org.apache.flink.runtime.checkpoint.filemerging

Class SegmentFileStateHandle

java.lang.Object

org.apache.flink.runtime.checkpoint.filemerging.SegmentFileStateHandle

All Implemented Interfaces:

Serializable, StateObject, StreamStateHandle

public class SegmentFileStateHandle
extends Object
implements StreamStateHandle

FileStateHandle for state that was written to a file segment. A SegmentFileStateHandle represents a LogicalFile, which has already been written to a segment in a physical file.

TODO (FLINK-32079): serialization and deserialization of SegmentFileStateHandle.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.runtime.state.StateObject

StateObject.StateObjectLocation, StateObject.StateObjectSizeStatsCollector

Field Summary

Fields

Modifier and Type	Field and Description
protected long	stateSize The size of the state in the file.

Constructor Summary

Constructors

Constructor and Description
SegmentFileStateHandle(org.apache.flink.core.fs.Path filePath, long startPos, long stateSize, CheckpointedStateScope scope) Creates a new segment file state for the given file path.

Method Summary

Modifier and Type	Method and Description
Optional<byte[]>	asBytesIfInMemory()
void	discardState() This method should be empty, so that JM is not in charge of the lifecycle of files in a file-merging checkpoint.
boolean	equals(Object o)
org.apache.flink.core.fs.Path	getFilePath() Gets the path where this handle's state is stored.
CheckpointedStateScope	getScope()
long	getStartPos()
long	getStateSize() Returns the size of the state in bytes.
PhysicalStateHandleID	getStreamStateHandleID()
int	hashCode()
org.apache.flink.core.fs.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

Methods inherited from interface org.apache.flink.runtime.state.StateObject

collectSizeStats

Field Detail

stateSize

protected final long stateSize

The size of the state in the file.

Constructor Detail

SegmentFileStateHandle

public SegmentFileStateHandle(org.apache.flink.core.fs.Path filePath,
                              long startPos,
                              long stateSize,
                              CheckpointedStateScope scope)

Creates a new segment file state for the given file path.

Parameters:

filePath - The path to the file that stores the state.

startPos - Start position of the segment in the physical file.

stateSize - Size of the segment.

scope - The state's scope, whether it is exclusive or shared.

Method Detail

discardState

public void discardState()

This method should be empty, so that JM is not in charge of the lifecycle of files in a file-merging checkpoint.

Specified by:

discardState in interface StateObject

getFilePath

public org.apache.flink.core.fs.Path getFilePath()

Gets the path where this handle's state is stored.

Returns:

The path where this handle's state is stored.

openInputStream

public org.apache.flink.core.fs.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

asBytesIfInMemory

public Optional<byte[]> asBytesIfInMemory()

Specified by:

asBytesIfInMemory in interface StreamStateHandle

Returns:

Content of this handle as bytes array if it is already in memory.

getStreamStateHandleID

public PhysicalStateHandleID getStreamStateHandleID()

Specified by:

getStreamStateHandleID in interface StreamStateHandle

Returns:

a unique identifier of this handle.

getStartPos

public long getStartPos()

getStateSize

public long getStateSize()

Description copied from interface: StateObject

Returns the size of the state in bytes. If 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.

getScope

public CheckpointedStateScope getScope()

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