ReorderingPacketBuffer Class Reference

Collaboration diagram for ReorderingPacketBuffer:

[legend]

Public Member Functions
	ReorderingPacketBuffer (BufferedPacketFactory *packetFactory)
virtual	~ReorderingPacketBuffer ()
void	reset ()
BufferedPacket *	getFreePacket (MultiFramedRTPSource *ourSource)
Boolean	storePacket (BufferedPacket *bPacket)
BufferedPacket *	getNextCompletedPacket (Boolean &packetLossPreceded)
void	releaseUsedPacket (BufferedPacket *packet)
void	freePacket (BufferedPacket *packet)
Boolean	isEmpty () const
void	setThresholdTime (unsigned uSeconds)
void	resetHaveSeenFirstPacket ()
Private Attributes
BufferedPacketFactory *	fPacketFactory
unsigned	fThresholdTime
Boolean	fHaveSeenFirstPacket
unsigned short	fNextExpectedSeqNo
BufferedPacket *	fHeadPacket
BufferedPacket *	fTailPacket
BufferedPacket *	fSavedPacket
Boolean	fSavedPacketFree

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Detailed Description

Definition at line 28 of file MultiFramedRTPSource.cpp.

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Constructor & Destructor Documentation

ReorderingPacketBuffer::ReorderingPacketBuffer

(

BufferedPacketFactory *

packetFactory

)

Definition at line 461 of file MultiFramedRTPSource.cpp.

References NULL.

  : fThresholdTime(100000) /* default reordering threshold: 100 ms */,
    fHaveSeenFirstPacket(False), fHeadPacket(NULL), fTailPacket(NULL), fSavedPacket(NULL), fSavedPacketFree(True) {
  fPacketFactory = (packetFactory == NULL)
    ? (new BufferedPacketFactory)
    : packetFactory;
}

ReorderingPacketBuffer::~ReorderingPacketBuffer

(

)

[virtual]

Definition at line 469 of file MultiFramedRTPSource.cpp.

References fPacketFactory, and reset().

                                                {
  reset();
  delete fPacketFactory;
}

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Member Function Documentation

void ReorderingPacketBuffer::reset

(

)

Definition at line 474 of file MultiFramedRTPSource.cpp.

References fHeadPacket, fSavedPacket, fSavedPacketFree, fTailPacket, NULL, and resetHaveSeenFirstPacket().

Referenced by MultiFramedRTPSource::doStopGettingFrames(), and ~ReorderingPacketBuffer().

                                   {
  if (fSavedPacketFree) delete fSavedPacket; // because fSavedPacket is not in the list
  delete fHeadPacket; // will also delete fSavedPacket if it's in the list
  resetHaveSeenFirstPacket();
  fHeadPacket = fTailPacket = fSavedPacket = NULL;
}

BufferedPacket * ReorderingPacketBuffer::getFreePacket

(

MultiFramedRTPSource *

ourSource

)

Definition at line 481 of file MultiFramedRTPSource.cpp.

References BufferedPacketFactory::createNewPacket(), False, fPacketFactory, fSavedPacket, fSavedPacketFree, NULL, and True.

Referenced by MultiFramedRTPSource::networkReadHandler1().

                                                                                     {
  if (fSavedPacket == NULL) { // we're being called for the first time
    fSavedPacket = fPacketFactory->createNewPacket(ourSource);
    fSavedPacketFree = True;
  }

  if (fSavedPacketFree == True) {
    fSavedPacketFree = False;
    return fSavedPacket;
  } else {
    return fPacketFactory->createNewPacket(ourSource);
  }
}

Boolean ReorderingPacketBuffer::storePacket

(

BufferedPacket *

bPacket

)

Definition at line 495 of file MultiFramedRTPSource.cpp.

References False, fHaveSeenFirstPacket, fHeadPacket, fNextExpectedSeqNo, fTailPacket, BufferedPacket::isFirstPacket(), BufferedPacket::nextPacket(), NULL, BufferedPacket::rtpSeqNo(), seqNumLT(), and True.

Referenced by MultiFramedRTPSource::networkReadHandler1().

                                                                   {
  unsigned short rtpSeqNo = bPacket->rtpSeqNo();

  if (!fHaveSeenFirstPacket) {
    fNextExpectedSeqNo = rtpSeqNo; // initialization
    bPacket->isFirstPacket() = True;
    fHaveSeenFirstPacket = True;
  }

  // Ignore this packet if its sequence number is less than the one
  // that we're looking for (in this case, it's been excessively delayed).
  if (seqNumLT(rtpSeqNo, fNextExpectedSeqNo)) return False;

  if (fTailPacket == NULL) {
    // Common case: There are no packets in the queue; this will be the first one:
    bPacket->nextPacket() = NULL;
    fHeadPacket = fTailPacket = bPacket;
    return True;
  }

  if (seqNumLT(fTailPacket->rtpSeqNo(), rtpSeqNo)) {
    // The next-most common case: There are packets already in the queue; this packet arrived in order => put it at the tail:
    bPacket->nextPacket() = NULL;
    fTailPacket->nextPacket() = bPacket;
    fTailPacket = bPacket;
    return True;
  } 

  if (rtpSeqNo == fTailPacket->rtpSeqNo()) {
    // This is a duplicate packet - ignore it
    return False;
  }

  // Rare case: This packet is out-of-order.  Run through the list (from the head), to figure out where it belongs:
  BufferedPacket* beforePtr = NULL;
  BufferedPacket* afterPtr = fHeadPacket;
  while (afterPtr != NULL) {
    if (seqNumLT(rtpSeqNo, afterPtr->rtpSeqNo())) break; // it comes here
    if (rtpSeqNo == afterPtr->rtpSeqNo()) {
      // This is a duplicate packet - ignore it
      return False;
    }

    beforePtr = afterPtr;
    afterPtr = afterPtr->nextPacket();
  }

  // Link our new packet between "beforePtr" and "afterPtr":
  bPacket->nextPacket() = afterPtr;
  if (beforePtr == NULL) {
    fHeadPacket = bPacket;
  } else {
    beforePtr->nextPacket() = bPacket;
  }

  return True;
}

BufferedPacket * ReorderingPacketBuffer::getNextCompletedPacket

(

Boolean &

packetLossPreceded

)

Definition at line 568 of file MultiFramedRTPSource.cpp.

References fHeadPacket, fNextExpectedSeqNo, fThresholdTime, BufferedPacket::isFirstPacket(), NULL, BufferedPacket::rtpSeqNo(), BufferedPacket::timeReceived(), and True.

Referenced by MultiFramedRTPSource::doGetNextFrame1().

                                                    {
  if (fHeadPacket == NULL) return NULL;

  // Check whether the next packet we want is already at the head
  // of the queue:
  // ASSERT: fHeadPacket->rtpSeqNo() >= fNextExpectedSeqNo
  if (fHeadPacket->rtpSeqNo() == fNextExpectedSeqNo) {
    packetLossPreceded = fHeadPacket->isFirstPacket();
        // (The very first packet is treated as if there was packet loss beforehand.)
    return fHeadPacket;
  }

  // We're still waiting for our desired packet to arrive.  However, if
  // our time threshold has been exceeded, then forget it, and return
  // the head packet instead:
  struct timeval timeNow;
  gettimeofday(&timeNow, NULL);
  unsigned uSecondsSinceReceived
    = (timeNow.tv_sec - fHeadPacket->timeReceived().tv_sec)*1000000
    + (timeNow.tv_usec - fHeadPacket->timeReceived().tv_usec);
  if (uSecondsSinceReceived > fThresholdTime) {
    fNextExpectedSeqNo = fHeadPacket->rtpSeqNo();
        // we've given up on earlier packets now
    packetLossPreceded = True;
    return fHeadPacket;
  }

  // Otherwise, keep waiting for our desired packet to arrive:
  return NULL;
}

void ReorderingPacketBuffer::releaseUsedPacket

(

BufferedPacket *

packet

)

Definition at line 553 of file MultiFramedRTPSource.cpp.

References fHeadPacket, fNextExpectedSeqNo, freePacket(), fTailPacket, BufferedPacket::nextPacket(), and NULL.

Referenced by MultiFramedRTPSource::doGetNextFrame1().

                                                                     {
  // ASSERT: packet == fHeadPacket
  // ASSERT: fNextExpectedSeqNo == packet->rtpSeqNo()
  ++fNextExpectedSeqNo; // because we're finished with this packet now

  fHeadPacket = fHeadPacket->nextPacket();
  if (!fHeadPacket) { 
    fTailPacket = NULL;
  }
  packet->nextPacket() = NULL;

  freePacket(packet);
}

void ReorderingPacketBuffer::freePacket

(

BufferedPacket *

packet

)

[inline]

Definition at line 38 of file MultiFramedRTPSource.cpp.

References fSavedPacket, fSavedPacketFree, and True.

Referenced by MultiFramedRTPSource::networkReadHandler1(), and releaseUsedPacket().

                                          {
    if (packet != fSavedPacket) {
      delete packet;
    } else {
      fSavedPacketFree = True;
    }
  }

Boolean ReorderingPacketBuffer::isEmpty

(

)

const [inline]

Definition at line 45 of file MultiFramedRTPSource.cpp.

References fHeadPacket, and NULL.

Referenced by MultiFramedRTPSource::doGetNextFrame1().

{ return fHeadPacket == NULL; }

void ReorderingPacketBuffer::setThresholdTime

(

unsigned

uSeconds

)

[inline]

Definition at line 47 of file MultiFramedRTPSource.cpp.

References fThresholdTime.

Referenced by MultiFramedRTPSource::setPacketReorderingThresholdTime().

{ fThresholdTime = uSeconds; }

void ReorderingPacketBuffer::resetHaveSeenFirstPacket

(

)

[inline]

Definition at line 48 of file MultiFramedRTPSource.cpp.

References False, and fHaveSeenFirstPacket.

Referenced by MultiFramedRTPSource::networkReadHandler1(), and reset().

{ fHaveSeenFirstPacket = False; }

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Field Documentation

BufferedPacketFactory* ReorderingPacketBuffer::fPacketFactory [private]

Definition at line 51 of file MultiFramedRTPSource.cpp.

Referenced by getFreePacket(), and ~ReorderingPacketBuffer().

unsigned ReorderingPacketBuffer::fThresholdTime [private]

Definition at line 52 of file MultiFramedRTPSource.cpp.

Referenced by getNextCompletedPacket(), and setThresholdTime().

Boolean ReorderingPacketBuffer::fHaveSeenFirstPacket [private]

Definition at line 53 of file MultiFramedRTPSource.cpp.

Referenced by resetHaveSeenFirstPacket(), and storePacket().

unsigned short ReorderingPacketBuffer::fNextExpectedSeqNo [private]

Definition at line 54 of file MultiFramedRTPSource.cpp.

Referenced by getNextCompletedPacket(), releaseUsedPacket(), and storePacket().

BufferedPacket* ReorderingPacketBuffer::fHeadPacket [private]

Definition at line 55 of file MultiFramedRTPSource.cpp.

Referenced by getNextCompletedPacket(), isEmpty(), releaseUsedPacket(), reset(), and storePacket().

BufferedPacket* ReorderingPacketBuffer::fTailPacket [private]

Definition at line 56 of file MultiFramedRTPSource.cpp.

Referenced by releaseUsedPacket(), reset(), and storePacket().

BufferedPacket* ReorderingPacketBuffer::fSavedPacket [private]

Definition at line 57 of file MultiFramedRTPSource.cpp.

Referenced by freePacket(), getFreePacket(), and reset().

Boolean ReorderingPacketBuffer::fSavedPacketFree [private]

Definition at line 59 of file MultiFramedRTPSource.cpp.

Referenced by freePacket(), getFreePacket(), and reset().

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The documentation for this class was generated from the following file:

• liveMedia/MultiFramedRTPSource.cpp

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