/*
 * 
 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * The contents of this file are subject to the Sun Community Source
 * License v3.0/Jini Technology Specific Attachment v 1.0 (the
 * "License"). You may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 * http://wwws.sun.com/software/jini/licensing/SCSL3_JiniTSA1.html.
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Reference Code is Jini Technology Core Platform code, v2.0. The
 * Developer of the Reference Code is Sun Microsystems, Inc.
 * 
 * Contributor(s): Sun Microsystems, Inc.
 * 
 * The contents of this file comply with the Jini Technology Core
 * Platform Compatibility Kit, v2.0A.
 * 
 * Tester(s): Sun Microsystems, Inc.
 * 
 * Test Platform(s):
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Solaris(TM)SPARC/x86
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Linux (Intel x86)
 * Java 2 SDK, Standard Edition, Version 1.4.2_03 for Windows (Intel Platform)
 * 
 */

package com.sun.jini.discovery;

import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import net.jini.core.constraint.InvocationConstraint;

/**
 * Represents a constraint on the size (in bytes) of multicast packets used in
 * the multicast request and multicast announcement discovery protocols.
 * Lookup services and discovery clients can use this constraint to limit the
 * size of multicast request and announcement packets sent, so as to avoid
 * fragmentation or loss when the packets traverse routers.  This constraint
 * can also be used to control the size of the buffers used to receive incoming
 * multicast request and announcement packets.
 *
 * @author Sun Microsystems, Inc.
 * @since 2.0
 */
public final class MulticastMaxPacketSize
    implements InvocationConstraint, Serializable
{
    private static final long serialVersionUID = 2277375127808559673L;

    /** The minimum allowable multicast packet size limit. */
    public static final int MIN_MAX_PACKET_SIZE = 512;

    /**
     * The multicast packet size limit.
     *
     * @serial
     */
    private final int size;

    /**
     * Creates a <code>MulticastMaxPacketSize</code> constraint for the given
     * multicast packet size limit.
     *
     * @param size the multicast packet size limit
     * @throws IllegalArgumentException if the given size is less than
     * {@link #MIN_MAX_PACKET_SIZE}.
     */
    public MulticastMaxPacketSize(int size) {
	if (size < MIN_MAX_PACKET_SIZE) {
	    throw new IllegalArgumentException("invalid size");
	}
	this.size = size;
    }

    /**
     * Returns the multicast packet size limit.
     *
     * @return the multicast packet size limit
     */
    public int getSize() {
	return size;
    }

    public int hashCode() {
	return MulticastMaxPacketSize.class.hashCode() + size;
    }

    public boolean equals(Object obj) {
	return obj instanceof MulticastMaxPacketSize &&
	       size == ((MulticastMaxPacketSize) obj).size;
    }

    public String toString() {
	return "MulticastMaxPacketSize[" + size + "]";
    }

    private void readObject(ObjectInputStream in)
	throws IOException, ClassNotFoundException
    {
	in.defaultReadObject();
	if (size <= MIN_MAX_PACKET_SIZE) {
	    throw new InvalidObjectException("invalid size");
	}
    }
}
