org.apache.flink.runtime.state.memory

Class ByteStreamStateHandle

java.lang.Object

org.apache.flink.runtime.state.memory.ByteStreamStateHandle

All Implemented Interfaces:

Serializable, StateObject, StreamStateHandle

public class ByteStreamStateHandle
extends Object
implements StreamStateHandle

A state handle that contains stream state in a byte array.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[]	data The state data.
protected String	handleName A unique name of by which this state handle is identified and compared.

Constructor Summary

Constructors

Constructor and Description
ByteStreamStateHandle(String handleName, byte[] data) Creates a new ByteStreamStateHandle containing the given data.

Method Summary

Methods

Modifier and Type	Method and Description
void	discardState() Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage.
boolean	equals(Object o)
byte[]	getData()
String	getHandleName()
long	getStateSize() Returns the size of the state in bytes.
int	hashCode()
FSDataInputStream	openInputStream() Returns an FSDataInputStream that can be used to read back the data that was previously written to the stream.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

data

protected final byte[] data

The state data.

handleName

protected final String handleName

A unique name of by which this state handle is identified and compared. Like a filename, all ByteStreamStateHandle with the exact same name must also have the exact same content in data.

Constructor Detail

ByteStreamStateHandle

public ByteStreamStateHandle(String handleName,
                     byte[] data)

Creates a new ByteStreamStateHandle containing the given data.

Method Detail

openInputStream

public FSDataInputStream openInputStream()
                                  throws IOException

Description copied from interface: StreamStateHandle

Returns an FSDataInputStream that can be used to read back the data that was previously written to the stream.

Specified by:

openInputStream in interface StreamStateHandle

Throws:

IOException

getData

public byte[] getData()

getHandleName

public String getHandleName()

discardState

public void discardState()

Description copied from interface: StateObject

Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage. This method is called when the state represented by this object will not be used any more.

Specified by:

discardState in interface StateObject

getStateSize

public long getStateSize()

Description copied from interface: StateObject

Returns the size of the state in bytes. If the the size is not known, this method should return 0.

The values produced by this method are only used for informational purposes and for metrics/monitoring. If this method returns wrong values, the checkpoints and recovery will still behave correctly. However, efficiency may be impacted (wrong space pre-allocation) and functionality that depends on metrics (like monitoring) will be impacted.

Note for implementors: This method should not perform any I/O operations while obtaining the state size (hence it does not declare throwing an IOException). Instead, the state size should be stored in the state object, or should be computable from the state stored in this object. The reason is that this method is called frequently by several parts of the checkpointing and issuing I/O requests from this method accumulates a heavy I/O load on the storage system at higher scale.

Specified by:

getStateSize in interface StateObject

Returns:

Size of the state in bytes.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object