/* * ** Network and Service Differentiation Extensions to GridSim 3.0 ** * * Gokul Poduval & Chen-Khong Tham * Computer Communication Networks (CCN) Lab * Dept of Electrical & Computer Engineering * National University of Singapore * August 2004 * * Licence: GPL - http://www.gnu.org/copyleft/gpl.html * * PacketScheduler.java - Implements a scheduler * */package gridsim.net;import eduni.simjava.*;import gridsim.*;import java.util.*;/** * This class provides a template for schedulers that will be used at routers. * Every egress port of a router needs to instantiate a PacketScheduler object * which it uses to determine the order in which packets should be sent out. * * @invariant $none * @since GridSim Toolkit 3.1 * @author Gokul Poduval & Chen-Khong Tham, National University of Singapore */public interface PacketScheduler{    /**     * Returns the baud rate of the egress port that is using this scheduler.     * If the baud rate is zero, it means you haven't set it up.     * @return the baud rate in bits/s     * @see gridsim.net.PacketScheduler#setBaudRate(double)     * @pre $none     * @post $result >= 0     */    public abstract double getBaudRate();    /**     * Sets the baud rate that this scheduler will be sending packets at.     * @param rate the baud rate of this scheduler (in bits/s)     * @pre rate > 0     * @post $none     */    public abstract boolean setBaudRate(double rate);    /**     * This method enques a packet in this scheduler. If the implementing class     * has buffer management policies too, then it should return <b>true</b> if     * the packet was successfully enqued. If the packet was dropped, or could     * not be accomodated due to any other reason, it should return     * <b>false</b>.     *     * @param np    A Packet to be enqued by this scheduler.     * @return <tt>true</tt> if enqued, <tt>false</tt> otherwise     * @pre np != null     * @post $none     */    public abstract boolean enque(Packet np);    /**     * Removes a single packet and returns it. This packet should be sent out     * by the router from the port using this scheduler.     *     * @return the packet to be sent out     * @pre $none     * @post $none     */    public abstract Packet deque();    /**     * Determines whether the scheduler is currently keeping any packets in     * its queue(s).     *     * @return <tt>true</tt> if no packets are enqueued, <tt>false</tt>     *         otherwise     * @pre $none     * @post $none     */    public abstract boolean isEmpty();    /**     * Determines the number of packets that are currently enqueued in this     * scheduler.     *     * @return the number of packets enqueud by this scheduler.     * @pre $none     * @post $none     */    public abstract int size();    /**     * Returns the name of this scheduler, if one was specified during setup.     * Otherwise "PacketScheduler" is returned. This could be used for debugging     * purposes.     *     * @return the name of this scheduler     * @pre $none     * @post $none     */    public abstract String getSchedName();    /**     * Returns the ID of this scheduler.     * @return the ID of this scheduler or <tt>-1</tt> if no ID is found     * @pre $none     * @post $none     */    public abstract int getSchedID();    /**     * Returns the router ID that hosts this scheduler.     * @return the router ID or <tt>-1</tt> if no ID is found     * @pre $none     * @post $none     */    public abstract int getRouterID();    /**     * Sets the router ID that hosts this scheduler.     * @param routerID  the router ID that hosts this scheduler     * @return <tt>true</tt> if successful or <tt>false</tt> otherwise     * @pre $none     * @post $none     */    public abstract boolean setRouterID(int routerID);} // end class