/**
* 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.hadoop.hdfs.server.datanode.fsdataset.impl;
import com.google.common.base.Preconditions;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.hadoop.util.Time;
import java.io.File;
import java.util.concurrent.atomic.AtomicLong;
@InterfaceAudience.Private
@InterfaceStability.Unstable
public abstract class RamDiskReplicaTracker {
static final Log LOG = LogFactory.getLog(RamDiskReplicaTracker.class);
FsDatasetImpl fsDataset;
static class RamDiskReplica implements Comparable<RamDiskReplica> {
private final String bpid;
private final long blockId;
private File savedBlockFile;
private File savedMetaFile;
private long lockedBytesReserved;
private long creationTime;
protected AtomicLong numReads = new AtomicLong(0);
protected boolean isPersisted;
/**
* RAM_DISK volume that holds the original replica.
*/
final FsVolumeSpi ramDiskVolume;
/**
* Persistent volume that holds or will hold the saved replica.
*/
FsVolumeImpl lazyPersistVolume;
RamDiskReplica(final String bpid, final long blockId,
final FsVolumeImpl ramDiskVolume,
long lockedBytesReserved) {
this.bpid = bpid;
this.blockId = blockId;
this.ramDiskVolume = ramDiskVolume;
this.lockedBytesReserved = lockedBytesReserved;
lazyPersistVolume = null;
savedMetaFile = null;
savedBlockFile = null;
creationTime = Time.monotonicNow();
isPersisted = false;
}
long getBlockId() {
return blockId;
}
String getBlockPoolId() {
return bpid;
}
FsVolumeImpl getLazyPersistVolume() {
return lazyPersistVolume;
}
void setLazyPersistVolume(FsVolumeImpl volume) {
Preconditions.checkState(!volume.isTransientStorage());
this.lazyPersistVolume = volume;
}
File getSavedBlockFile() {
return savedBlockFile;
}
File getSavedMetaFile() {
return savedMetaFile;
}
long getNumReads() { return numReads.get(); }
long getCreationTime() { return creationTime; }
boolean getIsPersisted() {return isPersisted; }
/**
* Record the saved meta and block files on the given volume.
*
* @param files Meta and block files, in that order.
*/
void recordSavedBlockFiles(File[] files) {
this.savedMetaFile = files[0];
this.savedBlockFile = files[1];
}
@Override
public int hashCode() {
return bpid.hashCode() ^ (int) blockId;
}
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other == null || getClass() != other.getClass()) {
return false;
}
RamDiskReplica otherState = (RamDiskReplica) other;
return (otherState.bpid.equals(bpid) && otherState.blockId == blockId);
}
// Delete the saved meta and block files. Failure to delete can be
// ignored, the directory scanner will retry the deletion later.
void deleteSavedFiles() {
if (savedBlockFile != null) {
if (!savedBlockFile.delete()) {
LOG.warn("Failed to delete block file " + savedBlockFile);
}
savedBlockFile = null;
}
if (savedMetaFile != null) {
if (!savedMetaFile.delete()) {
LOG.warn("Failed to delete meta file " + savedMetaFile);
}
savedMetaFile = null;
}
}
@Override
public int compareTo(RamDiskReplica other) {
int bpidResult = bpid.compareTo(other.bpid);
if (bpidResult == 0)
if (blockId == other.blockId) {
return 0;
} else if (blockId < other.blockId) {
return -1;
} else {
return 1;
}
return bpidResult;
}
@Override
public String toString() {
return "[BlockPoolID=" + bpid + "; BlockId=" + blockId + "]";
}
public long getLockedBytesReserved() {
return lockedBytesReserved;
}
}
/**
* Get an instance of the configured RamDiskReplicaTracker based on the
* the configuration property
* {@link org.apache.hadoop.hdfs.DFSConfigKeys#DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_KEY}.
*
* @param conf the configuration to be used
* @param dataset the FsDataset object.
* @return an instance of RamDiskReplicaTracker
*/
static RamDiskReplicaTracker getInstance(final Configuration conf,
final FsDatasetImpl fsDataset) {
final Class<? extends RamDiskReplicaTracker> trackerClass = conf.getClass(
DFSConfigKeys.DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_KEY,
DFSConfigKeys.DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_DEFAULT,
RamDiskReplicaTracker.class);
final RamDiskReplicaTracker tracker = ReflectionUtils.newInstance(
trackerClass, conf);
tracker.initialize(fsDataset);
return tracker;
}
void initialize(final FsDatasetImpl fsDataset) {
this.fsDataset = fsDataset;
}
/**
* Start tracking a new finalized replica on RAM disk.
*
* @param transientVolume RAM disk volume that stores the replica.
*/
abstract void addReplica(final String bpid, final long blockId,
final FsVolumeImpl transientVolume,
long lockedBytesReserved);
/**
* Invoked when a replica is opened by a client. This may be used as
* a heuristic by the eviction scheme.
*/
abstract void touch(final String bpid, final long blockId);
/**
* Get the next replica to write to persistent storage.
*/
abstract RamDiskReplica dequeueNextReplicaToPersist();
/**
* Invoked if a replica that was previously dequeued for persistence
* could not be successfully persisted. Add it back so it can be retried
* later.
*/
abstract void reenqueueReplicaNotPersisted(
final RamDiskReplica ramDiskReplica);
/**
* Invoked when the Lazy persist operation is started by the DataNode.
* @param checkpointVolume
*/
abstract void recordStartLazyPersist(
final String bpid, final long blockId, FsVolumeImpl checkpointVolume);
/**
* Invoked when the Lazy persist operation is complete.
*
* @param savedFiles The saved meta and block files, in that order.
*/
abstract void recordEndLazyPersist(
final String bpid, final long blockId, final File[] savedFiles);
/**
* Return a candidate replica to remove from RAM Disk. The exact replica
* to be returned may depend on the eviction scheme utilized.
*
* @return
*/
abstract RamDiskReplica getNextCandidateForEviction();
/**
* Return the number of replicas pending persistence to disk.
*/
abstract int numReplicasNotPersisted();
/**
* Discard all state we are tracking for the given replica.
*/
abstract void discardReplica(
final String bpid, final long blockId,
boolean deleteSavedCopies);
/**
* Return RamDiskReplica info given block pool id and block id
* Return null if it does not exist in RamDisk
*/
abstract RamDiskReplica getReplica(
final String bpid, final long blockId);
}