnection( $dbw );
1329 }
1330 } catch ( DBError $e ) {
1331 $readOnly = 0;
1332 }
1333 $this->trxProfiler->setSilenced( false );
1334 return $readOnly;
1335 },
1336 [ 'pcTTL' => $cache::TTL_PROC_LONG, 'busyValue' => 0 ]
1337 );
1338 }
1339
1340 public function allowLagged( $mode = null ) {
1341 if ( $mode === null ) {
1342 return $this->mAllowLagged;
1343 }
1344 $this->mAllowLagged = $mode;
1345
1346 return $this->mAllowLagged;
1347 }
1348
1349 public function pingAll() {
1350 $success = true;
1351 $this->forEachOpenConnection( function ( IDatabase $conn ) use ( &$success ) {
1352 if ( !$conn->ping() ) {
1353 $success = false;
1354 }
1355 } );
1356
1357 return $success;
1358 }
1359
1360 public function forEachOpenConnection( $callback, array $params = [] ) {
1361 foreach ( $this->mConns as $connsByServer ) {
1362 foreach ( $connsByServer as $serverConns ) {
1363 foreach ( $serverConns as $conn ) {
1364 $mergedParams = array_merge( [ $conn ], $params );
1365 call_user_func_array( $callback, $mergedParams );
1366 }
1367 }
1368 }
1369 }
1370
1371 public function forEachOpenMasterConnection( $callback, array $params = [] ) {
1372 $masterIndex = $this->getWriterIndex();
1373 foreach ( $this->mConns as $connsByServer ) {
1374 if ( isset( $connsByServer[$masterIndex] ) ) {
1375 /** @var IDatabase $conn */
1376 foreach ( $connsByServer[$masterIndex] as $conn ) {
1377 $mergedParams = array_merge( [ $conn ], $params );
1378 call_user_func_array( $callback, $mergedParams );
1379 }
1380 }
1381 }
1382 }
1383
1384 public function forEachOpenReplicaConnection( $callback, array $params = [] ) {
1385 foreach ( $this->mConns as $connsByServer ) {
1386 foreach ( $connsByServer as $i => $serverConns ) {
1387 if ( $i === $this->getWriterIndex() ) {
1388 continue; // skip master
1389 }
1390 foreach ( $serverConns as $conn ) {
1391 $mergedParams = array_merge( [ $conn ], $params );
1392 call_user_func_array( $callback, $mergedParams );
1393 }
1394 }
1395 }
1396 }
1397
1398 public function getMaxLag( $domain = false ) {
1399 $maxLag = -1;
1400 $host = '';
1401 $maxIndex = 0;
1402
1403 if ( $this->getServerCount() <= 1 ) {
1404 return [ $host, $maxLag, $maxIndex ]; // no replication = no lag
1405 }
1406
1407 $lagTimes = $this->getLagTimes( $domain );
1408 foreach ( $lagTimes as $i => $lag ) {
1409 if ( $this->mLoads[$i] > 0 && $lag > $maxLag ) {
1410 $maxLag = $lag;
1411 $host = $this->mServers[$i]['host'];
1412 $maxIndex = $i;
1413 }
1414 }
1415
1416 return [ $host, $maxLag, $maxIndex ];
1417 }
1418
1419 public function getLagTimes( $domain = false ) {
1420 if ( $this->getServerCount() <= 1 ) {
1421 return [ $this->getWriterIndex() => 0 ]; // no replication = no lag
1422 }
1423
1424 $knownLagTimes = []; // map of (server index => 0 seconds)
1425 $indexesWithLag = [];
1426 foreach ( $this->mServers as $i => $server ) {
1427 if ( empty( $server['is static'] ) ) {
1428 $indexesWithLag[] = $i; // DB server might have replication lag
1429 } else {
1430 $knownLagTimes[$i] = 0; // DB server is a non-replicating and read-only archive
1431 }
1432 }
1433
1434 return $this->getLoadMonitor()->getLagTimes( $indexesWithLag, $domain ) + $knownLagTimes;
1435 }
1436
1437 public function safeGetLag( IDatabase $conn ) {
1438 if ( $this->getServerCount() <= 1 ) {
1439 return 0;
1440 } else {
1441 return $conn->getLag();
1442 }
1443 }
1444
1445 public function safeWaitForMasterPos( IDatabase $conn, $pos = false, $timeout = 10 ) {
1446 if ( $this->getServerCount() <= 1 || !$conn->getLBInfo( 'replica' ) ) {
1447 return true; // server is not a replica DB
1448 }
1449
1450 if ( !$pos ) {
1451 // Get the current master position
1452 $dbw = $this->getConnection( self::DB_MASTER );
1453 $pos = $dbw->getMasterPos();
1454 $this->reuseConnection( $dbw );
1455 }
1456
1457 if ( $pos instanceof DBMasterPos ) {
1458 $result = $conn->masterPosWait( $pos, $timeout );
1459 if ( $result == -1 || is_null( $result ) ) {
1460 $msg = __METHOD__ . ": Timed out waiting on {$conn->getServer()} pos {$pos}";
1461 $this->replLogger->warning( "$msg" );
1462 $ok = false;
1463 } else {
1464 $this->replLogger->info( __METHOD__ . ": Done" );
1465 $ok = true;
1466 }
1467 } else {
1468 $ok = false; // something is misconfigured
1469 $this->replLogger->error( "Could not get master pos for {$conn->getServer()}." );
1470 }
1471
1472 return $ok;
1473 }
1474
1475 public function clearLagTimeCache() {
1476 $this->getLoadMonitor()->clearCaches();
1477 }
1478
1479 public function setTransactionListener( $name, callable $callback = null ) {
1480 if ( $callback ) {
1481 $this->trxRecurringCallbacks[$name] = $callback;
1482 } else {
1483 unset( $this->trxRecurringCallbacks[$name] );
1484 }
1485 $this->forEachOpenMasterConnection(
1486 function ( IDatabase $conn ) use ( $name, $callback ) {
1487 $conn->setTransactionListener( $name, $callback );
1488 }
1489 );
1490 }
1491
1492 public function setTableAliases( array $aliases ) {
1493 $this->tableAliases = $aliases;
1494 }
1495
1496 public function setDomainPrefix( $prefix ) {
1497 if ( $this->mConns['foreignUsed'] ) {
1498 // Do not switch connections to explicit foreign domains unless marked as free
1499 $domains = [];
1500 foreach ( $this->mConns['foreignUsed'] as $i => $connsByDomain ) {
1501 $domains = array_merge( $domains, array_keys( $connsByDomain ) );
1502 }
1503 $domains = implode( ', ', $domains );
1504 throw new DBUnexpectedError( null,
1505 "Foreign domain connections are still in use ($domains)." );
1506 }
1507
1508 $this->localDomain = new DatabaseDomain(
1509 $this->localDomain->getDatabase(),
1510 null,
1511 $prefix
1512 );
1513
1514 $this->forEachOpenConnection( function ( IDatabase $db ) use ( $prefix ) {
1515 $db->tablePrefix( $prefix );
1516 } );
1517 }
1518
1519 function __destruct() {
1520 // Avoid connection leaks for sanity
1521 $this->closeAll();
1522 }
1523 }
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