/**
* 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.Arrays;
import java.util.LinkedList;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList.Type;
import org.apache.hadoop.util.IntrusiveCollection;
import org.apache.hadoop.util.LightWeightGSet;
import org.apache.hadoop.util.IntrusiveCollection.Element;
import org.apache.hadoop.util.LightWeightGSet.LinkedElement;
/**
* Represents a cached block.
*/
@InterfaceAudience.LimitedPrivate({"HDFS"})
public final class CachedBlock implements Element,
LightWeightGSet.LinkedElement {
private static final Object[] EMPTY_ARRAY = new Object[0];
/**
* Block id.
*/
private final long blockId;
/**
* Used to implement #{LightWeightGSet.LinkedElement}
*/
private LinkedElement nextElement;
/**
* Bit 15: Mark
* Bit 0-14: cache replication factor.
*/
private short replicationAndMark;
/**
* Used to implement the CachedBlocksList.
*
* Since this CachedBlock can be in multiple CachedBlocksList objects,
* we need to be able to store multiple 'prev' and 'next' pointers.
* The triplets array does this.
*
* Each triplet contains a CachedBlockList object followed by a
* prev pointer, followed by a next pointer.
*/
private Object[] triplets;
public CachedBlock(long blockId, short replication, boolean mark) {
this.blockId = blockId;
this.triplets = EMPTY_ARRAY;
setReplicationAndMark(replication, mark);
}
public long getBlockId() {
return blockId;
}
@Override
public int hashCode() {
return (int)(blockId^(blockId>>>32));
}
@Override
public boolean equals(Object o) {
if (o == null) { return false; }
if (o == this) { return true; }
if (o.getClass() != this.getClass()) {
return false;
}
CachedBlock other = (CachedBlock)o;
return other.blockId == blockId;
}
public void setReplicationAndMark(short replication, boolean mark) {
assert replication >= 0;
replicationAndMark = (short)((replication << 1) | (mark ? 0x1 : 0x0));
}
public boolean getMark() {
return ((replicationAndMark & 0x1) != 0);
}
public short getReplication() {
return (short) (replicationAndMark >>> 1);
}
/**
* Return true if this CachedBlock is present on the given list.
*/
public boolean isPresent(CachedBlocksList cachedBlocksList) {
for (int i = 0; i < triplets.length; i += 3) {
CachedBlocksList list = (CachedBlocksList)triplets[i];
if (list == cachedBlocksList) {
return true;
}
}
return false;
}
/**
* Get a list of the datanodes which this block is cached,
* planned to be cached, or planned to be uncached on.
*
* @param type If null, this parameter is ignored.
* If it is non-null, we match only datanodes which
* have it on this list.
* See {@link DatanodeDescriptor#CachedBlocksList#Type}
* for a description of all the lists.
*
* @return The list of datanodes. Modifying this list does not
* alter the state of the CachedBlock.
*/
public List<DatanodeDescriptor> getDatanodes(Type type) {
List<DatanodeDescriptor> nodes = new LinkedList<DatanodeDescriptor>();
for (int i = 0; i < triplets.length; i += 3) {
CachedBlocksList list = (CachedBlocksList)triplets[i];
if ((type == null) || (list.getType() == type)) {
nodes.add(list.getDatanode());
}
}
return nodes;
}
@Override
public void insertInternal(IntrusiveCollection<? extends Element> list, Element prev,
Element next) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
throw new RuntimeException("Trying to re-insert an element that " +
"is already in the list.");
}
}
Object newTriplets[] = Arrays.copyOf(triplets, triplets.length + 3);
newTriplets[triplets.length] = list;
newTriplets[triplets.length + 1] = prev;
newTriplets[triplets.length + 2] = next;
triplets = newTriplets;
}
@Override
public void setPrev(IntrusiveCollection<? extends Element> list, Element prev) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
triplets[i + 1] = prev;
return;
}
}
throw new RuntimeException("Called setPrev on an element that wasn't " +
"in the list.");
}
@Override
public void setNext(IntrusiveCollection<? extends Element> list, Element next) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
triplets[i + 2] = next;
return;
}
}
throw new RuntimeException("Called setNext on an element that wasn't " +
"in the list.");
}
@Override
public void removeInternal(IntrusiveCollection<? extends Element> list) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
Object[] newTriplets = new Object[triplets.length - 3];
System.arraycopy(triplets, 0, newTriplets, 0, i);
System.arraycopy(triplets, i + 3, newTriplets, i,
triplets.length - (i + 3));
triplets = newTriplets;
return;
}
}
throw new RuntimeException("Called remove on an element that wasn't " +
"in the list.");
}
@Override
public Element getPrev(IntrusiveCollection<? extends Element> list) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
return (Element)triplets[i + 1];
}
}
throw new RuntimeException("Called getPrev on an element that wasn't " +
"in the list.");
}
@Override
public Element getNext(IntrusiveCollection<? extends Element> list) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
return (Element)triplets[i + 2];
}
}
throw new RuntimeException("Called getNext on an element that wasn't " +
"in the list.");
}
@Override
public boolean isInList(IntrusiveCollection<? extends Element> list) {
for (int i = 0; i < triplets.length; i += 3) {
if (triplets[i] == list) {
return true;
}
}
return false;
}
@Override
public String toString() {
return new StringBuilder().append("{").
append("blockId=").append(blockId).append(", ").
append("replication=").append(getReplication()).append(", ").
append("mark=").append(getMark()).append("}").
toString();
}
@Override // LightWeightGSet.LinkedElement
public void setNext(LinkedElement next) {
this.nextElement = next;
}
@Override // LightWeightGSet.LinkedElement
public LinkedElement getNext() {
return nextElement;
}
}