wikimedia /
mediawiki
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 LoadBalancer 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 LoadBalancer, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 30 | class LoadBalancer { |
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| 31 | /** @var array[] Map of (server index => server config array) */ |
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| 32 | private $mServers; |
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| 33 | /** @var array[] Map of (local/foreignUsed/foreignFree => server index => DatabaseBase array) */ |
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| 34 | private $mConns; |
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| 35 | /** @var array Map of (server index => weight) */ |
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| 36 | private $mLoads; |
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| 37 | /** @var array[] Map of (group => server index => weight) */ |
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| 38 | private $mGroupLoads; |
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| 39 | /** @var bool Whether to disregard replica DB lag as a factor in replica DB selection */ |
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| 40 | private $mAllowLagged; |
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| 41 | /** @var integer Seconds to spend waiting on replica DB lag to resolve */ |
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| 42 | private $mWaitTimeout; |
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| 43 | /** @var array LBFactory information */ |
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| 44 | private $mParentInfo; |
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| 45 | |||
| 46 | /** @var string The LoadMonitor subclass name */ |
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| 47 | private $mLoadMonitorClass; |
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| 48 | /** @var LoadMonitor */ |
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| 49 | private $mLoadMonitor; |
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| 50 | /** @var BagOStuff */ |
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| 51 | private $srvCache; |
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| 52 | /** @var WANObjectCache */ |
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| 53 | private $wanCache; |
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| 54 | /** @var TransactionProfiler */ |
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| 55 | protected $trxProfiler; |
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| 56 | |||
| 57 | /** @var bool|DatabaseBase Database connection that caused a problem */ |
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| 58 | private $mErrorConnection; |
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| 59 | /** @var integer The generic (not query grouped) replica DB index (of $mServers) */ |
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| 60 | private $mReadIndex; |
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| 61 | /** @var bool|DBMasterPos False if not set */ |
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| 62 | private $mWaitForPos; |
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| 63 | /** @var bool Whether the generic reader fell back to a lagged replica DB */ |
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| 64 | private $laggedReplicaMode = false; |
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| 65 | /** @var bool Whether the generic reader fell back to a lagged replica DB */ |
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| 66 | private $allReplicasDownMode = false; |
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| 67 | /** @var string The last DB selection or connection error */ |
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| 68 | private $mLastError = 'Unknown error'; |
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| 69 | /** @var string|bool Reason the LB is read-only or false if not */ |
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| 70 | private $readOnlyReason = false; |
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| 71 | /** @var integer Total connections opened */ |
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| 72 | private $connsOpened = 0; |
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| 73 | /** @var string|bool String if a requested DBO_TRX transaction round is active */ |
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| 74 | private $trxRoundId = false; |
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| 75 | /** @var array[] Map of (name => callable) */ |
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| 76 | private $trxRecurringCallbacks = []; |
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| 77 | |||
| 78 | /** @var integer Warn when this many connection are held */ |
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| 79 | const CONN_HELD_WARN_THRESHOLD = 10; |
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| 80 | /** @var integer Default 'max lag' when unspecified */ |
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| 81 | const MAX_LAG_DEFAULT = 10; |
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| 82 | /** @var integer Max time to wait for a replica DB to catch up (e.g. ChronologyProtector) */ |
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| 83 | const POS_WAIT_TIMEOUT = 10; |
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| 84 | /** @var integer Seconds to cache master server read-only status */ |
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| 85 | const TTL_CACHE_READONLY = 5; |
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| 86 | |||
| 87 | /** |
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| 88 | * @var boolean |
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| 89 | */ |
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| 90 | private $disabled = false; |
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| 91 | |||
| 92 | /** |
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| 93 | * @param array $params Array with keys: |
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| 94 | * - servers : Required. Array of server info structures. |
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| 95 | * - loadMonitor : Name of a class used to fetch server lag and load. |
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| 96 | * - readOnlyReason : Reason the master DB is read-only if so [optional] |
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| 97 | * - waitTimeout : Maximum time to wait for replicas for consistency [optional] |
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| 98 | * - srvCache : BagOStuff object [optional] |
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| 99 | * - wanCache : WANObjectCache object [optional] |
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| 100 | * @throws MWException |
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| 101 | */ |
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| 102 | public function __construct( array $params ) { |
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| 103 | if ( !isset( $params['servers'] ) ) { |
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| 104 | throw new MWException( __CLASS__ . ': missing servers parameter' ); |
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| 105 | } |
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| 106 | $this->mServers = $params['servers']; |
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| 107 | $this->mWaitTimeout = isset( $params['waitTimeout'] ) |
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| 108 | ? $params['waitTimeout'] |
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| 109 | : self::POS_WAIT_TIMEOUT; |
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| 110 | |||
| 111 | $this->mReadIndex = -1; |
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| 112 | $this->mWriteIndex = -1; |
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| 113 | $this->mConns = [ |
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| 114 | 'local' => [], |
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| 115 | 'foreignUsed' => [], |
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| 116 | 'foreignFree' => [] ]; |
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| 117 | $this->mLoads = []; |
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| 118 | $this->mWaitForPos = false; |
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| 119 | $this->mErrorConnection = false; |
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| 120 | $this->mAllowLagged = false; |
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| 121 | |||
| 122 | View Code Duplication | if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) { |
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| 123 | $this->readOnlyReason = $params['readOnlyReason']; |
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| 124 | } |
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| 125 | |||
| 126 | if ( isset( $params['loadMonitor'] ) ) { |
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| 127 | $this->mLoadMonitorClass = $params['loadMonitor']; |
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| 128 | } else { |
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| 129 | $master = reset( $params['servers'] ); |
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| 130 | if ( isset( $master['type'] ) && $master['type'] === 'mysql' ) { |
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| 131 | $this->mLoadMonitorClass = 'LoadMonitorMySQL'; |
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| 132 | } else { |
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| 133 | $this->mLoadMonitorClass = 'LoadMonitorNull'; |
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| 134 | } |
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| 135 | } |
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| 136 | |||
| 137 | foreach ( $params['servers'] as $i => $server ) { |
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| 138 | $this->mLoads[$i] = $server['load']; |
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| 139 | if ( isset( $server['groupLoads'] ) ) { |
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| 140 | foreach ( $server['groupLoads'] as $group => $ratio ) { |
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| 141 | if ( !isset( $this->mGroupLoads[$group] ) ) { |
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| 142 | $this->mGroupLoads[$group] = []; |
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| 143 | } |
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| 144 | $this->mGroupLoads[$group][$i] = $ratio; |
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| 145 | } |
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| 146 | } |
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| 147 | } |
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| 148 | |||
| 149 | if ( isset( $params['srvCache'] ) ) { |
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| 150 | $this->srvCache = $params['srvCache']; |
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| 151 | } else { |
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| 152 | $this->srvCache = new EmptyBagOStuff(); |
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| 153 | } |
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| 154 | if ( isset( $params['wanCache'] ) ) { |
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| 155 | $this->wanCache = $params['wanCache']; |
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| 156 | } else { |
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| 157 | $this->wanCache = WANObjectCache::newEmpty(); |
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| 158 | } |
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| 159 | if ( isset( $params['trxProfiler'] ) ) { |
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| 160 | $this->trxProfiler = $params['trxProfiler']; |
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| 161 | } else { |
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| 162 | $this->trxProfiler = new TransactionProfiler(); |
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| 163 | } |
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| 164 | } |
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| 165 | |||
| 166 | /** |
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| 167 | * Get a LoadMonitor instance |
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| 168 | * |
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| 169 | * @return LoadMonitor |
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| 170 | */ |
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| 171 | private function getLoadMonitor() { |
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| 172 | if ( !isset( $this->mLoadMonitor ) ) { |
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| 173 | $class = $this->mLoadMonitorClass; |
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| 174 | $this->mLoadMonitor = new $class( $this ); |
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| 175 | } |
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| 176 | |||
| 177 | return $this->mLoadMonitor; |
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| 178 | } |
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| 179 | |||
| 180 | /** |
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| 181 | * Get or set arbitrary data used by the parent object, usually an LBFactory |
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| 182 | * @param mixed $x |
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| 183 | * @return mixed |
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| 184 | */ |
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| 185 | public function parentInfo( $x = null ) { |
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| 186 | return wfSetVar( $this->mParentInfo, $x ); |
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| 187 | } |
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| 188 | |||
| 189 | /** |
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| 190 | * @param array $loads |
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| 191 | * @param bool|string $wiki Wiki to get non-lagged for |
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| 192 | * @param int $maxLag Restrict the maximum allowed lag to this many seconds |
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| 193 | * @return bool|int|string |
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| 194 | */ |
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| 195 | private function getRandomNonLagged( array $loads, $wiki = false, $maxLag = INF ) { |
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| 196 | $lags = $this->getLagTimes( $wiki ); |
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| 197 | |||
| 198 | # Unset excessively lagged servers |
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| 199 | foreach ( $lags as $i => $lag ) { |
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| 200 | if ( $i != 0 ) { |
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| 201 | # How much lag this server nominally is allowed to have |
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| 202 | $maxServerLag = isset( $this->mServers[$i]['max lag'] ) |
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| 203 | ? $this->mServers[$i]['max lag'] |
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| 204 | : self::MAX_LAG_DEFAULT; // default |
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| 205 | # Constrain that futher by $maxLag argument |
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| 206 | $maxServerLag = min( $maxServerLag, $maxLag ); |
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| 207 | |||
| 208 | $host = $this->getServerName( $i ); |
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| 209 | if ( $lag === false && !is_infinite( $maxServerLag ) ) { |
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| 210 | wfDebugLog( 'replication', "Server $host (#$i) is not replicating?" ); |
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| 211 | unset( $loads[$i] ); |
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| 212 | } elseif ( $lag > $maxServerLag ) { |
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| 213 | wfDebugLog( 'replication', "Server $host (#$i) has >= $lag seconds of lag" ); |
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| 214 | unset( $loads[$i] ); |
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| 215 | } |
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| 216 | } |
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| 217 | } |
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| 218 | |||
| 219 | # Find out if all the replica DBs with non-zero load are lagged |
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| 220 | $sum = 0; |
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| 221 | foreach ( $loads as $load ) { |
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| 222 | $sum += $load; |
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| 223 | } |
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| 224 | if ( $sum == 0 ) { |
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| 225 | # No appropriate DB servers except maybe the master and some replica DBs with zero load |
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| 226 | # Do NOT use the master |
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| 227 | # Instead, this function will return false, triggering read-only mode, |
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| 228 | # and a lagged replica DB will be used instead. |
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| 229 | return false; |
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| 230 | } |
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| 231 | |||
| 232 | if ( count( $loads ) == 0 ) { |
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| 233 | return false; |
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| 234 | } |
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| 235 | |||
| 236 | # Return a random representative of the remainder |
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| 237 | return ArrayUtils::pickRandom( $loads ); |
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| 238 | } |
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| 239 | |||
| 240 | /** |
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| 241 | * Get the index of the reader connection, which may be a replica DB |
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| 242 | * This takes into account load ratios and lag times. It should |
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| 243 | * always return a consistent index during a given invocation |
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| 244 | * |
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| 245 | * Side effect: opens connections to databases |
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| 246 | * @param string|bool $group Query group, or false for the generic reader |
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| 247 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
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| 248 | * @throws MWException |
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| 249 | * @return bool|int|string |
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| 250 | */ |
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| 251 | public function getReaderIndex( $group = false, $wiki = false ) { |
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| 252 | global $wgDBtype; |
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| 253 | |||
| 254 | # @todo FIXME: For now, only go through all this for mysql databases |
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| 255 | if ( $wgDBtype != 'mysql' ) { |
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| 256 | return $this->getWriterIndex(); |
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| 257 | } |
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| 258 | |||
| 259 | if ( count( $this->mServers ) == 1 ) { |
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| 260 | # Skip the load balancing if there's only one server |
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| 261 | return 0; |
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| 262 | } elseif ( $group === false && $this->mReadIndex >= 0 ) { |
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| 263 | # Shortcut if generic reader exists already |
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| 264 | return $this->mReadIndex; |
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| 265 | } |
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| 266 | |||
| 267 | # Find the relevant load array |
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| 268 | if ( $group !== false ) { |
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| 269 | if ( isset( $this->mGroupLoads[$group] ) ) { |
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| 270 | $nonErrorLoads = $this->mGroupLoads[$group]; |
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| 271 | } else { |
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| 272 | # No loads for this group, return false and the caller can use some other group |
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| 273 | wfDebugLog( 'connect', __METHOD__ . ": no loads for group $group\n" ); |
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| 274 | |||
| 275 | return false; |
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| 276 | } |
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| 277 | } else { |
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| 278 | $nonErrorLoads = $this->mLoads; |
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| 279 | } |
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| 280 | |||
| 281 | if ( !count( $nonErrorLoads ) ) { |
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| 282 | throw new MWException( "Empty server array given to LoadBalancer" ); |
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| 283 | } |
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| 284 | |||
| 285 | # Scale the configured load ratios according to the dynamic load (if the load monitor supports it) |
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| 286 | $this->getLoadMonitor()->scaleLoads( $nonErrorLoads, $group, $wiki ); |
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| 287 | |||
| 288 | $laggedReplicaMode = false; |
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| 289 | |||
| 290 | # No server found yet |
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| 291 | $i = false; |
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| 292 | # First try quickly looking through the available servers for a server that |
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| 293 | # meets our criteria |
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| 294 | $currentLoads = $nonErrorLoads; |
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| 295 | while ( count( $currentLoads ) ) { |
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| 296 | if ( $this->mAllowLagged || $laggedReplicaMode ) { |
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| 297 | $i = ArrayUtils::pickRandom( $currentLoads ); |
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| 298 | } else { |
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| 299 | $i = false; |
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| 300 | if ( $this->mWaitForPos && $this->mWaitForPos->asOfTime() ) { |
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| 301 | # ChronologyProtecter causes mWaitForPos to be set via sessions. |
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| 302 | # This triggers doWait() after connect, so it's especially good to |
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| 303 | # avoid lagged servers so as to avoid just blocking in that method. |
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| 304 | $ago = microtime( true ) - $this->mWaitForPos->asOfTime(); |
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| 305 | # Aim for <= 1 second of waiting (being too picky can backfire) |
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| 306 | $i = $this->getRandomNonLagged( $currentLoads, $wiki, $ago + 1 ); |
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| 307 | } |
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| 308 | if ( $i === false ) { |
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| 309 | # Any server with less lag than it's 'max lag' param is preferable |
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| 310 | $i = $this->getRandomNonLagged( $currentLoads, $wiki ); |
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| 311 | } |
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| 312 | if ( $i === false && count( $currentLoads ) != 0 ) { |
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| 313 | # All replica DBs lagged. Switch to read-only mode |
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| 314 | wfDebugLog( 'replication', "All replica DBs lagged. Switch to read-only mode" ); |
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| 315 | $i = ArrayUtils::pickRandom( $currentLoads ); |
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| 316 | $laggedReplicaMode = true; |
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| 317 | } |
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| 318 | } |
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| 319 | |||
| 320 | if ( $i === false ) { |
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| 321 | # pickRandom() returned false |
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| 322 | # This is permanent and means the configuration or the load monitor |
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| 323 | # wants us to return false. |
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| 324 | wfDebugLog( 'connect', __METHOD__ . ": pickRandom() returned false" ); |
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| 325 | |||
| 326 | return false; |
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| 327 | } |
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| 328 | |||
| 329 | $serverName = $this->getServerName( $i ); |
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| 330 | wfDebugLog( 'connect', __METHOD__ . ": Using reader #$i: $serverName..." ); |
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| 331 | |||
| 332 | $conn = $this->openConnection( $i, $wiki ); |
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| 333 | if ( !$conn ) { |
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| 334 | wfDebugLog( 'connect', __METHOD__ . ": Failed connecting to $i/$wiki" ); |
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| 335 | unset( $nonErrorLoads[$i] ); |
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| 336 | unset( $currentLoads[$i] ); |
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| 337 | $i = false; |
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| 338 | continue; |
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| 339 | } |
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| 340 | |||
| 341 | // Decrement reference counter, we are finished with this connection. |
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| 342 | // It will be incremented for the caller later. |
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| 343 | if ( $wiki !== false ) { |
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| 344 | $this->reuseConnection( $conn ); |
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| 345 | } |
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| 346 | |||
| 347 | # Return this server |
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| 348 | break; |
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| 349 | } |
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| 350 | |||
| 351 | # If all servers were down, quit now |
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| 352 | if ( !count( $nonErrorLoads ) ) { |
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| 353 | wfDebugLog( 'connect', "All servers down" ); |
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| 354 | } |
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| 355 | |||
| 356 | if ( $i !== false ) { |
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| 357 | # Replica DB connection successful. |
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| 358 | # Wait for the session master pos for a short time. |
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| 359 | if ( $this->mWaitForPos && $i > 0 ) { |
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| 360 | $this->doWait( $i ); |
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| 361 | } |
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| 362 | if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) { |
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| 363 | $this->mReadIndex = $i; |
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| 364 | # Record if the generic reader index is in "lagged replica DB" mode |
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| 365 | if ( $laggedReplicaMode ) { |
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| 366 | $this->laggedReplicaMode = true; |
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| 367 | } |
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| 368 | } |
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| 369 | $serverName = $this->getServerName( $i ); |
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| 370 | wfDebugLog( 'connect', __METHOD__ . |
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| 371 | ": using server $serverName for group '$group'\n" ); |
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| 372 | } |
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| 373 | |||
| 374 | return $i; |
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| 375 | } |
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| 376 | |||
| 377 | /** |
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| 378 | * Set the master wait position |
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| 379 | * If a DB_REPLICA connection has been opened already, waits |
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| 380 | * Otherwise sets a variable telling it to wait if such a connection is opened |
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| 381 | * @param DBMasterPos $pos |
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| 382 | */ |
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| 383 | public function waitFor( $pos ) { |
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| 384 | $this->mWaitForPos = $pos; |
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| 385 | $i = $this->mReadIndex; |
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| 386 | |||
| 387 | if ( $i > 0 ) { |
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| 388 | if ( !$this->doWait( $i ) ) { |
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| 389 | $this->laggedReplicaMode = true; |
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| 390 | } |
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| 391 | } |
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| 392 | } |
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| 393 | |||
| 394 | /** |
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| 395 | * Set the master wait position and wait for a "generic" replica DB to catch up to it |
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| 396 | * |
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| 397 | * This can be used a faster proxy for waitForAll() |
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| 398 | * |
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| 399 | * @param DBMasterPos $pos |
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| 400 | * @param int $timeout Max seconds to wait; default is mWaitTimeout |
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| 401 | * @return bool Success (able to connect and no timeouts reached) |
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| 402 | * @since 1.26 |
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| 403 | */ |
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| 404 | public function waitForOne( $pos, $timeout = null ) { |
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| 405 | $this->mWaitForPos = $pos; |
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| 406 | |||
| 407 | $i = $this->mReadIndex; |
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| 408 | if ( $i <= 0 ) { |
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| 409 | // Pick a generic replica DB if there isn't one yet |
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| 410 | $readLoads = $this->mLoads; |
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| 411 | unset( $readLoads[$this->getWriterIndex()] ); // replica DBs only |
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| 412 | $readLoads = array_filter( $readLoads ); // with non-zero load |
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| 413 | $i = ArrayUtils::pickRandom( $readLoads ); |
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| 414 | } |
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| 415 | |||
| 416 | View Code Duplication | if ( $i > 0 ) { |
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| 417 | $ok = $this->doWait( $i, true, $timeout ); |
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| 418 | } else { |
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| 419 | $ok = true; // no applicable loads |
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| 420 | } |
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| 421 | |||
| 422 | return $ok; |
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| 423 | } |
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| 424 | |||
| 425 | /** |
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| 426 | * Set the master wait position and wait for ALL replica DBs to catch up to it |
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| 427 | * @param DBMasterPos $pos |
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| 428 | * @param int $timeout Max seconds to wait; default is mWaitTimeout |
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| 429 | * @return bool Success (able to connect and no timeouts reached) |
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| 430 | */ |
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| 431 | public function waitForAll( $pos, $timeout = null ) { |
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| 432 | $this->mWaitForPos = $pos; |
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| 433 | $serverCount = count( $this->mServers ); |
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| 434 | |||
| 435 | $ok = true; |
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| 436 | for ( $i = 1; $i < $serverCount; $i++ ) { |
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| 437 | View Code Duplication | if ( $this->mLoads[$i] > 0 ) { |
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| 438 | $ok = $this->doWait( $i, true, $timeout ) && $ok; |
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| 439 | } |
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| 440 | } |
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| 441 | |||
| 442 | return $ok; |
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| 443 | } |
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| 444 | |||
| 445 | /** |
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| 446 | * Get any open connection to a given server index, local or foreign |
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| 447 | * Returns false if there is no connection open |
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| 448 | * |
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| 449 | * @param int $i |
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| 450 | * @return DatabaseBase|bool False on failure |
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| 451 | */ |
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| 452 | public function getAnyOpenConnection( $i ) { |
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| 453 | foreach ( $this->mConns as $conns ) { |
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| 454 | if ( !empty( $conns[$i] ) ) { |
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| 455 | return reset( $conns[$i] ); |
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| 456 | } |
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| 457 | } |
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| 458 | |||
| 459 | return false; |
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| 460 | } |
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| 461 | |||
| 462 | /** |
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| 463 | * Wait for a given replica DB to catch up to the master pos stored in $this |
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| 464 | * @param int $index Server index |
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| 465 | * @param bool $open Check the server even if a new connection has to be made |
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| 466 | * @param int $timeout Max seconds to wait; default is mWaitTimeout |
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| 467 | * @return bool |
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| 468 | */ |
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| 469 | protected function doWait( $index, $open = false, $timeout = null ) { |
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| 470 | $close = false; // close the connection afterwards |
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| 471 | |||
| 472 | // Check if we already know that the DB has reached this point |
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| 473 | $server = $this->getServerName( $index ); |
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| 474 | $key = $this->srvCache->makeGlobalKey( __CLASS__, 'last-known-pos', $server ); |
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| 475 | /** @var DBMasterPos $knownReachedPos */ |
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| 476 | $knownReachedPos = $this->srvCache->get( $key ); |
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| 477 | if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos ) ) { |
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| 478 | wfDebugLog( 'replication', __METHOD__ . |
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| 479 | ": replica DB $server known to be caught up (pos >= $knownReachedPos).\n" ); |
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| 480 | return true; |
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| 481 | } |
||
| 482 | |||
| 483 | // Find a connection to wait on, creating one if needed and allowed |
||
| 484 | $conn = $this->getAnyOpenConnection( $index ); |
||
| 485 | if ( !$conn ) { |
||
| 486 | if ( !$open ) { |
||
| 487 | wfDebugLog( 'replication', __METHOD__ . ": no connection open for $server\n" ); |
||
| 488 | |||
| 489 | return false; |
||
| 490 | } else { |
||
| 491 | $conn = $this->openConnection( $index, '' ); |
||
| 492 | if ( !$conn ) { |
||
| 493 | wfDebugLog( 'replication', __METHOD__ . ": failed to connect to $server\n" ); |
||
| 494 | |||
| 495 | return false; |
||
| 496 | } |
||
| 497 | // Avoid connection spam in waitForAll() when connections |
||
| 498 | // are made just for the sake of doing this lag check. |
||
| 499 | $close = true; |
||
| 500 | } |
||
| 501 | } |
||
| 502 | |||
| 503 | wfDebugLog( 'replication', __METHOD__ . ": Waiting for replica DB $server to catch up...\n" ); |
||
| 504 | $timeout = $timeout ?: $this->mWaitTimeout; |
||
| 505 | $result = $conn->masterPosWait( $this->mWaitForPos, $timeout ); |
||
| 506 | |||
| 507 | if ( $result == -1 || is_null( $result ) ) { |
||
| 508 | // Timed out waiting for replica DB, use master instead |
||
| 509 | $msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}"; |
||
| 510 | wfDebugLog( 'replication', "$msg\n" ); |
||
| 511 | wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) ); |
||
| 512 | $ok = false; |
||
| 513 | } else { |
||
| 514 | wfDebugLog( 'replication', __METHOD__ . ": Done\n" ); |
||
| 515 | $ok = true; |
||
| 516 | // Remember that the DB reached this point |
||
| 517 | $this->srvCache->set( $key, $this->mWaitForPos, BagOStuff::TTL_DAY ); |
||
| 518 | } |
||
| 519 | |||
| 520 | if ( $close ) { |
||
| 521 | $this->closeConnection( $conn ); |
||
| 522 | } |
||
| 523 | |||
| 524 | return $ok; |
||
| 525 | } |
||
| 526 | |||
| 527 | /** |
||
| 528 | * Get a connection by index |
||
| 529 | * This is the main entry point for this class. |
||
| 530 | * |
||
| 531 | * @param int $i Server index |
||
| 532 | * @param array|string|bool $groups Query group(s), or false for the generic reader |
||
| 533 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
||
| 534 | * |
||
| 535 | * @throws MWException |
||
| 536 | * @return DatabaseBase |
||
| 537 | */ |
||
| 538 | public function getConnection( $i, $groups = [], $wiki = false ) { |
||
| 539 | if ( $i === null || $i === false ) { |
||
| 540 | throw new MWException( 'Attempt to call ' . __METHOD__ . |
||
| 541 | ' with invalid server index' ); |
||
| 542 | } |
||
| 543 | |||
| 544 | if ( $wiki === wfWikiID() ) { |
||
| 545 | $wiki = false; |
||
| 546 | } |
||
| 547 | |||
| 548 | $groups = ( $groups === false || $groups === [] ) |
||
| 549 | ? [ false ] // check one "group": the generic pool |
||
| 550 | : (array)$groups; |
||
| 551 | |||
| 552 | $masterOnly = ( $i == DB_MASTER || $i == $this->getWriterIndex() ); |
||
| 553 | $oldConnsOpened = $this->connsOpened; // connections open now |
||
| 554 | |||
| 555 | if ( $i == DB_MASTER ) { |
||
| 556 | $i = $this->getWriterIndex(); |
||
| 557 | } else { |
||
| 558 | # Try to find an available server in any the query groups (in order) |
||
| 559 | foreach ( $groups as $group ) { |
||
| 560 | $groupIndex = $this->getReaderIndex( $group, $wiki ); |
||
| 561 | if ( $groupIndex !== false ) { |
||
| 562 | $i = $groupIndex; |
||
| 563 | break; |
||
| 564 | } |
||
| 565 | } |
||
| 566 | } |
||
| 567 | |||
| 568 | # Operation-based index |
||
| 569 | if ( $i == DB_REPLICA ) { |
||
| 570 | $this->mLastError = 'Unknown error'; // reset error string |
||
| 571 | # Try the general server pool if $groups are unavailable. |
||
| 572 | $i = in_array( false, $groups, true ) |
||
| 573 | ? false // don't bother with this if that is what was tried above |
||
| 574 | : $this->getReaderIndex( false, $wiki ); |
||
| 575 | # Couldn't find a working server in getReaderIndex()? |
||
| 576 | if ( $i === false ) { |
||
| 577 | $this->mLastError = 'No working replica DB server: ' . $this->mLastError; |
||
| 578 | |||
| 579 | return $this->reportConnectionError(); |
||
| 580 | } |
||
| 581 | } |
||
| 582 | |||
| 583 | # Now we have an explicit index into the servers array |
||
| 584 | $conn = $this->openConnection( $i, $wiki ); |
||
| 585 | if ( !$conn ) { |
||
| 586 | return $this->reportConnectionError(); |
||
| 587 | } |
||
| 588 | |||
| 589 | # Profile any new connections that happen |
||
| 590 | if ( $this->connsOpened > $oldConnsOpened ) { |
||
| 591 | $host = $conn->getServer(); |
||
| 592 | $dbname = $conn->getDBname(); |
||
| 593 | $trxProf = Profiler::instance()->getTransactionProfiler(); |
||
| 594 | $trxProf->recordConnection( $host, $dbname, $masterOnly ); |
||
| 595 | } |
||
| 596 | |||
| 597 | if ( $masterOnly ) { |
||
| 598 | # Make master-requested DB handles inherit any read-only mode setting |
||
| 599 | $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $wiki, $conn ) ); |
||
| 600 | } |
||
| 601 | |||
| 602 | return $conn; |
||
| 603 | } |
||
| 604 | |||
| 605 | /** |
||
| 606 | * Mark a foreign connection as being available for reuse under a different |
||
| 607 | * DB name or prefix. This mechanism is reference-counted, and must be called |
||
| 608 | * the same number of times as getConnection() to work. |
||
| 609 | * |
||
| 610 | * @param DatabaseBase $conn |
||
| 611 | * @throws MWException |
||
| 612 | */ |
||
| 613 | public function reuseConnection( $conn ) { |
||
| 614 | $serverIndex = $conn->getLBInfo( 'serverIndex' ); |
||
| 615 | $refCount = $conn->getLBInfo( 'foreignPoolRefCount' ); |
||
| 616 | if ( $serverIndex === null || $refCount === null ) { |
||
| 617 | /** |
||
| 618 | * This can happen in code like: |
||
| 619 | * foreach ( $dbs as $db ) { |
||
| 620 | * $conn = $lb->getConnection( DB_REPLICA, [], $db ); |
||
| 621 | * ... |
||
| 622 | * $lb->reuseConnection( $conn ); |
||
| 623 | * } |
||
| 624 | * When a connection to the local DB is opened in this way, reuseConnection() |
||
| 625 | * should be ignored |
||
| 626 | */ |
||
| 627 | return; |
||
| 628 | } |
||
| 629 | |||
| 630 | $dbName = $conn->getDBname(); |
||
| 631 | $prefix = $conn->tablePrefix(); |
||
| 632 | if ( strval( $prefix ) !== '' ) { |
||
| 633 | $wiki = "$dbName-$prefix"; |
||
| 634 | } else { |
||
| 635 | $wiki = $dbName; |
||
| 636 | } |
||
| 637 | if ( $this->mConns['foreignUsed'][$serverIndex][$wiki] !== $conn ) { |
||
| 638 | throw new MWException( __METHOD__ . ": connection not found, has " . |
||
| 639 | "the connection been freed already?" ); |
||
| 640 | } |
||
| 641 | $conn->setLBInfo( 'foreignPoolRefCount', --$refCount ); |
||
| 642 | if ( $refCount <= 0 ) { |
||
| 643 | $this->mConns['foreignFree'][$serverIndex][$wiki] = $conn; |
||
| 644 | unset( $this->mConns['foreignUsed'][$serverIndex][$wiki] ); |
||
| 645 | wfDebug( __METHOD__ . ": freed connection $serverIndex/$wiki\n" ); |
||
| 646 | } else { |
||
| 647 | wfDebug( __METHOD__ . ": reference count for $serverIndex/$wiki reduced to $refCount\n" ); |
||
| 648 | } |
||
| 649 | } |
||
| 650 | |||
| 651 | /** |
||
| 652 | * Get a database connection handle reference |
||
| 653 | * |
||
| 654 | * The handle's methods wrap simply wrap those of a DatabaseBase handle |
||
| 655 | * |
||
| 656 | * @see LoadBalancer::getConnection() for parameter information |
||
| 657 | * |
||
| 658 | * @param int $db |
||
| 659 | * @param array|string|bool $groups Query group(s), or false for the generic reader |
||
| 660 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
||
| 661 | * @return DBConnRef |
||
| 662 | */ |
||
| 663 | public function getConnectionRef( $db, $groups = [], $wiki = false ) { |
||
| 666 | |||
| 667 | /** |
||
| 668 | * Get a database connection handle reference without connecting yet |
||
| 669 | * |
||
| 670 | * The handle's methods wrap simply wrap those of a DatabaseBase handle |
||
| 671 | * |
||
| 672 | * @see LoadBalancer::getConnection() for parameter information |
||
| 673 | * |
||
| 674 | * @param int $db |
||
| 675 | * @param array|string|bool $groups Query group(s), or false for the generic reader |
||
| 676 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
||
| 677 | * @return DBConnRef |
||
| 678 | */ |
||
| 679 | public function getLazyConnectionRef( $db, $groups = [], $wiki = false ) { |
||
| 682 | |||
| 683 | /** |
||
| 684 | * Open a connection to the server given by the specified index |
||
| 685 | * Index must be an actual index into the array. |
||
| 686 | * If the server is already open, returns it. |
||
| 687 | * |
||
| 688 | * On error, returns false, and the connection which caused the |
||
| 689 | * error will be available via $this->mErrorConnection. |
||
| 690 | * |
||
| 691 | * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError. |
||
| 692 | * |
||
| 693 | * @param int $i Server index |
||
| 694 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
||
| 695 | * @return DatabaseBase|bool Returns false on errors |
||
| 696 | */ |
||
| 697 | public function openConnection( $i, $wiki = false ) { |
||
| 728 | |||
| 729 | /** |
||
| 730 | * Open a connection to a foreign DB, or return one if it is already open. |
||
| 731 | * |
||
| 732 | * Increments a reference count on the returned connection which locks the |
||
| 733 | * connection to the requested wiki. This reference count can be |
||
| 734 | * decremented by calling reuseConnection(). |
||
| 735 | * |
||
| 736 | * If a connection is open to the appropriate server already, but with the wrong |
||
| 737 | * database, it will be switched to the right database and returned, as long as |
||
| 738 | * it has been freed first with reuseConnection(). |
||
| 739 | * |
||
| 740 | * On error, returns false, and the connection which caused the |
||
| 741 | * error will be available via $this->mErrorConnection. |
||
| 742 | * |
||
| 743 | * @note If disable() was called on this LoadBalancer, this method will throw a DBAccessError. |
||
| 744 | * |
||
| 745 | * @param int $i Server index |
||
| 746 | * @param string $wiki Wiki ID to open |
||
| 747 | * @return DatabaseBase |
||
| 748 | */ |
||
| 749 | private function openForeignConnection( $i, $wiki ) { |
||
| 805 | |||
| 806 | /** |
||
| 807 | * Test if the specified index represents an open connection |
||
| 808 | * |
||
| 809 | * @param int $index Server index |
||
| 810 | * @access private |
||
| 811 | * @return bool |
||
| 812 | */ |
||
| 813 | private function isOpen( $index ) { |
||
| 820 | |||
| 821 | /** |
||
| 822 | * Really opens a connection. Uncached. |
||
| 823 | * Returns a Database object whether or not the connection was successful. |
||
| 824 | * @access private |
||
| 825 | * |
||
| 826 | * @param array $server |
||
| 827 | * @param bool $dbNameOverride |
||
| 828 | * @throws MWException |
||
| 829 | * @return DatabaseBase |
||
| 830 | */ |
||
| 831 | protected function reallyOpenConnection( $server, $dbNameOverride = false ) { |
||
| 832 | if ( $this->disabled ) { |
||
| 833 | throw new DBAccessError(); |
||
| 834 | } |
||
| 835 | |||
| 836 | if ( !is_array( $server ) ) { |
||
| 837 | throw new MWException( 'You must update your load-balancing configuration. ' . |
||
| 838 | 'See DefaultSettings.php entry for $wgDBservers.' ); |
||
| 839 | } |
||
| 840 | |||
| 841 | if ( $dbNameOverride !== false ) { |
||
| 842 | $server['dbname'] = $dbNameOverride; |
||
| 843 | } |
||
| 844 | |||
| 845 | // Let the handle know what the cluster master is (e.g. "db1052") |
||
| 846 | $masterName = $this->getServerName( 0 ); |
||
| 847 | $server['clusterMasterHost'] = $masterName; |
||
| 848 | |||
| 849 | // Log when many connection are made on requests |
||
| 850 | if ( ++$this->connsOpened >= self::CONN_HELD_WARN_THRESHOLD ) { |
||
| 851 | wfDebugLog( 'DBPerformance', __METHOD__ . ": " . |
||
| 852 | "{$this->connsOpened}+ connections made (master=$masterName)\n" . |
||
| 853 | wfBacktrace( true ) ); |
||
| 854 | } |
||
| 855 | |||
| 856 | # Create object |
||
| 857 | try { |
||
| 858 | $db = DatabaseBase::factory( $server['type'], $server ); |
||
| 859 | } catch ( DBConnectionError $e ) { |
||
| 860 | // FIXME: This is probably the ugliest thing I have ever done to |
||
| 861 | // PHP. I'm half-expecting it to segfault, just out of disgust. -- TS |
||
| 862 | $db = $e->db; |
||
| 863 | } |
||
| 864 | |||
| 865 | $db->setLBInfo( $server ); |
||
| 866 | $db->setLazyMasterHandle( |
||
| 867 | $this->getLazyConnectionRef( DB_MASTER, [], $db->getWikiID() ) |
||
| 868 | ); |
||
| 869 | $db->setTransactionProfiler( $this->trxProfiler ); |
||
| 870 | |||
| 871 | if ( $server['serverIndex'] === $this->getWriterIndex() ) { |
||
| 872 | if ( $this->trxRoundId !== false ) { |
||
| 873 | $this->applyTransactionRoundFlags( $db ); |
||
| 874 | } |
||
| 875 | foreach ( $this->trxRecurringCallbacks as $name => $callback ) { |
||
| 876 | $db->setTransactionListener( $name, $callback ); |
||
| 877 | } |
||
| 878 | } |
||
| 879 | |||
| 880 | return $db; |
||
| 881 | } |
||
| 882 | |||
| 883 | /** |
||
| 884 | * @throws DBConnectionError |
||
| 885 | * @return bool |
||
| 886 | */ |
||
| 887 | private function reportConnectionError() { |
||
| 916 | |||
| 917 | /** |
||
| 918 | * @return int |
||
| 919 | * @since 1.26 |
||
| 920 | */ |
||
| 921 | public function getWriterIndex() { |
||
| 924 | |||
| 925 | /** |
||
| 926 | * Returns true if the specified index is a valid server index |
||
| 927 | * |
||
| 928 | * @param string $i |
||
| 929 | * @return bool |
||
| 930 | */ |
||
| 931 | public function haveIndex( $i ) { |
||
| 934 | |||
| 935 | /** |
||
| 936 | * Returns true if the specified index is valid and has non-zero load |
||
| 937 | * |
||
| 938 | * @param string $i |
||
| 939 | * @return bool |
||
| 940 | */ |
||
| 941 | public function isNonZeroLoad( $i ) { |
||
| 944 | |||
| 945 | /** |
||
| 946 | * Get the number of defined servers (not the number of open connections) |
||
| 947 | * |
||
| 948 | * @return int |
||
| 949 | */ |
||
| 950 | public function getServerCount() { |
||
| 953 | |||
| 954 | /** |
||
| 955 | * Get the host name or IP address of the server with the specified index |
||
| 956 | * Prefer a readable name if available. |
||
| 957 | * @param string $i |
||
| 958 | * @return string |
||
| 959 | */ |
||
| 960 | public function getServerName( $i ) { |
||
| 961 | if ( isset( $this->mServers[$i]['hostName'] ) ) { |
||
| 962 | $name = $this->mServers[$i]['hostName']; |
||
| 963 | } elseif ( isset( $this->mServers[$i]['host'] ) ) { |
||
| 964 | $name = $this->mServers[$i]['host']; |
||
| 965 | } else { |
||
| 966 | $name = ''; |
||
| 967 | } |
||
| 968 | |||
| 969 | return ( $name != '' ) ? $name : 'localhost'; |
||
| 970 | } |
||
| 971 | |||
| 972 | /** |
||
| 973 | * Return the server info structure for a given index, or false if the index is invalid. |
||
| 974 | * @param int $i |
||
| 975 | * @return array|bool |
||
| 976 | */ |
||
| 977 | public function getServerInfo( $i ) { |
||
| 984 | |||
| 985 | /** |
||
| 986 | * Sets the server info structure for the given index. Entry at index $i |
||
| 987 | * is created if it doesn't exist |
||
| 988 | * @param int $i |
||
| 989 | * @param array $serverInfo |
||
| 990 | */ |
||
| 991 | public function setServerInfo( $i, array $serverInfo ) { |
||
| 994 | |||
| 995 | /** |
||
| 996 | * Get the current master position for chronology control purposes |
||
| 997 | * @return mixed |
||
| 998 | */ |
||
| 999 | public function getMasterPos() { |
||
| 1000 | # If this entire request was served from a replica DB without opening a connection to the |
||
| 1001 | # master (however unlikely that may be), then we can fetch the position from the replica DB. |
||
| 1002 | $masterConn = $this->getAnyOpenConnection( 0 ); |
||
| 1003 | if ( !$masterConn ) { |
||
| 1004 | $serverCount = count( $this->mServers ); |
||
| 1005 | for ( $i = 1; $i < $serverCount; $i++ ) { |
||
| 1006 | $conn = $this->getAnyOpenConnection( $i ); |
||
| 1007 | if ( $conn ) { |
||
| 1008 | return $conn->getSlavePos(); |
||
| 1009 | } |
||
| 1010 | } |
||
| 1011 | } else { |
||
| 1012 | return $masterConn->getMasterPos(); |
||
| 1013 | } |
||
| 1014 | |||
| 1015 | return false; |
||
| 1016 | } |
||
| 1017 | |||
| 1018 | /** |
||
| 1019 | * Disable this load balancer. All connections are closed, and any attempt to |
||
| 1020 | * open a new connection will result in a DBAccessError. |
||
| 1021 | * |
||
| 1022 | * @since 1.27 |
||
| 1023 | */ |
||
| 1024 | public function disable() { |
||
| 1028 | |||
| 1029 | /** |
||
| 1030 | * Close all open connections |
||
| 1031 | */ |
||
| 1032 | public function closeAll() { |
||
| 1044 | |||
| 1045 | /** |
||
| 1046 | * Close a connection |
||
| 1047 | * Using this function makes sure the LoadBalancer knows the connection is closed. |
||
| 1048 | * If you use $conn->close() directly, the load balancer won't update its state. |
||
| 1049 | * @param DatabaseBase $conn |
||
| 1050 | */ |
||
| 1051 | public function closeConnection( $conn ) { |
||
| 1070 | |||
| 1071 | /** |
||
| 1072 | * Commit transactions on all open connections |
||
| 1073 | * @param string $fname Caller name |
||
| 1074 | * @throws DBExpectedError |
||
| 1075 | */ |
||
| 1076 | public function commitAll( $fname = __METHOD__ ) { |
||
| 1102 | |||
| 1103 | /** |
||
| 1104 | * Perform all pre-commit callbacks that remain part of the atomic transactions |
||
| 1105 | * and disable any post-commit callbacks until runMasterPostTrxCallbacks() |
||
| 1106 | * @since 1.28 |
||
| 1107 | */ |
||
| 1108 | public function finalizeMasterChanges() { |
||
| 1117 | |||
| 1118 | /** |
||
| 1119 | * Perform all pre-commit checks for things like replication safety |
||
| 1120 | * @param array $options Includes: |
||
| 1121 | * - maxWriteDuration : max write query duration time in seconds |
||
| 1122 | * @throws DBTransactionError |
||
| 1123 | * @since 1.28 |
||
| 1124 | */ |
||
| 1125 | public function approveMasterChanges( array $options ) { |
||
| 1156 | |||
| 1157 | /** |
||
| 1158 | * Flush any master transaction snapshots and set DBO_TRX (if DBO_DEFAULT is set) |
||
| 1159 | * |
||
| 1160 | * The DBO_TRX setting will be reverted to the default in each of these methods: |
||
| 1161 | * - commitMasterChanges() |
||
| 1162 | * - rollbackMasterChanges() |
||
| 1163 | * - commitAll() |
||
| 1164 | * This allows for custom transaction rounds from any outer transaction scope. |
||
| 1165 | * |
||
| 1166 | * @param string $fname |
||
| 1167 | * @throws DBExpectedError |
||
| 1168 | * @since 1.28 |
||
| 1169 | */ |
||
| 1170 | public function beginMasterChanges( $fname = __METHOD__ ) { |
||
| 1201 | |||
| 1202 | /** |
||
| 1203 | * Issue COMMIT on all master connections where writes where done |
||
| 1204 | * @param string $fname Caller name |
||
| 1205 | * @throws DBExpectedError |
||
| 1206 | */ |
||
| 1207 | public function commitMasterChanges( $fname = __METHOD__ ) { |
||
| 1237 | |||
| 1238 | /** |
||
| 1239 | * Issue all pending post-COMMIT/ROLLBACK callbacks |
||
| 1240 | * @param integer $type IDatabase::TRIGGER_* constant |
||
| 1241 | * @return Exception|null The first exception or null if there were none |
||
| 1242 | * @since 1.28 |
||
| 1243 | */ |
||
| 1244 | public function runMasterPostTrxCallbacks( $type ) { |
||
| 1264 | |||
| 1265 | /** |
||
| 1266 | * Issue ROLLBACK only on master, only if queries were done on connection |
||
| 1267 | * @param string $fname Caller name |
||
| 1268 | * @throws DBExpectedError |
||
| 1269 | * @since 1.23 |
||
| 1270 | */ |
||
| 1271 | public function rollbackMasterChanges( $fname = __METHOD__ ) { |
||
| 1285 | |||
| 1286 | /** |
||
| 1287 | * Suppress all pending post-COMMIT/ROLLBACK callbacks |
||
| 1288 | * @return Exception|null The first exception or null if there were none |
||
| 1289 | * @since 1.28 |
||
| 1290 | */ |
||
| 1291 | public function suppressTransactionEndCallbacks() { |
||
| 1296 | |||
| 1297 | /** |
||
| 1298 | * @param DatabaseBase $conn |
||
| 1299 | */ |
||
| 1300 | private function applyTransactionRoundFlags( DatabaseBase $conn ) { |
||
| 1310 | |||
| 1311 | /** |
||
| 1312 | * @param DatabaseBase $conn |
||
| 1313 | */ |
||
| 1314 | private function undoTransactionRoundFlags( DatabaseBase $conn ) { |
||
| 1319 | |||
| 1320 | /** |
||
| 1321 | * Commit all replica DB transactions so as to flush any REPEATABLE-READ or SSI snapshot |
||
| 1322 | * |
||
| 1323 | * @param string $fname Caller name |
||
| 1324 | * @since 1.28 |
||
| 1325 | */ |
||
| 1326 | public function flushReplicaSnapshots( $fname = __METHOD__ ) { |
||
| 1327 | $this->forEachOpenReplicaConnection( function ( DatabaseBase $conn ) { |
||
| 1328 | $conn->clearSnapshot( __METHOD__ ); |
||
| 1329 | } ); |
||
| 1330 | } |
||
| 1331 | |||
| 1332 | /** |
||
| 1333 | * @return bool Whether a master connection is already open |
||
| 1334 | * @since 1.24 |
||
| 1335 | */ |
||
| 1336 | public function hasMasterConnection() { |
||
| 1339 | |||
| 1340 | /** |
||
| 1341 | * Determine if there are pending changes in a transaction by this thread |
||
| 1342 | * @since 1.23 |
||
| 1343 | * @return bool |
||
| 1344 | */ |
||
| 1345 | public function hasMasterChanges() { |
||
| 1360 | |||
| 1361 | /** |
||
| 1362 | * Get the timestamp of the latest write query done by this thread |
||
| 1363 | * @since 1.25 |
||
| 1364 | * @return float|bool UNIX timestamp or false |
||
| 1365 | */ |
||
| 1366 | View Code Duplication | public function lastMasterChangeTimestamp() { |
|
| 1380 | |||
| 1381 | /** |
||
| 1382 | * Check if this load balancer object had any recent or still |
||
| 1383 | * pending writes issued against it by this PHP thread |
||
| 1384 | * |
||
| 1385 | * @param float $age How many seconds ago is "recent" [defaults to mWaitTimeout] |
||
| 1386 | * @return bool |
||
| 1387 | * @since 1.25 |
||
| 1388 | */ |
||
| 1389 | public function hasOrMadeRecentMasterChanges( $age = null ) { |
||
| 1395 | |||
| 1396 | /** |
||
| 1397 | * Get the list of callers that have pending master changes |
||
| 1398 | * |
||
| 1399 | * @return array |
||
| 1400 | * @since 1.27 |
||
| 1401 | */ |
||
| 1402 | View Code Duplication | public function pendingMasterChangeCallers() { |
|
| 1418 | |||
| 1419 | /** |
||
| 1420 | * @note This method will trigger a DB connection if not yet done |
||
| 1421 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
||
| 1422 | * @return bool Whether the generic connection for reads is highly "lagged" |
||
| 1423 | */ |
||
| 1424 | public function getLaggedReplicaMode( $wiki = false ) { |
||
| 1440 | |||
| 1441 | /** |
||
| 1442 | * @param bool $wiki |
||
| 1443 | * @return bool |
||
| 1444 | * @deprecated 1.28; use getLaggedReplicaMode() |
||
| 1445 | */ |
||
| 1446 | public function getLaggedSlaveMode( $wiki = false ) { |
||
| 1449 | |||
| 1450 | /** |
||
| 1451 | * @note This method will never cause a new DB connection |
||
| 1452 | * @return bool Whether any generic connection used for reads was highly "lagged" |
||
| 1453 | * @since 1.28 |
||
| 1454 | */ |
||
| 1455 | public function laggedReplicaUsed() { |
||
| 1458 | |||
| 1459 | /** |
||
| 1460 | * @return bool |
||
| 1461 | * @since 1.27 |
||
| 1462 | * @deprecated Since 1.28; use laggedReplicaUsed() |
||
| 1463 | */ |
||
| 1464 | public function laggedSlaveUsed() { |
||
| 1467 | |||
| 1468 | /** |
||
| 1469 | * @note This method may trigger a DB connection if not yet done |
||
| 1470 | * @param string|bool $wiki Wiki ID, or false for the current wiki |
||
| 1471 | * @param DatabaseBase|null DB master connection; used to avoid loops [optional] |
||
| 1472 | * @return string|bool Reason the master is read-only or false if it is not |
||
| 1473 | * @since 1.27 |
||
| 1474 | */ |
||
| 1475 | public function getReadOnlyReason( $wiki = false, DatabaseBase $conn = null ) { |
||
| 1492 | |||
| 1493 | /** |
||
| 1494 | * @param string $wiki Wiki ID, or false for the current wiki |
||
| 1495 | * @param DatabaseBase|null DB master connectionl used to avoid loops [optional] |
||
| 1496 | * @return bool |
||
| 1497 | */ |
||
| 1498 | private function masterRunningReadOnly( $wiki, DatabaseBase $conn = null ) { |
||
| 1519 | |||
| 1520 | /** |
||
| 1521 | * Disables/enables lag checks |
||
| 1522 | * @param null|bool $mode |
||
| 1523 | * @return bool |
||
| 1524 | */ |
||
| 1525 | public function allowLagged( $mode = null ) { |
||
| 1533 | |||
| 1534 | /** |
||
| 1535 | * @return bool |
||
| 1536 | */ |
||
| 1537 | public function pingAll() { |
||
| 1547 | |||
| 1548 | /** |
||
| 1549 | * Call a function with each open connection object |
||
| 1550 | * @param callable $callback |
||
| 1551 | * @param array $params |
||
| 1552 | */ |
||
| 1553 | View Code Duplication | public function forEachOpenConnection( $callback, array $params = [] ) { |
|
| 1563 | |||
| 1564 | /** |
||
| 1565 | * Call a function with each open connection object to a master |
||
| 1566 | * @param callable $callback |
||
| 1567 | * @param array $params |
||
| 1568 | * @since 1.28 |
||
| 1569 | */ |
||
| 1570 | public function forEachOpenMasterConnection( $callback, array $params = [] ) { |
||
| 1582 | |||
| 1583 | /** |
||
| 1584 | * Call a function with each open replica DB connection object |
||
| 1585 | * @param callable $callback |
||
| 1586 | * @param array $params |
||
| 1587 | * @since 1.28 |
||
| 1588 | */ |
||
| 1589 | View Code Duplication | public function forEachOpenReplicaConnection( $callback, array $params = [] ) { |
|
| 1602 | |||
| 1603 | /** |
||
| 1604 | * Get the hostname and lag time of the most-lagged replica DB |
||
| 1605 | * |
||
| 1606 | * This is useful for maintenance scripts that need to throttle their updates. |
||
| 1607 | * May attempt to open connections to replica DBs on the default DB. If there is |
||
| 1608 | * no lag, the maximum lag will be reported as -1. |
||
| 1609 | * |
||
| 1610 | * @param bool|string $wiki Wiki ID, or false for the default database |
||
| 1611 | * @return array ( host, max lag, index of max lagged host ) |
||
| 1612 | */ |
||
| 1613 | public function getMaxLag( $wiki = false ) { |
||
| 1633 | |||
| 1634 | /** |
||
| 1635 | * Get an estimate of replication lag (in seconds) for each server |
||
| 1636 | * |
||
| 1637 | * Results are cached for a short time in memcached/process cache |
||
| 1638 | * |
||
| 1639 | * Values may be "false" if replication is too broken to estimate |
||
| 1640 | * |
||
| 1641 | * @param string|bool $wiki |
||
| 1642 | * @return int[] Map of (server index => float|int|bool) |
||
| 1643 | */ |
||
| 1644 | public function getLagTimes( $wiki = false ) { |
||
| 1652 | |||
| 1653 | /** |
||
| 1654 | * Get the lag in seconds for a given connection, or zero if this load |
||
| 1655 | * balancer does not have replication enabled. |
||
| 1656 | * |
||
| 1657 | * This should be used in preference to Database::getLag() in cases where |
||
| 1658 | * replication may not be in use, since there is no way to determine if |
||
| 1659 | * replication is in use at the connection level without running |
||
| 1660 | * potentially restricted queries such as SHOW SLAVE STATUS. Using this |
||
| 1661 | * function instead of Database::getLag() avoids a fatal error in this |
||
| 1662 | * case on many installations. |
||
| 1663 | * |
||
| 1664 | * @param IDatabase $conn |
||
| 1665 | * @return int|bool Returns false on error |
||
| 1666 | */ |
||
| 1667 | public function safeGetLag( IDatabase $conn ) { |
||
| 1674 | |||
| 1675 | /** |
||
| 1676 | * Wait for a replica DB to reach a specified master position |
||
| 1677 | * |
||
| 1678 | * This will connect to the master to get an accurate position if $pos is not given |
||
| 1679 | * |
||
| 1680 | * @param IDatabase $conn Replica DB |
||
| 1681 | * @param DBMasterPos|bool $pos Master position; default: current position |
||
| 1682 | * @param integer $timeout Timeout in seconds |
||
| 1683 | * @return bool Success |
||
| 1684 | * @since 1.27 |
||
| 1685 | */ |
||
| 1686 | public function safeWaitForMasterPos( IDatabase $conn, $pos = false, $timeout = 10 ) { |
||
| 1709 | |||
| 1710 | /** |
||
| 1711 | * Clear the cache for slag lag delay times |
||
| 1712 | * |
||
| 1713 | * This is only used for testing |
||
| 1714 | */ |
||
| 1715 | public function clearLagTimeCache() { |
||
| 1718 | |||
| 1719 | /** |
||
| 1720 | * Set a callback via DatabaseBase::setTransactionListener() on |
||
| 1721 | * all current and future master connections of this load balancer |
||
| 1722 | * |
||
| 1723 | * @param string $name Callback name |
||
| 1724 | * @param callable|null $callback |
||
| 1725 | * @since 1.28 |
||
| 1726 | */ |
||
| 1727 | public function setTransactionListener( $name, callable $callback = null ) { |
||
| 1739 | } |
||
| 1740 |
Loading history...
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: