queue.cpp

/*****************************************************************************
Copyright (c) 2001 - 2011, The Board of Trustees of the University of Illinois.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the
  above copyright notice, this list of conditions
  and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

* Neither the name of the University of Illinois
  nor the names of its contributors may be used to
  endorse or promote products derived from this
  software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*****************************************************************************/

/*****************************************************************************
written by
   Yunhong Gu, last updated 05/05/2011
*****************************************************************************/

#ifdef WIN32
   #include <winsock2.h>
   #include <ws2tcpip.h>
   #ifdef LEGACY_WIN32
      #include <wspiapi.h>
   #endif
#endif
#include <cstring>

#include "common.h"
#include "core.h"
#include "queue.h"

using namespace std;

CUnitQueue::CUnitQueue():
m_pQEntry(NULL),
m_pCurrQueue(NULL),
m_pLastQueue(NULL),
m_iSize(0),
m_iCount(0),
m_iMSS(),
m_iIPversion()
{
}

CUnitQueue::~CUnitQueue()
{
   CQEntry* p = m_pQEntry;

   while (p != NULL)
   {
      delete [] p->m_pUnit;
      delete [] p->m_pBuffer;

      CQEntry* q = p;
      if (p == m_pLastQueue)
         p = NULL;
      else
         p = p->m_pNext;
      delete q;
   }
}

int CUnitQueue::init(int size, int mss, int version)
{
   CQEntry* tempq = NULL;
   CUnit* tempu = NULL;
   char* tempb = NULL;

   try
   {
      tempq = new CQEntry;
      tempu = new CUnit [size];
      tempb = new char [size * mss];
   }
   catch (...)
   {
      delete tempq;
      delete [] tempu;
      delete [] tempb;

      return -1;
   }

   for (int i = 0; i < size; ++ i)
   {
      tempu[i].m_iFlag = 0;
      tempu[i].m_Packet.m_pcData = tempb + i * mss;
   }
   tempq->m_pUnit = tempu;
   tempq->m_pBuffer = tempb;
   tempq->m_iSize = size;

   m_pQEntry = m_pCurrQueue = m_pLastQueue = tempq;
   m_pQEntry->m_pNext = m_pQEntry;

   m_pAvailUnit = m_pCurrQueue->m_pUnit;

   m_iSize = size;
   m_iMSS = mss;
   m_iIPversion = version;

   return 0;
}

int CUnitQueue::increase()
{
   // adjust/correct m_iCount
   int real_count = 0;
   CQEntry* p = m_pQEntry;
   while (p != NULL)
   {
      CUnit* u = p->m_pUnit;
      for (CUnit* end = u + p->m_iSize; u != end; ++ u)
         if (u->m_iFlag != 0)
            ++ real_count;

      if (p == m_pLastQueue)
         p = NULL;
      else
         p = p->m_pNext;
   }
   m_iCount = real_count;
   if (double(m_iCount) / m_iSize < 0.9)
      return -1;

   CQEntry* tempq = NULL;
   CUnit* tempu = NULL;
   char* tempb = NULL;

   // all queues have the same size
   int size = m_pQEntry->m_iSize;

   try
   {
      tempq = new CQEntry;
      tempu = new CUnit [size];
      tempb = new char [size * m_iMSS];
   }
   catch (...)
   {
      delete tempq;
      delete [] tempu;
      delete [] tempb;

      return -1;
   }

   for (int i = 0; i < size; ++ i)
   {
      tempu[i].m_iFlag = 0;
      tempu[i].m_Packet.m_pcData = tempb + i * m_iMSS;
   }
   tempq->m_pUnit = tempu;
   tempq->m_pBuffer = tempb;
   tempq->m_iSize = size;

   m_pLastQueue->m_pNext = tempq;
   m_pLastQueue = tempq;
   m_pLastQueue->m_pNext = m_pQEntry;

   m_iSize += size;

   return 0;
}

int CUnitQueue::shrink()
{
   // currently queue cannot be shrunk.
   return -1;
}

CUnit* CUnitQueue::getNextAvailUnit()
{
   if (m_iCount * 10 > m_iSize * 9)
      increase();

   if (m_iCount >= m_iSize)
      return NULL;

   CQEntry* entrance = m_pCurrQueue;

   do
   {
      for (CUnit* sentinel = m_pCurrQueue->m_pUnit + m_pCurrQueue->m_iSize - 1; m_pAvailUnit != sentinel; ++ m_pAvailUnit)
         if (m_pAvailUnit->m_iFlag == 0)
            return m_pAvailUnit;

      if (m_pCurrQueue->m_pUnit->m_iFlag == 0)
      {
         m_pAvailUnit = m_pCurrQueue->m_pUnit;
         return m_pAvailUnit;
      }

      m_pCurrQueue = m_pCurrQueue->m_pNext;
      m_pAvailUnit = m_pCurrQueue->m_pUnit;
   } while (m_pCurrQueue != entrance);

   increase();

   return NULL;
}


CSndUList::CSndUList():
m_pHeap(NULL),
m_iArrayLength(4096),
m_iLastEntry(-1),
m_ListLock(),
m_pWindowLock(NULL),
m_pWindowCond(NULL),
m_pTimer(NULL)
{
   m_pHeap = new CSNode*[m_iArrayLength];
}

CSndUList::~CSndUList()
{
   delete [] m_pHeap;
}

void CSndUList::insert(int64_t ts, const CUDT* u)
{
   CGuard listguard(m_ListLock);

   // increase the heap array size if necessary
   if (m_iLastEntry == m_iArrayLength - 1)
   {
      CSNode** temp = NULL;

      try
      {
         temp = new CSNode*[m_iArrayLength * 2];
      }
      catch(...)
      {
         return;
      }

      memcpy(temp, m_pHeap, sizeof(CSNode*) * m_iArrayLength);
      m_iArrayLength *= 2;
      delete [] m_pHeap;
      m_pHeap = temp;
   }

   insert_(ts, u);
}

void CSndUList::update(const CUDT* u, bool reschedule)
{
   CGuard listguard(m_ListLock);

   CSNode* n = u->m_pSNode;

   if (n->m_iHeapLoc >= 0)
   {
      if (!reschedule)
         return;

      if (n->m_iHeapLoc == 0)
      {
         n->m_llTimeStamp = 1;
         m_pTimer->interrupt();
         return;
      }

      remove_(u);
   }

   insert_(1, u);
}

int CSndUList::pop(sockaddr*& addr, CPacket& pkt)
{
   CGuard listguard(m_ListLock);

   if (-1 == m_iLastEntry)
      return -1;

   // no pop until the next schedulled time
   uint64_t ts;
   CTimer::rdtsc(ts);
   if (ts < m_pHeap[0]->m_llTimeStamp)
      return -1;

   CUDT* u = m_pHeap[0]->m_pUDT;
   remove_(u);

   if (!u->m_bConnected || u->m_bBroken)
      return -1;

   // pack a packet from the socket
   if (u->packData(pkt, ts) <= 0)
      return -1;

   addr = u->m_pPeerAddr;

   // insert a new entry, ts is the next processing time
   if (ts > 0)
      insert_(ts, u);

   return 1;
}

void CSndUList::remove(const CUDT* u)
{
   CGuard listguard(m_ListLock);

   remove_(u);
}

uint64_t CSndUList::getNextProcTime()
{
   CGuard listguard(m_ListLock);

   if (-1 == m_iLastEntry)
      return 0;

   return m_pHeap[0]->m_llTimeStamp;
}

void CSndUList::insert_(int64_t ts, const CUDT* u)
{
   CSNode* n = u->m_pSNode;

   // do not insert repeated node
   if (n->m_iHeapLoc >= 0)
      return;

   m_iLastEntry ++;
   m_pHeap[m_iLastEntry] = n;
   n->m_llTimeStamp = ts;

   int q = m_iLastEntry;
   int p = q;
   while (p != 0)
   {
      p = (q - 1) >> 1;
      if (m_pHeap[p]->m_llTimeStamp > m_pHeap[q]->m_llTimeStamp)
      {
         CSNode* t = m_pHeap[p];
         m_pHeap[p] = m_pHeap[q];
         m_pHeap[q] = t;
         t->m_iHeapLoc = q;
         q = p;
      }
      else
         break;
   }

   n->m_iHeapLoc = q;

   // an earlier event has been inserted, wake up sending worker
   if (n->m_iHeapLoc == 0)
      m_pTimer->interrupt();

   // first entry, activate the sending queue
   if (0 == m_iLastEntry)
   {
	   m_pWindowLock->lock();
	   m_pWindowCond->notify_one();
	   m_pWindowLock->unlock();
   }
}

void CSndUList::remove_(const CUDT* u)
{
   CSNode* n = u->m_pSNode;

   if (n->m_iHeapLoc >= 0)
   {
      // remove the node from heap
      m_pHeap[n->m_iHeapLoc] = m_pHeap[m_iLastEntry];
      m_iLastEntry --;
      m_pHeap[n->m_iHeapLoc]->m_iHeapLoc = n->m_iHeapLoc;

      int q = n->m_iHeapLoc;
      int p = q * 2 + 1;
      while (p <= m_iLastEntry)
      {
         if ((p + 1 <= m_iLastEntry) && (m_pHeap[p]->m_llTimeStamp > m_pHeap[p + 1]->m_llTimeStamp))
            p ++;

         if (m_pHeap[q]->m_llTimeStamp > m_pHeap[p]->m_llTimeStamp)
         {
            CSNode* t = m_pHeap[p];
            m_pHeap[p] = m_pHeap[q];
            m_pHeap[p]->m_iHeapLoc = p;
            m_pHeap[q] = t;
            m_pHeap[q]->m_iHeapLoc = q;

            q = p;
            p = q * 2 + 1;
         }
         else
            break;
      }

      n->m_iHeapLoc = -1;
   }

   // the only event has been deleted, wake up immediately
   if (0 == m_iLastEntry)
      m_pTimer->interrupt();
}

//
CSndQueue::CSndQueue():
m_WorkerThread(),
m_pSndUList(NULL),
m_pChannel(NULL),
m_pTimer(NULL),
m_WindowLock(),
m_WindowCond(),
m_bClosing(false),
m_ExitCond()
{

}

CSndQueue::~CSndQueue()
{
   m_bClosing = true;

   m_WindowLock.lock();
   m_WindowCond.notify_one();
   m_WindowLock.unlock();
   if (m_WorkerThread.joinable())
	   m_WorkerThread.join();
   delete m_pSndUList;
}

void CSndQueue::init(CChannel* c, CTimer* t)
{
   m_pChannel = c;
   m_pTimer = t;
   m_pSndUList = new CSndUList;
   m_pSndUList->m_pWindowLock = &m_WindowLock;
   m_pSndUList->m_pWindowCond = &m_WindowCond;
   m_pSndUList->m_pTimer = m_pTimer;

   try {
	   m_WorkerThread = std::thread(CSndQueue::worker,this);
   }
   catch (const std::system_error& e) {
	   throw CUDTException(3, 1);
   }
}

#ifndef WIN32
   void* CSndQueue::worker(void* param)
#else
   DWORD WINAPI CSndQueue::worker(LPVOID param)
#endif
{
   CSndQueue* self = (CSndQueue*)param;

   while (!self->m_bClosing)
   {
      uint64_t ts = self->m_pSndUList->getNextProcTime();

      if (ts > 0)
      {
         // wait until next processing time of the first socket on the list
         uint64_t currtime;
         CTimer::rdtsc(currtime);
         if (currtime < ts)
            self->m_pTimer->sleepto(ts);

         // it is time to send the next pkt
         sockaddr* addr;
         CPacket pkt;
         if (self->m_pSndUList->pop(addr, pkt) < 0)
            continue;

         self->m_pChannel->sendto(addr, pkt);
      }
      else
      {
         std::unique_lock<std::mutex> lk(self->m_WindowLock);
         // wait here if there is no sockets with data to be sent
            if (!self->m_bClosing && (self->m_pSndUList->m_iLastEntry < 0))
               self->m_WindowCond.wait(lk);
         lk.unlock();
      }
   }

   #ifndef WIN32
      return NULL;
   #else
      self->m_ExitCond.notify_one();
      return 0;
   #endif
}

int CSndQueue::sendto(const sockaddr* addr, CPacket& packet)
{
   // send out the packet immediately (high priority), this is a control packet
   m_pChannel->sendto(addr, packet);
   return packet.getLength();
}


//
CRcvUList::CRcvUList():
m_pUList(NULL),
m_pLast(NULL)
{
}

CRcvUList::~CRcvUList()
{
}

void CRcvUList::insert(const CUDT* u)
{
   CRNode* n = u->m_pRNode;
   CTimer::rdtsc(n->m_llTimeStamp);

   if (NULL == m_pUList)
   {
      // empty list, insert as the single node
      n->m_pPrev = n->m_pNext = NULL;
      m_pLast = m_pUList = n;

      return;
   }

   // always insert at the end for RcvUList
   n->m_pPrev = m_pLast;
   n->m_pNext = NULL;
   m_pLast->m_pNext = n;
   m_pLast = n;
}

void CRcvUList::remove(const CUDT* u)
{
   CRNode* n = u->m_pRNode;

   if (!n->m_bOnList)
      return;

   if (NULL == n->m_pPrev)
   {
      // n is the first node
      m_pUList = n->m_pNext;
      if (NULL == m_pUList)
         m_pLast = NULL;
      else
         m_pUList->m_pPrev = NULL;
   }
   else
   {
      n->m_pPrev->m_pNext = n->m_pNext;
      if (NULL == n->m_pNext)
      {
         // n is the last node
         m_pLast = n->m_pPrev;
      }
      else
         n->m_pNext->m_pPrev = n->m_pPrev;
   }

   n->m_pNext = n->m_pPrev = NULL;
}

void CRcvUList::update(const CUDT* u)
{
   CRNode* n = u->m_pRNode;

   if (!n->m_bOnList)
      return;

   CTimer::rdtsc(n->m_llTimeStamp);

   // if n is the last node, do not need to change
   if (NULL == n->m_pNext)
      return;

   if (NULL == n->m_pPrev)
   {
      m_pUList = n->m_pNext;
      m_pUList->m_pPrev = NULL;
   }
   else
   {
      n->m_pPrev->m_pNext = n->m_pNext;
      n->m_pNext->m_pPrev = n->m_pPrev;
   }

   n->m_pPrev = m_pLast;
   n->m_pNext = NULL;
   m_pLast->m_pNext = n;
   m_pLast = n;
}

//
CHash::CHash():
m_pBucket(NULL),
m_iHashSize(0)
{
}

CHash::~CHash()
{
   for (int i = 0; i < m_iHashSize; ++ i)
   {
      CBucket* b = m_pBucket[i];
      while (NULL != b)
      {
         CBucket* n = b->m_pNext;
         delete b;
         b = n;
      }
   }

   delete [] m_pBucket;
}

void CHash::init(int size)
{
   m_pBucket = new CBucket* [size];

   for (int i = 0; i < size; ++ i)
      m_pBucket[i] = NULL;

   m_iHashSize = size;
}

CUDT* CHash::lookup(int32_t id)
{
   // simple hash function (% hash table size); suitable for socket descriptors
   CBucket* b = m_pBucket[id % m_iHashSize];

   while (NULL != b)
   {
      if (id == b->m_iID)
         return b->m_pUDT;
      b = b->m_pNext;
   }

   return NULL;
}

void CHash::insert(int32_t id, CUDT* u)
{
   CBucket* b = m_pBucket[id % m_iHashSize];

   CBucket* n = new CBucket;
   n->m_iID = id;
   n->m_pUDT = u;
   n->m_pNext = b;

   m_pBucket[id % m_iHashSize] = n;
}

void CHash::remove(int32_t id)
{
   CBucket* b = m_pBucket[id % m_iHashSize];
   CBucket* p = NULL;

   while (NULL != b)
   {
      if (id == b->m_iID)
      {
         if (NULL == p)
            m_pBucket[id % m_iHashSize] = b->m_pNext;
         else
            p->m_pNext = b->m_pNext;

         delete b;

         return;
      }

      p = b;
      b = b->m_pNext;
   }
}


//
CRendezvousQueue::CRendezvousQueue():
m_lRendezvousID(),
m_RIDVectorLock()
{

}

CRendezvousQueue::~CRendezvousQueue()
{
   for (list<CRL>::iterator i = m_lRendezvousID.begin(); i != m_lRendezvousID.end(); ++ i)
   {
      if (AF_INET == i->m_iIPversion)
         delete (sockaddr_in*)i->m_pPeerAddr;
      else
         delete (sockaddr_in6*)i->m_pPeerAddr;
   }

   m_lRendezvousID.clear();
}

void CRendezvousQueue::insert(const UDTSOCKET& id, CUDT* u, int ipv, const sockaddr* addr, uint64_t ttl)
{
   CGuard vg(m_RIDVectorLock);

   CRL r;
   r.m_iID = id;
   r.m_pUDT = u;
   r.m_iIPversion = ipv;
   r.m_pPeerAddr = (AF_INET == ipv) ? (sockaddr*)new sockaddr_in : (sockaddr*)new sockaddr_in6;
   memcpy(r.m_pPeerAddr, addr, (AF_INET == ipv) ? sizeof(sockaddr_in) : sizeof(sockaddr_in6));
   r.m_ullTTL = ttl;

   m_lRendezvousID.push_back(r);
}

void CRendezvousQueue::remove(const UDTSOCKET& id)
{
   CGuard vg(m_RIDVectorLock);

   for (list<CRL>::iterator i = m_lRendezvousID.begin(); i != m_lRendezvousID.end(); ++ i)
   {
      if (i->m_iID == id)
      {
         if (AF_INET == i->m_iIPversion)
            delete (sockaddr_in*)i->m_pPeerAddr;
         else
            delete (sockaddr_in6*)i->m_pPeerAddr;

         m_lRendezvousID.erase(i);

         return;
      }
   }
}

CUDT* CRendezvousQueue::retrieve(const sockaddr* addr, UDTSOCKET& id)
{
   CGuard vg(m_RIDVectorLock);

   // TODO: optimize search
   for (list<CRL>::iterator i = m_lRendezvousID.begin(); i != m_lRendezvousID.end(); ++ i)
   {
      if (CIPAddress::ipcmp(addr, i->m_pPeerAddr, i->m_iIPversion) && ((0 == id) || (id == i->m_iID)))
      {
         id = i->m_iID;
         return i->m_pUDT;
      }
   }

   return NULL;
}

void CRendezvousQueue::updateConnStatus()
{
   if (m_lRendezvousID.empty())
      return;

   CGuard vg(m_RIDVectorLock);

   for (list<CRL>::iterator i = m_lRendezvousID.begin(); i != m_lRendezvousID.end(); ++ i)
   {
      // avoid sending too many requests, at most 1 request per 250ms
      if (CTimer::getTime() - i->m_pUDT->m_llLastReqTime > 250000)
      {
         if (CTimer::getTime() >= i->m_ullTTL)
         {
            // connection timer expired, acknowledge app via epoll
            i->m_pUDT->m_bConnecting = false;
            CUDT::s_UDTUnited.m_EPoll.update_events(i->m_iID, i->m_pUDT->m_sPollID, UDT_EPOLL_ERR, true);
            continue;
         }

         CPacket request;
         char* reqdata = new char [i->m_pUDT->m_iPayloadSize];
         request.pack(0, NULL, reqdata, i->m_pUDT->m_iPayloadSize);
         // ID = 0, connection request
         request.m_iID = !i->m_pUDT->m_bRendezvous ? 0 : i->m_pUDT->m_ConnRes.m_iID;
         int hs_size = i->m_pUDT->m_iPayloadSize;
         i->m_pUDT->m_ConnReq.serialize(reqdata, hs_size);
         request.setLength(hs_size);
         i->m_pUDT->m_pSndQueue->sendto(i->m_pPeerAddr, request);
         i->m_pUDT->m_llLastReqTime = CTimer::getTime();
         delete [] reqdata;
      }
   }
}

//
CRcvQueue::CRcvQueue():
m_WorkerThread(),
m_UnitQueue(),
m_pRcvUList(NULL),
m_pHash(NULL),
m_pChannel(NULL),
m_pTimer(NULL),
m_iPayloadSize(),
m_bClosing(false),
m_ExitCond(),
m_LSLock(),
m_pListener(NULL),
m_pRendezvousQueue(NULL),
m_vNewEntry(),
m_IDLock(),
m_mBuffer(),
m_PassLock(),
m_PassCond()
{

}

CRcvQueue::~CRcvQueue()
{
   m_bClosing = true;

   if (m_WorkerThread.joinable())
	   m_WorkerThread.join();

   delete m_pRcvUList;
   delete m_pHash;
   delete m_pRendezvousQueue;

   // remove all queued messages
   for (map<int32_t, std::queue<CPacket*> >::iterator i = m_mBuffer.begin(); i != m_mBuffer.end(); ++ i)
   {
      while (!i->second.empty())
      {
         CPacket* pkt = i->second.front();
         delete [] pkt->m_pcData;
         delete pkt;
         i->second.pop();
      }
   }
}

void CRcvQueue::init(int qsize, int payload, int version, int hsize, CChannel* cc, CTimer* t)
{
   m_iPayloadSize = payload;

   m_UnitQueue.init(qsize, payload, version);

   m_pHash = new CHash;
   m_pHash->init(hsize);

   m_pChannel = cc;
   m_pTimer = t;

   m_pRcvUList = new CRcvUList;
   m_pRendezvousQueue = new CRendezvousQueue;

   try {
	   m_WorkerThread = std::thread(CRcvQueue::worker, this);
   }
   catch (const std::system_error& e) {
	   throw CUDTException(3, 1);
   }

}

#ifndef WIN32
   void* CRcvQueue::worker(void* param)
#else
   DWORD WINAPI CRcvQueue::worker(LPVOID param)
#endif
{
   CRcvQueue* self = (CRcvQueue*)param;

   sockaddr* addr = (AF_INET == self->m_UnitQueue.m_iIPversion) ? (sockaddr*) new sockaddr_in : (sockaddr*) new sockaddr_in6;
   CUDT* u = NULL;
   int32_t id;

   while (!self->m_bClosing)
   {
      #ifdef NO_BUSY_WAITING
         self->m_pTimer->tick();
      #endif

      // check waiting list, if new socket, insert it to the list
      while (self->ifNewEntry())
      {
         CUDT* ne = self->getNewEntry();
         if (NULL != ne)
         {
            self->m_pRcvUList->insert(ne);
            self->m_pHash->insert(ne->m_SocketID, ne);
         }
      }

      // find next available slot for incoming packet
      CUnit* unit = self->m_UnitQueue.getNextAvailUnit();
      if (NULL == unit)
      {
         // no space, skip this packet
         CPacket temp;
         temp.m_pcData = new char[self->m_iPayloadSize];
         temp.setLength(self->m_iPayloadSize);
         self->m_pChannel->recvfrom(addr, temp);
         delete [] temp.m_pcData;
         goto TIMER_CHECK;
      }

      unit->m_Packet.setLength(self->m_iPayloadSize);

      // reading next incoming packet, recvfrom returns -1 is nothing has been received
      if (self->m_pChannel->recvfrom(addr, unit->m_Packet) < 0)
         goto TIMER_CHECK;

      id = unit->m_Packet.m_iID;

      // ID 0 is for connection request, which should be passed to the listening socket or rendezvous sockets
      if (0 == id)
      {
         if (NULL != self->m_pListener)
            self->m_pListener->listen(addr, unit->m_Packet);
         else if (NULL != (u = self->m_pRendezvousQueue->retrieve(addr, id)))
         {
            // asynchronous connect: call connect here
            // otherwise wait for the UDT socket to retrieve this packet
            if (!u->m_bSynRecving)
               u->connect(unit->m_Packet);
            else
               self->storePkt(id, unit->m_Packet.clone());
         }
      }
      else if (id > 0)
      {
         if (NULL != (u = self->m_pHash->lookup(id)))
         {
            if (CIPAddress::ipcmp(addr, u->m_pPeerAddr, u->m_iIPversion))
            {
               if (u->m_bConnected && !u->m_bBroken && !u->m_bClosing)
               {
                  if (0 == unit->m_Packet.getFlag())
                     u->processData(unit);
                  else
                     u->processCtrl(unit->m_Packet);

                  u->checkTimers();
                  self->m_pRcvUList->update(u);
               }
            }
         }
         else if (NULL != (u = self->m_pRendezvousQueue->retrieve(addr, id)))
         {
            if (!u->m_bSynRecving)
               u->connect(unit->m_Packet);
            else
               self->storePkt(id, unit->m_Packet.clone());
         }
      }

TIMER_CHECK:
      // take care of the timing event for all UDT sockets

      uint64_t currtime;
      CTimer::rdtsc(currtime);

      CRNode* ul = self->m_pRcvUList->m_pUList;
      uint64_t ctime = currtime - 100000 * CTimer::getCPUFrequency();
      while ((NULL != ul) && (ul->m_llTimeStamp < ctime))
      {
         CUDT* u = ul->m_pUDT;

         if (u->m_bConnected && !u->m_bBroken && !u->m_bClosing)
         {
            u->checkTimers();
            self->m_pRcvUList->update(u);
         }
         else
         {
            // the socket must be removed from Hash table first, then RcvUList
            self->m_pHash->remove(u->m_SocketID);
            self->m_pRcvUList->remove(u);
            u->m_pRNode->m_bOnList = false;
         }

         ul = self->m_pRcvUList->m_pUList;
      }

      // Check connection requests status for all sockets in the RendezvousQueue.
      self->m_pRendezvousQueue->updateConnStatus();
   }

   if (AF_INET == self->m_UnitQueue.m_iIPversion)
      delete (sockaddr_in*)addr;
   else
      delete (sockaddr_in6*)addr;

   #ifndef WIN32
      return NULL;
   #else
	  self->m_ExitCond.notify_one();
      return 0;
   #endif
}

int CRcvQueue::recvfrom(int32_t id, CPacket& packet)
{
   std::unique_lock<std::mutex> bufferlock(m_PassLock);

   map<int32_t, std::queue<CPacket*> >::iterator i = m_mBuffer.find(id);

   if (i == m_mBuffer.end())
   {
      m_PassCond.wait_for(bufferlock,std::chrono::milliseconds(1000));

      i = m_mBuffer.find(id);
      if (i == m_mBuffer.end())
      {
         packet.setLength(-1);
         return -1;
      }
   }

   // retrieve the earliest packet
   CPacket* newpkt = i->second.front();

   if (packet.getLength() < newpkt->getLength())
   {
      packet.setLength(-1);
      return -1;
   }

   // copy packet content
   memcpy(packet.m_nHeader, newpkt->m_nHeader, CPacket::m_iPktHdrSize);
   memcpy(packet.m_pcData, newpkt->m_pcData, newpkt->getLength());
   packet.setLength(newpkt->getLength());

   delete [] newpkt->m_pcData;
   delete newpkt;

   // remove this message from queue, 
   // if no more messages left for this socket, release its data structure
   i->second.pop();
   if (i->second.empty())
      m_mBuffer.erase(i);

   return packet.getLength();
}

int CRcvQueue::setListener(CUDT* u)
{
   CGuard lslock(m_LSLock);

   if (NULL != m_pListener)
      return -1;

   m_pListener = u;
   return 0;
}

void CRcvQueue::removeListener(const CUDT* u)
{
   CGuard lslock(m_LSLock);

   if (u == m_pListener)
      m_pListener = NULL;
}

void CRcvQueue::registerConnector(const UDTSOCKET& id, CUDT* u, int ipv, const sockaddr* addr, uint64_t ttl)
{
   m_pRendezvousQueue->insert(id, u, ipv, addr, ttl);
}

void CRcvQueue::removeConnector(const UDTSOCKET& id)
{
   m_pRendezvousQueue->remove(id);

   CGuard bufferlock(m_PassLock);

   map<int32_t, std::queue<CPacket*> >::iterator i = m_mBuffer.find(id);
   if (i != m_mBuffer.end())
   {
      while (!i->second.empty())
      {
         delete [] i->second.front()->m_pcData;
         delete i->second.front();
         i->second.pop();
      }
      m_mBuffer.erase(i);
   }
}

void CRcvQueue::setNewEntry(CUDT* u)
{
   CGuard listguard(m_IDLock);
   m_vNewEntry.push_back(u);
}

bool CRcvQueue::ifNewEntry()
{
   return !(m_vNewEntry.empty());
}

CUDT* CRcvQueue::getNewEntry()
{
   CGuard listguard(m_IDLock);

   if (m_vNewEntry.empty())
      return NULL;

   CUDT* u = (CUDT*)*(m_vNewEntry.begin());
   m_vNewEntry.erase(m_vNewEntry.begin());

   return u;
}

void CRcvQueue::storePkt(int32_t id, CPacket* pkt)
{
   CGuard bufferlock(m_PassLock);   

   map<int32_t, std::queue<CPacket*> >::iterator i = m_mBuffer.find(id);

   if (i == m_mBuffer.end())
   {
      m_mBuffer[id].push(pkt);

	  m_PassCond.notify_one();
   }
   else
   {
      //avoid storing too many packets, in case of malfunction or attack
      if (i->second.size() > 16)
         return;

      i->second.push(pkt);
   }
}