Using the Tracing System

Posted on Tue 01 February 2022 in Journal

构造一个追踪系统很重要

在服务器开发及问题诊断中，日志 Log，追踪 Trace 和度量 Metrics 是最重要的手段。

Log 大家都很熟悉了，主要的要求是

分组，分组，易于分类
高吞吐量，高性能，日志打得再多也不会影响主要业务
节约，不会过多占用磁盘空间，可以覆盖重写，并且可按时间归档
安全，不包含敏感信息

Trace 对于算法验证和问题诊断来说更加重要，它不同于日志，它是对于数据流或工作流的记录

以之前提到的 ns-3 为例，为 myfirst.cc 添加 AsciiTrace 和 PcapTrace

#include "ns3/core-module.h"
#include "ns3/network-module.h"
#include "ns3/internet-module.h"
#include "ns3/point-to-point-module.h"
#include "ns3/applications-module.h"

// Default Network Topology
//
//       10.1.1.0
// n0 -------------- n1
//    point-to-point
//

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("FirstScriptExample");

int
main (int argc, char *argv[])
{
  CommandLine cmd (__FILE__);
  cmd.Parse (argc, argv);

  Time::SetResolution (Time::NS);
  LogComponentEnable ("UdpEchoClientApplication", LOG_LEVEL_INFO);
  LogComponentEnable ("UdpEchoServerApplication", LOG_LEVEL_INFO);

  NodeContainer nodes;
  nodes.Create (2);

  PointToPointHelper pointToPoint;
  pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
  pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));

  NetDeviceContainer devices;
  devices = pointToPoint.Install (nodes);

  InternetStackHelper stack;
  stack.Install (nodes);

  Ipv4AddressHelper address;
  address.SetBase ("10.1.1.0", "255.255.255.0");

  Ipv4InterfaceContainer interfaces = address.Assign (devices);

  UdpEchoServerHelper echoServer (9);

  ApplicationContainer serverApps = echoServer.Install (nodes.Get (1));
  serverApps.Start (Seconds (1.0));
  serverApps.Stop (Seconds (10.0));

  UdpEchoClientHelper echoClient (interfaces.GetAddress (1), 9);
  echoClient.SetAttribute ("MaxPackets", UintegerValue (1));
  echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.0)));
  echoClient.SetAttribute ("PacketSize", UintegerValue (1024));

  ApplicationContainer clientApps = echoClient.Install (nodes.Get (0));
  clientApps.Start (Seconds (2.0));
  clientApps.Stop (Seconds (10.0));

  //add AsciiTrace
  AsciiTraceHelper ascii;
  pointToPoint.EnableAsciiAll (ascii.CreateFileStream ("myfirst.tr"));

  //add PcapTrace
  pointToPoint.EnablePcapAll ("myfirst");

  Simulator::Run ();
  Simulator::Destroy ();
  return 0;
}

生成的 ascii trace 文件如下

# more myfirst.tr

+ 2 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enqueue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)
- 2 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Dequeue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)
r 2.00369 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/MacRx ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)
+ 2.00369 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enqueue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.2 > 10.1.1.1) ns3::UdpHeader (length: 1032 9 > 49153) Payload (size=1024)
- 2.00369 /NodeList/1/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Dequeue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.2 > 10.1.1.1) ns3::UdpHeader (length: 1032 9 > 49153) Payload (size=1024)
r 2.00737 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/MacRx ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 DSCP Default ECN Not-ECT ttl 64 id 0 protocol 17 offset (bytes) 0 flags [none] length: 1052 10.1.1.2 > 10.1.1.1) ns3::UdpHeader (length: 1032 9 > 49153) Payload (size=1024)

Note that each line in the trace file begins with a lone character (has a space after it). This character will have the following meaning:

+: An enqueue operation occurred on the device queue;
-: A dequeue operation occurred on the device queue;
d: A packet was dropped, typically because the queue was full;
r: A packet was received by the net device.

生成的 pcap trace 文件如下

ll myfirst*
-rw-r--r-- 1 root root 2164 Feb 20 15:05 myfirst-0-0.pcap
-rw-r--r-- 1 root root 2164 Feb 20 15:05 myfirst-1-0.pcap
-rw-r--r-- 1 root root 1954 Feb 20 15:05 myfirst.tr


# tcpdump -nn -tt -r myfirst-0-0.pcap
reading from file myfirst-0-0.pcap, link-type PPP (PPP)
2.000000 IP 10.1.1.1.49153 > 10.1.1.2.9: UDP, length 1024
2.007372 IP 10.1.1.2.9 > 10.1.1.1.49153: UDP, length 1024
root@node2:/home/walter/workspace/webrtc/ns-allinone-3.35/ns-3.35# tcpdump -nn -tt -r myfirst-1-0.pcap
reading from file myfirst-1-0.pcap, link-type PPP (PPP)
2.003686 IP 10.1.1.1.49153 > 10.1.1.2.9: UDP, length 1024
2.003686 IP 10.1.1.2.9 > 10.1.1.1.49153: UDP, length 1024

ns-3 的 tracing 系统基本上可以分为三部分

Tracing Sources 它是指一个实体，表示追踪的来源，是追踪信息的生产者，可以标记追踪信息发生的时间，提供一个访问底层数据的方法，以及提供对状态变化给出相应的指示
Tracing Sinks

它是指追踪信息的消费者

Tracing connection

它是指将生产者 Tracing Sources 和消费者 Tracing Sinks 联系起来

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构造一个追踪系统很重要

生成的 ascii trace 文件如下

生成的 pcap trace 文件如下

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