churngen.cc

这是关于覆盖网的各种负载均衡算法的程序。好好研究

/* $Id: churnGen.cc,v 1.4 2005/08/02 19:35:48 jonathan Exp $
 * Jonathan Ledlie, Harvard University.
 * Copyright 2005.  All rights reserved.
 */

#include <stdio.h>
#include <stdlib.h>
#ifdef LINUX
#include <getopt.h>
#endif
#include <sys/types.h>
#include <unistd.h>
#include <algorithm>
#include <vector>

#include "math_util.h"
#include "error.h"
#include "distributions.h"

FILE *logFP;
int previousBirth = 0;
bool debug = false;

void birth (int id, int round) {
  printf ("%d b %d\n", round, id);
  previousBirth = round;
}

void death (int id, int round) {
  printf ("%d d %d\n", round, id);
  int session = round - previousBirth;
  fprintf (logFP, "%d\n", session);
}

char *usage = \
"Usage: churn, Distributions\n" \
"            -l lifetime distribution\n" \
"            -u chance of a node being up at beginning\n" \
"            -s random seed\n" \
"            -b time to begin recording\n" \
"            -e time to end recording\n" \
"            -n number of nodes\n" \
"\n" \
"Distributions:\n" \
" Pareto       P/scale/shape\n" \
" Normal       N/mean/stddev\n" \
" Zipf         Z/alpha/num-elements\n" \
" Poisson      F/mean\n" \
" Uniform      U [0..1)\n" \
" Constant     C/value\n"
"\n Run the output through sort -n\n";

void printUsage () {
  printf ("%s", usage);
  exit (-1);
}

void printUsage (char* problem) {
  printf ("%s\n", problem);
  printUsage ();
}

int main (int argc, char **argv) {
  char c = 0;
  char *lifetimeDistStr = NULL;
  Distribution *lifetimeDist;
  DistributionFactory *distFactory = NULL;
  int seed = getpid ();
  int nodeCount = -1;
  double pctUp = .5;
  int beginRecord = -1, endRecord = -1;

  char filename[20];
  memset (filename, 0, 20);
  sprintf (filename, "churnGen.log");
  if ((logFP = fopen(filename, "w")) == NULL) {
    printf("%s: file write open error.\n", filename);
    exit (-1);
  }

  distFactory = new DistributionFactory ();

  while ( (c = getopt(argc,argv,"n:l:u:s:b:e:")) >= 0) {
    switch (c) {
    case 'l'://lifetime distribution
      lifetimeDistStr = optarg;
      lifetimeDist = distFactory->newDistribution (lifetimeDistStr);
      if (lifetimeDist == NULL)
      	printUsage ("Problem with lifetime distribution");
      break;
    case 'u'://
      pctUp = atof (optarg);
      if (pctUp > 1. || pctUp <= 0.) {//pctUp should  be (0,1]
      	printUsage ("Problem with up pct.");
      }
      break;
    case 's'://radom seed
      seed = atoi (optarg);
      break;
    case 'b'://begin record time
      beginRecord = atoi (optarg);
      break;
    case 'e':// end record time
      endRecord = atoi (optarg);
      break;
    case 'n'://node count
      nodeCount = atoi (optarg);
      break;
    default:
      printUsage ();
      break;
    }
  }

  if (beginRecord < 0 || endRecord <= 0) {
    printUsage ("Error in begin or end record.");
  }
  if (nodeCount <= 0) {
    printUsage ("Error in number of nodes.");
  }

  SRand (seed);//设置随机数种子

  int halfway = (endRecord - beginRecord)/2;
  printf ("%d r 0\n", halfway);

  for (int i = 0; i < nodeCount; i++) {//对各个节点产生事件
    previousBirth = 0;//
    int round = 0;//初始时间
    bool up = true;//
    if (randPct() < pctUp) {//generate multiple events in a same round 0
      ;
    } else {
      round = (int)(lifetimeDist->next());//产生下一轮
    }
	
    bool beenBorn = false;//是否产生了该节点

    //generate events for the same node
    while (round < endRecord) {
      if (up) {//死掉的节点
		if (round >= beginRecord) {
		  birth (i, round-beginRecord);//产生该节点
		  beenBorn = true;
		}
		up = false;
      } else {//活着的节点
		if (round >= beginRecord) {
			  if (!beenBorn) {//
			    birth (i, 0);
			  }
			  death (i, round-beginRecord);
		}
		up = true;//标记死掉
      }

	//产生一个活着或者死掉的间隔
      int session = 0;
      while (session == 0) {
	session = (int)(lifetimeDist->next());
      }
      round += session;
    }
  }

  fclose (logFP);

}