org.apache.flink.runtime.checkpoint

Interface CompletedCheckpointStore

All Known Implementing Classes:

AbstractCompleteCheckpointStore, DeactivatedCheckpointCompletedCheckpointStore, DefaultCompletedCheckpointStore, EmbeddedCompletedCheckpointStore, StandaloneCompletedCheckpointStore

public interface CompletedCheckpointStore

A bounded LIFO-queue of CompletedCheckpoint instances.

Field Summary

Fields

Modifier and Type	Field and Description
static org.slf4j.Logger	LOG

Method Summary

Modifier and Type	Method and Description
CompletedCheckpoint	addCheckpointAndSubsumeOldestOne(CompletedCheckpoint checkpoint, CheckpointsCleaner checkpointsCleaner, Runnable postCleanup) Adds a CompletedCheckpoint instance to the list of completed checkpoints.
List<CompletedCheckpoint>	getAllCheckpoints() Returns all CompletedCheckpoint instances.
default CompletedCheckpoint	getLatestCheckpoint() Returns the latest CompletedCheckpoint instance or null if none was added.
default long	getLatestCheckpointId() Returns the id of the latest completed checkpoints.
int	getMaxNumberOfRetainedCheckpoints() Returns the max number of retained checkpoints.
int	getNumberOfRetainedCheckpoints() Returns the current number of retained checkpoints.
SharedStateRegistry	getSharedStateRegistry() Returns the SharedStateRegistry used to register the shared state.
boolean	requiresExternalizedCheckpoints() This method returns whether the completed checkpoint store requires checkpoints to be externalized.
void	shutdown(JobStatus jobStatus, CheckpointsCleaner checkpointsCleaner) Shuts down the store.

Field Detail

LOG

static final org.slf4j.Logger LOG

Method Detail

addCheckpointAndSubsumeOldestOne

@Nullable
CompletedCheckpoint addCheckpointAndSubsumeOldestOne(CompletedCheckpoint checkpoint,
                                                               CheckpointsCleaner checkpointsCleaner,
                                                               Runnable postCleanup)
                                                        throws Exception

Adds a CompletedCheckpoint instance to the list of completed checkpoints.

Only a bounded number of checkpoints is kept. When exceeding the maximum number of retained checkpoints, the oldest one will be discarded.

After FLINK-24611, SharedStateRegistry.unregisterUnusedState(long) should be called here to subsume unused state. Note, the CompletedCheckpoint passed to SharedStateRegistry.registerAllAfterRestored(org.apache.flink.runtime.checkpoint.CompletedCheckpoint, org.apache.flink.runtime.jobgraph.RestoreMode) or SharedStateRegistryFactory.create(java.util.concurrent.Executor, java.util.Collection<org.apache.flink.runtime.checkpoint.CompletedCheckpoint>, org.apache.flink.runtime.jobgraph.RestoreMode) must be the same object as the input parameter, otherwise the state may be deleted by mistake.

After FLINK-25872, CheckpointsCleaner.cleanSubsumedCheckpoints(long, java.util.Set<java.lang.Long>, java.lang.Runnable, java.util.concurrent.Executor) should be called explicitly here.

Returns:

the subsumed oldest completed checkpoint if possible, return null if no checkpoint needs to be discarded on subsume.

Throws:

Exception

getLatestCheckpoint

default CompletedCheckpoint getLatestCheckpoint()
                                         throws Exception

Returns the latest CompletedCheckpoint instance or null if none was added.

Throws:

Exception

getLatestCheckpointId

default long getLatestCheckpointId()

Returns the id of the latest completed checkpoints.

shutdown

void shutdown(JobStatus jobStatus,
              CheckpointsCleaner checkpointsCleaner)
       throws Exception

Shuts down the store.

The job status is forwarded and used to decide whether state should actually be discarded or kept. SharedStateRegistry.unregisterUnusedState(long) and CheckpointsCleaner.cleanSubsumedCheckpoints(long, java.util.Set<java.lang.Long>, java.lang.Runnable, java.util.concurrent.Executor) should be called here to subsume unused state.

Parameters:

jobStatus - Job state on shut down

checkpointsCleaner - that will cleanup completed checkpoints if needed

Throws:

Exception

getAllCheckpoints

List<CompletedCheckpoint> getAllCheckpoints()
                                     throws Exception

Returns all CompletedCheckpoint instances.

Returns an empty list if no checkpoint has been added yet.

Throws:

Exception

getNumberOfRetainedCheckpoints

int getNumberOfRetainedCheckpoints()

Returns the current number of retained checkpoints.

getMaxNumberOfRetainedCheckpoints

int getMaxNumberOfRetainedCheckpoints()

Returns the max number of retained checkpoints.

requiresExternalizedCheckpoints

boolean requiresExternalizedCheckpoints()

This method returns whether the completed checkpoint store requires checkpoints to be externalized. Externalized checkpoints have their meta data persisted, which the checkpoint store can exploit (for example by simply pointing the persisted metadata).

Returns:

True, if the store requires that checkpoints are externalized before being added, false if the store stores the metadata itself.

getSharedStateRegistry

SharedStateRegistry getSharedStateRegistry()

Returns the SharedStateRegistry used to register the shared state.