X-Git-Url: https://git.heureux-cyclage.org/?a=blobdiff_plain;f=includes%2Fdb%2Floadbalancer%2FLoadBalancer.php;h=bc9465ba60a0fa38a529e8e021d09c5e5dc18127;hb=52010e6d21d8bdefa1c89fbc9421850185cc5011;hp=3fcd34929c16a92395fe37414860bb881ad10317;hpb=f22024c7c2ce02f1304ca84040831a0f13bd9cb9;p=lhc%2Fweb%2Fwiklou.git

diff --git a/includes/db/loadbalancer/LoadBalancer.php b/includes/db/loadbalancer/LoadBalancer.php
index 3fcd34929c..bc9465ba60 100644
--- a/includes/db/loadbalancer/LoadBalancer.php
+++ b/includes/db/loadbalancer/LoadBalancer.php
@@ -55,19 +55,26 @@ class LoadBalancer {
 	/** @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 ) {
@@ -85,10 +92,13 @@ class LoadBalancer {
 			'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 {
@@ -152,10 +162,10 @@ class LoadBalancer {
 	/**
 	 * @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
@@ -327,7 +337,7 @@ class LoadBalancer {
 				$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 );
@@ -350,7 +360,7 @@ class LoadBalancer {
 		if ( $i > 0 ) {
 			if ( !$this->doWait( $i ) ) {
 				$this->mServers[$i]['slave pos'] = $this->getAnyOpenConnection( $i )->getSlavePos();
-				$this->mLaggedSlaveMode = true;
+				$this->laggedSlaveMode = true;
 			}
 		}
 	}
@@ -546,6 +556,11 @@ class LoadBalancer {
 			$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;
 	}
 
@@ -1131,13 +1146,56 @@ class LoadBalancer {
 	}
 
 	/**
+	 * @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;
 	}
 
 	/**
@@ -1221,12 +1279,14 @@ class LoadBalancer {
 	}
 
 	/**
-	 * 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 ) {