Hostmap.QueryIndex is really hot

hostmap.go

@@ -543,6 +543,17 @@ func (hm *HostMap) unlockedDeleteHostInfo(hostinfo *HostInfo) bool {
 	return final
 }
 
+func (hm *HostMap) QueryIndexCached(index uint32, cache map[uint32]*HostInfo) *HostInfo {
+	if out, ok := cache[index]; ok {
+		return out
+	}
+	out := hm.QueryIndex(index)
+	if out != nil {
+		cache[index] = out
+	}
+	return out
+}
+
 func (hm *HostMap) QueryIndex(index uint32) *HostInfo {
 	hm.RLock()
 	if h, ok := hm.Indexes[index]; ok {

interface.go

@@ -363,15 +363,17 @@ func (f *Interface) listenOut(i int) {
 	fwPacket := &firewall.ParsedPacket{}
 	nb := make([]byte, 12, 12)
 	scratch := make([]byte, mtu)
+	hostmapCache := map[uint32]*HostInfo{} //todo is this stupid
 
 	listener := func(fromUdpAddr netip.AddrPort, payload []byte) {
-		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, scratch, payload, h, fwPacket, lhh, nb, i, ctCache.Get())
+		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, scratch, payload, h, fwPacket, lhh, nb, i, ctCache.Get(), hostmapCache)
 	}
 
 	flusher := func() {
 		if err := f.batchers[i].Flush(); err != nil {
 			f.l.Error("Failed to flush tun coalescer", "error", err)
 		}
+		clear(hostmapCache)
 	}
 
 	err := li.ListenOut(listener, flusher)

outside.go

@@ -26,7 +26,7 @@ var ErrOutOfWindow = errors.New("out of window packet")
 // readOutsidePackets processes one received underlay packet.
 // Message payloads are decrypted IN PLACE, so packet must stay untouched
 // by the caller until the batcher for queue q has been flushed
-func (f *Interface) readOutsidePackets(via ViaSender, scratch []byte, packet []byte, h *header.H, fwPacket *firewall.ParsedPacket, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
+func (f *Interface) readOutsidePackets(via ViaSender, scratch []byte, packet []byte, h *header.H, fwPacket *firewall.ParsedPacket, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, hmCache map[uint32]*HostInfo) {
 	err := h.Parse(packet)
 	if err != nil {
 		// Hole punch packets are 0 or 1 byte big, so lets ignore printing those errors
@@ -94,7 +94,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, scratch []byte, packet []b
 	if isMessageRelay {
 		hostinfo = f.hostMap.QueryRelayIndex(h.RemoteIndex)
 	} else {
-		hostinfo = f.hostMap.QueryIndex(h.RemoteIndex)
+		hostinfo = f.hostMap.QueryIndexCached(h.RemoteIndex, hmCache)
 	}
 
 	// At this point we should have a valid existing tunnel, verify and send
@@ -124,7 +124,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, scratch []byte, packet []b
 			}
 			return
 		}
-		f.handleOutsideRelayPacket(hostinfo, via, scratch, packet, h, fwPacket, lhf, nb, q, localCache)
+		f.handleOutsideRelayPacket(hostinfo, via, scratch, packet, h, fwPacket, lhf, nb, q, localCache, hmCache)
 		return
 	}
 
@@ -186,7 +186,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, scratch []byte, packet []b
 	}
 }
 
-func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, scratch []byte, packet []byte, h *header.H, fwPacket *firewall.ParsedPacket, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
+func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, scratch []byte, packet []byte, h *header.H, fwPacket *firewall.ParsedPacket, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache, hmCache map[uint32]*HostInfo) {
 	// Successfully validated the thing. Get rid of the Relay header and the AEAD tag
 	signedPayload := packet[header.Len : len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
 	// Pull the Roaming parts up here, and return in all call paths.
@@ -213,7 +213,7 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
 			relay:     relay,
 			IsRelayed: true,
 		}
-		f.readOutsidePackets(via, scratch, signedPayload, h, fwPacket, lhf, nb, q, localCache)
+		f.readOutsidePackets(via, scratch, signedPayload, h, fwPacket, lhf, nb, q, localCache, hmCache)
 	case ForwardingType:
 		// Find the target HostInfo relay object
 		targetHI, targetRelay, err := f.hostMap.QueryVpnAddrsRelayFor(hostinfo.vpnAddrs, relay.PeerAddr)