org.cinchapi.concourse.server.storage.temp.Queue.java Source code

Introduction

Here is the source code for org.cinchapi.concourse.server.storage.temp.Queue.java

Source

/*
 * The MIT License (MIT)
 * 
 * Copyright (c) 2013-2014 Jeff Nelson, Cinchapi Software Collective
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package org.cinchapi.concourse.server.storage.temp;

import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import com.google.common.collect.Lists;

/**
 * A {@link Queue} is a very simple form of {@link Limbo} that represents
 * data as a sequence of {@link Write} objects. New data is appended to the
 * sequence and the returned {@link Iterator} traverses the list.
 * 
 * @author jnelson
 */
public class Queue extends Limbo {

    /**
     * Revisions are stored as a sequential list of {@link Write} objects, which
     * means most reads are <em>at least</em> an O(n) scan.
     */
    protected final List<Write> writes;

    /**
     * Construct a Limbo with enough capacity for {@code initialSize}. If
     * necessary, the structure will grow to accommodate more data.
     * 
     * @param initialSize
     */
    public Queue(int initialSize) {
        writes = Lists.newArrayListWithCapacity(initialSize);
    }

    /**
     * Return an unmodifiable copy of the writes contained in the Queue.
     * 
     * @return the writes
     */
    public List<Write> getWrites() {
        return Collections.unmodifiableList(writes);
    }

    @Override
    public Iterator<Write> iterator() {
        return writes.iterator();
    }

    @Override
    public boolean insert(Write write) {
        writeLock.lock();
        try {
            return writes.add(write);
        } finally {
            writeLock.unlock();
        }
    }

    @Override
    public void start() {
        // do nothing
    }

    @Override
    public void stop() {
        // do nothing
    }

    @Override
    public Iterator<Write> reverseIterator() {
        List<Write> copy = Lists.newArrayList(writes);
        Collections.reverse(copy);
        return copy.iterator();
    }

}