org.apache.flink.runtime.checkpoint

Interface CompletedCheckpointStore

All Known Implementing Classes:

StandaloneCompletedCheckpointStore, ZooKeeperCompletedCheckpointStore

public interface CompletedCheckpointStore

A bounded LIFO-queue of CompletedCheckpoint instances.

Method Summary

Modifier and Type	Method and Description
void	addCheckpoint(CompletedCheckpoint checkpoint) Adds a CompletedCheckpoint instance to the list of completed checkpoints.
List<CompletedCheckpoint>	getAllCheckpoints() Returns all CompletedCheckpoint instances.
CompletedCheckpoint	getLatestCheckpoint() Returns the latest CompletedCheckpoint instance or null if none was added.
int	getMaxNumberOfRetainedCheckpoints() Returns the max number of retained checkpoints.
int	getNumberOfRetainedCheckpoints() Returns the current number of retained checkpoints.
void	recover() Recover available CompletedCheckpoint instances.
boolean	requiresExternalizedCheckpoints() This method returns whether the completed checkpoint store requires checkpoints to be externalized.
void	shutdown(JobStatus jobStatus) Shuts down the store.

Method Detail

recover

void recover()
      throws Exception

Recover available CompletedCheckpoint instances.

After a call to this method, getLatestCheckpoint() returns the latest available checkpoint.

Throws:

Exception

addCheckpoint

void addCheckpoint(CompletedCheckpoint checkpoint)
            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.

Throws:

Exception

getLatestCheckpoint

CompletedCheckpoint getLatestCheckpoint()
                                 throws Exception

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

Throws:

Exception

shutdown

void shutdown(JobStatus jobStatus)
       throws Exception

Shuts down the store.

The job status is forwarded and used to decide whether state should actually be discarded or kept.

Parameters:

jobStatus - Job state on shut down

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.