Add PubSub observer+ hooks (they can modify as well)

libp2p/protocols/pubsub/floodsub.nim

@@ -138,6 +138,7 @@ method unsubscribe*(f: FloodSub,
     await f.sendSubs(p, topics.mapIt(it.topic).deduplicate(), false)
 
 method initPubSub*(f: FloodSub) =
+  procCall PubSub(f).initPubSub()
   f.peers = initTable[string, PubSubPeer]()
   f.topics = initTable[string, Topic]()
   f.floodsub = initTable[string, HashSet[string]]()

libp2p/protocols/pubsub/pubsub.nim

@@ -16,6 +16,7 @@ import pubsubpeer,
        ../../peerinfo
 
 export PubSubPeer
+export PubSubObserver
 
 logScope:
   topic = "PubSub"
@@ -42,6 +43,7 @@ type
     sign*: bool                       # enable message signing
     cleanupLock: AsyncLock
     validators*: Table[string, HashSet[ValidatorHandler]]
+    observers: ref seq[PubSubObserver] # ref as in smart_ptr
 
 proc sendSubs*(p: PubSub,
                peer: PubSubPeer,
@@ -72,6 +74,7 @@ method rpcHandler*(p: PubSub,
                    rpcMsgs: seq[RPCMsg]) {.async, base.} =
   ## handle rpc messages
   trace "processing RPC message", peer = peer.id, msgs = rpcMsgs.len
+
   for m in rpcMsgs:                                # for all RPC messages
     trace "processing messages", msg = m.shortLog
     if m.subscriptions.len > 0:                    # if there are any subscriptions
@@ -104,6 +107,7 @@ proc getPeer(p: PubSub,
 
   p.peers[peer.id] = peer
   peer.refs.inc # increment reference cound
+  peer.observers = p.observers
   result = peer
 
 method handleConn*(p: PubSub,
@@ -201,7 +205,7 @@ method publish*(p: PubSub,
 
 method initPubSub*(p: PubSub) {.base.} =
   ## perform pubsub initializaion
-  discard
+  p.observers = new(seq[PubSubObserver])
 
 method start*(p: PubSub) {.async, base.} =
   ## start pubsub
@@ -253,3 +257,10 @@ proc newPubSub*(P: typedesc[PubSub],
              sign: sign,
              cleanupLock: newAsyncLock())
   result.initPubSub()
+
+proc addObserver*(p: PubSub; observer: PubSubObserver) = p.observers[] &= observer
+
+proc removeObserver*(p: PubSub; observer: PubSubObserver) =
+  let idx = p.observers[].find(observer)
+  if idx != -1:
+    p.observers[].del(idx)

libp2p/protocols/pubsub/pubsubpeer.nim

@@ -23,6 +23,10 @@ logScope:
   topic = "PubSubPeer"
 
 type
+  PubSubObserver* = ref object
+    onRecv*: proc(peer: PubSubPeer; msgs: var RPCMsg) {.gcsafe.}
+    onSend*: proc(peer: PubSubPeer; msgs: var RPCMsg) {.gcsafe.}
+
   PubSubPeer* = ref object of RootObj
     proto: string # the protocol that this peer joined from
     sendConn: Connection
@@ -33,6 +37,7 @@ type
     recvdRpcCache: TimedCache[string] # cache for already received messages
     refs*: int # refcount of the connections this peer is handling
     onConnect: AsyncEvent
+    observers*: ref seq[PubSubObserver] # ref as in smart_ptr
 
   RPCHandler* = proc(peer: PubSubPeer, msg: seq[RPCMsg]): Future[void] {.gcsafe.}
 
@@ -58,8 +63,11 @@ proc handle*(p: PubSubPeer, conn: Connection) {.async.} =
         trace "message already received, skipping", peer = p.id
         continue
 
-      let msg = decodeRpcMsg(data)
+      var msg = decodeRpcMsg(data)
       trace "decoded msg from peer", peer = p.id, msg = msg.shortLog
+      # trigger hooks
+      for obs in p.observers[]:
+        obs.onRecv(p, msg)
       await p.handler(p, @[msg])
       p.recvdRpcCache.put($hexData.hash)
   except CatchableError as exc:
@@ -71,9 +79,14 @@ proc handle*(p: PubSubPeer, conn: Connection) {.async.} =
 
 proc send*(p: PubSubPeer, msgs: seq[RPCMsg]) {.async.} =
   try:
-    for m in msgs:
+    for m in msgs.items:
       trace "sending msgs to peer", toPeer = p.id
       let encoded = encodeRpcMsg(m)
+      # trigger hooks
+      if p.observers[].len > 0:
+        var mm = m
+        for obs in p.observers[]:
+          obs.onSend(p, mm)
       let encodedHex = encoded.buffer.toHex()
       if encoded.buffer.len <= 0:
         trace "empty message, skipping", peer = p.id

tests/pubsub/testgossipsub.nim

@@ -268,6 +268,18 @@ suite "GossipSub":
 
       await nodes[1].subscribe("foobar", handler)
       await waitSub(nodes[0], nodes[1], "foobar")
+
+      var observed = 0
+      let
+        obs1 = PubSubObserver(onRecv: proc(peer: PubSubPeer; msgs: var RPCMsg) =
+          inc observed
+        )
+        obs2 = PubSubObserver(onSend: proc(peer: PubSubPeer; msgs: var RPCMsg) =
+          inc observed
+        )
+      nodes[1].pubsub.get().addObserver(obs1)
+      nodes[0].pubsub.get().addObserver(obs2)
+
       await nodes[0].publish("foobar", cast[seq[byte]]("Hello!"))
 
       var gossipSub1: GossipSub = GossipSub(nodes[0].pubSub.get())
@@ -283,7 +295,7 @@ suite "GossipSub":
       await nodes[1].stop()
       await allFuturesThrowing(wait)
 
-      result = true
+      result = observed == 2
 
     check:
       waitFor(runTests()) == true