Package com.linkedin.venice.message

Class KafkaKey

java.lang.Object

com.linkedin.venice.message.KafkaKey

public class KafkaKey
extends java.lang.Object

Class which stores the components of a Kafka Key, and is the format specified in the KafkaKeySerializer.

Field Summary

Fields

Modifier and Type	Field	Description
static int	CONTROL_MESSAGE_KAFKA_KEY_LENGTH	For control messages, the Key part of the KafkaKey includes the producer GUID, segment and sequence number.
static KafkaKey	HEART_BEAT

Constructor Summary

Constructors

Constructor	Description
KafkaKey(byte keyHeaderByte, byte[] key)
KafkaKey(MessageType messageType, byte[] key)

Method Summary

Modifier and Type	Method	Description
int	getEstimatedObjectSizeOnHeap()
byte[]	getKey()
byte	getKeyHeaderByte()	The key header byte is the first byte in the content of the Kafka key.
int	getKeyLength()
boolean	isControlMessage()
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

CONTROL_MESSAGE_KAFKA_KEY_LENGTH

public static final int CONTROL_MESSAGE_KAFKA_KEY_LENGTH

For control messages, the Key part of the KafkaKey includes the producer GUID, segment and sequence number. N.B.: This could be optimized further by defining an Avro record to hold this data, since Avro would use variable length encoding for the two integers, which would be smaller than their regular size.

HEART_BEAT

public static final KafkaKey HEART_BEAT

Constructor Detail

KafkaKey

public KafkaKey(@Nonnull
                MessageType messageType,
                byte[] key)

KafkaKey

public KafkaKey(byte keyHeaderByte,
                byte[] key)

Method Detail

getKeyHeaderByte

public byte getKeyHeaderByte()

The key header byte is the first byte in the content of the Kafka key. This is significant because it affects Kafka's Log Compaction. For MessageType.PUT and MessageType.DELETE, we want to use the exact same Kafka key, so the header byte needs to be the same. For control messages, however, we want them to be name-spaced on their own, so that they do not collide with the data when Log Compaction runs.

Returns:

a single byte: '0' for PUT and DELETE, or '2' for CONTROL_MESSAGE

isControlMessage

public boolean isControlMessage()

Returns:

true if this key corresponds to a control message, and false otherwise.

getKey

public byte[] getKey()

Returns:

the content of the key (everything beyond the first byte)

getKeyLength

public int getKeyLength()

getEstimatedObjectSizeOnHeap

public int getEstimatedObjectSizeOnHeap()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object