<?php
/**
*
- * @package MediaWiki
*/
-/**
- * Depends on the database object
- */
-require_once( 'Database.php' );
-
-
-# Scale polling time so that under overload conditions, the database server
-# receives a SHOW STATUS query at an average interval of this many microseconds
-define( 'AVG_STATUS_POLL', 2000 );
-
/**
* Database load balancing object
*
* @todo document
- * @package MediaWiki
*/
class LoadBalancer {
/* private */ var $mServers, $mConnections, $mLoads, $mGroupLoads;
/* private */ var $mWaitForFile, $mWaitForPos, $mWaitTimeout;
/* private */ var $mLaggedSlaveMode, $mLastError = 'Unknown error';
- function LoadBalancer( $servers, $failFunction = false, $waitTimeout = 10, $waitForMasterNow = false )
+ function __construct( $servers, $failFunction = false, $waitTimeout = 10, $waitForMasterNow = false )
{
$this->mServers = $servers;
$this->mFailFunction = $failFunction;
$this->mWriteIndex = -1;
$this->mForce = -1;
$this->mConnections = array();
- $this->mLastIndex = 1;
+ $this->mLastIndex = -1;
$this->mLoads = array();
$this->mWaitForFile = false;
$this->mWaitForPos = false;
# Unset excessively lagged servers
$lags = $this->getLagTimes();
foreach ( $lags as $i => $lag ) {
- if ( isset( $this->mServers[$i]['max lag'] ) && $lag > $this->mServers[$i]['max lag'] ) {
+ if ( $i != 0 && isset( $this->mServers[$i]['max lag'] ) &&
+ ( $lag === false || $lag > $this->mServers[$i]['max lag'] ) )
+ {
unset( $loads[$i] );
}
}
* Side effect: opens connections to databases
*/
function getReaderIndex() {
- global $wgReadOnly, $wgDBClusterTimeout;
+ global $wgReadOnly, $wgDBClusterTimeout, $wgDBAvgStatusPoll;
$fname = 'LoadBalancer::getReaderIndex';
wfProfileIn( $fname );
$i = false;
if ( $this->mForce >= 0 ) {
$i = $this->mForce;
+ } elseif ( count( $this->mServers ) == 1 ) {
+ # Skip the load balancing if there's only one server
+ $i = 0;
} else {
if ( $this->mReadIndex >= 0 ) {
$i = $this->mReadIndex;
$i = $this->getRandomNonLagged( $loads );
if ( $i === false && count( $loads ) != 0 ) {
# All slaves lagged. Switch to read-only mode
- $wgReadOnly = wfMsgNoDB( 'readonly_lag' );
+ $wgReadOnly = wfMsgNoDBForContent( 'readonly_lag' );
$i = $this->pickRandom( $loads );
}
}
unset( $loads[$i] );
$sleepTime = 0;
} else {
- $status = $this->mConnections[$i]->getStatus("Thread%");
- if ( isset( $this->mServers[$i]['max threads'] ) &&
- $status['Threads_running'] > $this->mServers[$i]['max threads'] )
- {
+ if ( isset( $this->mServers[$i]['max threads'] ) ) {
+ $status = $this->mConnections[$i]->getStatus("Thread%");
+ if ( $status['Threads_running'] > $this->mServers[$i]['max threads'] ) {
# Too much load, back off and wait for a while.
# The sleep time is scaled by the number of threads connected,
# to produce a roughly constant global poll rate.
- $sleepTime = AVG_STATUS_POLL * $status['Threads_connected'];
+ $sleepTime = $wgDBAvgStatusPoll * $status['Threads_connected'];
# If we reach the timeout and exit the loop, don't use it
$i = false;
- } else {
+ } else {
$done = true;
$sleepTime = 0;
+ }
+ } else {
+ $done = true;
+ $sleepTime = 0;
}
}
} else {
# Query groups
if ( !is_array( $groups ) ) {
- $groupIndex = $this->getGroupIndex( $groups, $i );
+ $groupIndex = $this->getGroupIndex( $groups );
if ( $groupIndex !== false ) {
$i = $groupIndex;
}
} else {
foreach ( $groups as $group ) {
- $groupIndex = $this->getGroupIndex( $group, $i );
+ $groupIndex = $this->getGroupIndex( $group );
if ( $groupIndex !== false ) {
$i = $groupIndex;
break;
extract( $server );
# Get class for this database type
$class = 'Database' . ucfirst( $type );
- if ( !class_exists( $class ) ) {
- require_once( "$class.php" );
- }
# Create object
$db = new $class( $host, $user, $password, $dbname, 1, $flags );
return $db;
}
- function reportConnectionError( &$conn )
- {
+ function reportConnectionError( &$conn ) {
$fname = 'LoadBalancer::reportConnectionError';
wfProfileIn( $fname );
# Prevent infinite recursion
* Save master pos to the session and to memcached, if the session exists
*/
function saveMasterPos() {
- global $wgSessionStarted;
- if ( $wgSessionStarted && count( $this->mServers ) > 1 ) {
+ if ( session_id() != '' && count( $this->mServers ) > 1 ) {
# If this entire request was served from a slave without opening a connection to the
# master (however unlikely that may be), then we can fetch the position from the slave.
if ( empty( $this->mConnections[0] ) ) {
}
}
}
+
+ /* Issue COMMIT only on master, only if queries were done on connection */
+ function commitMasterChanges() {
+ // Always 0, but who knows.. :)
+ $i = $this->getWriterIndex();
+ if (array_key_exists($i,$this->mConnections)) {
+ if ($this->mConnections[$i]->lastQuery() != '') {
+ $this->mConnections[$i]->immediateCommit();
+ }
+ }
+ }
function waitTimeout( $value = NULL ) {
return wfSetVar( $this->mWaitTimeout, $value );
* Results are cached for a short time in memcached
*/
function getLagTimes() {
- global $wgDBname;
-
wfProfileIn( __METHOD__ );
$expiry = 5;
$requestRate = 10;
global $wgMemc;
- $times = $wgMemc->get( "$wgDBname:lag_times" );
+ $times = $wgMemc->get( wfMemcKey( 'lag_times' ) );
if ( $times ) {
# Randomly recache with probability rising over $expiry
$elapsed = time() - $times['timestamp'];
wfProfileOut( __METHOD__ );
return $times;
}
+ wfIncrStats( 'lag_cache_miss_expired' );
+ } else {
+ wfIncrStats( 'lag_cache_miss_absent' );
}
# Cache key missing or expired
# Add a timestamp key so we know when it was cached
$times['timestamp'] = time();
- $wgMemc->set( "$wgDBname:lag_times", $times, $expiry );
+ $wgMemc->set( wfMemcKey( 'lag_times' ), $times, $expiry );
# But don't give the timestamp to the caller
unset($times['timestamp']);
- wfIncrStats( 'lag_cache_miss' );
wfProfileOut( __METHOD__ );
return $times;
}
}
-?>
+
dépôts / lhc / web / wiklou.git / blobdiff