org.apache.flink.runtime.state

Class IncrementalKeyedStateHandle

java.lang.Object

org.apache.flink.runtime.state.IncrementalKeyedStateHandle

All Implemented Interfaces:

Serializable, CompositeStateHandle, KeyedStateHandle, StateObject

public class IncrementalKeyedStateHandle
extends Object
implements KeyedStateHandle

The handle to states of an incremental snapshot.

The states contained in an incremental snapshot include:

• Created shared state which includes shared files produced since the last completed checkpoint. These files can be referenced by succeeding checkpoints if the checkpoint succeeds to complete.
• Referenced shared state which includes the shared files materialized in previous checkpoints. Until we this is registered to a SharedStateRegistry, all referenced shared state handles are only placeholders, so that we do not send state handles twice from which we know that they already exist on the checkpoint coordinator.
• Private state which includes all other files, typically mutable, that cannot be shared by other checkpoints.
• Backend meta state which includes the information of existing states.

When this should become a completed checkpoint on the checkpoint coordinator, it must first be registered with a SharedStateRegistry, so that all placeholder state handles to previously existing state are replaced with the originals. IMPORTANT: This class currently overrides equals and hash code only for testing purposes. They should not be called from production code. This means this class is also not suited to serve as a key, e.g. in hash maps.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
IncrementalKeyedStateHandle(UUID backendIdentifier, KeyGroupRange keyGroupRange, long checkpointId, Map<StateHandleID,StreamStateHandle> sharedState, Map<StateHandleID,StreamStateHandle> privateState, StreamStateHandle metaStateHandle)

Method Summary

Modifier and Type	Method and Description
SharedStateRegistryKey	createSharedStateRegistryKeyFromFileName(StateHandleID shId) Create a unique key to register one of our shared state handles.
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) This method is should only be called in tests! This should never serve as key in a hash map.
UUID	getBackendIdentifier()
long	getCheckpointId()
KeyedStateHandle	getIntersection(KeyGroupRange keyGroupRange) Returns a state over a range that is the intersection between this handle's key-group range and the provided key-group range.
KeyGroupRange	getKeyGroupRange() Returns the range of the key groups contained in the state.
StreamStateHandle	getMetaStateHandle()
Map<StateHandleID,StreamStateHandle>	getPrivateState()
Map<StateHandleID,StreamStateHandle>	getSharedState()
SharedStateRegistry	getSharedStateRegistry()
long	getStateSize() Returns the size of the state in bytes.
int	hashCode() This method should only be called in tests! This should never serve as key in a hash map.
void	registerSharedStates(SharedStateRegistry stateRegistry) Register both newly created and already referenced shared states in the given SharedStateRegistry.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

IncrementalKeyedStateHandle

public IncrementalKeyedStateHandle(UUID backendIdentifier,
                                   KeyGroupRange keyGroupRange,
                                   long checkpointId,
                                   Map<StateHandleID,StreamStateHandle> sharedState,
                                   Map<StateHandleID,StreamStateHandle> privateState,
                                   StreamStateHandle metaStateHandle)

Method Detail

getKeyGroupRange

public KeyGroupRange getKeyGroupRange()

Description copied from interface: KeyedStateHandle

Returns the range of the key groups contained in the state.

Specified by:

getKeyGroupRange in interface KeyedStateHandle

getCheckpointId

public long getCheckpointId()

getSharedState

public Map<StateHandleID,StreamStateHandle> getSharedState()

getPrivateState

public Map<StateHandleID,StreamStateHandle> getPrivateState()

getMetaStateHandle

public StreamStateHandle getMetaStateHandle()

getBackendIdentifier

public UUID getBackendIdentifier()

getSharedStateRegistry

public SharedStateRegistry getSharedStateRegistry()

getIntersection

public KeyedStateHandle getIntersection(KeyGroupRange keyGroupRange)

Description copied from interface: KeyedStateHandle

Returns a state over a range that is the intersection between this handle's key-group range and the provided key-group range.

Specified by:

getIntersection in interface KeyedStateHandle

Parameters:

keyGroupRange - The key group range to intersect with

discardState

public void discardState()
                  throws Exception

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

Throws:

Exception

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.

registerSharedStates

public void registerSharedStates(SharedStateRegistry stateRegistry)

Description copied from interface: CompositeStateHandle

Register both newly created and already referenced shared states in the given SharedStateRegistry. This method is called when the checkpoint successfully completes or is recovered from failures.

After this is completed, newly created shared state is considered as published is no longer owned by this handle. This means that it should no longer be deleted as part of calls to StateObject.discardState(). Instead, StateObject.discardState() will trigger an unregistration from the registry.

Specified by:

registerSharedStates in interface CompositeStateHandle

Parameters:

stateRegistry - The registry where shared states are registered.

createSharedStateRegistryKeyFromFileName

@VisibleForTesting
public SharedStateRegistryKey createSharedStateRegistryKeyFromFileName(StateHandleID shId)

Create a unique key to register one of our shared state handles.

equals

@VisibleForTesting
public boolean equals(Object o)

This method is should only be called in tests! This should never serve as key in a hash map.

Overrides:

equals in class Object

hashCode

@VisibleForTesting
public int hashCode()

This method should only be called in tests! This should never serve as key in a hash map.

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object