csma-channel.cc

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/*
 * Copyright (c) 2007 Emmanuelle Laprise
 * Copyright (c) 2012 Jeff Young
 * Copyright (c) 2014 Murphy McCauley
 * Copyright (c) 2017 Luciano Jerez Chaves
 *
 * 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: Emmanuelle Laprise <emmanuelle.laprise@bluekazoo.ca>
 * Author: Jeff Young <jyoung9@gatech.edu>
 * Author: Murphy McCauley <murphy.mccauley@gmail.com>
 * Author: Luciano Jerez Chaves <ljerezchaves@gmail.com>
 */
 
#include "csma-channel.h"
 
#include "csma-net-device.h"
 
#include "ns3/log.h"
#include "ns3/packet.h"
#include "ns3/simulator.h"
 
namespace ns3
{
 
NS_LOG_COMPONENT_DEFINE("CsmaChannel");
 
NS_OBJECT_ENSURE_REGISTERED(CsmaChannel);
 
TypeId
CsmaChannel::GetTypeId()
{
    static TypeId tid =
        TypeId("ns3::CsmaChannel")
            .SetParent<Channel>()
            .SetGroupName("Csma")
            .AddConstructor<CsmaChannel>()
            .AddAttribute(
                "DataRate",
                "The transmission data rate to be provided to devices connected to the channel",
                DataRateValue(DataRate(0xffffffff)),
                MakeDataRateAccessor(&CsmaChannel::m_bps),
                MakeDataRateChecker())
            .AddAttribute("Delay",
                          "Transmission delay through the channel",
                          TimeValue(Seconds(0)),
                          MakeTimeAccessor(&CsmaChannel::m_delay),
                          MakeTimeChecker())
            .AddAttribute("FullDuplex",
                          "Whether the channel is full-duplex mode.",
                          TypeId::ATTR_CONSTRUCT,
                          BooleanValue(false),
                          MakeBooleanAccessor(&CsmaChannel::m_fullDuplex),
                          MakeBooleanChecker());
    return tid;
}
 
CsmaChannel::CsmaChannel()
    : Channel()
{
    NS_LOG_FUNCTION_NOARGS();
    m_deviceList.clear();
}
 
CsmaChannel::~CsmaChannel()
{
    NS_LOG_FUNCTION(this);
    m_deviceList.clear();
}
 
int32_t
CsmaChannel::Attach(Ptr<CsmaNetDevice> device)
{
    NS_LOG_FUNCTION(this << device);
    NS_ASSERT(device);
 
    //
    // For full-duplex links we can only attach two devices to the same channel
    // since there is no backoff mechanism for concurrent transmissions.
    //
    if (m_fullDuplex && m_deviceList.size() >= 2)
    {
        NS_LOG_DEBUG("Falling back to half-duplex");
        m_fullDuplex = false;
    }
 
    CsmaDeviceRec rec(device);
 
    m_deviceList.push_back(rec);
    SetState(m_deviceList.size() - 1, IDLE);
    SetCurrentSrc(m_deviceList.size() - 1, m_deviceList.size() - 1);
    return (m_deviceList.size() - 1);
}
 
bool
CsmaChannel::Reattach(Ptr<CsmaNetDevice> device)
{
    NS_LOG_FUNCTION(this << device);
    NS_ASSERT(device);
 
    std::vector<CsmaDeviceRec>::iterator it;
    for (it = m_deviceList.begin(); it < m_deviceList.end(); it++)
    {
        if (it->devicePtr == device)
        {
            if (!it->active)
            {
                it->active = true;
                return true;
            }
            else
            {
                return false;
            }
        }
    }
    return false;
}
 
bool
CsmaChannel::Reattach(uint32_t deviceId)
{
    NS_LOG_FUNCTION(this << deviceId);
 
    if (deviceId >= m_deviceList.size())
    {
        return false;
    }
 
    if (m_deviceList[deviceId].active)
    {
        return false;
    }
    else
    {
        m_deviceList[deviceId].active = true;
        return true;
    }
}
 
bool
CsmaChannel::Detach(uint32_t deviceId)
{
    NS_LOG_FUNCTION(this << deviceId);
 
    if (deviceId < m_deviceList.size())
    {
        if (!m_deviceList[deviceId].active)
        {
            NS_LOG_WARN("CsmaChannel::Detach(): Device is already detached (" << deviceId << ")");
            return false;
        }
 
        m_deviceList[deviceId].active = false;
 
        if ((GetState(deviceId) == TRANSMITTING) && (GetCurrentSrc(deviceId) == deviceId))
        {
            NS_LOG_WARN("CsmaChannel::Detach(): Device is currently"
                        << "transmitting (" << deviceId << ")");
        }
 
        return true;
    }
    else
    {
        return false;
    }
}
 
bool
CsmaChannel::Detach(Ptr<CsmaNetDevice> device)
{
    NS_LOG_FUNCTION(this << device);
    NS_ASSERT(device);
 
    std::vector<CsmaDeviceRec>::iterator it;
    for (it = m_deviceList.begin(); it < m_deviceList.end(); it++)
    {
        if ((it->devicePtr == device) && (it->active))
        {
            it->active = false;
            return true;
        }
    }
    return false;
}
 
bool
CsmaChannel::TransmitStart(Ptr<const Packet> p, uint32_t srcId)
{
    NS_LOG_FUNCTION(this << p << srcId);
    NS_LOG_INFO("UID is " << p->GetUid() << ")");
 
    if (GetState(srcId) != IDLE)
    {
        NS_LOG_WARN("CsmaChannel::TransmitStart(): State is not IDLE");
        return false;
    }
 
    if (!IsActive(srcId))
    {
        NS_LOG_ERROR(
            "CsmaChannel::TransmitStart(): Selected source is not currently attached to network");
        return false;
    }
 
    NS_LOG_LOGIC("switch to TRANSMITTING");
    SetCurrentPkt(srcId, p->Copy());
    SetCurrentSrc(srcId, srcId);
    SetState(srcId, TRANSMITTING);
    return true;
}
 
bool
CsmaChannel::IsActive(uint32_t deviceId)
{
    return (m_deviceList[deviceId].active);
}
 
bool
CsmaChannel::IsFullDuplex() const
{
    return m_fullDuplex;
}
 
bool
CsmaChannel::TransmitEnd(uint32_t srcId)
{
    NS_LOG_FUNCTION(this << GetCurrentPkt(srcId) << GetCurrentSrc(srcId));
    NS_LOG_INFO("UID is " << GetCurrentPkt(srcId)->GetUid() << ")");
 
    NS_ASSERT(GetState(srcId) == TRANSMITTING);
    SetState(srcId, PROPAGATING);
 
    bool retVal = true;
 
    if (!IsActive(GetCurrentSrc(srcId)))
    {
        NS_LOG_ERROR("CsmaChannel::TransmitEnd(): Seclected source was detached before the end of "
                     "the transmission");
        retVal = false;
    }
 
    NS_LOG_LOGIC("Schedule event in " << m_delay.As(Time::S));
 
    NS_LOG_LOGIC("Receive");
 
    std::vector<CsmaDeviceRec>::iterator it;
    for (it = m_deviceList.begin(); it < m_deviceList.end(); it++)
    {
        if (it->IsActive() && it->devicePtr != m_deviceList[GetCurrentSrc(srcId)].devicePtr)
        {
            // schedule reception events
            Simulator::ScheduleWithContext(it->devicePtr->GetNode()->GetId(),
                                           m_delay,
                                           &CsmaNetDevice::Receive,
                                           it->devicePtr,
                                           GetCurrentPkt(srcId)->Copy(),
                                           m_deviceList[GetCurrentSrc(srcId)].devicePtr);
        }
    }
 
    // Schedule for the TX side to go back to IDLE.
    if (IsFullDuplex())
    {
        //
        // In full-duplex mode, the channel should be IDLE during propagation
        // since it's ok to start transmitting again. In this case, we don't need
        // to wait for the channel delay.
        //
        PropagationCompleteEvent(srcId);
    }
    else
    {
        //
        // In half-duplex mode, the channel can only go back to IDLE after
        // propagation delay.
        //
        Simulator::Schedule(m_delay, &CsmaChannel::PropagationCompleteEvent, this, srcId);
    }
    return retVal;
}
 
void
CsmaChannel::PropagationCompleteEvent(uint32_t deviceId)
{
    NS_LOG_FUNCTION(this << GetCurrentPkt(deviceId));
    NS_LOG_INFO("UID is " << GetCurrentPkt(deviceId)->GetUid() << ")");
 
    NS_ASSERT(GetState(deviceId) == PROPAGATING);
    SetState(deviceId, IDLE);
}
 
uint32_t
CsmaChannel::GetNumActDevices()
{
    int numActDevices = 0;
    std::vector<CsmaDeviceRec>::iterator it;
    for (it = m_deviceList.begin(); it < m_deviceList.end(); it++)
    {
        if (it->active)
        {
            numActDevices++;
        }
    }
    return numActDevices;
}
 
std::size_t
CsmaChannel::GetNDevices() const
{
    return m_deviceList.size();
}
 
Ptr<CsmaNetDevice>
CsmaChannel::GetCsmaDevice(std::size_t i) const
{
    return m_deviceList[i].devicePtr;
}
 
int32_t
CsmaChannel::GetDeviceNum(Ptr<CsmaNetDevice> device)
{
    std::vector<CsmaDeviceRec>::iterator it;
    int i = 0;
    for (it = m_deviceList.begin(); it < m_deviceList.end(); it++)
    {
        if (it->devicePtr == device)
        {
            if (it->active)
            {
                return i;
            }
            else
            {
                return -2;
            }
        }
        i++;
    }
    return -1;
}
 
bool
CsmaChannel::IsBusy(uint32_t deviceId)
{
    if (GetState(deviceId) == IDLE)
    {
        return false;
    }
    else
    {
        return true;
    }
}
 
DataRate
CsmaChannel::GetDataRate()
{
    return m_bps;
}
 
Time
CsmaChannel::GetDelay()
{
    return m_delay;
}
 
CsmaChannel::WireState
CsmaChannel::GetState(uint32_t deviceId)
{
    return m_state[m_fullDuplex ? deviceId : 0];
}
 
Ptr<NetDevice>
CsmaChannel::GetDevice(std::size_t i) const
{
    return GetCsmaDevice(i);
}
 
Ptr<Packet>
CsmaChannel::GetCurrentPkt(uint32_t deviceId)
{
    return m_currentPkt[m_fullDuplex ? deviceId : 0];
}
 
void
CsmaChannel::SetCurrentPkt(uint32_t deviceId, Ptr<Packet> pkt)
{
    m_currentPkt[m_fullDuplex ? deviceId : 0] = pkt;
}
 
uint32_t
CsmaChannel::GetCurrentSrc(uint32_t deviceId)
{
    return m_currentSrc[m_fullDuplex ? deviceId : 0];
}
 
void
CsmaChannel::SetCurrentSrc(uint32_t deviceId, uint32_t transmitterId)
{
    m_currentSrc[m_fullDuplex ? deviceId : 0] = transmitterId;
}
 
void
CsmaChannel::SetState(uint32_t deviceId, CsmaChannel::WireState state)
{
    m_state[m_fullDuplex ? deviceId : 0] = state;
}
 
CsmaDeviceRec::CsmaDeviceRec()
{
    active = false;
}
 
CsmaDeviceRec::CsmaDeviceRec(Ptr<CsmaNetDevice> device)
{
    devicePtr = device;
    active = true;
}
 
CsmaDeviceRec::CsmaDeviceRec(const CsmaDeviceRec& deviceRec)
{
    devicePtr = deviceRec.devicePtr;
    active = deviceRec.active;
}
 
bool
CsmaDeviceRec::IsActive() const
{
    return active;
}
 
} // namespace ns3