Removed ProfilerStandard and ProfilerSimpleTrace

[lhc/web/wiklou.git] / includes / db / LoadBalancer.php

diff --git a/includes/db/LoadBalancer.php b/includes/db/LoadBalancer.php
index 07645bd..f1b3238 100644 (file)
--- a/includes/db/LoadBalancer.php
+++ b/includes/db/LoadBalancer.php
@@ -151,17 +151,23 @@ 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
         * @return bool|int|string
         */
-       private function getRandomNonLagged( array $loads, $wiki = false ) {
-               # Unset excessively lagged servers
+       private function getRandomNonLagged( array $loads, $wiki = false, $maxLag = INF ) {
                $lags = $this->getLagTimes( $wiki );
+
+               # Unset excessively lagged servers
                foreach ( $lags as $i => $lag ) {
                        if ( $i != 0 ) {
+                               $maxServerLag = $maxLag;
+                               if ( isset( $this->mServers[$i]['max lag'] ) ) {
+                                       $maxServerLag = min( $maxServerLag, $this->mServers[$i]['max lag'] );
+                               }
                                if ( $lag === false ) {
                                        wfDebugLog( 'replication', "Server #$i is not replicating" );
                                        unset( $loads[$i] );
-                               } elseif ( isset( $this->mServers[$i]['max lag'] ) && $lag > $this->mServers[$i]['max lag'] ) {
+                               } elseif ( $lag > $maxServerLag ) {
                                        wfDebugLog( 'replication', "Server #$i is excessively lagged ($lag seconds)" );
                                        unset( $loads[$i] );
                                }
@@ -252,7 +258,19 @@ class LoadBalancer {
                        if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
                                $i = ArrayUtils::pickRandom( $currentLoads );
                        } else {
-                               $i = $this->getRandomNonLagged( $currentLoads, $wiki );
+                               $i = false;
+                               if ( $this->mWaitForPos && $this->mWaitForPos->asOfTime() ) {
+                                       # ChronologyProtecter causes mWaitForPos to be set via sessions.
+                                       # This triggers doWait() after connect, so it's especially good to
+                                       # avoid lagged servers so as to avoid just blocking in that method.
+                                       $ago = microtime( true ) - $this->mWaitForPos->asOfTime();
+                                       # Aim for <= 1 second of waiting (being too picky can backfire)
+                                       $i = $this->getRandomNonLagged( $currentLoads, $wiki, $ago + 1 );
+                               }
+                               if ( $i === false ) {
+                                       # Any server with less lag than it's 'max lag' param is preferable
+                                       $i = $this->getRandomNonLagged( $currentLoads, $wiki );
+                               }
                                if ( $i === false && count( $currentLoads ) != 0 ) {
                                        # All slaves lagged. Switch to read-only mode
                                        wfDebugLog( 'replication', "All slaves lagged. Switch to read-only mode" );
@@ -438,7 +456,7 @@ class LoadBalancer {
         * @throws MWException
         * @return DatabaseBase
         */
-       public function &getConnection( $i, $groups = array(), $wiki = false ) {
+       public function getConnection( $i, $groups = array(), $wiki = false ) {
                wfProfileIn( __METHOD__ );
 
                if ( $i === null || $i === false ) {
@@ -451,17 +469,14 @@ class LoadBalancer {
                        $wiki = false;
                }
 
-               # Query groups
+               $groups = ( $groups === false || $groups === array() )
+                       ? array( false ) // check one "group": the generic pool
+                       : (array)$groups;
+
                if ( $i == DB_MASTER ) {
                        $i = $this->getWriterIndex();
-               } elseif ( !is_array( $groups ) ) {
-                       $groupIndex = $this->getReaderIndex( $groups, $wiki );
-                       if ( $groupIndex !== false ) {
-                               $serverName = $this->getServerName( $groupIndex );
-                               wfDebug( __METHOD__ . ": using server $serverName for group $groups\n" );
-                               $i = $groupIndex;
-                       }
                } else {
+                       # Try to find an available server in any the query groups (in order)
                        foreach ( $groups as $group ) {
                                $groupIndex = $this->getReaderIndex( $group, $wiki );
                                if ( $groupIndex !== false ) {
@@ -476,7 +491,10 @@ class LoadBalancer {
                # Operation-based index
                if ( $i == DB_SLAVE ) {
                        $this->mLastError = 'Unknown error'; // reset error string
-                       $i = $this->getReaderIndex( false, $wiki );
+                       # Try the general server pool if $groups are unavailable.
+                       $i = in_array( false, $groups, true )
+                               ? false // don't bother with this if that is what was tried above
+                               : $this->getReaderIndex( false, $wiki );
                        # Couldn't find a working server in getReaderIndex()?
                        if ( $i === false ) {
                                $this->mLastError = 'No working slave server: ' . $this->mLastError;