storeditemcollection.java

High performance DB query

/*
 * @(#)$Id: StoredItemCollection.java,v 1.7 2004/07/02 23:59:20 huebsch Exp $
 *
 * Copyright (c) 2001-2004 Regents of the University of California.
 * All rights reserved.
 *
 * This file is distributed under the terms in the attached BERKELEY-LICENSE
 * file. If you do not find these files, copies can be found by writing to:
 * Computer Science Division, Database Group, Universite of California,
 * 617 Soda Hall #1776, Berkeley, CA 94720-1776. Attention: Berkeley License
 *
 * Copyright (c) 2003-2004 Intel Corporation. All rights reserved.
 *
 * This file is distributed under the terms in the attached INTEL-LICENSE file.
 * If you do not find these files, copies can be found by writing to:
 * Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300,
 * Berkeley, CA, 94704.  Attention:  Intel License Inquiry.
 */


package overlay.provider.basic;

import java.util.ArrayList;
import java.util.Iterator;
import services.network.Payload;
import util.network.serialization.GenericByteBuffer;
import util.network.serialization.SerializationManager;
import util.network.serialization.SerializeList;

/**
 * Class StoredItemCollection
 *
 */
public class StoredItemCollection implements Payload {

    public static long serialVersionUID =
        SerializationManager.getSerialUID(
            "overlay.provider.basic.StoredItemCollection");
    private ArrayList items;
    private int size;

    /**
     * DeSerialize the object from the provided GenericByteBuffer.
     *
     * @param inputBuffer
     */
    public StoredItemCollection(GenericByteBuffer inputBuffer) {
        this.items = SerializeList.deSerializeHomogenousArrayList(inputBuffer);

        Iterator theItems = iterator();

        this.size = 0;

        while (theItems.hasNext()) {
            this.size += SerializationManager.getPayloadSize(
                ((StoredItem) theItems.next()));
        }
    }

    /**
     * Serialize the object into the provided GenericByteBuffer.
     *
     * @param outputBuffer
     * @return
     */
    public long serialize(GenericByteBuffer outputBuffer) {
        SerializeList.serializeHomogenous(outputBuffer, items);

        return serialVersionUID;
    }

    /** Default Constructor, creates an empty collection */
    public StoredItemCollection() {
        items = new ArrayList();
        size = 0;
    }

    /**
     * Appends another item to this collection
     * @param item the item to be appended
     */
    public void addItem(StoredItem item) {
        size += SerializationManager.getPayloadSize(item);

        items.add(item);
    }

    /**
     * Appends another collection to this collection
     * @param collection the collection to be appended
     */
    public void addCollection(StoredItemCollection collection) {
        for (int i = 0; i < collection.size(); i++) {
            addItem(collection.getItem(i));
        }
    }

    /**
     * Retrieve stored items from collection
     * @param index the index of the iteme requested
     * @return the requested item from the collection
     */
    public StoredItem getItem(int index) {
        return (StoredItem) items.get(index);
    }

    /**
     * Method iterator
     * @return
     */
    public Iterator iterator() {
        return items.iterator();
    }

    /**
     * Retrieve objects embedded in stored items from collection
     * @return the requested item from the collection
     */
    public Iterator objectIterator() {
        return new StoredItemIterator(items.iterator());
    }

    /**
     * Determine the number of items stored in this collection
     * @return number of items in the collection
     */
    public int size() {
        return items.size();
    }

    /**
     * Sums the size of the items in the collection (calls getSize for each item)
     * @return size in bytes of the collection
     */
    public int getSize() {
        return size;
    }

    /**
     * Outputs name and value
     * @return a text string with all the tuples in the collection
     */
    public String toString() {
        return "<StoredItemCollection: " + items + ">";
    }
}


/**
 * Class StoredItemIterator
 *
 */
class StoredItemIterator implements Iterator {

    private Iterator collectionIterator;

    /**
     * Constructor StoredItemIterator
     *
     * @param collectionIterator
     */
    protected StoredItemIterator(Iterator collectionIterator) {
        this.collectionIterator = collectionIterator;
    }

    /**
     * Method hasNext
     * @return
     */
    public boolean hasNext() {
        return collectionIterator.hasNext();
    }

    /**
     * Method next
     * @return
     */
    public Object next() {
        return ((StoredItem) collectionIterator.next()).object;
    }

    /**
     * Method remove
     */
    public void remove() {
        throw new UnsupportedOperationException();
    }
}