Replace per-pair gain/pan mutex locking with snapshot

src/channel.cpp

@@ -315,21 +315,6 @@ void CChannel::SetGain ( const int iChanID, const float fNewGain )
     }
 }
 
-float CChannel::GetGain ( const int iChanID )
-{
-    QMutexLocker locker ( &Mutex );
-
-    // get value (make sure channel ID is in range)
-    if ( ( iChanID >= 0 ) && ( iChanID < MAX_NUM_CHANNELS ) )
-    {
-        return vecfGains[iChanID];
-    }
-    else
-    {
-        return 0;
-    }
-}
-
 void CChannel::SetPan ( const int iChanID, const float fNewPan )
 {
     QMutexLocker locker ( &Mutex );
@@ -342,18 +327,31 @@ void CChannel::SetPan ( const int iChanID, const float fNewPan )
     }
 }
 
-float CChannel::GetPan ( const int iChanID )
+/// @brief Copies a consistent snapshot of gain and panning settings for the requested channel IDs under Mutex.
+/// @param vecChanIDs Channel IDs to read, in the order used for the output vectors.
+/// @param iNumClients Number of leading entries to read and populate. All three vectors must contain at least this many entries.
+/// @param vecGains Receives each requested channel's gain, or zero for an out-of-range channel ID.
+/// @param vecPannings Receives each requested channel's panning, or zero for an out-of-range channel ID.
+void CChannel::GetGainsAndPannings ( const CVector<int>& vecChanIDs, const int iNumClients, CVector<float>& vecGains, CVector<float>& vecPannings )
 {
     QMutexLocker locker ( &Mutex );
 
-    // get value (make sure channel ID is in range)
-    if ( ( iChanID >= 0 ) && ( iChanID < MAX_NUM_CHANNELS ) )
+    // copy the gain and pan values of the connected channels
+    for ( int j = 0; j < iNumClients; j++ )
     {
-        return vecfPannings[iChanID];
-    }
-    else
-    {
-        return 0;
+        const int iChanID = vecChanIDs[j];
+
+        if ( ( iChanID >= 0 ) && ( iChanID < MAX_NUM_CHANNELS ) )
+        {
+            vecGains[j]    = vecfGains[iChanID];
+            vecPannings[j] = vecfPannings[iChanID];
+        }
+        else
+        {
+            // should not happen
+            vecGains[j]    = 0;
+            vecPannings[j] = 0;
+        }
     }
 }
 

src/channel.h

@@ -121,11 +121,11 @@ class CChannel : public QObject
     void CreateMuteStateHasChangedMes ( const int iChanID, const bool bIsMuted ) { Protocol.CreateMuteStateHasChangedMes ( iChanID, bIsMuted ); }
 
     void  SetGain ( const int iChanID, const float fNewGain );
-    float GetGain ( const int iChanID );
     float GetFadeInGain() { return static_cast<float> ( iFadeInCnt ) / iFadeInCntMax; }
 
-    void  SetPan ( const int iChanID, const float fNewPan );
-    float GetPan ( const int iChanID );
+    void SetPan ( const int iChanID, const float fNewPan );
+
+    void GetGainsAndPannings ( const CVector<int>& vecChanIDs, const int iNumClients, CVector<float>& vecGains, CVector<float>& vecPannings );
 
     void SetRemoteChanGain ( const int iId, const float fGain ) { Protocol.CreateChanGainMes ( iId, fGain ); }
 

src/server.cpp

@@ -896,15 +896,16 @@ void CServer::DecodeReceiveData ( const int iChanCnt, const int iNumClients )
         CurOpusDecoder = nullptr;
     }
 
-    // get gains of all connected channels
+    // get gains and pannings of all connected channels, compacted to the
+    // order of "vecChanIDsCurConChan".
+    // The second index of "vecvecfGains" does not represent
+    // the channel ID! Therefore we have to use
+    // "vecChanIDsCurConChan" to query the IDs of the currently
+    // connected channels
+    vecChannels[iCurChanID].GetGainsAndPannings ( vecChanIDsCurConChan, iNumClients, vecvecfGains[iChanCnt], vecvecfPannings[iChanCnt] );
+
     for ( int j = 0; j < iNumClients; j++ )
     {
-        // The second index of "vecvecdGains" does not represent
-        // the channel ID! Therefore we have to use
-        // "vecChanIDsCurConChan" to query the IDs of the currently
-        // connected channels
-        vecvecfGains[iChanCnt][j] = vecChannels[iCurChanID].GetGain ( vecChanIDsCurConChan[j] );
-
         // consider audio fade-in
         vecvecfGains[iChanCnt][j] *= vecChannels[vecChanIDsCurConChan[j]].GetFadeInGain();
 
@@ -914,9 +915,6 @@ void CServer::DecodeReceiveData ( const int iChanCnt, const int iNumClients )
         {
             vecvecfGains[iChanCnt][j] *= vecChannels[iCurChanID].GetFadeInGain();
         }
-
-        // panning
-        vecvecfPannings[iChanCnt][j] = vecChannels[iCurChanID].GetPan ( vecChanIDsCurConChan[j] );
     }
 
     // If the server frame size is smaller than the received OPUS frame size, we need a conversion