/////////////////////////////////////////////////////////
// Module		TrafficCop.java
// Version		1.00
// Language		Java
// Author		Sudhakar Chandrasekaran (thaths@netscape.com)
// History
// 05/16/97		Genesis:  In the beginning.....
//				Largely based on 'TrafficController' from the JavaWorld
//				article about crawlers
//
// Legalese                
// Copyright (C) 1996-1997 Sudhakar Chandrasekharan  
//
// This program is free software;  you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the 
// Free Software Foundation; either version 2 of the license, or (at your 
// option) any later version.
//
// This program is distributed in the hope that it will be useful, but 
// WITHOUT ANY WARRANTY; without even the implied warranty of 
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
// General Public License for more details.  Writers of free software 
// cannot afford getting sued!
// 
// You should have received a copy  of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc., 
// 675 Mass Ave., Cambridge, MA 02139, USA.
//
// Sudhakar "Thaths" Chandrasekharan, 20 April 1997.
////////////////////////////////////////////////////////

public class TrafficCop
{
	int tokenDB[];
	int currentCrowd;
	int maximumCrowdSize;

	// Constructor
	// Taking the maimum size of a crowd to control, initialize
	// the crowd to empty and mark all tokens as avialbel
	public TrafficCop (int max) {
		maximumCrowdSize = max;
		currentCrowd = 0;

		tokenDB = new int [maximumCrowdSize];
		for (int i=0; i < maximumCrowdSize; i++) {
			tokenDB[i] = -1;
		}
	}

	public synchronized int getToken() {
		while (currentCrowd == maximumCrowdSize) {
			try {
				wait();
			} catch (InterruptedException imOnlySleeping) {
			}
		}

		int i;
		for (i=0; i < maximumCrowdSize; i++) {
			if (tokenDB[i] == -1) {
				tokenDB[i] = i;
				currentCrowd++;
				break;
			}
		}
		return i;
	}

	public synchronized void returnToken(int token) {
		tokenDB[token] = -1;
		currentCrowd --;

		notifyAll();
	}
}