/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1990-1997 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *
 * Here is one set of parameters from one of my simulations:
 * 
 * ed [ q_weight=0.002 thresh=5 linterm=30 maxthresh=15
 *         mean_pktsize=500 dropmech=random-drop queue-size=60
 *         plot-file=none bytes=false doubleq=false dqthresh=50 
 *	   wait=true ]
 * 
 * 1/"linterm" is the max probability of dropping a packet. 
 * There are different options that make the code
 * more messy that it would otherwise be.  For example,
 * "doubleq" and "dqthresh" are for a queue that gives priority to
 *   small (control) packets, 
 * "bytes" indicates whether the queue should be measured in bytes 
 *   or in packets, 
 * "dropmech" indicates whether the drop function should be random-drop 
 *   or drop-tail when/if the queue overflows, and 
 *   the commented-out Holt-Winters method for computing the average queue 
 *   size can be ignored.
 * "wait" indicates whether the gateway should wait between dropping
 *   packets.
 *
 * @(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/red.h,v 1.23 2000/07/20 04:56:29 ratul Exp $ (LBL)
 */

/*
 * SRED: Stabilized RED
 * Author: Srinivas R. Avasarala (Computer Science, Purdue University) 
 *
 * Note that this code is written based on the paper, T. J. Ott, T. V. Lakshman,
 * and L. H. Wong, "SRED: Stabilized RED," in Proceedings of IEEE INFOCOM, March 1999.  
 */


#ifndef ns_sred_h
#define ns_sred_h

#include "queue.h"

#include "trace.h"
class LinkDelay;

struct zombie {
	int fid;		/* flow identifier */
	int count;	/* count of pkts of this flow in this zombie */
	double timestamp;
	// xombie() : fid(0), count(0), timestamp(0.0) { }
};

#define M 1000

class SREDQueue : public Queue {
 public:
	SREDQueue(const char * = "Drop");
 protected:
	int command(int argc, const char*const* argv);
	void reset();
	Packet* deque();
	double calc_psred();
	double calc_simple_pzap(double prob_sred);
	double calc_full_pzap(double prob_sred, int hit);
	void enque(Packet* pkt);
	void trace(TracedVar* v);	/* routine to write trace records */

	int full_sred_;			/* boolean, TRUE:= full SRED, FALSE:= simple SRED */
	struct zombie zombielist[M];
	int listsize_;
	double p_overwrite_;
	double p_t_;			/* hit frequency */
	double p_max_;			/* maximum drop probability */
	double alpha_;			/* alpha = p/M = p_overwrite/M */
	

	LinkDelay* link_;		/* outgoing link */
	PacketQueue *q_; 		/* underlying (usually) FIFO queue */
		
	int bcount_;			/* byte count */
	int qib_;			/* bool: queue measured in bytes? */
	NsObject* drop_tgt_;		/* drop target */
	NsObject* drop_trace_;		//early drop trace
	char traceType[20];		//the preferred type for early droptrace
					//better be less than 19 chars long
	int which_;

	Tcl_Channel tchan_;		/* place to write trace records */
	TracedInt curq_;		/* current qlen seen by arrivals */
};

#endif