Faster channel lookup

src/channel.cpp

@@ -400,22 +400,6 @@ void CChannel::OnChangeChanPan ( int iChanID, float fNewPan ) { SetPan ( iChanID
 
 void CChannel::OnChangeChanInfo ( CChannelCoreInfo ChanInfo ) { SetChanInfo ( ChanInfo ); }
 
-bool CChannel::GetAddress ( CHostAddress& RetAddr )
-{
-    QMutexLocker locker ( &Mutex );
-
-    if ( IsConnected() )
-    {
-        RetAddr = InetAddr;
-        return true;
-    }
-    else
-    {
-        RetAddr = CHostAddress();
-        return false;
-    }
-}
-
 void CChannel::OnNetTranspPropsReceived ( CNetworkTransportProps NetworkTransportProps )
 {
     // only the server shall act on network transport properties message

src/channel.h

@@ -84,7 +84,6 @@ class CChannel : public QObject
     bool IsEnabled() { return bIsEnabled; }
 
     void                SetAddress ( const CHostAddress NAddr ) { InetAddr = NAddr; }
-    bool                GetAddress ( CHostAddress& RetAddr );
     const CHostAddress& GetAddress() const { return InetAddr; }
 
     void ResetInfo()

src/server.cpp

@@ -235,6 +235,7 @@ CServer::CServer ( const int          iNewMaxNumChan,
     bUseDoubleSystemFrameSize ( bNUseDoubleSystemFrameSize ),
     bUseMultithreading ( bNUseMultithreading ),
     iMaxNumChannels ( iNewMaxNumChan ),
+    iCurNumChannels ( 0 ),
     Socket ( this, iPortNumber, iQosNumber, strServerBindIP, bNEnableIPv6 ),
     Logging(),
     iFrameCount ( 0 ),
@@ -410,6 +411,7 @@ CServer::CServer ( const int          iNewMaxNumChan,
     for ( i = 0; i < iMaxNumChannels; i++ )
     {
         vecChannels[i].SetEnable ( true );
+        vecChannelOrder[i] = i;
     }
 
     int iAvailableCores = QThread::idealThreadCount();
@@ -1054,10 +1056,15 @@ void CServer::DecodeReceiveData ( const int iChanCnt, const int iNumClients )
                     emit ClientDisconnected ( iCurChanID ); // TODO do this outside the mutex lock?
                 }
 
+                FreeChannel ( iCurChanID ); // note that the channel is now not in use
+
                 // note that no mutex is needed for this shared resource since it is not a
                 // read-modify-write operation but an atomic write and also each thread can
                 // only set it to true and never to false
                 bChannelIsNowDisconnected = true;
+
+                // since the channel is no longer in use, we should return
+                return;
             }
 
             // get pointer to coded data
@@ -1461,59 +1468,145 @@ void CServer::CreateOtherMuteStateChanged ( const int iCurChanID, const int iOth
     }
 }
 
-int CServer::GetFreeChan()
+int CServer::GetNumberOfConnectedClients()
 {
-    // look for a free channel
-    for ( int i = 0; i < iMaxNumChannels; i++ )
+    QMutexLocker locker ( &MutexChanOrder );
+
+    return iCurNumChannels;
+}
+
+// CServer::FindChannel() is called for every received audio packet or connected protocol
+// packet, to find the channel ID associated with the source IP address and port.
+// In order to search as efficiently as possible, a list of active channel IDs is stored
+// in vecChannelOrder[], sorted by IP and port (according to CHostAddress::Compare()),
+// and a binary search is used to find either the existing channel, or the position at
+// which a new channel should be inserted.
+
+int CServer::FindChannel ( const CHostAddress& CheckAddr, const bool bAllowNew )
+{
+    int iNewChanID = INVALID_CHANNEL_ID;
+
+    QMutexLocker locker ( &MutexChanOrder );
+
+    int l = 0, r = iCurNumChannels, i;
+
+    // use binary search to find the channel
+    while ( r > l )
     {
-        if ( !vecChannels[i].IsConnected() )
+        int t   = ( r + l ) / 2;
+        int cmp = CheckAddr.Compare ( vecChannels[vecChannelOrder[t]].GetAddress() );
+
+        if ( cmp == 0 )
         {
-            return i;
+            // address and port match
+            return vecChannelOrder[t];
         }
+
+        if ( cmp < 0 )
+        {
+            l = t + 1;
+        }
+        else
+        {
+            r = t;
+        }
+    }
+
+    // existing channel not found - return if we cannot create a new channel
+    if ( !bAllowNew || iCurNumChannels >= iMaxNumChannels )
+    {
+        return INVALID_CHANNEL_ID;
+    }
+
+    // allocate a new channel
+    i          = iCurNumChannels++; // save index of free channel and increment count
+    iNewChanID = vecChannelOrder[i];
+    InitChannel ( iNewChanID, CheckAddr );
+
+    // now l == r == position in vecChannelOrder to insert iNewChanID
+    // move channel IDs up by one starting at the top and working down
+    while ( i > r )
+    {
+        int j              = i--;
+        vecChannelOrder[j] = vecChannelOrder[i];
     }
+    // insert the new channel ID in the correct place
+    vecChannelOrder[i] = iNewChanID;
+
+    // DumpChannels ( __FUNCTION__ );
 
-    // no free channel found, return invalid ID
-    return INVALID_CHANNEL_ID;
+    return iNewChanID;
 }
 
-int CServer::GetNumberOfConnectedClients()
+void CServer::InitChannel ( const int iNewChanID, const CHostAddress& InetAddr )
 {
-    int iNumConnClients = 0;
+    // initialize new channel by storing the calling host address
+    vecChannels[iNewChanID].SetAddress ( InetAddr );
+
+    // reset channel info
+    vecChannels[iNewChanID].ResetInfo();
 
-    // check all possible channels for connection status
+    // reset the channel gains/pans of current channel, at the same
+    // time reset gains/pans of this channel ID for all other channels
     for ( int i = 0; i < iMaxNumChannels; i++ )
     {
-        if ( vecChannels[i].IsConnected() )
+        vecChannels[iNewChanID].SetGain ( i, 1.0 );
+        vecChannels[iNewChanID].SetPan ( i, 0.5 );
+
+        // other channels (we do not distinguish the case if
+        // i == iCurChanID for simplicity)
+        vecChannels[i].SetGain ( iNewChanID, 1.0 );
+        vecChannels[i].SetPan ( iNewChanID, 0.5 );
+    }
+}
+
+// CServer::FreeChannel() is called to remove a channel from the list of active channels.
+// The remaining ordered IDs are moved down by one space, and the freed ID is moved to the
+// end, ready to be reused by the next new connection.
+
+void CServer::FreeChannel ( const int iCurChanID )
+{
+    QMutexLocker locker ( &MutexChanOrder );
+
+    for ( int i = 0; i < iCurNumChannels; i++ )
+    {
+        if ( vecChannelOrder[i] == iCurChanID )
         {
-            // this channel is connected, increment counter
-            iNumConnClients++;
+            --iCurNumChannels;
+
+            // move channel IDs down by one starting at the bottom and working up
+            while ( i < iCurNumChannels )
+            {
+                int j              = i++;
+                vecChannelOrder[j] = vecChannelOrder[i];
+            }
+            // put deleted channel at the end ready for re-use
+            vecChannelOrder[i] = iCurChanID;
+
+            // DumpChannels ( __FUNCTION__ );
+
+            return;
         }
     }
 
-    return iNumConnClients;
+    qWarning() << "FreeChannel() called with invalid channel ID";
 }
 
-int CServer::FindChannel ( const CHostAddress& CheckAddr )
+void CServer::DumpChannels ( const QString& title )
 {
-    CHostAddress InetAddr;
+    qDebug() << qUtf8Printable ( title );
 
-    // check for all possible channels if IP is already in use
     for ( int i = 0; i < iMaxNumChannels; i++ )
     {
-        // the "GetAddress" gives a valid address and returns true if the
-        // channel is connected
-        if ( vecChannels[i].GetAddress ( InetAddr ) )
+        int iChanID = vecChannelOrder[i];
+
+        if ( i == iCurNumChannels )
         {
-            // IP found, return channel number
-            if ( InetAddr == CheckAddr )
-            {
-                return i;
-            }
+            qDebug() << "----------";
         }
-    }
 
-    // IP not found, return invalid ID
-    return INVALID_CHANNEL_ID;
+        qDebug() << qUtf8Printable ( QString ( "%1: [%2] %3" ).arg ( i, 3 ).arg ( iChanID ).arg ( vecChannels[iChanID].GetAddress().toString() ) );
+    }
 }
 
 void CServer::OnProtcolCLMessageReceived ( int iRecID, CVector<uint8_t> vecbyMesBodyData, CHostAddress RecHostAddr )
@@ -1543,48 +1636,13 @@ bool CServer::PutAudioData ( const CVector<uint8_t>& vecbyRecBuf, const int iNum
     QMutexLocker locker ( &Mutex );
 
     bool bNewConnection = false; // init return value
-    bool bChanOK        = true;  // init with ok, might be overwritten
 
     // Get channel ID ------------------------------------------------------
     // check address
-    iCurChanID = FindChannel ( HostAdr );
-
-    if ( iCurChanID == INVALID_CHANNEL_ID )
-    {
-        // a new client is calling, look for free channel
-        iCurChanID = GetFreeChan();
+    iCurChanID = FindChannel ( HostAdr, true /* allow new */ );
 
-        if ( iCurChanID != INVALID_CHANNEL_ID )
-        {
-            // initialize current channel by storing the calling host
-            // address
-            vecChannels[iCurChanID].SetAddress ( HostAdr );
-
-            // reset channel info
-            vecChannels[iCurChanID].ResetInfo();
-
-            // reset the channel gains/pans of current channel, at the same
-            // time reset gains/pans of this channel ID for all other channels
-            for ( int i = 0; i < iMaxNumChannels; i++ )
-            {
-                vecChannels[iCurChanID].SetGain ( i, 1.0 );
-                vecChannels[iCurChanID].SetPan ( i, 0.5 );
-
-                // other channels (we do not distinguish the case if
-                // i == iCurChanID for simplicity)
-                vecChannels[i].SetGain ( iCurChanID, 1.0 );
-                vecChannels[i].SetPan ( iCurChanID, 0.5 );
-            }
-        }
-        else
-        {
-            // no free channel available
-            bChanOK = false;
-        }
-    }
-
-    // Put received audio data in jitter buffer ----------------------------
-    if ( bChanOK )
+    // If channel is valid or new, put received audio data in jitter buffer ----------------------------
+    if ( iCurChanID != INVALID_CHANNEL_ID )
     {
         // put packet in socket buffer
         if ( vecChannels[iCurChanID].PutAudioData ( vecbyRecBuf, iNumBytesRead, HostAdr ) == PS_NEW_CONNECTION )
@@ -1603,8 +1661,6 @@ void CServer::GetConCliParam ( CVector<CHostAddress>& vecHostAddresses,
                                CVector<int>&          veciJitBufNumFrames,
                                CVector<int>&          veciNetwFrameSizeFact )
 {
-    CHostAddress InetAddr;
-
     // init return values
     vecHostAddresses.Init ( iMaxNumChannels );
     vecsName.Init ( iMaxNumChannels );
@@ -1614,10 +1670,10 @@ void CServer::GetConCliParam ( CVector<CHostAddress>& vecHostAddresses,
     // check all possible channels
     for ( int i = 0; i < iMaxNumChannels; i++ )
     {
-        if ( vecChannels[i].GetAddress ( InetAddr ) )
+        if ( vecChannels[i].IsConnected() )
         {
             // get requested data
-            vecHostAddresses[i]      = InetAddr;
+            vecHostAddresses[i]      = vecChannels[i].GetAddress();
             vecsName[i]              = vecChannels[i].GetName();
             veciJitBufNumFrames[i]   = vecChannels[i].GetSockBufNumFrames();
             veciNetwFrameSizeFact[i] = vecChannels[i].GetNetwFrameSizeFact();

src/server.h

@@ -257,8 +257,10 @@ class CServer : public QObject, public CServerSlots<MAX_NUM_CHANNELS>
     // access functions for actual channels
     bool IsConnected ( const int iChanNum ) { return vecChannels[iChanNum].IsConnected(); }
 
-    int                   GetFreeChan();
-    int                   FindChannel ( const CHostAddress& CheckAddr );
+    int                   FindChannel ( const CHostAddress& CheckAddr, const bool bAllowNew = false );
+    void                  InitChannel ( const int iNewChanID, const CHostAddress& InetAddr );
+    void                  FreeChannel ( const int iCurChanID );
+    void                  DumpChannels ( const QString& title );
     int                   GetNumberOfConnectedClients();
     CVector<CChannelInfo> CreateChannelList();
 
@@ -305,8 +307,13 @@ class CServer : public QObject, public CServerSlots<MAX_NUM_CHANNELS>
 
     // do not use the vector class since CChannel does not have appropriate
     // copy constructor/operator
-    CChannel  vecChannels[MAX_NUM_CHANNELS];
-    int       iMaxNumChannels;
+    CChannel vecChannels[MAX_NUM_CHANNELS];
+    int      iMaxNumChannels;
+
+    int    iCurNumChannels;
+    int    vecChannelOrder[MAX_NUM_CHANNELS];
+    QMutex MutexChanOrder;
+
     CProtocol ConnLessProtocol;
     QMutex    Mutex;
     QMutex    MutexWelcomeMessage;

src/util.cpp

@@ -877,6 +877,50 @@ bool NetworkUtil::IsPrivateNetworkIP ( const QHostAddress& qhAddr )
     return false;
 }
 
+// CHostAddress methods
+// Compare() - compare two CHostAddress objects, and return an ordering between them:
+// 0 - they are equal
+// <0 - this comes before other
+// >0 - this comes after other
+// The order is not important, so long as it is consistent, for use in a binary search.
+
+int CHostAddress::Compare ( const CHostAddress& other ) const
+{
+    // compare port first, as it is cheap, and clients will often use random ports
+
+    if ( iPort != other.iPort )
+    {
+        return (int) iPort - (int) other.iPort;
+    }
+
+    // compare protocols before addresses
+
+    QAbstractSocket::NetworkLayerProtocol thisProto  = InetAddr.protocol();
+    QAbstractSocket::NetworkLayerProtocol otherProto = other.InetAddr.protocol();
+
+    if ( thisProto != otherProto )
+    {
+        return (int) thisProto - (int) otherProto;
+    }
+
+    // now we know both addresses are the same protocol
+
+    if ( thisProto == QAbstractSocket::IPv6Protocol )
+    {
+        // compare IPv6 addresses
+        Q_IPV6ADDR thisAddr  = InetAddr.toIPv6Address();
+        Q_IPV6ADDR otherAddr = other.InetAddr.toIPv6Address();
+
+        return memcmp ( &thisAddr, &otherAddr, sizeof ( Q_IPV6ADDR ) );
+    }
+
+    // compare IPv4 addresses
+    quint32 thisAddr  = InetAddr.toIPv4Address();
+    quint32 otherAddr = other.InetAddr.toIPv4Address();
+
+    return (int) thisAddr - (int) otherAddr;
+}
+
 // Instrument picture data base ------------------------------------------------
 CVector<CInstPictures::CInstPictProps>& CInstPictures::GetTable ( const bool bReGenerateTable )
 {

src/util.h

@@ -720,6 +720,8 @@ class CHostAddress
     // compare operator
     bool operator== ( const CHostAddress& CompAddr ) const { return ( ( CompAddr.InetAddr == InetAddr ) && ( CompAddr.iPort == iPort ) ); }
 
+    int Compare ( const CHostAddress& other ) const;
+
     QString toString ( const EStringMode eStringMode = SM_IP_PORT ) const
     {
         QString strReturn = InetAddr.toString();