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Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like LBFactory often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use LBFactory, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 31 | abstract class LBFactory implements ILBFactory { |
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| 32 | /** @var ChronologyProtector */ |
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| 33 | protected $chronProt; |
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| 34 | /** @var object|string Class name or object With profileIn/profileOut methods */ |
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| 35 | protected $profiler; |
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| 36 | /** @var TransactionProfiler */ |
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| 37 | protected $trxProfiler; |
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| 38 | /** @var LoggerInterface */ |
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| 39 | protected $replLogger; |
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| 40 | /** @var LoggerInterface */ |
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| 41 | protected $connLogger; |
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| 42 | /** @var LoggerInterface */ |
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| 43 | protected $queryLogger; |
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| 44 | /** @var LoggerInterface */ |
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| 45 | protected $perfLogger; |
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| 46 | /** @var callable Error logger */ |
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| 47 | protected $errorLogger; |
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| 48 | /** @var BagOStuff */ |
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| 49 | protected $srvCache; |
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| 50 | /** @var BagOStuff */ |
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| 51 | protected $memCache; |
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| 52 | /** @var WANObjectCache */ |
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| 53 | protected $wanCache; |
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| 54 | |||
| 55 | /** @var DatabaseDomain Local domain */ |
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| 56 | protected $localDomain; |
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| 57 | /** @var string Local hostname of the app server */ |
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| 58 | protected $hostname; |
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| 59 | /** @var array Web request information about the client */ |
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| 60 | protected $requestInfo; |
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| 61 | |||
| 62 | /** @var mixed */ |
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| 63 | protected $ticket; |
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| 64 | /** @var string|bool String if a requested DBO_TRX transaction round is active */ |
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| 65 | protected $trxRoundId = false; |
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| 66 | /** @var string|bool Reason all LBs are read-only or false if not */ |
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| 67 | protected $readOnlyReason = false; |
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| 68 | /** @var callable[] */ |
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| 69 | protected $replicationWaitCallbacks = []; |
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| 70 | |||
| 71 | /** @var bool Whether this PHP instance is for a CLI script */ |
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| 72 | protected $cliMode; |
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| 73 | /** @var string Agent name for query profiling */ |
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| 74 | protected $agent; |
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| 75 | |||
| 76 | private static $loggerFields = |
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| 77 | [ 'replLogger', 'connLogger', 'queryLogger', 'perfLogger' ]; |
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| 78 | |||
| 79 | public function __construct( array $conf ) { |
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| 80 | $this->localDomain = isset( $conf['localDomain'] ) |
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| 81 | ? DatabaseDomain::newFromId( $conf['localDomain'] ) |
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| 82 | : DatabaseDomain::newUnspecified(); |
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| 83 | |||
| 84 | View Code Duplication | if ( isset( $conf['readOnlyReason'] ) && is_string( $conf['readOnlyReason'] ) ) { |
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| 85 | $this->readOnlyReason = $conf['readOnlyReason']; |
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| 86 | } |
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| 87 | |||
| 88 | $this->srvCache = isset( $conf['srvCache'] ) ? $conf['srvCache'] : new EmptyBagOStuff(); |
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| 89 | $this->memCache = isset( $conf['memCache'] ) ? $conf['memCache'] : new EmptyBagOStuff(); |
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| 90 | $this->wanCache = isset( $conf['wanCache'] ) |
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| 91 | ? $conf['wanCache'] |
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| 92 | : WANObjectCache::newEmpty(); |
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| 93 | |||
| 94 | foreach ( self::$loggerFields as $key ) { |
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| 95 | $this->$key = isset( $conf[$key] ) ? $conf[$key] : new \Psr\Log\NullLogger(); |
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| 96 | } |
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| 97 | $this->errorLogger = isset( $conf['errorLogger'] ) |
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| 98 | ? $conf['errorLogger'] |
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| 99 | : function ( Exception $e ) { |
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| 100 | trigger_error( E_USER_WARNING, get_class( $e ) . ': ' . $e->getMessage() ); |
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| 101 | }; |
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| 102 | |||
| 103 | $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null; |
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| 104 | $this->trxProfiler = isset( $conf['trxProfiler'] ) |
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| 105 | ? $conf['trxProfiler'] |
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| 106 | : new TransactionProfiler(); |
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| 107 | |||
| 108 | $this->requestInfo = [ |
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| 109 | 'IPAddress' => isset( $_SERVER[ 'REMOTE_ADDR' ] ) ? $_SERVER[ 'REMOTE_ADDR' ] : '', |
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| 110 | 'UserAgent' => isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : '', |
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| 111 | 'ChronologyProtection' => 'true' |
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| 112 | ]; |
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| 113 | |||
| 114 | $this->cliMode = isset( $params['cliMode'] ) ? $params['cliMode'] : PHP_SAPI === 'cli'; |
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| 115 | $this->hostname = isset( $conf['hostname'] ) ? $conf['hostname'] : gethostname(); |
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| 116 | $this->agent = isset( $params['agent'] ) ? $params['agent'] : ''; |
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| 117 | |||
| 118 | $this->ticket = mt_rand(); |
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| 119 | } |
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| 120 | |||
| 121 | public function destroy() { |
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| 122 | $this->shutdown( self::SHUTDOWN_NO_CHRONPROT ); |
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| 123 | $this->forEachLBCallMethod( 'disable' ); |
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| 124 | } |
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| 125 | |||
| 126 | public function shutdown( |
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| 127 | $mode = self::SHUTDOWN_CHRONPROT_SYNC, callable $workCallback = null |
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| 128 | ) { |
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| 129 | $chronProt = $this->getChronologyProtector(); |
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| 130 | if ( $mode === self::SHUTDOWN_CHRONPROT_SYNC ) { |
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| 131 | $this->shutdownChronologyProtector( $chronProt, $workCallback, 'sync' ); |
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| 132 | } elseif ( $mode === self::SHUTDOWN_CHRONPROT_ASYNC ) { |
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| 133 | $this->shutdownChronologyProtector( $chronProt, null, 'async' ); |
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| 134 | } |
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| 135 | |||
| 136 | $this->commitMasterChanges( __METHOD__ ); // sanity |
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| 137 | } |
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| 138 | |||
| 139 | /** |
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| 140 | * @see ILBFactory::newMainLB() |
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| 141 | * @param bool $domain |
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| 142 | * @return LoadBalancer |
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| 143 | */ |
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| 144 | abstract public function newMainLB( $domain = false ); |
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| 145 | |||
| 146 | /** |
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| 147 | * @see ILBFactory::getMainLB() |
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| 148 | * @param bool $domain |
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| 149 | * @return LoadBalancer |
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| 150 | */ |
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| 151 | abstract public function getMainLB( $domain = false ); |
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| 152 | |||
| 153 | /** |
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| 154 | * @see ILBFactory::newExternalLB() |
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| 155 | * @param string $cluster |
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| 156 | * @return LoadBalancer |
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| 157 | */ |
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| 158 | abstract public function newExternalLB( $cluster ); |
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| 159 | |||
| 160 | /** |
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| 161 | * @see ILBFactory::getExternalLB() |
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| 162 | * @param string $cluster |
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| 163 | * @return LoadBalancer |
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| 164 | */ |
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| 165 | abstract public function getExternalLB( $cluster ); |
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| 166 | |||
| 167 | /** |
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| 168 | * Call a method of each tracked load balancer |
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| 169 | * |
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| 170 | * @param string $methodName |
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| 171 | * @param array $args |
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| 172 | */ |
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| 173 | protected function forEachLBCallMethod( $methodName, array $args = [] ) { |
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| 174 | $this->forEachLB( |
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| 175 | function ( ILoadBalancer $loadBalancer, $methodName, array $args ) { |
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| 176 | call_user_func_array( [ $loadBalancer, $methodName ], $args ); |
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| 177 | }, |
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| 178 | [ $methodName, $args ] |
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| 179 | ); |
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| 180 | } |
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| 181 | |||
| 182 | public function flushReplicaSnapshots( $fname = __METHOD__ ) { |
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| 183 | $this->forEachLBCallMethod( 'flushReplicaSnapshots', [ $fname ] ); |
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| 184 | } |
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| 185 | |||
| 186 | public function commitAll( $fname = __METHOD__, array $options = [] ) { |
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| 187 | $this->commitMasterChanges( $fname, $options ); |
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| 188 | $this->forEachLBCallMethod( 'commitAll', [ $fname ] ); |
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| 189 | } |
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| 190 | |||
| 191 | public function beginMasterChanges( $fname = __METHOD__ ) { |
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| 192 | if ( $this->trxRoundId !== false ) { |
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| 193 | throw new DBTransactionError( |
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| 194 | null, |
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| 195 | "$fname: transaction round '{$this->trxRoundId}' already started." |
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| 196 | ); |
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| 197 | } |
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| 198 | $this->trxRoundId = $fname; |
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| 199 | // Set DBO_TRX flags on all appropriate DBs |
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| 200 | $this->forEachLBCallMethod( 'beginMasterChanges', [ $fname ] ); |
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| 201 | } |
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| 202 | |||
| 203 | public function commitMasterChanges( $fname = __METHOD__, array $options = [] ) { |
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| 204 | if ( $this->trxRoundId !== false && $this->trxRoundId !== $fname ) { |
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| 205 | throw new DBTransactionError( |
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| 206 | null, |
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| 207 | "$fname: transaction round '{$this->trxRoundId}' still running." |
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| 208 | ); |
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| 209 | } |
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| 210 | /** @noinspection PhpUnusedLocalVariableInspection */ |
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| 211 | $scope = $this->getScopedPHPBehaviorForCommit(); // try to ignore client aborts |
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| 212 | // Run pre-commit callbacks and suppress post-commit callbacks, aborting on failure |
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| 213 | $this->forEachLBCallMethod( 'finalizeMasterChanges' ); |
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| 214 | $this->trxRoundId = false; |
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| 215 | // Perform pre-commit checks, aborting on failure |
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| 216 | $this->forEachLBCallMethod( 'approveMasterChanges', [ $options ] ); |
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| 217 | // Log the DBs and methods involved in multi-DB transactions |
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| 218 | $this->logIfMultiDbTransaction(); |
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| 219 | // Actually perform the commit on all master DB connections and revert DBO_TRX |
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| 220 | $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] ); |
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| 221 | // Run all post-commit callbacks |
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| 222 | /** @var Exception $e */ |
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| 223 | $e = null; // first callback exception |
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| 224 | $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$e ) { |
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| 225 | $ex = $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_COMMIT ); |
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| 226 | $e = $e ?: $ex; |
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| 227 | } ); |
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| 228 | // Commit any dangling DBO_TRX transactions from callbacks on one DB to another DB |
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| 229 | $this->forEachLBCallMethod( 'commitMasterChanges', [ $fname ] ); |
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| 230 | // Throw any last post-commit callback error |
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| 231 | if ( $e instanceof Exception ) { |
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| 232 | throw $e; |
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| 233 | } |
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| 234 | } |
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| 235 | |||
| 236 | public function rollbackMasterChanges( $fname = __METHOD__ ) { |
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| 237 | $this->trxRoundId = false; |
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| 238 | $this->forEachLBCallMethod( 'suppressTransactionEndCallbacks' ); |
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| 239 | $this->forEachLBCallMethod( 'rollbackMasterChanges', [ $fname ] ); |
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| 240 | // Run all post-rollback callbacks |
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| 241 | $this->forEachLB( function ( ILoadBalancer $lb ) { |
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| 242 | $lb->runMasterPostTrxCallbacks( IDatabase::TRIGGER_ROLLBACK ); |
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| 243 | } ); |
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| 244 | } |
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| 245 | |||
| 246 | /** |
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| 247 | * Log query info if multi DB transactions are going to be committed now |
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| 248 | */ |
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| 249 | private function logIfMultiDbTransaction() { |
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| 250 | $callersByDB = []; |
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| 251 | $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$callersByDB ) { |
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| 252 | $masterName = $lb->getServerName( $lb->getWriterIndex() ); |
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| 253 | $callers = $lb->pendingMasterChangeCallers(); |
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| 254 | if ( $callers ) { |
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| 255 | $callersByDB[$masterName] = $callers; |
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| 256 | } |
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| 257 | } ); |
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| 258 | |||
| 259 | if ( count( $callersByDB ) >= 2 ) { |
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| 260 | $dbs = implode( ', ', array_keys( $callersByDB ) ); |
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| 261 | $msg = "Multi-DB transaction [{$dbs}]:\n"; |
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| 262 | foreach ( $callersByDB as $db => $callers ) { |
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| 263 | $msg .= "$db: " . implode( '; ', $callers ) . "\n"; |
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| 264 | } |
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| 265 | $this->queryLogger->info( $msg ); |
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| 266 | } |
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| 267 | } |
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| 268 | |||
| 269 | public function hasMasterChanges() { |
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| 270 | $ret = false; |
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| 271 | $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) { |
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| 272 | $ret = $ret || $lb->hasMasterChanges(); |
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| 273 | } ); |
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| 274 | |||
| 275 | return $ret; |
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| 276 | } |
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| 277 | |||
| 278 | public function laggedReplicaUsed() { |
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| 279 | $ret = false; |
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| 280 | $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$ret ) { |
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| 281 | $ret = $ret || $lb->laggedReplicaUsed(); |
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| 282 | } ); |
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| 283 | |||
| 284 | return $ret; |
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| 285 | } |
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| 286 | |||
| 287 | public function hasOrMadeRecentMasterChanges( $age = null ) { |
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| 288 | $ret = false; |
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| 289 | $this->forEachLB( function ( ILoadBalancer $lb ) use ( $age, &$ret ) { |
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| 290 | $ret = $ret || $lb->hasOrMadeRecentMasterChanges( $age ); |
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| 291 | } ); |
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| 292 | return $ret; |
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| 293 | } |
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| 294 | |||
| 295 | public function waitForReplication( array $opts = [] ) { |
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| 296 | $opts += [ |
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| 297 | 'domain' => false, |
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| 298 | 'cluster' => false, |
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| 299 | 'timeout' => 60, |
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| 300 | 'ifWritesSince' => null |
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| 301 | ]; |
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| 302 | |||
| 303 | if ( $opts['domain'] === false && isset( $opts['wiki'] ) ) { |
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| 304 | $opts['domain'] = $opts['wiki']; // b/c |
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| 305 | } |
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| 306 | |||
| 307 | // Figure out which clusters need to be checked |
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| 308 | /** @var ILoadBalancer[] $lbs */ |
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| 309 | $lbs = []; |
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| 310 | if ( $opts['cluster'] !== false ) { |
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| 311 | $lbs[] = $this->getExternalLB( $opts['cluster'] ); |
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| 312 | } elseif ( $opts['domain'] !== false ) { |
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| 313 | $lbs[] = $this->getMainLB( $opts['domain'] ); |
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| 314 | } else { |
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| 315 | $this->forEachLB( function ( ILoadBalancer $lb ) use ( &$lbs ) { |
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| 316 | $lbs[] = $lb; |
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| 317 | } ); |
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| 318 | if ( !$lbs ) { |
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| 319 | return; // nothing actually used |
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| 320 | } |
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| 321 | } |
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| 322 | |||
| 323 | // Get all the master positions of applicable DBs right now. |
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| 324 | // This can be faster since waiting on one cluster reduces the |
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| 325 | // time needed to wait on the next clusters. |
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| 326 | $masterPositions = array_fill( 0, count( $lbs ), false ); |
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| 327 | foreach ( $lbs as $i => $lb ) { |
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| 328 | if ( $lb->getServerCount() <= 1 ) { |
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| 329 | // Bug 27975 - Don't try to wait for replica DBs if there are none |
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| 330 | // Prevents permission error when getting master position |
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| 331 | continue; |
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| 332 | } elseif ( $opts['ifWritesSince'] |
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| 333 | && $lb->lastMasterChangeTimestamp() < $opts['ifWritesSince'] |
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| 334 | ) { |
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| 335 | continue; // no writes since the last wait |
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| 336 | } |
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| 337 | $masterPositions[$i] = $lb->getMasterPos(); |
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| 338 | } |
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| 339 | |||
| 340 | // Run any listener callbacks *after* getting the DB positions. The more |
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| 341 | // time spent in the callbacks, the less time is spent in waitForAll(). |
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| 342 | foreach ( $this->replicationWaitCallbacks as $callback ) { |
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| 343 | $callback(); |
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| 344 | } |
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| 345 | |||
| 346 | $failed = []; |
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| 347 | foreach ( $lbs as $i => $lb ) { |
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| 348 | if ( $masterPositions[$i] ) { |
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| 349 | // The DBMS may not support getMasterPos() |
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| 350 | if ( !$lb->waitForAll( $masterPositions[$i], $opts['timeout'] ) ) { |
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| 351 | $failed[] = $lb->getServerName( $lb->getWriterIndex() ); |
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| 352 | } |
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| 353 | } |
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| 354 | } |
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| 355 | |||
| 356 | if ( $failed ) { |
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| 357 | throw new DBReplicationWaitError( |
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| 358 | null, |
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| 359 | "Could not wait for replica DBs to catch up to " . |
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| 360 | implode( ', ', $failed ) |
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| 361 | ); |
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| 362 | } |
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| 363 | } |
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| 364 | |||
| 365 | public function setWaitForReplicationListener( $name, callable $callback = null ) { |
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| 372 | |||
| 373 | public function getEmptyTransactionTicket( $fname ) { |
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| 383 | |||
| 384 | public function commitAndWaitForReplication( $fname, $ticket, array $opts = [] ) { |
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| 409 | |||
| 410 | public function getChronologyProtectorTouched( $dbName ) { |
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| 413 | |||
| 414 | public function disableChronologyProtection() { |
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| 417 | |||
| 418 | /** |
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| 419 | * @return ChronologyProtector |
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| 420 | */ |
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| 421 | protected function getChronologyProtector() { |
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| 449 | |||
| 450 | /** |
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| 451 | * Get and record all of the staged DB positions into persistent memory storage |
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| 452 | * |
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| 453 | * @param ChronologyProtector $cp |
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| 454 | * @param callable|null $workCallback Work to do instead of waiting on syncing positions |
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| 455 | * @param string $mode One of (sync, async); whether to wait on remote datacenters |
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| 456 | */ |
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| 457 | protected function shutdownChronologyProtector( |
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| 482 | |||
| 483 | /** |
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| 484 | * Base parameters to LoadBalancer::__construct() |
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| 485 | * @return array |
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| 486 | */ |
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| 487 | final protected function baseLoadBalancerParams() { |
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| 504 | |||
| 505 | /** |
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| 506 | * @param ILoadBalancer $lb |
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| 507 | */ |
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| 508 | protected function initLoadBalancer( ILoadBalancer $lb ) { |
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| 513 | |||
| 514 | public function setDomainPrefix( $prefix ) { |
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| 525 | |||
| 526 | public function closeAll() { |
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| 529 | |||
| 530 | public function setAgentName( $agent ) { |
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| 533 | |||
| 534 | public function appendPreShutdownTimeAsQuery( $url, $time ) { |
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| 546 | |||
| 547 | public function setRequestInfo( array $info ) { |
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| 550 | |||
| 551 | /** |
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| 552 | * Make PHP ignore user aborts/disconnects until the returned |
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| 553 | * value leaves scope. This returns null and does nothing in CLI mode. |
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| 554 | * |
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| 555 | * @return ScopedCallback|null |
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| 556 | */ |
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| 557 | View Code Duplication | final protected function getScopedPHPBehaviorForCommit() { |
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| 567 | |||
| 568 | function __destruct() { |
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| 571 | } |
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| 572 |
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Let’s assume that you have a directory layout like this:
. |-- OtherDir | |-- Bar.php | `-- Foo.php `-- SomeDir `-- Foo.phpand let’s assume the following content of
Bar.php:If both files
OtherDir/Foo.phpandSomeDir/Foo.phpare loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.phpHowever, as
OtherDir/Foo.phpdoes not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: