org.apache.flink.runtime.state

Class CheckpointStorageLocationReference

java.lang.Object

org.apache.flink.runtime.state.CheckpointStorageLocationReference

All Implemented Interfaces:

Serializable

public class CheckpointStorageLocationReference
extends Object
implements Serializable

A reference to a storage location. This is a wrapper around an array of bytes that are subject to interpretation by the state backend's storage locations (similar as a serializer needs to interpret byte streams). There is special handling for a 'default location', which can be used as an optimization by state backends, when no extra information is needed to determine where the checkpoints should be stored (all information can be derived from the configuration and the checkpoint id).

Why is this simply a byte array?

The reference is represented via raw bytes, which are subject to interpretation by the state backends. We did not add any more typing and serialization abstraction in between, because these types need to serialize/deserialize fast in between network streams (byte buffers) and barriers. We may ultimately add some more typing if we simply keep the byte buffers for the checkpoint barriers and forward them, thus saving decoding and re-encoding these references repeatedly.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
CheckpointStorageLocationReference(byte[] encodedReference) Creates a new location reference.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
static CheckpointStorageLocationReference	getDefault()
byte[]	getReferenceBytes() Gets the reference bytes.
int	hashCode()
boolean	isDefaultReference() Returns true, if this object is the default reference.
protected Object	readResolve() readResolve() preserves the singleton property of the default value.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CheckpointStorageLocationReference

public CheckpointStorageLocationReference(byte[] encodedReference)

Creates a new location reference.

Parameters:

encodedReference - The location reference, represented as bytes (non null)

Method Detail

getReferenceBytes

public byte[] getReferenceBytes()

Gets the reference bytes.

Important: For efficiency, this method does not make a defensive copy, so the caller must not modify the bytes in the array.

isDefaultReference

public boolean isDefaultReference()

Returns true, if this object is the default reference.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

readResolve

protected final Object readResolve()
                            throws ObjectStreamException

readResolve() preserves the singleton property of the default value.

Throws:

ObjectStreamException

getDefault

public static CheckpointStorageLocationReference getDefault()