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The Netty project is an effort to provide an asynchronous event-driven network application framework and tools for rapid development of maintainable high performance and high scalability protocol servers and clients. In other words, Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.

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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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.jboss.netty.channel.local;

import java.net.SocketAddress;

/**
 * An endpoint in the local transport.  Each endpoint is identified by a unique
 * case-insensitive string, except for the pre-defined value called
 * {@code "ephemeral"}.
 *
 * Ephemeral Address
 *
 * An ephemeral address is an anonymous address which is assigned temporarily
 * and is released as soon as the connection is closed.  All ephemeral addresses
 * have the same ID, {@code "ephemeral"}, but they are not equal to each other.
 * @apiviz.landmark
 */
public final class LocalAddress extends SocketAddress implements Comparable {

    private static final long serialVersionUID = -3601961747680808645L;

    public static final String EPHEMERAL = "ephemeral";

    private final String id;
    private final boolean ephemeral;

    /**
     * Creates a new instance with the specified ID.
     */
    public LocalAddress(int id) {
        this(String.valueOf(id));
    }

    /**
     * Creates a new instance with the specified ID.
     */
    public LocalAddress(String id) {
        if (id == null) {
            throw new NullPointerException("id");
        }
        id = id.trim().toLowerCase();
        if (id.length() == 0) {
            throw new IllegalArgumentException("empty id");
        }
        this.id = id;
        ephemeral = "ephemeral".equals(id);
    }

    /**
     * Returns the ID of this address.
     */
    public String getId() {
        return id;
    }

    /**
     * Returns {@code true} if and only if this address is ephemeral.
     */
    public boolean isEphemeral() {
        return ephemeral;
    }

    @Override
    public int hashCode() {
        if (ephemeral) {
            return System.identityHashCode(this);
        } else {
            return id.hashCode();
        }
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof LocalAddress)) {
            return false;
        }

        if (ephemeral) {
            return this == o;
        } else {
            return getId().equals(((LocalAddress) o).getId());
        }
    }

    // FIXME: This comparison is broken!  Assign distinct port numbers for
    //        ephemeral ports, just like O/S does for port number 0.  It will
    //        break backward compatibility though.

    public int compareTo(LocalAddress o) {
        if (ephemeral) {
            if (o.ephemeral) {
                if (this == o) {
                    return 0;
                }

                int a = System.identityHashCode(this);
                int b = System.identityHashCode(o);
                if (a < b) {
                    return -1;
                } else if (a > b) {
                    return 1;
                } else {
                    throw new Error(
                            "Two different ephemeral addresses have " +
                            "same identityHashCode.");
                }
            } else {
                return 1;
            }
        } else {
            if (o.ephemeral) {
                return -1;
            } else {
                return getId().compareTo(o.getId());
            }
        }
    }

    @Override
    public String toString() {
        return "local:" + getId();
    }
}