/*
 * LoadBalanceManager.java
 *
 * Load Balance Manager data and operations for a greedy selection of 
 * servers.
 *
 *  Created by: Arthur L. Blais
 *              Visteon/Ford Microelectronics Inc.
 *              Colorado Springs, CO
 *
 *  Date: Fri Sep 24 08:43:13 MDT 1999
 *
 *  Wed Mar 29 07:21:05 MST 2000: add random selection for adversarial tests
 *
 ****************************************************************************
 *
 *   Class Methods
 *
 *
 ****************************************************************************
 */
 
import java.util.Random;

public class LoadBalanceManager {

  int id;                                // id number
  int serverCount;                       // total number of servers
  int firstServer = 0;                   // first min server
  int server[];                          // server reqeust count
  int managerType;                       // LBM type, 0 = greedy, 1 = random

  // Pseudo-Random Variate Seeds
  private static long seed = 98391;
  // random number instances
  private static Random randNumber; // = new Random( seed );

  public LoadBalanceManager( int n, int s, int t ) {

    id = n;
    serverCount = s;
    managerType = t;

    server = new int[ serverCount ];

    for ( int i = 0; i < serverCount; i++ ) {
       server[i] = 0;
    }

    randNumber = new Random( seed );
  }

  /**
   * getId
   */
  int getId() {
    return id;
  }  

  /**
   * requestComplete
   */
  void requestComplete( int s ) {

     server[s]--;
  }

  /**
   * nextServer
   *
   * If manager type is random
   * then randomly select a server
   * else select server with greedy selection
   */
  int nextServer() {

    int nextServer;

    if ( managerType == 1 ) {
      // random manager
      nextServer = Math.abs( randNumber.nextInt() ) % serverCount;
      server[nextServer]++;

      return( nextServer );  
    }
    
    // greedy manager
    nextServer = firstServer % server.length;
    int min = 999999;
    int minServer = nextServer;

    int i = 0;
    //    for ( int i = 0; i < server.length; i++ ) {
    while ( i++ < server.length ) {

      if ( server[nextServer] < min ) {
         min = server[nextServer];
         minServer = nextServer;
      }
      nextServer++;
      nextServer %= server.length;
    }

    server[ minServer ]++;
    firstServer++;

    return( minServer );  
  }

}