chore: adding observer on message sent

waku/node/waku_node.nim

@@ -392,6 +392,61 @@ proc startRelay*(node: WakuNode) {.async.} =
 
   info "relay started successfully"
 
+proc generateRelayObserver(node: WakuNode): PubSubObserver =
+  proc logMessageInfo(peer: PubSubPeer, msgs: var RPCMsg, onRecv: bool) =
+    for msg in msgs.messages:
+      let msg_id = node.wakuRelay.msgIdProvider(msg).valueOr:
+        warn "Error generating message id",
+          my_peer_id = node.peerId,
+          from_peer_id = peer.peerId,
+          topic = msg.topic,
+          error = $error
+        continue
+
+      let msg_id_short = shortLog(msg_id)
+
+      let wakuMessage = WakuMessage.decode(msg.data).valueOr:
+        warn "Error decoding to Waku Message",
+          my_peer_id = node.peerId,
+          msg_id = msg_id_short,
+          from_peer_id = peer.peerId,
+          topic = msg.topic,
+          error = $error
+        continue
+
+      let msg_hash = computeMessageHash(msg.topic, wakuMessage).to0xHex()
+
+      if onRecv:
+        notice "received relay message",
+          my_peer_id = node.peerId,
+          msg_hash = msg_hash,
+          msg_id = msg_id_short,
+          from_peer_id = peer.peerId,
+          topic = msg.topic,
+          receivedTime = getNowInNanosecondTime(),
+          payloadSizeBytes = wakuMessage.payload.len
+
+        let msgSizeKB = wakuMessage.payload.len / 1000
+        waku_node_messages.inc(labelValues = ["relay"])
+        waku_histogram_message_size.observe(msgSizeKB)
+      else:
+        notice "sent relay message",
+          my_peer_id = node.peerId,
+          msg_hash = msg_hash,
+          msg_id = msg_id_short,
+          to_peer_id = peer.peerId,
+          topic = msg.topic,
+          sentTime = getNowInNanosecondTime(),
+          payloadSizeBytes = wakuMessage.payload.len
+
+  proc onRecv(peer: PubSubPeer, msgs: var RPCMsg) =
+    discard
+
+  proc onSend(peer: PubSubPeer, msgs: var RPCMsg) =
+    logMessageInfo(peer, msgs, onRecv = false)
+
+  return PubSubObserver(onRecv: onRecv, onSend: onSend)
+
 proc mountRelay*(
     node: WakuNode,
     pubsubTopics: seq[string] = @[],
@@ -412,6 +467,11 @@ proc mountRelay*(
 
   node.wakuRelay = initRes.value
 
+  # register relay observers for logging
+  debug "Registering Relay observers"
+  let observerLogger = node.generateRelayObserver()
+  node.wakuRelay.addObserver(observerLogger)
+
   ## Add peer exchange handler
   if peerExchangeHandler.isSome():
     node.wakuRelay.parameters.enablePX = true

waku/waku_relay/protocol.nim

@@ -180,6 +180,9 @@ proc addValidator*(
 ) {.gcsafe.} =
   w.wakuValidators.add((handler, errorMessage))
 
+proc addObserver*(w: WakuRelay, observer: PubSubObserver) {.gcsafe.} =
+  procCall GossipSub(w).addObserver(observer)
+
 method start*(w: WakuRelay) {.async, base.} =
   debug "start"
   await procCall GossipSub(w).start()