/**
* 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;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.apache.hadoop.HadoopIllegalArgumentException;
import org.apache.hadoop.hdfs.protocol.Block;
/**
* Maintains the replicas map.
*/
class ReplicasMap {
// Object using which this class is synchronized
private final Object mutex;
// Map of block pool Id to another map of block Id to ReplicaInfo.
private Map<String, Map<Long, ReplicaInfo>> map =
new HashMap<String, Map<Long, ReplicaInfo>>();
ReplicasMap(Object mutex) {
if (mutex == null) {
throw new HadoopIllegalArgumentException(
"Object to synchronize on cannot be null");
}
this.mutex = mutex;
}
String[] getBlockPoolList() {
synchronized(mutex) {
return map.keySet().toArray(new String[map.keySet().size()]);
}
}
private void checkBlockPool(String bpid) {
if (bpid == null) {
throw new IllegalArgumentException("Block Pool Id is null");
}
}
private void checkBlock(Block b) {
if (b == null) {
throw new IllegalArgumentException("Block is null");
}
}
/**
* Get the meta information of the replica that matches both block id
* and generation stamp
* @param bpid block pool id
* @param block block with its id as the key
* @return the replica's meta information
* @throws IllegalArgumentException if the input block or block pool is null
*/
ReplicaInfo get(String bpid, Block block) {
checkBlockPool(bpid);
checkBlock(block);
ReplicaInfo replicaInfo = get(bpid, block.getBlockId());
if (replicaInfo != null &&
block.getGenerationStamp() == replicaInfo.getGenerationStamp()) {
return replicaInfo;
}
return null;
}
/**
* Get the meta information of the replica that matches the block id
* @param bpid block pool id
* @param blockId a block's id
* @return the replica's meta information
*/
ReplicaInfo get(String bpid, long blockId) {
checkBlockPool(bpid);
synchronized(mutex) {
Map<Long, ReplicaInfo> m = map.get(bpid);
return m != null ? m.get(blockId) : null;
}
}
/**
* Add a replica's meta information into the map
*
* @param bpid block pool id
* @param replicaInfo a replica's meta information
* @return previous meta information of the replica
* @throws IllegalArgumentException if the input parameter is null
*/
ReplicaInfo add(String bpid, ReplicaInfo replicaInfo) {
checkBlockPool(bpid);
checkBlock(replicaInfo);
synchronized(mutex) {
Map<Long, ReplicaInfo> m = map.get(bpid);
if (m == null) {
// Add an entry for block pool if it does not exist already
m = new HashMap<Long, ReplicaInfo>();
map.put(bpid, m);
}
return m.put(replicaInfo.getBlockId(), replicaInfo);
}
}
/**
* Remove the replica's meta information from the map that matches
* the input block's id and generation stamp
* @param bpid block pool id
* @param block block with its id as the key
* @return the removed replica's meta information
* @throws IllegalArgumentException if the input block is null
*/
ReplicaInfo remove(String bpid, Block block) {
checkBlockPool(bpid);
checkBlock(block);
synchronized(mutex) {
Map<Long, ReplicaInfo> m = map.get(bpid);
if (m != null) {
Long key = Long.valueOf(block.getBlockId());
ReplicaInfo replicaInfo = m.get(key);
if (replicaInfo != null &&
block.getGenerationStamp() == replicaInfo.getGenerationStamp()) {
return m.remove(key);
}
}
}
return null;
}
/**
* Remove the replica's meta information from the map if present
* @param bpid block pool id
* @param the block id of the replica to be removed
* @return the removed replica's meta information
*/
ReplicaInfo remove(String bpid, long blockId) {
checkBlockPool(bpid);
synchronized(mutex) {
Map<Long, ReplicaInfo> m = map.get(bpid);
if (m != null) {
return m.remove(blockId);
}
}
return null;
}
/**
* Get the size of the map for given block pool
* @param bpid block pool id
* @return the number of replicas in the map
*/
int size(String bpid) {
Map<Long, ReplicaInfo> m = null;
synchronized(mutex) {
m = map.get(bpid);
return m != null ? m.size() : 0;
}
}
/**
* Get a collection of the replicas for given block pool
* This method is <b>not synchronized</b>. It needs to be synchronized
* externally using the mutex, both for getting the replicas
* values from the map and iterating over it. Mutex can be accessed using
* {@link #getMutext()} method.
*
* @param bpid block pool id
* @return a collection of the replicas belonging to the block pool
*/
Collection<ReplicaInfo> replicas(String bpid) {
Map<Long, ReplicaInfo> m = null;
m = map.get(bpid);
return m != null ? m.values() : null;
}
void initBlockPool(String bpid) {
checkBlockPool(bpid);
synchronized(mutex) {
Map<Long, ReplicaInfo> m = map.get(bpid);
if (m == null) {
// Add an entry for block pool if it does not exist already
m = new HashMap<Long, ReplicaInfo>();
map.put(bpid, m);
}
}
}
void cleanUpBlockPool(String bpid) {
checkBlockPool(bpid);
synchronized(mutex) {
map.remove(bpid);
}
}
/**
* Give access to mutex used for synchronizing ReplicasMap
* @return object used as lock
*/
Object getMutext() {
return mutex;
}
}