private $mLoadMonitorClass;
/** @var LoadMonitor */
private $mLoadMonitor;
+ /** @var BagOStuff */
+ private $srvCache;
/** @var bool|DatabaseBase Database connection that caused a problem */
private $mErrorConnection;
/** @var bool|DBMasterPos False if not set */
private $mWaitForPos;
/** @var bool Whether the generic reader fell back to a lagged slave */
- private $mLaggedSlaveMode;
+ private $laggedSlaveMode = false;
+ /** @var bool Whether the generic reader fell back to a lagged slave */
+ private $slavesDownMode = false;
/** @var string The last DB selection or connection error */
private $mLastError = 'Unknown error';
+ /** @var string|bool Reason the LB is read-only or false if not */
+ private $readOnlyReason = false;
/** @var integer Total connections opened */
private $connsOpened = 0;
/** @var integer Warn when this many connection are held */
const CONN_HELD_WARN_THRESHOLD = 10;
+ /** @var integer Default 'max lag' when unspecified */
+ const MAX_LAG = 10;
+ /** @var integer Max time to wait for a slave to catch up (e.g. ChronologyProtector) */
+ const POS_WAIT_TIMEOUT = 10;
/**
* @param array $params Array with keys:
- * servers Required. Array of server info structures.
- * loadMonitor Name of a class used to fetch server lag and load.
+ * - servers : Required. Array of server info structures.
+ * - loadMonitor : Name of a class used to fetch server lag and load.
+ * - readOnlyReason : Reason the master DB is read-only if so [optional]
* @throws MWException
*/
public function __construct( array $params ) {
throw new MWException( __CLASS__ . ': missing servers parameter' );
}
$this->mServers = $params['servers'];
- $this->mWaitTimeout = 10;
+ $this->mWaitTimeout = self::POS_WAIT_TIMEOUT;
$this->mReadIndex = -1;
$this->mWriteIndex = -1;
'foreignFree' => array() );
$this->mLoads = array();
$this->mWaitForPos = false;
- $this->mLaggedSlaveMode = false;
$this->mErrorConnection = false;
$this->mAllowLagged = false;
+ if ( isset( $params['readOnlyReason'] ) && is_string( $params['readOnlyReason'] ) ) {
+ $this->readOnlyReason = $params['readOnlyReason'];
+ }
+
if ( isset( $params['loadMonitor'] ) ) {
$this->mLoadMonitorClass = $params['loadMonitor'];
} else {
}
}
}
+
+ $this->srvCache = ObjectCache::getLocalServerInstance();
}
/**
/**
* @param array $loads
* @param bool|string $wiki Wiki to get non-lagged for
- * @param float $maxLag Restrict the maximum allowed lag to this many seconds
+ * @param int $maxLag Restrict the maximum allowed lag to this many seconds
* @return bool|int|string
*/
- private function getRandomNonLagged( array $loads, $wiki = false, $maxLag = INF ) {
+ private function getRandomNonLagged( array $loads, $wiki = false, $maxLag = self::MAX_LAG ) {
$lags = $this->getLagTimes( $wiki );
# Unset excessively lagged servers
$this->mReadIndex = $i;
# Record if the generic reader index is in "lagged slave" mode
if ( $laggedSlaveMode ) {
- $this->mLaggedSlaveMode = true;
+ $this->laggedSlaveMode = true;
}
}
$serverName = $this->getServerName( $i );
if ( $i > 0 ) {
if ( !$this->doWait( $i ) ) {
$this->mServers[$i]['slave pos'] = $this->getAnyOpenConnection( $i )->getSlavePos();
- $this->mLaggedSlaveMode = true;
+ $this->laggedSlaveMode = true;
}
}
}
protected function doWait( $index, $open = false, $timeout = null ) {
$close = false; // close the connection afterwards
- # Find a connection to wait on, creating one if needed and allowed
+ // Check if we already know that the DB has reached this point
+ $server = $this->getServerName( $index );
+ $key = $this->srvCache->makeGlobalKey( __CLASS__, 'last-known-pos', $server );
+ /** @var DBMasterPos $knownReachedPos */
+ $knownReachedPos = $this->srvCache->get( $key );
+ if ( $knownReachedPos && $knownReachedPos->hasReached( $this->mWaitForPos ) ) {
+ wfDebugLog( 'replication', __METHOD__ . ": Slave $server known to be caught up.\n" );
+ return true;
+ }
+
+ // Find a connection to wait on, creating one if needed and allowed
$conn = $this->getAnyOpenConnection( $index );
if ( !$conn ) {
if ( !$open ) {
- wfDebug( __METHOD__ . ": no connection open\n" );
+ wfDebugLog( 'replication', __METHOD__ . ": no connection open for $server\n" );
return false;
} else {
$conn = $this->openConnection( $index, '' );
if ( !$conn ) {
- wfDebug( __METHOD__ . ": failed to open connection\n" );
+ wfDebugLog( 'replication', __METHOD__ . ": failed to open connection to $server\n" );
return false;
}
}
}
- wfDebug( __METHOD__ . ": Waiting for slave #$index to catch up...\n" );
+ wfDebugLog( 'replication', __METHOD__ . ": Waiting for slave $server to catch up...\n" );
$timeout = $timeout ?: $this->mWaitTimeout;
$result = $conn->masterPosWait( $this->mWaitForPos, $timeout );
if ( $result == -1 || is_null( $result ) ) {
- # Timed out waiting for slave, use master instead
- $server = $server = $this->getServerName( $index );
+ // Timed out waiting for slave, use master instead
$msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
- wfDebug( "$msg\n" );
+ wfDebugLog( 'replication', "$msg\n" );
wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
$ok = false;
} else {
- wfDebug( __METHOD__ . ": Done\n" );
+ wfDebugLog( 'replication', __METHOD__ . ": Done\n" );
$ok = true;
+ // Remember that the DB reached this point
+ $this->srvCache->set( $key, $this->mWaitForPos, BagOStuff::TTL_DAY );
}
if ( $close ) {
$trxProf->recordConnection( $host, $dbname, $masterOnly );
}
- # Make master connections read only if in lagged slave mode
- if ( $masterOnly && $this->getServerCount() > 1 && $this->getLaggedSlaveMode() ) {
- $conn->setLBInfo( 'readOnlyReason',
- 'The database has been automatically locked ' .
- 'while the slave database servers catch up to the master'
- );
+ if ( $masterOnly ) {
+ # Make master-requested DB handles inherit any read-only mode setting
+ $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $wiki ) );
}
return $conn;
$refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
if ( $serverIndex === null || $refCount === null ) {
wfDebug( __METHOD__ . ": this connection was not opened as a foreign connection\n" );
-
/**
* This can happen in code like:
* foreach ( $dbs as $db ) {
* When a connection to the local DB is opened in this way, reuseConnection()
* should be ignored
*/
-
return;
}
/**
* @note This method will trigger a DB connection if not yet done
+ *
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
* @return bool Whether the generic connection for reads is highly "lagged"
*/
- public function getLaggedSlaveMode() {
- # Get a generic reader connection
- $this->getConnection( DB_SLAVE );
+ public function getLaggedSlaveMode( $wiki = false ) {
+ // No-op if there is only one DB (also avoids recursion)
+ if ( !$this->laggedSlaveMode && $this->getServerCount() > 1 ) {
+ try {
+ // See if laggedSlaveMode gets set
+ $conn = $this->getConnection( DB_SLAVE, false, $wiki );
+ $this->reuseConnection( $conn );
+ } catch ( DBConnectionError $e ) {
+ // Avoid expensive re-connect attempts and failures
+ $this->slavesDownMode = true;
+ $this->laggedSlaveMode = true;
+ }
+ }
- return $this->mLaggedSlaveMode;
+ return $this->laggedSlaveMode;
}
/**
* @since 1.27
*/
public function laggedSlaveUsed() {
- return $this->mLaggedSlaveMode;
+ return $this->laggedSlaveMode;
+ }
+
+ /**
+ * @note This method may trigger a DB connection if not yet done
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
+ * @return string|bool Reason the master is read-only or false if it is not
+ * @since 1.27
+ */
+ public function getReadOnlyReason( $wiki = false ) {
+ if ( $this->readOnlyReason !== false ) {
+ return $this->readOnlyReason;
+ } elseif ( $this->getLaggedSlaveMode( $wiki ) ) {
+ if ( $this->slavesDownMode ) {
+ return 'The database has been automatically locked ' .
+ 'until the slave database servers become available';
+ } else {
+ return 'The database has been automatically locked ' .
+ 'while the slave database servers catch up to the master.';
+ }
+ }
+
+ return false;
}
/**
dépôts / lhc / web / wiklou.git / blobdiff