Add metrics to utp router (#488)

* Add metrics to utp router

eth/utp/utp_router.nim

@@ -8,11 +8,26 @@
 
 import
   std/[tables, options, sugar],
-  chronos, bearssl, chronicles,
+  chronos, bearssl, chronicles, metrics,
   ../keys,
   ./utp_socket,
   ./packets
 
+declareCounter utp_received_packets,
+  "All correct received uTP packets"
+declareCounter utp_failed_packets,
+  "All received uTP packets which failed decoding"
+declareGauge utp_established_connections,
+  "Current number of established uTP sockets"
+declareCounter utp_allowed_incoming,
+  "Total number of allowed incoming connections"
+declareCounter utp_declined_incoming,
+  "Total number of declined incoming connections"
+declareCounter utp_success_outgoing,
+  "Total number of succesful outgoing connections"
+declareCounter utp_failed_outgoing,
+  "Total number of failed outgoing connections"
+
 logScope:
   topics = "utp_router"
 
@@ -66,6 +81,7 @@ proc getUtpSocket[A](s: UtpRouter[A], k: UtpSocketKey[A]): Option[UtpSocket[A]]
 
 proc deRegisterUtpSocket[A](s: UtpRouter[A], socket: UtpSocket[A]) =
   s.sockets.del(socket.socketKey)
+  utp_established_connections.set(int64(len(s.sockets)))
 
 iterator allSockets[A](s: UtpRouter[A]): UtpSocket[A] =
   for socket in s.sockets.values():
@@ -78,6 +94,7 @@ proc len*[A](s: UtpRouter[A]): int =
 proc registerUtpSocket[A](p: UtpRouter, s: UtpSocket[A]) =
   ## Register socket, overwriting already existing one
   p.sockets[s.socketKey] = s
+  utp_established_connections.set(int64(len(p.sockets)))
   # Install deregister handler, so when socket gets closed, in will be promptly
   # removed from open sockets table
   s.registerCloseCallback(proc () = p.deRegisterUtpSocket(s))
@@ -171,10 +188,12 @@ proc processPacket[A](r: UtpRouter[A], p: Packet, sender: A) {.async.}=
         incomingSocket.startIncomingSocket()
         # Based on configuration, socket is passed to upper layer either in SynRecv
         # or Connected state
+        utp_allowed_incoming.inc()
         info "Accepting incoming connection",
           to = incomingSocket.socketKey
         asyncSpawn r.acceptConnection(r, incomingSocket)
       else:
+        utp_declined_incoming.inc()
         debug "Connection declined"
   else:
     let socketKey = UtpSocketKey[A].init(sender, p.header.connectionId)
@@ -194,8 +213,10 @@ proc processIncomingBytes*[A](r: UtpRouter[A], bytes: seq[byte], sender: A) {.as
   if (not r.closed):
     let dec = decodePacket(bytes)
     if (dec.isOk()):
+      utp_received_packets.inc()
       await processPacket[A](r, dec.get(), sender)
     else:
+      utp_failed_packets.inc()
       let err = dec.error()
       warn "failed to decode packet from address", address = sender, msg = err
 
@@ -227,10 +248,12 @@ proc connect[A](s: UtpSocket[A]): Future[ConnectionResult[A]] {.async.}=
 
     try:
       await startFut
+      utp_success_outgoing.inc()
       info "Outgoing connection successful",
         to = s.socketKey
       return ok(s)
     except ConnectionError:
+      utp_failed_outgoing.inc()
       info "Outgoing connection timed-out",
         to = s.socketKey
       s.destroy()