521 lines
14 KiB
C++
521 lines
14 KiB
C++
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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/*
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* Copyright (c) 2016 NITK Surathkal
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation;
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Authors: Shravya Ks <shravya.ks0@gmail.com>
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* Smriti Murali <m.smriti.95@gmail.com>
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* Mohit P. Tahiliani <tahiliani@nitk.edu.in>
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*/
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/*
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* PORT NOTE: This code was ported from ns-2.36rc1 (queue/pie.cc).
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* Most of the comments are also ported from the same.
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*/
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#include "ns3/log.h"
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#include "ns3/enum.h"
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#include "ns3/uinteger.h"
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#include "ns3/double.h"
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#include "ns3/simulator.h"
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#include "ns3/abort.h"
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#include "pie-queue-disc.h"
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#include "ns3/drop-tail-queue.h"
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namespace ns3 {
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NS_LOG_COMPONENT_DEFINE ("PieQueueDisc");
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NS_OBJECT_ENSURE_REGISTERED (PieQueueDisc);
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TypeId PieQueueDisc::GetTypeId (void)
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{
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static TypeId tid = TypeId ("ns3::PieQueueDisc")
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.SetParent<QueueDisc> ()
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.SetGroupName ("TrafficControl")
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.AddConstructor<PieQueueDisc> ()
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.AddAttribute ("MeanPktSize",
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"Average of packet size",
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UintegerValue (1000),
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MakeUintegerAccessor (&PieQueueDisc::m_meanPktSize),
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MakeUintegerChecker<uint32_t> ())
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.AddAttribute ("A",
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"Value of alpha",
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DoubleValue (0.125),
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MakeDoubleAccessor (&PieQueueDisc::m_a),
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MakeDoubleChecker<double> ())
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.AddAttribute ("B",
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"Value of beta",
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DoubleValue (1.25),
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MakeDoubleAccessor (&PieQueueDisc::m_b),
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MakeDoubleChecker<double> ())
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.AddAttribute ("Tupdate",
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"Time period to calculate drop probability",
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TimeValue (Seconds (0.015)),
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MakeTimeAccessor (&PieQueueDisc::m_tUpdate),
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MakeTimeChecker ())
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.AddAttribute ("Supdate",
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"Start time of the update timer",
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TimeValue (Seconds (0)),
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MakeTimeAccessor (&PieQueueDisc::m_sUpdate),
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MakeTimeChecker ())
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.AddAttribute ("MaxSize",
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"The maximum number of packets accepted by this queue disc",
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QueueSizeValue (QueueSize ("25p")),
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MakeQueueSizeAccessor (&QueueDisc::SetMaxSize,
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&QueueDisc::GetMaxSize),
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MakeQueueSizeChecker ())
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.AddAttribute ("DequeueThreshold",
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"Minimum queue size in bytes before dequeue rate is measured",
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UintegerValue (16384),
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MakeUintegerAccessor (&PieQueueDisc::m_dqThreshold),
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MakeUintegerChecker<uint32_t> ())
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.AddAttribute ("QueueDelayReference",
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"Desired queue delay",
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TimeValue (Seconds (0.015)),
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MakeTimeAccessor (&PieQueueDisc::m_qDelayRef),
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MakeTimeChecker ())
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.AddAttribute ("MaxBurstAllowance",
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"Current max burst allowance before random drop",
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TimeValue (Seconds (0.15)),
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MakeTimeAccessor (&PieQueueDisc::m_maxBurst),
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MakeTimeChecker ())
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.AddAttribute ("UseDequeueRateEstimator",
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"Enable/Disable usage of Dequeue Rate Estimator",
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BooleanValue (false),
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MakeBooleanAccessor (&PieQueueDisc::m_useDqRateEstimator),
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MakeBooleanChecker ())
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.AddAttribute ("UseCapDropAdjustment",
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"Enable/Disable Cap Drop Adjustment feature mentioned in RFC 8033",
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BooleanValue (true),
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MakeBooleanAccessor (&PieQueueDisc::m_isCapDropAdjustment),
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MakeBooleanChecker ())
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.AddAttribute ("UseEcn",
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"True to use ECN (packets are marked instead of being dropped)",
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BooleanValue (false),
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MakeBooleanAccessor (&PieQueueDisc::m_useEcn),
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MakeBooleanChecker ())
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.AddAttribute ("MarkEcnThreshold",
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"ECN marking threshold (RFC 8033 suggests 0.1 (i.e., 10%) default)",
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DoubleValue (0.1),
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MakeDoubleAccessor (&PieQueueDisc::m_markEcnTh),
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MakeDoubleChecker<double> (0,1))
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.AddAttribute ("UseDerandomization",
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"Enable/Disable Derandomization feature mentioned in RFC 8033",
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BooleanValue (false),
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MakeBooleanAccessor (&PieQueueDisc::m_useDerandomization),
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MakeBooleanChecker ())
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;
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return tid;
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}
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PieQueueDisc::PieQueueDisc ()
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: QueueDisc (QueueDiscSizePolicy::SINGLE_INTERNAL_QUEUE)
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{
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NS_LOG_FUNCTION (this);
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m_uv = CreateObject<UniformRandomVariable> ();
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m_rtrsEvent = Simulator::Schedule (m_sUpdate, &PieQueueDisc::CalculateP, this);
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}
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PieQueueDisc::~PieQueueDisc ()
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{
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NS_LOG_FUNCTION (this);
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}
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void
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PieQueueDisc::DoDispose (void)
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{
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NS_LOG_FUNCTION (this);
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m_uv = 0;
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m_rtrsEvent.Cancel ();
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QueueDisc::DoDispose ();
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}
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Time
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PieQueueDisc::GetQueueDelay (void)
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{
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return m_qDelay;
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}
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int64_t
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PieQueueDisc::AssignStreams (int64_t stream)
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{
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NS_LOG_FUNCTION (this << stream);
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m_uv->SetStream (stream);
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return 1;
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}
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bool
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PieQueueDisc::DoEnqueue (Ptr<QueueDiscItem> item)
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{
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NS_LOG_FUNCTION (this << item);
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QueueSize nQueued = GetCurrentSize ();
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if (nQueued + item > GetMaxSize ())
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{
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// Drops due to queue limit: reactive
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DropBeforeEnqueue (item, FORCED_DROP);
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m_accuProb = 0;
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return false;
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}
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else if (DropEarly (item, nQueued.GetValue ()))
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{
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if (!m_useEcn || m_dropProb >= m_markEcnTh || !Mark (item, UNFORCED_MARK))
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{
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// Early probability drop: proactive
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DropBeforeEnqueue (item, UNFORCED_DROP);
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m_accuProb = 0;
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return false;
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}
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}
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// No drop
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bool retval = GetInternalQueue (0)->Enqueue (item);
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// If Queue::Enqueue fails, QueueDisc::DropBeforeEnqueue is called by the
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// internal queue because QueueDisc::AddInternalQueue sets the trace callback
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NS_LOG_LOGIC ("\t bytesInQueue " << GetInternalQueue (0)->GetNBytes ());
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NS_LOG_LOGIC ("\t packetsInQueue " << GetInternalQueue (0)->GetNPackets ());
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return retval;
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}
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void
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PieQueueDisc::InitializeParams (void)
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{
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// Initially queue is empty so variables are initialize to zero except m_dqCount
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m_inMeasurement = false;
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m_dqCount = DQCOUNT_INVALID;
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m_dropProb = 0;
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m_avgDqRate = 0.0;
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m_dqStart = 0;
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m_burstState = NO_BURST;
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m_qDelayOld = Time (Seconds (0));
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m_accuProb = 0.0;
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}
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bool PieQueueDisc::DropEarly (Ptr<QueueDiscItem> item, uint32_t qSize)
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{
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NS_LOG_FUNCTION (this << item << qSize);
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if (m_burstAllowance.GetSeconds () > 0)
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{
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// If there is still burst_allowance left, skip random early drop.
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return false;
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}
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if (m_burstState == NO_BURST)
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{
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m_burstState = IN_BURST_PROTECTING;
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m_burstAllowance = m_maxBurst;
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}
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double p = m_dropProb;
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uint32_t packetSize = item->GetSize ();
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if (GetMaxSize ().GetUnit () == QueueSizeUnit::BYTES)
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{
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p = p * packetSize / m_meanPktSize;
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}
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// Safeguard PIE to be work conserving (Section 4.1 of RFC 8033)
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if ((m_qDelayOld.GetSeconds () < (0.5 * m_qDelayRef.GetSeconds ())) && (m_dropProb < 0.2))
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{
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return false;
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}
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else if (GetMaxSize ().GetUnit () == QueueSizeUnit::BYTES && qSize <= 2 * m_meanPktSize)
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{
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return false;
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}
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else if (GetMaxSize ().GetUnit () == QueueSizeUnit::PACKETS && qSize <= 2)
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{
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return false;
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}
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if (m_useDerandomization)
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{
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if (m_dropProb == 0)
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{
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m_accuProb = 0;
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}
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m_accuProb += m_dropProb;
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if (m_accuProb < 0.85)
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{
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return false;
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}
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else if (m_accuProb >= 8.5)
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{
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return true;
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}
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}
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double u = m_uv->GetValue ();
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if (u > p)
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{
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return false;
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}
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return true;
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}
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void PieQueueDisc::CalculateP ()
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{
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NS_LOG_FUNCTION (this);
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Time qDelay;
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double p = 0.0;
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bool missingInitFlag = false;
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if (m_useDqRateEstimator)
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{
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if (m_avgDqRate > 0)
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{
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qDelay = Time (Seconds (GetInternalQueue (0)->GetNBytes () / m_avgDqRate));
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}
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else
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{
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qDelay = Time (Seconds (0));
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missingInitFlag = true;
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}
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m_qDelay = qDelay;
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}
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else
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{
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qDelay = m_qDelay;
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}
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NS_LOG_DEBUG ("Queue delay while calculating probability: " << qDelay.GetMilliSeconds () << "ms");
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if (m_burstAllowance.GetSeconds () > 0)
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{
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m_dropProb = 0;
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}
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else
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{
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p = m_a * (qDelay.GetSeconds () - m_qDelayRef.GetSeconds ()) + m_b * (qDelay.GetSeconds () - m_qDelayOld.GetSeconds ());
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if (m_dropProb < 0.000001)
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{
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p /= 2048;
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}
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else if (m_dropProb < 0.00001)
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{
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p /= 512;
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}
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else if (m_dropProb < 0.0001)
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{
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p /= 128;
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}
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else if (m_dropProb < 0.001)
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{
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p /= 32;
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}
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else if (m_dropProb < 0.01)
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{
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p /= 8;
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}
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else if (m_dropProb < 0.1)
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{
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p /= 2;
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}
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else
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{
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// The pseudocode in Section 4.2 of RFC 8033 suggests to use this for
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// assignment of p, but this assignment causes build failure on Mac OS
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// p = p;
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}
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// Cap Drop Adjustment (Section 5.5 of RFC 8033)
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if (m_isCapDropAdjustment && (m_dropProb >= 0.1) && (p > 0.02))
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{
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p = 0.02;
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}
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}
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p += m_dropProb;
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// For non-linear drop in prob
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// Decay the drop probability exponentially (Section 4.2 of RFC 8033)
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if (qDelay.GetSeconds () == 0 && m_qDelayOld.GetSeconds () == 0)
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{
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p *= 0.98;
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}
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// bound the drop probability (Section 4.2 of RFC 8033)
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if (p < 0)
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{
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m_dropProb = 0;
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}
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else if (p > 1)
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{
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m_dropProb = 1;
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}
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else
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{
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m_dropProb = p;
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}
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// Section 4.4 #2
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if (m_burstAllowance < m_tUpdate)
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{
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m_burstAllowance = Time (Seconds (0));
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}
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else
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{
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m_burstAllowance -= m_tUpdate;
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}
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uint32_t burstResetLimit = static_cast<uint32_t>(BURST_RESET_TIMEOUT / m_tUpdate.GetSeconds ());
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if ( (qDelay.GetSeconds () < 0.5 * m_qDelayRef.GetSeconds ()) && (m_qDelayOld.GetSeconds () < (0.5 * m_qDelayRef.GetSeconds ())) && (m_dropProb == 0) && !missingInitFlag )
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{
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m_dqCount = DQCOUNT_INVALID;
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m_avgDqRate = 0.0;
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}
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if ( (qDelay.GetSeconds () < 0.5 * m_qDelayRef.GetSeconds ()) && (m_qDelayOld.GetSeconds () < (0.5 * m_qDelayRef.GetSeconds ())) && (m_dropProb == 0) && (m_burstAllowance.GetSeconds () == 0))
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{
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if (m_burstState == IN_BURST_PROTECTING)
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{
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m_burstState = IN_BURST;
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m_burstReset = 0;
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}
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else if (m_burstState == IN_BURST)
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{
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m_burstReset++;
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if (m_burstReset > burstResetLimit)
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{
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m_burstReset = 0;
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m_burstState = NO_BURST;
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}
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}
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}
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else if (m_burstState == IN_BURST)
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{
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m_burstReset = 0;
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}
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m_qDelayOld = qDelay;
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m_rtrsEvent = Simulator::Schedule (m_tUpdate, &PieQueueDisc::CalculateP, this);
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}
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Ptr<QueueDiscItem>
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PieQueueDisc::DoDequeue ()
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{
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NS_LOG_FUNCTION (this);
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if (GetInternalQueue (0)->IsEmpty ())
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{
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NS_LOG_LOGIC ("Queue empty");
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return 0;
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}
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Ptr<QueueDiscItem> item = GetInternalQueue (0)->Dequeue ();
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double now = Simulator::Now ().GetSeconds ();
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uint32_t pktSize = item->GetSize ();
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// if not in a measurement cycle and the queue has built up to dq_threshold,
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// start the measurement cycle
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if (m_useDqRateEstimator)
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{
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if ( (GetInternalQueue (0)->GetNBytes () >= m_dqThreshold) && (!m_inMeasurement) )
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{
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m_dqStart = now;
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m_dqCount = 0;
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m_inMeasurement = true;
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}
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if (m_inMeasurement)
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{
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m_dqCount += pktSize;
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// done with a measurement cycle
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if (m_dqCount >= m_dqThreshold)
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{
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double tmp = now - m_dqStart;
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if (tmp > 0)
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{
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if (m_avgDqRate == 0)
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{
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m_avgDqRate = m_dqCount / tmp;
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}
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else
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{
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m_avgDqRate = (0.5 * m_avgDqRate) + (0.5 * (m_dqCount / tmp));
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}
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}
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NS_LOG_DEBUG ("Average Dequeue Rate after Dequeue: " << m_avgDqRate);
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// restart a measurement cycle if there is enough data
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if (GetInternalQueue (0)->GetNBytes () > m_dqThreshold)
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{
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m_dqStart = now;
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m_dqCount = 0;
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m_inMeasurement = true;
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}
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else
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{
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m_dqCount = 0;
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m_inMeasurement = false;
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}
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}
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}
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}
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else
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{
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m_qDelay = Time (Seconds (now - item->GetTimeStamp ().GetSeconds ()));
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if (GetInternalQueue (0)->GetNBytes () == 0)
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{
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m_qDelay = Time (Seconds (0));
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}
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}
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return item;
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}
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bool
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PieQueueDisc::CheckConfig (void)
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{
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NS_LOG_FUNCTION (this);
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if (GetNQueueDiscClasses () > 0)
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{
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NS_LOG_ERROR ("PieQueueDisc cannot have classes");
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return false;
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}
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if (GetNPacketFilters () > 0)
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{
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NS_LOG_ERROR ("PieQueueDisc cannot have packet filters");
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return false;
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}
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if (GetNInternalQueues () == 0)
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{
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// add a DropTail queue
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AddInternalQueue (CreateObjectWithAttributes<DropTailQueue<QueueDiscItem> >
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("MaxSize", QueueSizeValue (GetMaxSize ())));
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}
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if (GetNInternalQueues () != 1)
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{
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NS_LOG_ERROR ("PieQueueDisc needs 1 internal queue");
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return false;
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}
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return true;
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}
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} //namespace ns3
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