use same outbound tunnel for streaming as long as possible

Streaming.cpp

@@ -21,7 +21,8 @@ namespace stream
 		const i2p::data::LeaseSet& remote): m_Service (service), m_SendStreamID (0), 
 		m_SequenceNumber (0), m_LastReceivedSequenceNumber (-1), m_IsOpen (false),  
 		m_LeaseSetUpdated (true), m_LocalDestination (local), 
-		m_RemoteLeaseSet (&remote), m_ReceiveTimer (m_Service), m_ResendTimer (m_Service)
+		m_RemoteLeaseSet (&remote), m_CurrentOutboundTunnel (nullptr), 
+		m_ReceiveTimer (m_Service), m_ResendTimer (m_Service)
 	{
 		m_RecvStreamID = i2p::context.GetRandomNumberGenerator ().GenerateWord32 ();
 		UpdateCurrentRemoteLease ();
@@ -30,7 +31,8 @@ namespace stream
 	Stream::Stream (boost::asio::io_service& service, StreamingDestination * local):
 		m_Service (service), m_SendStreamID (0), m_SequenceNumber (0), m_LastReceivedSequenceNumber (-1), 
 		m_IsOpen (false), m_LeaseSetUpdated (true), m_LocalDestination (local),
-		m_RemoteLeaseSet (nullptr), m_ReceiveTimer (m_Service), m_ResendTimer (m_Service)
+		m_RemoteLeaseSet (nullptr), m_CurrentOutboundTunnel (nullptr), 
+		m_ReceiveTimer (m_Service), m_ResendTimer (m_Service)
 	{
 		m_RecvStreamID = i2p::context.GetRandomNumberGenerator ().GenerateWord32 ();
 	}
@@ -102,6 +104,7 @@ namespace stream
 			{
 				// we have received duplicate. Most likely our outbound tunnel is dead
 				LogPrint ("Duplicate message ", receivedSeqn, " received");
+				m_CurrentOutboundTunnel = nullptr; // pick another outbound tunnel 
 				UpdateCurrentRemoteLease (); // pick another lease
 				SendQuickAck (); // resend ack for previous message again
 				delete packet; // packet dropped
@@ -401,8 +404,8 @@ namespace stream
 			m_LeaseSetUpdated = false;
 		}	
 
-		auto outboundTunnel = m_LocalDestination->GetTunnelPool ()->GetNextOutboundTunnel ();
-		if (outboundTunnel)
+		m_CurrentOutboundTunnel = m_LocalDestination->GetTunnelPool ()->GetNextOutboundTunnel (m_CurrentOutboundTunnel);
+		if (m_CurrentOutboundTunnel)
 		{
 			auto ts = i2p::util::GetMillisecondsSinceEpoch ();
 			if (ts >= m_CurrentRemoteLease.endDate)
@@ -422,7 +425,7 @@ namespace stream
 								});	
 					leaseSet = nullptr; // send leaseSet only one time
 				}
-				outboundTunnel->SendTunnelDataMsg (msgs);
+				m_CurrentOutboundTunnel->SendTunnelDataMsg (msgs);
 			}	
 			else
 				LogPrint ("All leases are expired");
@@ -458,6 +461,7 @@ namespace stream
 			}	
 			if (packets.size () > 0)
 			{
+				m_CurrentOutboundTunnel = nullptr; // pick another outbound tunnel 
 				UpdateCurrentRemoteLease (); // pick another lease
 				SendPackets (packets);
 			}	

Streaming.h

@@ -128,6 +128,7 @@ namespace stream
 			i2p::data::Identity m_RemoteIdentity;
 			const i2p::data::LeaseSet * m_RemoteLeaseSet;
 			i2p::data::Lease m_CurrentRemoteLease;
+			i2p::tunnel::OutboundTunnel * m_CurrentOutboundTunnel;
 			std::queue<Packet *> m_ReceiveQueue;
 			std::set<Packet *, PacketCmp> m_SavedPackets;
 			std::set<Packet *, PacketCmp> m_SentPackets;

TunnelPool.cpp

@@ -74,22 +74,28 @@ namespace tunnel
 		return v;
 	}
 
-	OutboundTunnel * TunnelPool::GetNextOutboundTunnel () 
+	OutboundTunnel * TunnelPool::GetNextOutboundTunnel (OutboundTunnel * suggested) 
 	{
-		return GetNextTunnel (m_OutboundTunnels);
+		return GetNextTunnel (m_OutboundTunnels, suggested);
 	}	
 
-	InboundTunnel * TunnelPool::GetNextInboundTunnel ()
+	InboundTunnel * TunnelPool::GetNextInboundTunnel (InboundTunnel * suggested)
 	{
-		return GetNextTunnel (m_InboundTunnels);
+		return GetNextTunnel (m_InboundTunnels, suggested);
 	}
 
 	template<class TTunnels>
-	typename TTunnels::value_type TunnelPool::GetNextTunnel (TTunnels& tunnels)
+	typename TTunnels::value_type TunnelPool::GetNextTunnel (TTunnels& tunnels, 
+		typename TTunnels::value_type suggested)
 	{
 		if (tunnels.empty ()) return nullptr;
+		uint64_t ts = i2p::util::GetSecondsSinceEpoch ();
+		if (suggested && tunnels.count (suggested) > 0 && 
+		    ts + TUNNEL_EXPIRATION_THRESHOLD <= suggested->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
+				return suggested;
 		for (auto it: tunnels)
-			if (!it->IsFailed ())
+			if (!it->IsFailed () && ts + TUNNEL_EXPIRATION_THRESHOLD <= 
+				it->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
 					return it;
 		return nullptr;
 	}

TunnelPool.h

@@ -19,6 +19,7 @@ namespace tunnel
 	class InboundTunnel;
 	class OutboundTunnel;
 
+	const int TUNNEL_EXPIRATION_THRESHOLD = 60; // 1 minute
 	class TunnelPool // per local destination
 	{
 		public:
@@ -37,8 +38,8 @@ namespace tunnel
 			void TunnelCreated (OutboundTunnel * createdTunnel);
 			void TunnelExpired (OutboundTunnel * expiredTunnel);
 			std::vector<InboundTunnel *> GetInboundTunnels (int num) const;
-			OutboundTunnel * GetNextOutboundTunnel ();
-			InboundTunnel * GetNextInboundTunnel ();
+			OutboundTunnel * GetNextOutboundTunnel (OutboundTunnel * suggested = nullptr);
+			InboundTunnel * GetNextInboundTunnel (InboundTunnel * suggested = nullptr);
 			const i2p::data::IdentHash& GetIdentHash () { return m_LocalDestination.GetIdentHash (); };			
 
 			void TestTunnels ();
@@ -51,7 +52,8 @@ namespace tunnel
 			void RecreateInboundTunnel (InboundTunnel * tunnel);
 			void RecreateOutboundTunnel (OutboundTunnel * tunnel);
 			template<class TTunnels>
-			typename TTunnels::value_type GetNextTunnel (TTunnels& tunnels);
+			typename TTunnels::value_type GetNextTunnel (TTunnels& tunnels, 
+				typename TTunnels::value_type suggested = nullptr);
 			
 		private: