org.apache.flink.runtime.state

Interface SharedStateRegistry

All Superinterfaces:

AutoCloseable

All Known Implementing Classes:

SharedStateRegistryImpl

public interface SharedStateRegistry
extends AutoCloseable

This registry manages state that is shared across (incremental) checkpoints, and is responsible for deleting shared state that is no longer used in any valid checkpoint.

A SharedStateRegistry will be deployed in the CheckpointCoordinator to keep track of usage of StreamStateHandles by a key that (logically) identifies them.

Field Summary

Fields

Modifier and Type	Field and Description
static SharedStateRegistryFactory	DEFAULT_FACTORY A singleton object for the default implementation of a SharedStateRegistryFactory

Method Summary

Modifier and Type	Method and Description
void	checkpointCompleted(long checkpointId)
void	registerAll(Iterable<? extends CompositeStateHandle> stateHandles, long checkpointID) Register given shared states in the registry.
void	registerAllAfterRestored(CompletedCheckpoint checkpoint, RestoreMode mode) Set the lowest checkpoint ID below which no state is discarded, inclusive.
default StreamStateHandle	registerReference(SharedStateRegistryKey registrationKey, StreamStateHandle state, long checkpointID) Shortcut for registerReference(SharedStateRegistryKey, StreamStateHandle, long, boolean) with preventDiscardingCreatedCheckpoint = false.
StreamStateHandle	registerReference(SharedStateRegistryKey registrationKey, StreamStateHandle state, long checkpointID, boolean preventDiscardingCreatedCheckpoint) Register a reference to the given shared state in the registry.
Set<Long>	unregisterUnusedState(long lowestCheckpointID) Unregister state that is not referenced by the given checkpoint ID or any newer.

Methods inherited from interface java.lang.AutoCloseable

close

Field Detail

DEFAULT_FACTORY

static final SharedStateRegistryFactory DEFAULT_FACTORY

A singleton object for the default implementation of a SharedStateRegistryFactory

Method Detail

registerReference

default StreamStateHandle registerReference(SharedStateRegistryKey registrationKey,
                                            StreamStateHandle state,
                                            long checkpointID)

Shortcut for registerReference(SharedStateRegistryKey, StreamStateHandle, long, boolean) with preventDiscardingCreatedCheckpoint = false.

registerReference

StreamStateHandle registerReference(SharedStateRegistryKey registrationKey,
                                    StreamStateHandle state,
                                    long checkpointID,
                                    boolean preventDiscardingCreatedCheckpoint)

Register a reference to the given shared state in the registry. If there is already a state handle registered under the given key, the "new" state handle is disposed .

IMPORTANT: caller should check the state handle returned by the result, because the registry is performing de-duplication and could potentially return a handle that is supposed to replace the one from the registration request.

Parameters:

state - the shared state for which we register a reference.

checkpointID - which uses the state

preventDiscardingCreatedCheckpoint - as long as this state is still in use. The "checkpoint that created the state" is recorded on the first state registration.

Returns:

the result of this registration request, consisting of the state handle that is registered under the key by the end of the operation and its current reference count.

unregisterUnusedState

Set<Long> unregisterUnusedState(long lowestCheckpointID)

Unregister state that is not referenced by the given checkpoint ID or any newer.

Parameters:

lowestCheckpointID - which is still valid.

Returns:

a set of checkpointID which is still in use.

registerAll

void registerAll(Iterable<? extends CompositeStateHandle> stateHandles,
                 long checkpointID)

Register given shared states in the registry.

NOTE: For state from checkpoints from other jobs or runs (i.e. after recovery), please use registerAllAfterRestored(CompletedCheckpoint, RestoreMode)

Parameters:

stateHandles - The shared states to register.

checkpointID - which uses the states.

registerAllAfterRestored

void registerAllAfterRestored(CompletedCheckpoint checkpoint,
                              RestoreMode mode)

Set the lowest checkpoint ID below which no state is discarded, inclusive.

After recovery from an incremental checkpoint, its state should NOT be discarded, even if not used anymore (unless recovering in CLAIM mode).

This should hold for both cases: when recovering from that initial checkpoint; and from any subsequent checkpoint derived from it.

checkpointCompleted

void checkpointCompleted(long checkpointId)