1 files changed, 224 insertions, 0 deletions
diff --git a/includes/debug/logger/monolog/KafkaHandler.php b/includes/debug/logger/monolog/KafkaHandler.php
new file mode 100644
index 00000000..59d7764a
--- /dev/null
+++ b/includes/debug/logger/monolog/KafkaHandler.php
@@ -0,0 +1,224 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\Logger\Monolog;
+
+use Kafka\MetaDataFromKafka;
+use Kafka\Produce;
+use MediaWiki\Logger\LoggerFactory;
+use Monolog\Handler\AbstractProcessingHandler;
+use Monolog\Logger;
+use Psr\Log\LoggerInterface;
+
+/**
+ * Log handler sends log events to a kafka server.
+ *
+ * Constructor options array arguments:
+ * * alias: map from monolog channel to kafka topic name. When no
+ *	  alias exists the topic "monolog_$channel" will be used.
+ * * swallowExceptions: Swallow exceptions that occur while talking to
+ *    kafka. Defaults to false.
+ * * logExceptions: Log exceptions talking to kafka here. Either null,
+ *    the name of a channel to log to, or an object implementing
+ *    FormatterInterface. Defaults to null.
+ *
+ * Requires the nmred/kafka-php library, version >= 1.3.0
+ *
+ * @since 1.26
+ * @author Erik Bernhardson <ebernhardson@wikimedia.org>
+ * @copyright © 2015 Erik Bernhardson and Wikimedia Foundation.
+ */
+class KafkaHandler extends AbstractProcessingHandler {
+	/**
+	 * @var Produce Sends requests to kafka
+	 */
+	protected $produce;
+
+	/**
+	 * @var array Optional handler configuration
+	 */
+	protected $options;
+
+	/**
+	 * @var array Map from topic name to partition this request produces to
+	 */
+	protected $partitions = array();
+
+	/**
+	 * @var array defaults for constructor options
+	 */
+	private static $defaultOptions = array(
+		'alias' => array(), // map from monolog channel to kafka topic
+		'swallowExceptions' => false, // swallow exceptions sending records
+		'logExceptions' => null, // A PSR3 logger to inform about errors
+	);
+
+	/**
+	 * @param Produce $produce Kafka instance to produce through
+	 * @param array $options optional handler configuration
+	 * @param int $level The minimum logging level at which this handler will be triggered
+	 * @param bool $bubble Whether the messages that are handled can bubble up the stack or not
+	 */
+	public function __construct( Produce $produce, array $options, $level = Logger::DEBUG, $bubble = true ) {
+		parent::__construct( $level, $bubble );
+		$this->produce = $produce;
+		$this->options = array_merge( self::$defaultOptions, $options );
+	}
+
+	/**
+	 * Constructs the necessary support objects and returns a KafkaHandler
+	 * instance.
+	 *
+	 * @param string[] $kafkaServers
+	 * @param array $options
+	 * @param int $level The minimum logging level at which this handle will be triggered
+	 * @param bool $bubble Whether the messages that are handled can bubble the stack or not
+	 * @return KafkaHandler
+	 */
+	public static function factory( $kafkaServers, array $options = array(), $level = Logger::DEBUG, $bubble = true ) {
+		$metadata = new MetaDataFromKafka( $kafkaServers );
+		$produce = new Produce( $metadata );
+		if ( isset( $options['logExceptions'] ) && is_string( $options['logExceptions'] ) ) {
+			$options['logExceptions'] = LoggerFactory::getInstance( $options['logExceptions'] );
+		}
+		return new self( $produce, $options, $level, $bubble );
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	protected function write( array $record ) {
+		if ( $record['formatted'] !== null ) {
+			$this->addMessages( $record['channel'], array( $record['formatted'] ) );
+			$this->send();
+		}
+	}
+
+	/**
+	 * {@inheritDoc}
+	 */
+	public function handleBatch( array $batch ) {
+		$channels = array();
+		foreach ( $batch as $record ) {
+			if ( $record['level'] < $this->level ) {
+				continue;
+			}
+			$channels[$record['channel']][] = $this->processRecord( $record );
+		}
+
+		$formatter = $this->getFormatter();
+		foreach ( $channels as $channel => $records ) {
+			$messages = array();
+			foreach ( $records as $idx => $record ) {
+				$message = $formatter->format( $record );
+				if ( $message !== null ) {
+					$messages[] = $message;
+				}
+			}
+			if ( $messages ) {
+				$this->addMessages($channel, $messages);
+			}
+		}
+
+		$this->send();
+	}
+
+	/**
+	 * Send any records in the kafka client internal queue.
+	 */
+	protected function send() {
+		try {
+			$this->produce->send();
+		} catch ( \Kafka\Exception $e ) {
+			$ignore = $this->warning(
+				'Error sending records to kafka: {exception}',
+				array( 'exception' => $e ) );
+			if ( !$ignore ) {
+				throw $e;
+			}
+		}
+	}
+
+	/**
+	 * @param string $topic Name of topic to get partition for
+	 * @return int|null The random partition to produce to for this request,
+	 *  or null if a partition could not be determined.
+	 */
+	protected function getRandomPartition( $topic ) {
+		if ( !array_key_exists( $topic, $this->partitions ) ) {
+			try {
+				$partitions = $this->produce->getAvailablePartitions( $topic );
+			} catch ( \Kafka\Exception $e ) {
+				$ignore = $this->warning(
+					'Error getting metadata for kafka topic {topic}: {exception}',
+					array( 'topic' => $topic, 'exception' => $e ) );
+				if ( $ignore ) {
+					return null;
+				}
+				throw $e;
+			}
+			if ( $partitions ) {
+				$key = array_rand( $partitions );
+				$this->partitions[$topic] = $partitions[$key];
+			} else {
+				$details = $this->produce->getClient()->getTopicDetail( $topic );
+				$ignore = $this->warning(
+					'No partitions available for kafka topic {topic}',
+					array( 'topic' => $topic, 'kafka' => $details )
+				);
+				if ( !$ignore ) {
+					throw new \RuntimeException( "No partitions available for kafka topic $topic" );
+				}
+				$this->partitions[$topic] = null;
+			}
+		}
+		return $this->partitions[$topic];
+	}
+
+	/**
+	 * Adds records for a channel to the Kafka client internal queue.
+	 *
+	 * @param string $channel Name of Monolog channel records belong to
+	 * @param array $records List of records to append
+	 */
+	protected function addMessages( $channel, array $records ) {
+		if ( isset( $this->options['alias'][$channel] ) ) {
+			$topic = $this->options['alias'][$channel];
+		} else {
+			$topic = "monolog_$channel";
+		}
+		$partition = $this->getRandomPartition( $topic );
+		if ( $partition !== null ) {
+			$this->produce->setMessages( $topic, $partition, $records );
+		}
+	}
+
+	/**
+	 * @param string $message PSR3 compatible message string
+	 * @param array $context PSR3 compatible log context
+	 * @return bool true if caller should ignore warning
+	 */
+	protected function warning( $message, array $context = array() ) {
+		if ( $this->options['logExceptions'] instanceof LoggerInterface ) {
+			$this->options['logExceptions']->warning( $message, $context );
+		}
+		return $this->options['swallowExceptions'];
+	}
+}