Stagger send

libp2p/protocols/pubsub/gossipsub.nim

@@ -25,6 +25,7 @@ import ./pubsub,
        ./rpc/[messages, message],
        ../protocol,
        ../../stream/connection,
+       ../../utils/semaphore,
        ../../peerinfo,
        ../../peerid,
        ../../utility,
@@ -268,6 +269,7 @@ proc handleControl(g: GossipSub, peer: PubSubPeer, control: ControlMessage) =
     respControl.iwant.add(iwant)
   respControl.prune.add(g.handleGraft(peer, control.graft))
   let messages = g.handleIWant(peer, control.iwant)
+  g.handleDontSend(peer, control.dontSend)
 
   if
     respControl.prune.len > 0 or
@@ -332,14 +334,36 @@ proc validateAndRelay(g: GossipSub,
       g.floodsub.withValue(t, peers): toSendPeers.incl(peers[])
       g.mesh.withValue(t, peers): toSendPeers.incl(peers[])
 
+    if msg.data.len >= g.parameters.lazyPushThreshold:
+      g.broadcast(toSendPeers, RPCMsg(control: some(ControlMessage(dontSend: @[ControlIHave(messageIds: @[msgId])]))))
+
     # Don't send it to source peer, or peers that
     # sent it during validation
     toSendPeers.excl(peer)
     toSendPeers.excl(seenPeers)
 
-    # In theory, if topics are the same in all messages, we could batch - we'd
-    # also have to be careful to only include validated messages
-    g.broadcast(toSendPeers, RPCMsg(messages: @[msg]))
+    if msg.data.len < g.parameters.lazyPushThreshold:
+      # In theory, if topics are the same in all messages, we could batch - we'd
+      # also have to be careful to only include validated messages
+      g.broadcast(toSendPeers, RPCMsg(messages: @[msg]))
+    else:
+      let sem = newAsyncSemaphore(1)
+      var peers = toSeq(toSendPeers)
+      g.rng.shuffle(peers)
+
+      proc sendToOne(p: PubSubPeer) {.async.} =
+        await sem.acquire()
+        defer: sem.release()
+
+        let fut = p.gotMsgs.mgetOrPut(msgId, newFuture[void]())
+        if fut.completed: return
+        g.broadcast(@[p], RPCMsg(messages: @[msg]))
+        await fut or sleepAsync(200.milliseconds)
+        if not fut.completed:
+          echo g.switch.peerInfo.peerId, ": timeout from ", p.peerId
+
+      for p in peers:
+        asyncSpawn sendToOne(p)
     trace "forwared message to peers", peers = toSendPeers.len, msgId, peer
     for topic in msg.topicIds:
       if topic notin g.topics: continue
@@ -563,7 +587,28 @@ method publish*(g: GossipSub,
 
   g.mcache.put(msgId, msg)
 
-  g.broadcast(peers, RPCMsg(messages: @[msg]))
+  if data.len < g.parameters.lazyPushThreshold:
+    g.broadcast(peers, RPCMsg(messages: @[msg]))
+  else:
+    g.broadcast(peers, RPCMsg(control: some(ControlMessage(dontSend: @[ControlIHave(messageIds: @[msgId])]))))
+
+    var peersSeq = toSeq(peers)
+    g.rng.shuffle(peersSeq)
+
+    let sem = newAsyncSemaphore(1)
+    proc sendToOne(p: PubSubPeer) {.async.} =
+      await sem.acquire()
+      defer: sem.release()
+
+      let fut = p.gotMsgs.mgetOrPut(msgId, newFuture[void]())
+      if fut.completed: return
+      g.broadcast(@[p], RPCMsg(messages: @[msg]))
+      await fut or sleepAsync(200.milliseconds)
+      if not fut.completed:
+        echo g.switch.peerInfo.peerId, ": timeout from ", p.peerId
+
+    for p in peersSeq:
+      asyncSpawn sendToOne(p)
 
   if g.knownTopics.contains(topic):
     libp2p_pubsub_messages_published.inc(peers.len.int64, labelValues = [topic])

libp2p/protocols/pubsub/gossipsub/behavior.nim

@@ -245,6 +245,15 @@ proc handlePrune*(g: GossipSub, peer: PubSubPeer, prunes: seq[ControlPrune]) {.r
       for handler in g.routingRecordsHandler:
         handler(peer.peerId, topic, routingRecords)
 
+proc handleDontSend*(g: GossipSub,
+                     peer: PubSubPeer,
+                     dontSend: seq[ControlIHave]) {.raises: [Defect].} =
+  for ds in dontSend:
+    for x in ds.messageIds:
+      let fut = peer.gotMsgs.mgetOrPut(x, newFuture[void]())
+      if not fut.completed:
+        fut.complete()
+
 proc handleIHave*(g: GossipSub,
                  peer: PubSubPeer,
                  ihaves: seq[ControlIHave]): ControlIWant {.raises: [Defect].} =

libp2p/protocols/pubsub/gossipsub/types.nim

@@ -117,6 +117,8 @@ type
     dOut*: int
     dLazy*: int
 
+    lazyPushThreshold*: int
+
     heartbeatInterval*: Duration
 
     historyLength*: int

libp2p/protocols/pubsub/pubsubpeer.nim

@@ -60,6 +60,7 @@ type
     peerId*: PeerId
     handler*: RPCHandler
     observers*: ref seq[PubSubObserver] # ref as in smart_ptr
+    gotMsgs*: Table[MessageId, Future[void]]
 
     score*: float64
     iWantBudget*: int

libp2p/protocols/pubsub/rpc/messages.nim

@@ -42,6 +42,7 @@ type
 
     ControlMessage* = object
       ihave*: seq[ControlIHave]
+      dontSend*: seq[ControlIHave]
       iwant*: seq[ControlIWant]
       graft*: seq[ControlGraft]
       prune*: seq[ControlPrune]

libp2p/protocols/pubsub/rpc/protobuf.nim

@@ -90,6 +90,8 @@ proc write*(pb: var ProtoBuffer, field: int, control: ControlMessage) =
     ipb.write(3, graft)
   for prune in control.prune:
     ipb.write(4, prune)
+  for ihave in control.dontSend:
+    ipb.write(5, ihave)
   if len(ipb.buffer) > 0:
     ipb.finish()
     pb.write(field, ipb)
@@ -210,6 +212,7 @@ proc decodeControl*(pb: ProtoBuffer): ProtoResult[Option[ControlMessage]] {.
     var control: ControlMessage
     var cpb = initProtoBuffer(buffer)
     var ihavepbs: seq[seq[byte]]
+    var dontsendpbs: seq[seq[byte]]
     var iwantpbs: seq[seq[byte]]
     var graftpbs: seq[seq[byte]]
     var prunepbs: seq[seq[byte]]
@@ -225,6 +228,9 @@ proc decodeControl*(pb: ProtoBuffer): ProtoResult[Option[ControlMessage]] {.
     if ? cpb.getRepeatedField(4, prunepbs):
       for item in prunepbs:
         control.prune.add(? decodePrune(initProtoBuffer(item)))
+    if ? cpb.getRepeatedField(5, dontsendpbs):
+      for item in dontsendpbs:
+        control.dontSend.add(? decodeIHave(initProtoBuffer(item)))
     trace "decodeControl: message statistics", graft_count = len(control.graft),
                                                prune_count = len(control.prune),
                                                ihave_count = len(control.ihave),