send NACKs

Streaming.cpp

@@ -126,6 +126,13 @@ namespace stream
 				LogPrint ("Missing messages from ", m_LastReceivedSequenceNumber + 1, " to ", receivedSeqn - 1);
 				// save message and wait for missing message again
 				SavePacket (packet);
+				// send NACKs for missing messages ASAP
+				if (m_IsAckSendScheduled)
+				{
+					m_IsAckSendScheduled = false;	
+					m_AckSendTimer.cancel ();
+				}
+				SendQuickAck ();
 			}	
 		}	
 	}	
@@ -320,6 +327,18 @@ namespace stream
 		
 	void Stream::SendQuickAck ()
 	{
+		int32_t lastReceivedSeqn = m_LastReceivedSequenceNumber;
+		if (!m_SavedPackets.empty ())
+		{
+			int32_t seqn = (*m_SavedPackets.rbegin ())->GetSeqn ();
+			if (seqn > lastReceivedSeqn) lastReceivedSeqn = seqn;
+		}	
+		if (lastReceivedSeqn < 0) 
+		{	
+			LogPrint (eLogError, "No packets have been received yet");
+			return;
+		}
+		
 		Packet p;
 		uint8_t * packet = p.GetBuffer ();	
 		size_t size = 0;
@@ -329,10 +348,35 @@ namespace stream
 		size += 4; // receiveStreamID
 		*(uint32_t *)(packet + size) = 0; // this is plain Ack message
 		size += 4; // sequenceNum
-		*(uint32_t *)(packet + size) = htobe32 (m_LastReceivedSequenceNumber);
+		*(uint32_t *)(packet + size) = htobe32 (lastReceivedSeqn);
 		size += 4; // ack Through
-		packet[size] = 0; 
-		size++; // NACK count
+		if (lastReceivedSeqn > m_LastReceivedSequenceNumber) 
+		{	
+			// fill NACKs
+			uint8_t * nacks = packet + size + 1;
+			uint8_t numNacks = 0;
+			auto nextSeqn = m_LastReceivedSequenceNumber + 1;
+			for (auto it: m_SavedPackets)
+			{
+				auto seqn = it->GetSeqn ();
+				for (uint32_t i = nextSeqn; i < seqn; i++)
+				{
+					*(uint32_t *)nacks = htobe32 (i);
+					nacks += 4;
+					numNacks++;
+				}	
+				nextSeqn = seqn + 1;
+			}
+			packet[size] = numNacks; 
+			size++; // NACK count	
+			packet += numNacks*4; // NACKs
+		}	
+		else
+		{
+			// No NACKs
+			packet[size] = 0; 
+			size++; // NACK count		
+		}	
 		size++; // resend delay
 		*(uint16_t *)(packet + size) = 0; // nof flags set
 		size += 2; // flags