namenode/src/main/java/org/apache/crail/namenode/FileBlocks.java

/*
 *
 * 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.crail.namenode;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.Queue;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.apache.crail.CrailNodeType;
import org.apache.crail.conf.CrailConstants;

public class FileBlocks extends AbstractNode {
	private ArrayList<NameNodeBlockInfo> blocks;
	private final ReentrantReadWriteLock lock;
	private final Lock readLock;
	private final Lock writeLock;
	
	public FileBlocks(long fd, int fileComponent, CrailNodeType type, int storageClass, int locationClass, boolean enumerable) {
		super(fd, fileComponent, type, storageClass, locationClass, enumerable);
		this.blocks = new ArrayList<NameNodeBlockInfo>(CrailConstants.NAMENODE_FILEBLOCKS);
		this.lock = new ReentrantReadWriteLock();
		this.readLock = lock.readLock();
		this.writeLock = lock.writeLock();
	}

	@Override
	public NameNodeBlockInfo getBlock(int index) {
		readLock.lock();
		try {
			if (index < blocks.size()){
				return blocks.get(index);
			} else {
				return null;
			}
		} catch(Exception e){ 
			return null;
		} finally {
			readLock.unlock();
		}
	}

	@Override
	public boolean addBlock(int index, NameNodeBlockInfo block) {
		writeLock.lock();
		try {
			if (index == blocks.size()){
				blocks.add(index, block);
				return true;
			} else {
				return false;
			}
		} finally {
			writeLock.unlock();
		}
	}

	@Override
	public void freeBlocks(BlockStore blockStore) throws Exception {
		readLock.lock();
		try {
			Iterator<NameNodeBlockInfo> iter = blocks.iterator();
			while (iter.hasNext()){
				NameNodeBlockInfo blockInfo = iter.next();
				blockStore.addBlock(blockInfo);
			}	
		} finally {
			readLock.unlock();
		}
	}

	@Override
	public AbstractNode putChild(AbstractNode child) throws Exception {
		throw new Exception("Attempt to add a child to a non-container type");
	}

	@Override
	public AbstractNode getChild(int component) throws Exception {
		throw new Exception("Attempto to retrieve child from non-container type");
	}

	@Override
	public AbstractNode removeChild(int component) throws Exception {
		throw new Exception("Attempt to remove child from non-container type");
	}

	@Override
	public void clearChildren(Queue<AbstractNode> queue) throws Exception {
		throw new Exception("Attempt collect children from non-container type");
	}
}