/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2006 INRIA
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
 */

// This program can be used to benchmark packet serialization/deserialization
// operations using Headers and Tags, for various numbers of packets 'n'
// Sample usage:  ./ns3 run 'bench-packets --n=10000'

#include "ns3/command-line.h"
#include "ns3/system-wall-clock-ms.h"
#include "ns3/packet.h"
#include "ns3/packet-metadata.h"
#include <iostream>
#include <sstream>
#include <string>
#include <stdlib.h> // for exit ()
#include <limits>
#include <algorithm>

using namespace ns3;

/// BenchHeader class used for benchmarking packet serialization/deserialization
template <int N>
class BenchHeader : public Header
{
public:
  BenchHeader ();
  /**
   * Returns true if the header has been deserialized and the
   * deserialization was correct.  If Deserialize() has not yet been
   * called on the header, will return false.
   *
   * \returns true if success, false if failed or if deserialization not tried
   */
  bool IsOk (void) const;

  /**
   * Register this type.
   * \return The TypeId.
   */
  static TypeId GetTypeId (void);
  virtual TypeId GetInstanceTypeId (void) const;
  virtual void Print (std::ostream &os) const;
  virtual uint32_t GetSerializedSize (void) const;
  virtual void Serialize (Buffer::Iterator start) const;
  virtual uint32_t Deserialize (Buffer::Iterator start);
private:
  /**
   * Get type name function
   * \returns the type name string
   */
  static std::string GetTypeName (void);
  bool m_ok; ///< variable to track whether deserialization succeeded
};

template <int N>
BenchHeader<N>::BenchHeader ()
  : m_ok (false)
{}

template <int N>
bool
BenchHeader<N>::IsOk (void) const
{
  return m_ok;
}

template <int N>
std::string
BenchHeader<N>::GetTypeName (void)
{
  std::ostringstream oss;
  oss << "ns3::BenchHeader<" << N << ">";
  return oss.str ();
}

template <int N>
TypeId
BenchHeader<N>::GetTypeId (void)
{
  static TypeId tid = TypeId (GetTypeName ())
    .SetParent<Header> ()
    .SetGroupName ("Utils")
    .HideFromDocumentation ()
    .AddConstructor<BenchHeader <N> > ()
    ;
  return tid;
}
template <int N>
TypeId
BenchHeader<N>::GetInstanceTypeId (void) const
{
  return GetTypeId ();
}

template <int N>
void
BenchHeader<N>::Print (std::ostream &os) const
{
  NS_ASSERT (false);
}
template <int N>
uint32_t
BenchHeader<N>::GetSerializedSize (void) const
{
  return N;
}
template <int N>
void
BenchHeader<N>::Serialize (Buffer::Iterator start) const
{
  start.WriteU8 (N, N);
}
template <int N>
uint32_t
BenchHeader<N>::Deserialize (Buffer::Iterator start)
{
  m_ok = true;
  for (int i = 0; i < N; i++)
    {
      if (start.ReadU8 () != N)
        {
          m_ok = false;
        }
    }
  return N;
}

/// BenchTag class used for benchmarking packet serialization/deserialization
template <int N>
class BenchTag : public Tag
{
public:
  /**
   * Get the bench tag name.
   * \return the name.
   */
  static std::string GetName (void) {
    std::ostringstream oss;
    oss << "anon::BenchTag<" << N << ">";
    return oss.str ();
  }
  /**
   * Register this type.
   * \return The TypeId.
   */
  static TypeId GetTypeId (void) {
    static TypeId tid = TypeId (GetName ())
      .SetParent<Tag> ()
      .SetGroupName ("Utils")
      .HideFromDocumentation ()
      .AddConstructor<BenchTag<N> > ()
      ;
    return tid;
  }
  virtual TypeId GetInstanceTypeId (void) const {
    return GetTypeId ();
  }
  virtual uint32_t GetSerializedSize (void) const {
    return N;
  }
  virtual void Serialize (TagBuffer buf) const {
    for (uint32_t i = 0; i < N; ++i)
      {
        buf.WriteU8 (N);
      }
  }
  virtual void Deserialize (TagBuffer buf) {
    for (uint32_t i = 0; i < N; ++i)
      {
        buf.ReadU8 ();
      }
  }
  virtual void Print (std::ostream &os) const {
    os << "N=" << N;
  }
  BenchTag ()
    : Tag () {}
};


static void
benchD (uint32_t n)
{
  BenchHeader<25> ipv4;
  BenchHeader<8> udp;
  BenchTag<16> tag1;
  BenchTag<17> tag2;

  for (uint32_t i = 0; i < n; i++) {
    Ptr<Packet> p = Create<Packet> (2000);
    p->AddPacketTag (tag1);
    p->AddHeader (udp);
    p->RemovePacketTag (tag1);
    p->AddPacketTag (tag2);
    p->AddHeader (ipv4);
    Ptr<Packet> o = p->Copy ();
    o->RemoveHeader (ipv4);
    p->RemovePacketTag (tag2);
    o->RemoveHeader (udp);
  }
}



static void
benchA (uint32_t n)
{
  BenchHeader<25> ipv4;
  BenchHeader<8> udp;

  // The original version of this program did not use BenchHeader::IsOK ()
  // Below are two asserts that suggest how it can be used.
  NS_ASSERT_MSG (ipv4.IsOk () == false, "IsOk() should be false before deserialization");
  for (uint32_t i = 0; i < n; i++) {
    Ptr<Packet> p = Create<Packet> (2000);
    p->AddHeader (udp);
    p->AddHeader (ipv4);
    Ptr<Packet> o = p->Copy ();
    o->RemoveHeader (ipv4);
    o->RemoveHeader (udp);
  }
  NS_ASSERT_MSG (ipv4.IsOk () == true, "IsOk() should be true after deserialization");
}

static void
benchB (uint32_t n)
{
  BenchHeader<25> ipv4;
  BenchHeader<8> udp;

  for (uint32_t i = 0; i < n; i++) {
    Ptr<Packet> p = Create<Packet> (2000);
    p->AddHeader (udp);
    p->AddHeader (ipv4);
  }
}

static void
C2 (Ptr<Packet> p)
{
  BenchHeader<8> udp;

  p->RemoveHeader (udp);
}

static void
C1 (Ptr<Packet> p)
{
  BenchHeader<25> ipv4;
  p->RemoveHeader (ipv4);
  C2 (p);
}

static void
benchC (uint32_t n)
{
  BenchHeader<25> ipv4;
  BenchHeader<8> udp;

  for (uint32_t i = 0; i < n; i++) {
    Ptr<Packet> p = Create<Packet> (2000);
    p->AddHeader (udp);
    p->AddHeader (ipv4);
    C1 (p);
  }
}

static void
benchFragment (uint32_t n)
{
  BenchHeader<25> ipv4;
  BenchHeader<8> udp;

  for (uint32_t i= 0; i < n; i++) {
    Ptr<Packet> p = Create<Packet> (2000);
    p->AddHeader (udp);
    p->AddHeader (ipv4);

    Ptr<Packet> frag0 = p->CreateFragment (0, 250);
    Ptr<Packet> frag1 = p->CreateFragment (250, 250);
    Ptr<Packet> frag2 = p->CreateFragment (500, 500);
    Ptr<Packet> frag3 = p->CreateFragment (1000, 500);
    Ptr<Packet> frag4 = p->CreateFragment (1500, 500);

    /* Mix fragments in different order */
    frag2->AddAtEnd (frag3);
    frag4->AddAtEnd (frag1);
    frag2->AddAtEnd (frag4);
    frag0->AddAtEnd (frag2);

    frag0->RemoveHeader (ipv4);
    frag0->RemoveHeader (udp);
  }
}

static void
benchByteTags (uint32_t n)
{
  for (uint32_t i = 0; i < n; i++)
    {
      Ptr<Packet> p = Create<Packet> (2000);
      for (uint32_t j = 0; j < 100; j++)
        {
          BenchTag<0> tag;
          p->AddByteTag (tag);
        }
      Ptr<Packet> q = Create<Packet> (1000);

      // This should trigger adjustment of all byte tags
      q->AddAtEnd (p);
    }
}

static uint64_t
runBenchOneIteration (void (*bench) (uint32_t), uint32_t n)
{
  SystemWallClockMs time;
  time.Start ();
  (*bench) (n);
  uint64_t deltaMs = time.End ();
  return deltaMs;
}


static void
runBench (void (*bench) (uint32_t), uint32_t n, uint32_t minIterations, char const *name)
{
  uint64_t minDelay = std::numeric_limits<uint64_t>::max();
  for (uint32_t i = 0; i < minIterations; i++)
    {
      uint64_t delay = runBenchOneIteration(bench, n);
      minDelay = std::min(minDelay, delay);
    }
  double ps = n;
  ps *= 1000;
  ps /= minDelay;
  std::cout << ps << " packets/s"
            << " (" << minDelay << " ms elapsed)\t"
            << name
            << std::endl;
}

int main (int argc, char *argv[])
{
  uint32_t n = 0;
  uint32_t minIterations = 1;
  bool enablePrinting = false;

  CommandLine cmd (__FILE__);
  cmd.Usage ("Benchmark Packet class");
  cmd.AddValue ("n", "number of iterations", n);
  cmd.AddValue ("min-iterations", "number of subiterations to minimize iteration time over", minIterations);
  cmd.AddValue ("enable-printing", "enable packet printing", enablePrinting);
  cmd.Parse (argc, argv);

  if (n == 0)
    {
      std::cerr << "Error-- number of packets must be specified " <<
        "by command-line argument --n=(number of packets)" << std::endl;
      exit (1);
    }
  std::cout << "Running bench-packets with n=" << n << std::endl;
  std::cout << "All tests begin by adding UDP and IPv4 headers." << std::endl;

  runBench (&benchA, n, minIterations, "Copy packet, remove headers");
  runBench (&benchB, n, minIterations, "Just add headers");
  runBench (&benchC, n, minIterations, "Remove by func call");
  runBench (&benchD, n, minIterations, "Intermixed add/remove headers and tags");
  runBench (&benchFragment, n, minIterations, "Fragmentation and concatenation");
  runBench (&benchByteTags, n, minIterations, "Benchmark byte tags");

  return 0;
}