examples/tutorial/teller.cpp

/**************************************************************************
 *
 * teller.cpp - Bank teller sample program.
 *
 * $Id: //stdlib/dev/examples/stdlib/tutorial/teller.cpp#12 $
 *
 ***************************************************************************
 *
 * Copyright (c) 1994-2005 Quovadx,  Inc., acting through its  Rogue Wave
 * Software division. Licensed 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.
 * 
 **************************************************************************/

#include <queue>
#include <iostream>
#include <vector>

#include <teller.h>

//  A very unsatisfactory, but very portable implementation
//  of a linear congruential pseudorandom number generator.
//  (Apologies to D. Lehmer, D. Knuth, R. Sedgewick, et al.)
static unsigned long int lcg_seed = 0;
inline unsigned long int lcg_rand (int n)
{
    lcg_seed = ((lcg_seed * 11321) + 1) % 32575;
    return (int) (((double) lcg_seed / 32575.0) * n);
}

int main ()
{
    const int numberOfTellers = 5;
    const int numberOfMinutes = 60;
    double totalWait          = 0;
    int numberOfCustomers     = 0;

    std::vector<Teller> teller (numberOfTellers);
    std::queue<Customer> line;

    for (int t = 0; t < numberOfMinutes; t++) {
        if (lcg_rand (10) < 9)
            line.push (Customer (t));
        
        for (int i = 0; i < numberOfTellers; i++) {
            if (teller[i].isFree () && !line.empty ()) {
                Customer& frontCustomer = line.front ();
                numberOfCustomers++;
                totalWait += t - frontCustomer.arrivalTime;
                teller[i].addCustomer (frontCustomer);
                line.pop ();
            }
        }
    }

    std::cout << "average wait: "
              << (totalWait / numberOfCustomers) << std::endl;

    return 0;
}