org.apache.flink.runtime.blob.PermanentBlobCache Maven / Gradle / Ivy
/*
* 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.blob;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.api.common.JobID;
import org.apache.flink.configuration.BlobServerOptions;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.util.FileUtils;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import static org.apache.flink.util.Preconditions.checkNotNull;
/**
* Provides a cache for permanent BLOB files including a per-job ref-counting and a staged cleanup.
*
* When requesting BLOBs via {@link #getFile(JobID, PermanentBlobKey)}, the cache will first
* attempt to serve the file from its local cache. Only if the local cache does not contain the
* desired BLOB, it will try to download it from a distributed HA file system (if available) or the
* BLOB server.
*
*
If files for a job are not needed any more, they will enter a staged, i.e. deferred, cleanup.
* Files may thus still be be accessible upon recovery and do not need to be re-downloaded.
*/
public class PermanentBlobCache extends AbstractBlobCache implements PermanentBlobService {
/**
* Job reference counters with a time-to-live (TTL).
*/
@VisibleForTesting
static class RefCount {
/**
* Number of references to a job.
*/
public int references = 0;
/**
* Timestamp in milliseconds when any job data should be cleaned up (no cleanup for
* non-positive values).
*/
public long keepUntil = -1;
}
/**
* Map to store the number of references to a specific job.
*/
private final Map jobRefCounters = new HashMap<>();
/**
* Time interval (ms) to run the cleanup task; also used as the default TTL.
*/
private final long cleanupInterval;
/**
* Timer task to execute the cleanup at regular intervals.
*/
private final Timer cleanupTimer;
/**
* Instantiates a new cache for permanent BLOBs which are also available in an HA store.
*
* @param serverAddress
* address of the {@link BlobServer} to use for fetching files from
* @param blobClientConfig
* global configuration
* @param blobView
* (distributed) HA blob store file system to retrieve files from first
*
* @throws IOException
* thrown if the (local or distributed) file storage cannot be created or is not usable
*/
public PermanentBlobCache(
final InetSocketAddress serverAddress,
final Configuration blobClientConfig,
final BlobView blobView) throws IOException {
super(serverAddress, blobClientConfig, blobView,
LoggerFactory.getLogger(PermanentBlobCache.class));
// Initializing the clean up task
this.cleanupTimer = new Timer(true);
this.cleanupInterval = blobClientConfig.getLong(BlobServerOptions.CLEANUP_INTERVAL) * 1000;
this.cleanupTimer.schedule(new PermanentBlobCleanupTask(), cleanupInterval, cleanupInterval);
}
/**
* Registers use of job-related BLOBs.
*
* Using any other method to access BLOBs, e.g. {@link #getFile}, is only valid within
* calls to registerJob(JobID) and {@link #releaseJob(JobID)}.
*
* @param jobId
* ID of the job this blob belongs to
*
* @see #releaseJob(JobID)
*/
public void registerJob(JobID jobId) {
checkNotNull(jobId);
synchronized (jobRefCounters) {
RefCount ref = jobRefCounters.get(jobId);
if (ref == null) {
ref = new RefCount();
jobRefCounters.put(jobId, ref);
} else {
// reset cleanup timeout
ref.keepUntil = -1;
}
++ref.references;
}
}
/**
* Unregisters use of job-related BLOBs and allow them to be released.
*
* @param jobId
* ID of the job this blob belongs to
*
* @see #registerJob(JobID)
*/
public void releaseJob(JobID jobId) {
checkNotNull(jobId);
synchronized (jobRefCounters) {
RefCount ref = jobRefCounters.get(jobId);
if (ref == null || ref.references == 0) {
log.warn("improper use of releaseJob() without a matching number of registerJob() calls for jobId " + jobId);
return;
}
--ref.references;
if (ref.references == 0) {
ref.keepUntil = System.currentTimeMillis() + cleanupInterval;
}
}
}
public int getNumberOfReferenceHolders(JobID jobId) {
checkNotNull(jobId);
synchronized (jobRefCounters) {
RefCount ref = jobRefCounters.get(jobId);
if (ref == null) {
return 0;
} else {
return ref.references;
}
}
}
public int getNumberOfCachedJobs() {
return jobRefCounters.size();
}
/**
* Returns the path to a local copy of the file associated with the provided job ID and blob
* key.
*
*
We will first attempt to serve the BLOB from the local storage. If the BLOB is not in
* there, we will try to download it from the HA store, or directly from the {@link BlobServer}.
*
* @param jobId
* ID of the job this blob belongs to
* @param key
* blob key associated with the requested file
*
* @return The path to the file.
*
* @throws java.io.FileNotFoundException
* if the BLOB does not exist;
* @throws IOException
* if any other error occurs when retrieving the file
*/
@Override
public File getFile(JobID jobId, PermanentBlobKey key) throws IOException {
checkNotNull(jobId);
return getFileInternal(jobId, key);
}
/**
* Returns a file handle to the file associated with the given blob key on the blob
* server.
*
* @param jobId
* ID of the job this blob belongs to (or null if job-unrelated)
* @param key
* identifying the file
*
* @return file handle to the file
*
* @throws IOException
* if creating the directory fails
*/
@VisibleForTesting
public File getStorageLocation(JobID jobId, BlobKey key) throws IOException {
checkNotNull(jobId);
return BlobUtils.getStorageLocation(storageDir, jobId, key);
}
/**
* Returns the job reference counters - for testing purposes only!
*
* @return job reference counters (internal state!)
*/
@VisibleForTesting
Map getJobRefCounters() {
return jobRefCounters;
}
/**
* Cleanup task which is executed periodically to delete BLOBs whose ref-counter reached
* 0.
*/
class PermanentBlobCleanupTask extends TimerTask {
/**
* Cleans up BLOBs which are not referenced anymore.
*/
@Override
public void run() {
synchronized (jobRefCounters) {
Iterator> entryIter = jobRefCounters.entrySet().iterator();
final long currentTimeMillis = System.currentTimeMillis();
while (entryIter.hasNext()) {
Map.Entry entry = entryIter.next();
RefCount ref = entry.getValue();
if (ref.references <= 0 && ref.keepUntil > 0 && currentTimeMillis >= ref.keepUntil) {
JobID jobId = entry.getKey();
final File localFile =
new File(BlobUtils.getStorageLocationPath(storageDir.getAbsolutePath(), jobId));
/*
* NOTE: normally it is not required to acquire the write lock to delete the job's
* storage directory since there should be noone accessing it with the ref
* counter being 0 - acquire it just in case, to always be on the safe side
*/
readWriteLock.writeLock().lock();
boolean success = false;
try {
FileUtils.deleteDirectory(localFile);
success = true;
} catch (Throwable t) {
log.warn("Failed to locally delete job directory " + localFile.getAbsolutePath(), t);
} finally {
readWriteLock.writeLock().unlock();
}
// let's only remove this directory from cleanup if the cleanup was successful
// (does not need the write lock)
if (success) {
entryIter.remove();
}
}
}
}
}
}
@Override
protected void cancelCleanupTask() {
cleanupTimer.cancel();
}
}