/**
* 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.namenode;
import java.util.*;
import org.apache.hadoop.hdfs.protocol.Block;
/* Class for keeping track of under replication blocks
* Blocks have replication priority, with priority 0 indicating the highest
* Blocks have only one replicas has the highest
*/
class UnderReplicatedBlocks implements Iterable<Block> {
static final int LEVEL = 3;
private List<TreeSet<Block>> priorityQueues = new ArrayList<TreeSet<Block>>();
/* constructor */
UnderReplicatedBlocks() {
for(int i=0; i<LEVEL; i++) {
priorityQueues.add(new TreeSet<Block>());
}
}
/**
* Empty the queues.
*/
void clear() {
for(int i=0; i<LEVEL; i++) {
priorityQueues.get(i).clear();
}
}
/* Return the total number of under replication blocks */
synchronized int size() {
int size = 0;
for (int i=0; i<LEVEL; i++) {
size += priorityQueues.get(i).size();
}
return size;
}
/* Check if a block is in the neededReplication queue */
synchronized boolean contains(Block block) {
for(TreeSet<Block> set:priorityQueues) {
if(set.contains(block)) { return true; }
}
return false;
}
/* Return the priority of a block
* @param block a under replication block
* @param curReplicas current number of replicas of the block
* @param expectedReplicas expected number of replicas of the block
*/
private int getPriority(Block block,
int curReplicas,
int decommissionedReplicas,
int expectedReplicas) {
if (curReplicas<0 || curReplicas>=expectedReplicas) {
return LEVEL; // no need to replicate
} else if(curReplicas==0) {
// If there are zero non-decommissioned replica but there are
// some decommissioned replicas, then assign them highest priority
if (decommissionedReplicas > 0) {
return 0;
}
return 2; // keep these blocks in needed replication.
} else if(curReplicas==1) {
return 0; // highest priority
} else if(curReplicas*3<expectedReplicas) {
return 1;
} else {
return 2;
}
}
/* add a block to a under replication queue according to its priority
* @param block a under replication block
* @param curReplicas current number of replicas of the block
* @param expectedReplicas expected number of replicas of the block
*/
synchronized boolean add(
Block block,
int curReplicas,
int decomissionedReplicas,
int expectedReplicas) {
if(curReplicas<0 || expectedReplicas <= curReplicas) {
return false;
}
int priLevel = getPriority(block, curReplicas, decomissionedReplicas,
expectedReplicas);
if(priLevel != LEVEL && priorityQueues.get(priLevel).add(block)) {
NameNode.stateChangeLog.debug(
"BLOCK* NameSystem.UnderReplicationBlock.add:"
+ block
+ " has only "+curReplicas
+ " replicas and need " + expectedReplicas
+ " replicas so is added to neededReplications"
+ " at priority level " + priLevel);
return true;
}
return false;
}
/* remove a block from a under replication queue */
synchronized boolean remove(Block block,
int oldReplicas,
int decommissionedReplicas,
int oldExpectedReplicas) {
int priLevel = getPriority(block, oldReplicas,
decommissionedReplicas,
oldExpectedReplicas);
return remove(block, priLevel);
}
/* remove a block from a under replication queue given a priority*/
boolean remove(Block block, int priLevel) {
if(priLevel >= 0 && priLevel < LEVEL
&& priorityQueues.get(priLevel).remove(block)) {
NameNode.stateChangeLog.debug(
"BLOCK* NameSystem.UnderReplicationBlock.remove: "
+ "Removing block " + block
+ " from priority queue "+ priLevel);
return true;
} else {
for(int i=0; i<LEVEL; i++) {
if(i!=priLevel && priorityQueues.get(i).remove(block)) {
NameNode.stateChangeLog.debug(
"BLOCK* NameSystem.UnderReplicationBlock.remove: "
+ "Removing block " + block
+ " from priority queue "+ i);
return true;
}
}
}
return false;
}
/* update the priority level of a block */
synchronized void update(Block block, int curReplicas,
int decommissionedReplicas,
int curExpectedReplicas,
int curReplicasDelta, int expectedReplicasDelta) {
int oldReplicas = curReplicas-curReplicasDelta;
int oldExpectedReplicas = curExpectedReplicas-expectedReplicasDelta;
int curPri = getPriority(block, curReplicas, decommissionedReplicas, curExpectedReplicas);
int oldPri = getPriority(block, oldReplicas, decommissionedReplicas, oldExpectedReplicas);
NameNode.stateChangeLog.debug("UnderReplicationBlocks.update " +
block +
" curReplicas " + curReplicas +
" curExpectedReplicas " + curExpectedReplicas +
" oldReplicas " + oldReplicas +
" oldExpectedReplicas " + oldExpectedReplicas +
" curPri " + curPri +
" oldPri " + oldPri);
if(oldPri != LEVEL && oldPri != curPri) {
remove(block, oldPri);
}
if(curPri != LEVEL && priorityQueues.get(curPri).add(block)) {
NameNode.stateChangeLog.debug(
"BLOCK* NameSystem.UnderReplicationBlock.update:"
+ block
+ " has only "+curReplicas
+ " replicas and need " + curExpectedReplicas
+ " replicas so is added to neededReplications"
+ " at priority level " + curPri);
}
}
/* return an iterator of all the under replication blocks */
public synchronized BlockIterator iterator() {
return new BlockIterator();
}
class BlockIterator implements Iterator<Block> {
private int level;
private List<Iterator<Block>> iterators = new ArrayList<Iterator<Block>>();
BlockIterator()
{
level=0;
for(int i=0; i<LEVEL; i++) {
iterators.add(priorityQueues.get(i).iterator());
}
}
private void update() {
while(level< LEVEL-1 && !iterators.get(level).hasNext()) {
level++;
}
}
public Block next() {
update();
return iterators.get(level).next();
}
public boolean hasNext() {
update();
return iterators.get(level).hasNext();
}
public void remove() {
iterators.get(level).remove();
}
public int getPriority() {
return level;
};
}
}