* @ingroup Database
*/
class LoadBalancer {
- /** @var array Map of (server index => server config array) */
+ /** @var array[] Map of (server index => server config array) */
private $mServers;
- /** @var array Map of (local/foreignUsed/foreignFree => server index => DatabaseBase array) */
+ /** @var array[] Map of (local/foreignUsed/foreignFree => server index => DatabaseBase array) */
private $mConns;
/** @var array Map of (server index => weight) */
private $mLoads;
- /** @var array Map of (group => server index => weight) */
+ /** @var array[] Map of (group => server index => weight) */
private $mGroupLoads;
/** @var bool Whether to disregard slave lag as a factor in slave selection */
private $mAllowLagged;
private $mLaggedSlaveMode;
/** @var string The last DB selection or connection error */
private $mLastError = 'Unknown error';
+ /** @var integer Total connections opened */
+ private $connsOpened = 0;
/** @var ProcessCacheLRU */
private $mProcCache;
+ /** @var integer Warn when this many connection are held */
+ const CONN_HELD_WARN_THRESHOLD = 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.
* @throws MWException
*/
- function __construct( $params ) {
+ public function __construct( array $params ) {
if ( !isset( $params['servers'] ) ) {
throw new MWException( __CLASS__ . ': missing servers parameter' );
}
*
* @return LoadMonitor
*/
- function getLoadMonitor() {
+ private function getLoadMonitor() {
if ( !isset( $this->mLoadMonitor ) ) {
$class = $this->mLoadMonitorClass;
$this->mLoadMonitor = new $class( $this );
* @param mixed $x
* @return mixed
*/
- function parentInfo( $x = null ) {
+ public function parentInfo( $x = null ) {
return wfSetVar( $this->mParentInfo, $x );
}
* @param array $weights
* @return bool|int|string
*/
- function pickRandom( $weights ) {
+ public function pickRandom( array $weights ) {
return ArrayUtils::pickRandom( $weights );
}
/**
* @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
*/
- function getRandomNonLagged( $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] );
}
* always return a consistent index during a given invocation
*
* Side effect: opens connections to databases
- * @param bool|string $group
- * @param bool|string $wiki
+ * @param string|bool $group Query group, or false for the generic reader
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
* @throws MWException
* @return bool|int|string
*/
- function getReaderIndex( $group = false, $wiki = false ) {
+ public function getReaderIndex( $group = false, $wiki = false ) {
global $wgReadOnly, $wgDBtype;
# @todo FIXME: For now, only go through all this for mysql databases
return $this->mReadIndex;
}
- $section = new ProfileSection( __METHOD__ );
-
# Find the relevant load array
if ( $group !== false ) {
if ( isset( $this->mGroupLoads[$group] ) ) {
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" );
* @param DBMasterPos $pos
*/
public function waitFor( $pos ) {
- wfProfileIn( __METHOD__ );
$this->mWaitForPos = $pos;
$i = $this->mReadIndex;
$this->mLaggedSlaveMode = true;
}
}
- wfProfileOut( __METHOD__ );
}
/**
* @return bool Success (able to connect and no timeouts reached)
*/
public function waitForAll( $pos, $timeout = null ) {
- wfProfileIn( __METHOD__ );
$this->mWaitForPos = $pos;
$serverCount = count( $this->mServers );
$ok = $this->doWait( $i, true, $timeout ) && $ok;
}
}
- wfProfileOut( __METHOD__ );
return $ok;
}
* @param int $i
* @return DatabaseBase|bool False on failure
*/
- function getAnyOpenConnection( $i ) {
+ public function getAnyOpenConnection( $i ) {
foreach ( $this->mConns as $conns ) {
if ( !empty( $conns[$i] ) ) {
return reset( $conns[$i] );
if ( $result == -1 || is_null( $result ) ) {
# Timed out waiting for slave, use master instead
- $server = $this->mServers[$index];
+ $server = $this->mServers[$index]['host'];
$msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
wfDebug( "$msg\n" );
wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
* This is the main entry point for this class.
*
* @param int $i Server index
- * @param array $groups Query groups
- * @param bool|string $wiki Wiki ID
+ * @param array|string|bool $groups Query group(s), or false for the generic reader
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
*
* @throws MWException
* @return DatabaseBase
*/
- public function &getConnection( $i, $groups = array(), $wiki = false ) {
- wfProfileIn( __METHOD__ );
-
+ public function getConnection( $i, $groups = array(), $wiki = false ) {
if ( $i === null || $i === false ) {
- wfProfileOut( __METHOD__ );
throw new MWException( 'Attempt to call ' . __METHOD__ .
' with invalid server index' );
}
$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 ) {
# 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;
- wfProfileOut( __METHOD__ );
return $this->reportConnectionError();
}
# Now we have an explicit index into the servers array
$conn = $this->openConnection( $i, $wiki );
if ( !$conn ) {
- wfProfileOut( __METHOD__ );
return $this->reportConnectionError();
}
- wfProfileOut( __METHOD__ );
-
return $conn;
}
* @see LoadBalancer::getConnection() for parameter information
*
* @param int $db
- * @param mixed $groups
- * @param bool|string $wiki
+ * @param array|string|bool $groups Query group(s), or false for the generic reader
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
* @return DBConnRef
*/
public function getConnectionRef( $db, $groups = array(), $wiki = false ) {
* @see LoadBalancer::getConnection() for parameter information
*
* @param int $db
- * @param mixed $groups
- * @param bool|string $wiki
+ * @param array|string|bool $groups Query group(s), or false for the generic reader
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
* @return DBConnRef
*/
public function getLazyConnectionRef( $db, $groups = array(), $wiki = false ) {
* error will be available via $this->mErrorConnection.
*
* @param int $i Server index
- * @param bool|string $wiki Wiki ID to open
+ * @param string|bool $wiki Wiki ID, or false for the current wiki
* @return DatabaseBase
*
* @access private
*/
- function openConnection( $i, $wiki = false ) {
- wfProfileIn( __METHOD__ );
+ public function openConnection( $i, $wiki = false ) {
if ( $wiki !== false ) {
$conn = $this->openForeignConnection( $i, $wiki );
- wfProfileOut( __METHOD__ );
return $conn;
}
$conn = false;
}
}
- wfProfileOut( __METHOD__ );
return $conn;
}
* @param string $wiki Wiki ID to open
* @return DatabaseBase
*/
- function openForeignConnection( $i, $wiki ) {
- wfProfileIn( __METHOD__ );
+ private function openForeignConnection( $i, $wiki ) {
list( $dbName, $prefix ) = wfSplitWikiID( $wiki );
if ( isset( $this->mConns['foreignUsed'][$i][$wiki] ) ) {
// Reuse an already-used connection
$refCount = $conn->getLBInfo( 'foreignPoolRefCount' );
$conn->setLBInfo( 'foreignPoolRefCount', $refCount + 1 );
}
- wfProfileOut( __METHOD__ );
return $conn;
}
* @access private
* @return bool
*/
- function isOpen( $index ) {
+ private function isOpen( $index ) {
if ( !is_integer( $index ) ) {
return false;
}
* @throws MWException
* @return DatabaseBase
*/
- function reallyOpenConnection( $server, $dbNameOverride = false ) {
+ protected function reallyOpenConnection( $server, $dbNameOverride = false ) {
if ( !is_array( $server ) ) {
throw new MWException( 'You must update your load-balancing configuration. ' .
'See DefaultSettings.php entry for $wgDBservers.' );
$server['dbname'] = $dbNameOverride;
}
+ // Log when many connection are made on requests
+ if ( ++$this->connsOpened >= self::CONN_HELD_WARN_THRESHOLD ) {
+ $masterAddr = $this->getServerName( 0 );
+ wfDebugLog( 'DBPerformance', __METHOD__ . ": " .
+ "{$this->connsOpened}+ connections made (master=$masterAddr)\n" .
+ wfBacktrace( true ) );
+ }
+
# Create object
try {
$db = DatabaseBase::factory( $server['type'], $server );
/**
* @return int
*/
- function getWriterIndex() {
+ private function getWriterIndex() {
return 0;
}
* @param string $i
* @return bool
*/
- function haveIndex( $i ) {
+ public function haveIndex( $i ) {
return array_key_exists( $i, $this->mServers );
}
* @param string $i
* @return bool
*/
- function isNonZeroLoad( $i ) {
+ public function isNonZeroLoad( $i ) {
return array_key_exists( $i, $this->mServers ) && $this->mLoads[$i] != 0;
}
*
* @return int
*/
- function getServerCount() {
+ public function getServerCount() {
return count( $this->mServers );
}
* @param string $i
* @return string
*/
- function getServerName( $i ) {
+ public function getServerName( $i ) {
if ( isset( $this->mServers[$i]['hostName'] ) ) {
return $this->mServers[$i]['hostName'];
} elseif ( isset( $this->mServers[$i]['host'] ) ) {
* @param int $i
* @return array|bool
*/
- function getServerInfo( $i ) {
+ public function getServerInfo( $i ) {
if ( isset( $this->mServers[$i] ) ) {
return $this->mServers[$i];
} else {
* @param int $i
* @param array $serverInfo
*/
- function setServerInfo( $i, $serverInfo ) {
+ public function setServerInfo( $i, array $serverInfo ) {
$this->mServers[$i] = $serverInfo;
}
* Get the current master position for chronology control purposes
* @return mixed
*/
- function getMasterPos() {
+ public function getMasterPos() {
# 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.
$masterConn = $this->getAnyOpenConnection( 0 );
/**
* Close all open connections
*/
- function closeAll() {
+ public function closeAll() {
foreach ( $this->mConns as $conns2 ) {
foreach ( $conns2 as $conns3 ) {
/** @var DatabaseBase $conn */
'foreignFree' => array(),
'foreignUsed' => array(),
);
+ $this->connsOpened = 0;
}
/**
* If you use $conn->close() directly, the load balancer won't update its state.
* @param DatabaseBase $conn
*/
- function closeConnection( $conn ) {
+ public function closeConnection( $conn ) {
$done = false;
foreach ( $this->mConns as $i1 => $conns2 ) {
foreach ( $conns2 as $i2 => $conns3 ) {
if ( $conn === $candidateConn ) {
$conn->close();
unset( $this->mConns[$i1][$i2][$i3] );
+ --$this->connsOpened;
$done = true;
break;
}
/**
* Commit transactions on all open connections
*/
- function commitAll() {
+ public function commitAll() {
foreach ( $this->mConns as $conns2 ) {
foreach ( $conns2 as $conns3 ) {
/** @var DatabaseBase[] $conns3 */
/**
* Issue COMMIT only on master, only if queries were done on connection
*/
- function commitMasterChanges() {
+ public function commitMasterChanges() {
// Always 0, but who knows.. :)
$masterIndex = $this->getWriterIndex();
foreach ( $this->mConns as $conns2 ) {
* Issue ROLLBACK only on master, only if queries were done on connection
* @since 1.23
*/
- function rollbackMasterChanges() {
+ public function rollbackMasterChanges() {
// Always 0, but who knows.. :)
$masterIndex = $this->getWriterIndex();
foreach ( $this->mConns as $conns2 ) {
* @return bool Whether a master connection is already open
* @since 1.24
*/
- function hasMasterConnection() {
+ public function hasMasterConnection() {
return $this->isOpen( $this->getWriterIndex() );
}
* @since 1.23
* @return bool
*/
- function hasMasterChanges() {
+ public function hasMasterChanges() {
// Always 0, but who knows.. :)
$masterIndex = $this->getWriterIndex();
foreach ( $this->mConns as $conns2 ) {
* @param mixed $value
* @return mixed
*/
- function waitTimeout( $value = null ) {
+ public function waitTimeout( $value = null ) {
return wfSetVar( $this->mWaitTimeout, $value );
}
/**
* @return bool
*/
- function getLaggedSlaveMode() {
+ public function getLaggedSlaveMode() {
return $this->mLaggedSlaveMode;
}
* @param null|bool $mode
* @return bool
*/
- function allowLagged( $mode = null ) {
+ public function allowLagged( $mode = null ) {
if ( $mode === null ) {
return $this->mAllowLagged;
}
/**
* @return bool
*/
- function pingAll() {
+ public function pingAll() {
$success = true;
foreach ( $this->mConns as $conns2 ) {
foreach ( $conns2 as $conns3 ) {
* @param callable $callback
* @param array $params
*/
- function forEachOpenConnection( $callback, $params = array() ) {
+ public function forEachOpenConnection( $callback, array $params = array() ) {
foreach ( $this->mConns as $conns2 ) {
foreach ( $conns2 as $conns3 ) {
foreach ( $conns3 as $conn ) {
* @param bool|string $wiki Wiki ID, or false for the default database
* @return array ( host, max lag, index of max lagged host )
*/
- function getMaxLag( $wiki = false ) {
+ public function getMaxLag( $wiki = false ) {
$maxLag = -1;
$host = '';
$maxIndex = 0;
* Results are cached for a short time in memcached/process cache
*
* @param string|bool $wiki
- * @return array Map of (server index => seconds)
+ * @return int[] Map of (server index => seconds)
*/
- function getLagTimes( $wiki = false ) {
+ public function getLagTimes( $wiki = false ) {
if ( $this->getServerCount() <= 1 ) {
return array( 0 => 0 ); // no replication = no lag
}
* @param DatabaseBase $conn
* @return int
*/
- function safeGetLag( $conn ) {
+ public function safeGetLag( $conn ) {
if ( $this->getServerCount() == 1 ) {
return 0;
} else {
/**
* Clear the cache for slag lag delay times
*/
- function clearLagTimeCache() {
+ public function clearLagTimeCache() {
$this->mProcCache->clear( 'slave_lag' );
}
}
*/
class DBConnRef implements IDatabase {
/** @var LoadBalancer */
- protected $lb;
+ private $lb;
/** @var DatabaseBase|null */
- protected $conn;
+ private $conn;
/** @var array|null */
- protected $params;
+ private $params;
/**
* @param LoadBalancer $lb
return call_user_func_array( array( $this->conn, $name ), $arguments );
}
- function __destruct() {
+ public function __destruct() {
if ( $this->conn !== null ) {
$this->lb->reuseConnection( $this->conn );
}
dépôts / lhc / web / wiklou.git / blobdiff