P2PSim中重要函数的说明

环境：RedHat9上安装的P2Psim0.3

目的：在P2Psim使用Vivaldi协议仿真

现状：主程序代码中关于vivaldi协议的部分注释掉了。

思路：从主函数分析代码，找到原因。

vivaldi协议主函数是vivalditest.C

#ifndef __VIVALDITEST_H
#define __VIVALDITEST_H

#include "p2psim/p2protocol.h"
#include "vivaldinode.h"

class VivaldiTest : public VivaldiNode {
public:
  VivaldiTest(IPAddress i, Args &args);
  ~VivaldiTest();
  string proto_name() { return "VivaldiTest"; }

  virtual void join(Args*);
  virtual void leave(Args*) { }
  virtual void crash(Args*) { }
  virtual void insert(Args*) { }
  virtual void lookup(Args*) { }
  virtual void nodeevent (Args *);

  virtual void initstate ();
  void tick(void *);
  void status();
  double error();
  vector<IPAddress> best_n (unsigned int n);
  void total_error(double &x05, double &x50, double &x95);
  void node_errors(double &x05, double &x50, double &x95);
  vector<IPAddress> _nip_best;
  vector<IPAddress> _nip;
  vector<IPAddress> _nip_far;
  int _neighbors_far;

 private:
  int _ticks;
  int _grid_config;
  int _ring_config;
  int _landmark_config;
  int _near_config;

  bool _aux_added; 
  //some neighbor adding strategies
  // need to run after _all is filled
  // in. This flag lets us run them once

  Vivaldi *_vivaldi;
  static vector<VivaldiTest*> _all;

  int _next_neighbor;
  int _neighbors; // if > 0, fix the number of neighbors
  uint _total_nodes;
  int _vis;
  double _last_error;
  bool _joined;
  int _far_percent;

  uint _old_all_size;

  void handler(void *, void *);

  void addRingNeighbors ();
  void addGridNeighbors ();
  void addRandNeighbors ();
  void addLandmarkNeighbors ();
  void addNearNeighbors ();
  void print_all_loc();
};

#endif // __VIVALDITEST_H

vivalditest继承于vivaldinode类

void VivaldiNode::update_error (vector<Sample> samples)
{
  double expect = dist (_c, samples[0]._c);  
  double actual = samples[0]._latency;
  if (actual < 0) return;
  double rel_error = fabs(expect - actual)/actual;
  if (_pred_err < 0) 
    _pred_err = rel_error;
  else if (_samples[0]._error < 0) 
    //    _pred_err = _pred_err;    ;
  else {
    double ce = _pred_err*_pred_err;
    double he = samples[0]._error*samples[0]._error;
    double new_pred_err = rel_error*(ce/(he + ce)) + _pred_err*(he/(he + ce));
    _pred_err = (19*_pred_err + new_pred_err)/20.0;
    if (_pred_err > 1.0) _pred_err = 1.0;
  }
}

vivaldinode又继承于p2protocol

主要参数
#define MODEL_EUCLIDEAN 3   //嵌入欧式空间，其他有sphere空间、toroidal曲面空间
#define ALG_VIVALDI 1   //最基本的vivaldi算法
#define ALG_SIMPLEX 2
#define ALG_PERFECT 3 

adaptive  //调整的时间间隔
_timestep  //最小的timestep
_pred_err  //running average of prediction error
_window_size //历史窗口大小
_model_type  //空间类型
_model  
_algorithm_type  //算法类型
_algorithm
_c           //current estimated coordinates
_samples      //RTT的历史记录（每个元素：_c, _latency, _whoIP, _error）
_init_samples   //RTT初始记录


主要函数
Sample lowest_latency(vector<Sample> v);   //从历史记录中找出最小的时延
Coord net_force(Coord c, vector<Sample> v);  //多个节点的合力共同更新本节点坐标
vector<double> get_weights (vector<Sample> v);  //多个参考节点的所对应的误差
void update_error (vector<Sample> v);         //更新本地节点误差
double dist(VivaldiNode::Coord a, VivaldiNode::Coord b);  //计算2个Vivaldi节点的距离
template<class BT, class AT, class RT> bool doRPC(IPAddress dst, void (BT::* fn)(AT *, RT *), AT *args, RT *ret)  //发送消息函数，dynamic_cast，
【
      VivaldiNode * t = dynamic_cast<VivaldiNode *>(getpeer(dst));  //peer包含dst自己吗？
      Topology *topo = Network::Instance ()->gettopology ();
】

P2protocol继承于Node

class P2Protocol : public Node {
public:
  P2Protocol(IPAddress);
  virtual ~P2Protocol();

  typedef void (P2Protocol::*event_f)(Args*);
  virtual void join(Args*) = 0;
  virtual void crash(Args*) {}
  virtual void lookup(Args*) = 0;
  virtual void nodeevent(Args*) = 0;
};

Node类继承于Observed

主要参数
_ip
static string _protocol;
static Args _args;
static Time _collect_stat_time;
static bool _collect_stat;
IPAddress _first_ip;
IPAddress _prev_ip;


主要函数
ip()
heaer()
alive()
static void Receive(void*);
Node *getpeer(IPAddress);   // find peer protocol of my sub-type on a distant node.

//统计性函数
  // statistic collection
  typedef uint stat_type;
  const static stat_type STAT_LOOKUP = 0;
  unsigned long get_out_bw_stat() { return node_live_outbytes;}
  void record_bw_stat(stat_type type, uint num_ids, uint num_else);
  static void record_inout_bw_stat(IPAddress src, IPAddress dst, uint num_ids, uint num_else);
  void record_in_bytes(uint b);
  void record_out_bytes(uint b); 
  static void record_lookup_stat(IPAddress src, IPAddress dst, Time interval, 
				 bool complete, bool correct, 
				 uint num_hops = 0, uint num_timeouts = 0, 
				 Time time_timeouts = 0);

  void record_join();
  void record_crash();
  static void print_stats();
  static void print_dist_stats(vector<double> v);

Observed类记录网络仿真日志

class Observed {
public:
  void registerObserver(Observer *);
  void unregisterObserver(Observer *);
  void notifyObservers(ObserverInfo* = 0);

protected:
  Observed();
  virtual ~Observed() { }

private:
  set<Observer*> _observers;
  bool _hasObservers;
  virtual void dummy() { } // make dynamic_cast<Kelips*>(Observed*) work
};

p2psim中主要指标参数有