/** @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 = 30;
/**
* @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 ) {
'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 {
/**
* @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;
}
}
}
$trxProf->recordConnection( $host, $dbname, $masterOnly );
}
+ if ( $masterOnly ) {
+ # Make master-requested DB handles inherit any read-only mode setting
+ $conn->setLBInfo( 'readOnlyReason', $this->getReadOnlyReason( $wiki ) );
+ }
+
return $conn;
}
}
/**
+ * @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
+ $this->getConnection( DB_SLAVE, false, $wiki );
+ } catch ( DBConnectionError $e ) {
+ // Avoid expensive re-connect attempts and failures
+ $this->slavesDownMode = true;
+ $this->laggedSlaveMode = true;
+ }
+ }
+
+ return $this->laggedSlaveMode;
+ }
+
+ /**
+ * @note This method will never cause a new DB connection
+ * @return bool Whether any generic connection used for reads was highly "lagged"
+ * @since 1.27
+ */
+ public function laggedSlaveUsed() {
+ 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 $this->mLaggedSlaveMode;
+ return false;
}
/**
}
/**
- * Get lag time for each server
+ * Get an estimate of replication lag (in seconds) for each server
*
* Results are cached for a short time in memcached/process cache
*
+ * Values may be "false" if replication is too broken to estimate
+ *
* @param string|bool $wiki
- * @return int[] Map of (server index => seconds)
+ * @return int[] Map of (server index => float|int|bool)
*/
public function getLagTimes( $wiki = false ) {
if ( $this->getServerCount() <= 1 ) {
dépôts / lhc / web / wiklou.git / blobdiff