org.apache.flink.runtime.checkpoint.CompletedCheckpointStore Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.checkpoint;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.api.common.JobStatus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.List;
import java.util.ListIterator;
/** A bounded LIFO-queue of {@link CompletedCheckpoint} instances. */
public interface CompletedCheckpointStore {
Logger LOG = LoggerFactory.getLogger(CompletedCheckpointStore.class);
/**
* Recover available {@link CompletedCheckpoint} instances.
*
* After a call to this method, {@link #getLatestCheckpoint(boolean)} returns the latest
* available checkpoint.
*/
void recover() throws Exception;
/**
* Adds a {@link 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.
*/
void addCheckpoint(
CompletedCheckpoint checkpoint,
CheckpointsCleaner checkpointsCleaner,
Runnable postCleanup)
throws Exception;
/**
* Returns the latest {@link CompletedCheckpoint} instance or null if none was
* added.
*/
default CompletedCheckpoint getLatestCheckpoint(boolean isPreferCheckpointForRecovery)
throws Exception {
List allCheckpoints = getAllCheckpoints();
if (allCheckpoints.isEmpty()) {
return null;
}
CompletedCheckpoint lastCompleted = allCheckpoints.get(allCheckpoints.size() - 1);
if (isPreferCheckpointForRecovery
&& allCheckpoints.size() > 1
&& lastCompleted.getProperties().isSavepoint()) {
ListIterator listIterator =
allCheckpoints.listIterator(allCheckpoints.size() - 1);
while (listIterator.hasPrevious()) {
CompletedCheckpoint prev = listIterator.previous();
if (!prev.getProperties().isSavepoint()) {
LOG.info(
"Found a completed checkpoint ({}) before the latest savepoint, will use it to recover!",
prev);
return prev;
}
}
LOG.info("Did not find earlier checkpoint, using latest savepoint to recover.");
}
return lastCompleted;
}
/**
* Shuts down the store.
*
* The job status is forwarded and used to decide whether state should actually be discarded
* or kept.
*
* @param jobStatus Job state on shut down
*/
void shutdown(JobStatus jobStatus, CheckpointsCleaner checkpointsCleaner, Runnable postCleanup)
throws Exception;
/**
* Returns all {@link CompletedCheckpoint} instances.
*
*
Returns an empty list if no checkpoint has been added yet.
*/
List getAllCheckpoints() throws Exception;
/** Returns the current number of retained checkpoints. */
int getNumberOfRetainedCheckpoints();
/** Returns the max number of retained checkpoints. */
int getMaxNumberOfRetainedCheckpoints();
/**
* 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).
*
* @return True, if the store requires that checkpoints are externalized before being added,
* false if the store stores the metadata itself.
*/
boolean requiresExternalizedCheckpoints();
@VisibleForTesting
static CompletedCheckpointStore storeFor(
Runnable postCleanupAction, CompletedCheckpoint... checkpoints) throws Exception {
StandaloneCompletedCheckpointStore store =
new StandaloneCompletedCheckpointStore(checkpoints.length);
CheckpointsCleaner checkpointsCleaner = new CheckpointsCleaner();
for (final CompletedCheckpoint checkpoint : checkpoints) {
store.addCheckpoint(checkpoint, checkpointsCleaner, postCleanupAction);
}
return store;
}
}