private $mLaggedSlaveMode;
/** @var string The last DB selection or connection error */
private $mLastError = 'Unknown error';
- /** @var array Process cache of LoadMonitor::getLagTimes() */
- private $mLagTimes;
+ /** @var ProcessCacheLRU */
+ private $mProcCache;
/**
* @param array $params Array with keys:
}
}
}
+
+ $this->mProcCache = new ProcessCacheLRU( 30 );
}
/**
return $i;
}
- /**
- * Wait for a specified number of microseconds, and return the period waited
- * @param int $t
- * @return int
- */
- function sleep( $t ) {
- wfProfileIn( __METHOD__ );
- wfDebug( __METHOD__ . ": waiting $t us\n" );
- usleep( $t );
- wfProfileOut( __METHOD__ );
-
- return $t;
- }
-
/**
* Set the master wait position
* If a DB_SLAVE connection has been opened already, waits
* @return bool
*/
protected function doWait( $index, $open = false, $timeout = null ) {
- # Find a connection to wait on
+ $close = false; // close the connection afterwards
+
+ # Find a connection to wait on, creating one if needed and allowed
$conn = $this->getAnyOpenConnection( $index );
if ( !$conn ) {
if ( !$open ) {
return false;
}
+ // Avoid connection spam in waitForAll() when connections
+ // are made just for the sake of doing this lag check.
+ $close = true;
}
}
if ( $result == -1 || is_null( $result ) ) {
# Timed out waiting for slave, use master instead
- wfDebug( __METHOD__ . ": Timed out waiting for slave #$index pos {$this->mWaitForPos}\n" );
-
- return false;
+ $server = $this->mServers[$index];
+ $msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
+ wfDebug( "$msg\n" );
+ wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
+ $ok = false;
} else {
wfDebug( __METHOD__ . ": Done\n" );
+ $ok = true;
+ }
- return true;
+ if ( $close ) {
+ $this->closeConnection( $conn );
}
+
+ return $ok;
}
/**
$conn = reset( $this->mConns['foreignFree'][$i] );
$oldWiki = key( $this->mConns['foreignFree'][$i] );
- if ( !$conn->selectDB( $dbName ) ) {
+ // The empty string as a DB name means "don't care".
+ // DatabaseMysqlBase::open() already handle this on connection.
+ if ( $dbName !== '' && !$conn->selectDB( $dbName ) ) {
$this->mLastError = "Error selecting database $dbName on server " .
$conn->getServer() . " from client host " . wfHostname() . "\n";
$this->mErrorConnection = $conn;
*/
private function reportConnectionError() {
$conn = $this->mErrorConnection; // The connection which caused the error
+ $context = array(
+ 'method' => __METHOD__,
+ 'last_error' => $this->mLastError,
+ );
if ( !is_object( $conn ) ) {
// No last connection, probably due to all servers being too busy
- wfLogDBError( "LB failure with no last connection. Connection error: {$this->mLastError}" );
+ wfLogDBError(
+ "LB failure with no last connection. Connection error: {last_error}",
+ $context
+ );
// If all servers were busy, mLastError will contain something sensible
throw new DBConnectionError( null, $this->mLastError );
} else {
- $server = $conn->getProperty( 'mServer' );
- wfLogDBError( "Connection error: {$this->mLastError} ({$server})" );
- $conn->reportConnectionError( "{$this->mLastError} ({$server})" ); // throws DBConnectionError
+ $context['db_server'] = $conn->getProperty( 'mServer' );
+ wfLogDBError(
+ "Connection error: {last_error} ({db_server})",
+ $context
+ );
+ $conn->reportConnectionError( "{$this->mLastError} ({$context['db_server']})" ); // throws DBConnectionError
}
return false; /* not reached */
}
/**
- * Get the hostname and lag time of the most-lagged slave.
+ * Get the hostname and lag time of the most-lagged slave
+ *
* This is useful for maintenance scripts that need to throttle their updates.
* May attempt to open connections to slaves on the default DB. If there is
* no lag, the maximum lag will be reported as -1.
$host = '';
$maxIndex = 0;
- if ( $this->getServerCount() <= 1 ) { // no replication = no lag
- return array( $host, $maxLag, $maxIndex );
+ if ( $this->getServerCount() <= 1 ) {
+ return array( $host, $maxLag, $maxIndex ); // no replication = no lag
}
- // Try to get the max lag info from the server cache
- $key = 'loadbalancer:maxlag:cluster:' . $this->mServers[0]['host'];
- $cache = ObjectCache::newAccelerator( array(), 'hash' );
- $maxLagInfo = $cache->get( $key ); // (host, lag, index)
-
- // Fallback to connecting to each slave and getting the lag
- if ( !$maxLagInfo ) {
- foreach ( $this->mServers as $i => $conn ) {
- if ( $i == $this->getWriterIndex() ) {
- continue; // nothing to check
- }
- $conn = false;
- if ( $wiki === false ) {
- $conn = $this->getAnyOpenConnection( $i );
- }
- if ( !$conn ) {
- $conn = $this->openConnection( $i, $wiki );
- }
- if ( !$conn ) {
- continue;
- }
- $lag = $conn->getLag();
- if ( $lag > $maxLag ) {
- $maxLag = $lag;
- $host = $this->mServers[$i]['host'];
- $maxIndex = $i;
- }
+ $lagTimes = $this->getLagTimes( $wiki );
+ foreach ( $lagTimes as $i => $lag ) {
+ if ( $lag > $maxLag ) {
+ $maxLag = $lag;
+ $host = $this->mServers[$i]['host'];
+ $maxIndex = $i;
}
- $maxLagInfo = array( $host, $maxLag, $maxIndex );
- $cache->set( $key, $maxLagInfo, 5 );
}
- return $maxLagInfo;
+ return array( $host, $maxLag, $maxIndex );
}
/**
* Get lag time for each server
- * Results are cached for a short time in memcached, and indefinitely in the process cache
+ *
+ * Results are cached for a short time in memcached/process cache
*
* @param string|bool $wiki
* @return array Map of (server index => seconds)
*/
function getLagTimes( $wiki = false ) {
- # Try process cache
- if ( isset( $this->mLagTimes ) ) {
- return $this->mLagTimes;
+ if ( $this->getServerCount() <= 1 ) {
+ return array( 0 => 0 ); // no replication = no lag
}
- if ( $this->getServerCount() == 1 ) {
- # No replication
- $this->mLagTimes = array( 0 => 0 );
- } else {
- # Send the request to the load monitor
- $this->mLagTimes = $this->getLoadMonitor()->getLagTimes(
- array_keys( $this->mServers ), $wiki );
+
+ if ( $this->mProcCache->has( 'slave_lag', 'times', 1 ) ) {
+ return $this->mProcCache->get( 'slave_lag', 'times' );
}
- return $this->mLagTimes;
+ # Send the request to the load monitor
+ $times = $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $wiki );
+
+ $this->mProcCache->set( 'slave_lag', 'times', $times );
+
+ return $times;
}
/**
}
/**
- * Clear the cache for getLagTimes
+ * Clear the cache for slag lag delay times
*/
function clearLagTimeCache() {
- $this->mLagTimes = null;
+ $this->mProcCache->clear( 'slave_lag' );
}
}
/**
- * Helper class to handle automatically marking connectons as reusable (via RAII pattern)
+ * Helper class to handle automatically marking connections as reusable (via RAII pattern)
* as well handling deferring the actual network connection until the handle is used
*
* @ingroup Database
dépôts / lhc / web / wiklou.git / blobdiff