bandwidth_filter.cc

这是一个著名的应用层组播中间件的源码

//Copyright (c) 2004, Charles Killian, Adolfo Rodriguez, Dejan Kostic, Sooraj Bhat, and Amin Vahdat
//All rights reserved.
//
//Redistribution and use in source and binary forms, with or without
//modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
//   * 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.
//   * Neither the names of Duke University nor The University of
//     California, San Diego, nor the names of its contributors
//     may be used to endorse or promote products derived from
//     this software without specific prior written permission.
//
//THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.

#include "bandwidth_filter.h"
#include <stdio.h>
#include "scheduler.h"
#include "macedon.h"

bandwidth_filter::bandwidth_filter( )
{
  history_count =0;
  value = 0.0;
  time_initial = Scheduler::instance().clock();

}

bandwidth_filter::~bandwidth_filter()
{
}

// ---------------------------------------------- 
// get_value
// ---------------------------------------------- 

double  bandwidth_filter::get_value ()
{
  check();
  double result = value;
  return  result;
}


// ---------------------------------------------- 
// clear
// ---------------------------------------------- 

void  bandwidth_filter::clear ()
{
  history.clear ();
  value = 0.0;
}


// ---------------------------------------------- 
// update
// ---------------------------------------------- 

void  bandwidth_filter::update (int size)
{
  double now =  Scheduler::instance().clock();

  history.push_back (bandwidth_pair (size,now));
  history_count++;
  check();
}



// ---------------------------------------------- 
// check
// ---------------------------------------------- 

void bandwidth_filter::check ()
{
  double elapsed_time;
  double now = Scheduler::instance().clock();

  while (history_count && (now - history.front().when)> BANDWIDTH_WINDOW) {
    history.pop_front();
    history_count--;
  }      
  
  if (history_count == 0 ) {
    value = 0.0;
  }
  else {
    if (now-time_initial < BANDWIDTH_WINDOW)
      elapsed_time = now-time_initial;
    else
      elapsed_time = BANDWIDTH_WINDOW;
    int total_bytes = 0;
    for(list<bandwidth_pair>::iterator it =  history.begin();
	it != history.end(); ++it) 
      {
	bandwidth_pair r=*it;
	total_bytes+=r.size;
      }
    value = total_bytes*8/elapsed_time;
  }

}