452 lines
15 KiB
Nim
452 lines
15 KiB
Nim
## Nim-LibP2P
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## Copyright (c) 2019 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import tables, sets, options, sequtils, random
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import chronos, chronicles
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import pubsub,
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floodsub,
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pubsubpeer,
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mcache,
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timedcache,
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rpc/[messages, message],
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../../crypto/crypto,
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../protocol,
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../../peerinfo,
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../../connection,
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../../peer,
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../../errors
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logScope:
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topic = "GossipSub"
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const GossipSubCodec* = "/meshsub/1.0.0"
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# overlay parameters
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const GossipSubD* = 6
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const GossipSubDlo* = 4
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const GossipSubDhi* = 12
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# gossip parameters
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const GossipSubHistoryLength* = 5
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const GossipSubHistoryGossip* = 3
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# heartbeat interval
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const GossipSubHeartbeatInitialDelay* = 100.millis
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const GossipSubHeartbeatInterval* = 1.seconds
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# fanout ttl
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const GossipSubFanoutTTL* = 1.minutes
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type
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GossipSub* = ref object of FloodSub
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mesh*: Table[string, HashSet[string]] # meshes - topic to peer
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fanout*: Table[string, HashSet[string]] # fanout - topic to peer
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gossipsub*: Table[string, HashSet[string]] # topic to peer map of all gossipsub peers
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lastFanoutPubSub*: Table[string, Moment] # last publish time for fanout topics
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gossip*: Table[string, seq[ControlIHave]] # pending gossip
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control*: Table[string, ControlMessage] # pending control messages
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mcache*: MCache # messages cache
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heartbeatCancel*: Future[void] # cancelation future for heartbeat interval
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heartbeatLock: AsyncLock # hearbeat lock to prevent two concecutive concurent hearbeats
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# TODO: This belong in chronos, temporary left here until chronos is updated
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proc addInterval(every: Duration, cb: CallbackFunc,
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udata: pointer = nil): Future[void] =
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## Arrange the callback ``cb`` to be called on every ``Duration`` window
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var retFuture = newFuture[void]("gossipsub.addInterval(Duration)")
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proc interval(arg: pointer = nil) {.gcsafe.}
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proc scheduleNext() =
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if not retFuture.finished():
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addTimer(Moment.fromNow(every), interval)
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proc interval(arg: pointer = nil) {.gcsafe.} =
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cb(udata)
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scheduleNext()
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scheduleNext()
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return retFuture
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method init(g: GossipSub) =
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proc handler(conn: Connection, proto: string) {.async.} =
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## main protocol handler that gets triggered on every
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## connection for a protocol string
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## e.g. ``/floodsub/1.0.0``, etc...
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##
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await g.handleConn(conn, proto)
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g.handler = handler
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g.codec = GossipSubCodec
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method handleDisconnect(g: GossipSub, peer: PubSubPeer) {.async.} =
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## handle peer disconnects
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trace "peer disconnected", peer=peer.id
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await procCall FloodSub(g).handleDisconnect(peer)
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for t in g.gossipsub.keys:
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g.gossipsub[t].excl(peer.id)
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for t in g.mesh.keys:
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g.mesh[t].excl(peer.id)
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for t in g.fanout.keys:
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g.fanout[t].excl(peer.id)
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method subscribeTopic*(g: GossipSub,
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topic: string,
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subscribe: bool,
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peerId: string) {.gcsafe.} =
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procCall PubSub(g).subscribeTopic(topic, subscribe, peerId)
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if topic notin g.gossipsub:
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g.gossipsub[topic] = initHashSet[string]()
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if subscribe:
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trace "adding subscription for topic", peer = peerId, name = topic
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# subscribe the peer to the topic
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g.gossipsub[topic].incl(peerId)
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else:
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trace "removing subscription for topic", peer = peerId, name = topic
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# unsubscribe the peer from the topic
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g.gossipsub[topic].excl(peerId)
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proc handleGraft(g: GossipSub,
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peer: PubSubPeer,
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grafts: seq[ControlGraft],
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respControl: var ControlMessage) =
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for graft in grafts:
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trace "processing graft message", peer = peer.id,
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topicID = graft.topicID
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if graft.topicID in g.topics:
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if g.mesh.len < GossipSubD:
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g.mesh[graft.topicID].incl(peer.id)
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else:
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g.gossipsub[graft.topicID].incl(peer.id)
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else:
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respControl.prune.add(ControlPrune(topicID: graft.topicID))
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proc handlePrune(g: GossipSub, peer: PubSubPeer, prunes: seq[ControlPrune]) =
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for prune in prunes:
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trace "processing prune message", peer = peer.id,
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topicID = prune.topicID
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if prune.topicID in g.mesh:
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g.mesh[prune.topicID].excl(peer.id)
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proc handleIHave(g: GossipSub, peer: PubSubPeer, ihaves: seq[
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ControlIHave]): ControlIWant =
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for ihave in ihaves:
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trace "processing ihave message", peer = peer.id,
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topicID = ihave.topicID
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if ihave.topicID in g.mesh:
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for m in ihave.messageIDs:
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if m notin g.seen:
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result.messageIDs.add(m)
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proc handleIWant(g: GossipSub, peer: PubSubPeer, iwants: seq[
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ControlIWant]): seq[Message] =
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for iwant in iwants:
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for mid in iwant.messageIDs:
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trace "processing iwant message", peer = peer.id,
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messageID = mid
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let msg = g.mcache.get(mid)
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if msg.isSome:
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result.add(msg.get())
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method rpcHandler(g: GossipSub,
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peer: PubSubPeer,
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rpcMsgs: seq[RPCMsg]) {.async.} =
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await procCall PubSub(g).rpcHandler(peer, rpcMsgs)
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for m in rpcMsgs: # for all RPC messages
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if m.messages.len > 0: # if there are any messages
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var toSendPeers: HashSet[string] = initHashSet[string]()
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for msg in m.messages: # for every message
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trace "processing message with id", msg = msg.msgId
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if msg.msgId in g.seen:
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trace "message already processed, skipping", msg = msg.msgId
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continue
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g.seen.put(msg.msgId) # add the message to the seen cache
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if g.verifySignature and not msg.verify(peer.peerInfo):
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trace "dropping message due to failed signature verification"
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continue
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if not (await g.validate(msg)):
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trace "dropping message due to failed validation"
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continue
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# this shouldn't happen
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if g.peerInfo.peerId == msg.fromPeerId():
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trace "skipping messages from self", msg = msg.msgId
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continue
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for t in msg.topicIDs: # for every topic in the message
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if t in g.floodsub:
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toSendPeers.incl(g.floodsub[t]) # get all floodsub peers for topic
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if t in g.mesh:
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toSendPeers.incl(g.mesh[t]) # get all mesh peers for topic
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if t in g.topics: # if we're subscribed to the topic
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for h in g.topics[t].handler:
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trace "calling handler for message", msg = msg.msgId,
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topicId = t,
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localPeer = g.peerInfo.id,
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fromPeer = msg.fromPeerId().pretty
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await h(t, msg.data) # trigger user provided handler
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# forward the message to all peers interested in it
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for p in toSendPeers:
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if p in g.peers:
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let id = g.peers[p].peerInfo.peerId
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trace "about to forward message to peer", peerId = id
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if id != peer.peerInfo.peerId:
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let msgs = m.messages.filterIt(
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# don't forward to message originator
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id != it.fromPeerId()
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)
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var sent: seq[Future[void]]
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if msgs.len > 0:
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trace "forwarding message to", peerId = id
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sent.add(g.peers[p].send(@[RPCMsg(messages: msgs)]))
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sent = await allFinished(sent)
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checkFutures(sent)
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var respControl: ControlMessage
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if m.control.isSome:
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var control: ControlMessage = m.control.get()
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let iWant: ControlIWant = g.handleIHave(peer, control.ihave)
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if iWant.messageIDs.len > 0:
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respControl.iwant.add(iWant)
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let messages: seq[Message] = g.handleIWant(peer, control.iwant)
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g.handleGraft(peer, control.graft, respControl)
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g.handlePrune(peer, control.prune)
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if respControl.graft.len > 0 or respControl.prune.len > 0 or
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respControl.ihave.len > 0 or respControl.iwant.len > 0:
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await peer.send(@[RPCMsg(control: some(respControl), messages: messages)])
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proc replenishFanout(g: GossipSub, topic: string) {.async.} =
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## get fanout peers for a topic
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trace "about to replenish fanout"
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if topic notin g.fanout:
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g.fanout[topic] = initHashSet[string]()
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if g.fanout[topic].len < GossipSubDLo:
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trace "replenishing fanout", peers = g.fanout[topic].len
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if topic in g.gossipsub:
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for p in g.gossipsub[topic]:
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if not g.fanout[topic].containsOrIncl(p):
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if g.fanout[topic].len == GossipSubD:
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break
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trace "fanout replenished with peers", peers = g.fanout[topic].len
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proc rebalanceMesh(g: GossipSub, topic: string) {.async.} =
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trace "about to rebalance mesh"
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# create a mesh topic that we're subscribing to
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if topic notin g.mesh:
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g.mesh[topic] = initHashSet[string]()
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if g.mesh[topic].len < GossipSubDlo:
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trace "replenishing mesh"
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# replenish the mesh if we're below GossipSubDlo
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while g.mesh[topic].len < GossipSubD:
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trace "gathering peers", peers = g.mesh[topic].len
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var id: string
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if topic in g.fanout and g.fanout[topic].len > 0:
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id = g.fanout[topic].pop()
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trace "got fanout peer", peer = id
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elif topic in g.gossipsub and g.gossipsub[topic].len > 0:
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id = g.gossipsub[topic].pop()
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trace "got gossipsub peer", peer = id
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else:
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trace "no more peers"
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break
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g.mesh[topic].incl(id)
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if id in g.peers:
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let p = g.peers[id]
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# send a graft message to the peer
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await p.sendGraft(@[topic])
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# prune peers if we've gone over
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if g.mesh[topic].len > GossipSubDhi:
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trace "pruning mesh"
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while g.mesh[topic].len > GossipSubD:
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trace "pruning peers", peers = g.mesh[topic].len
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let id = toSeq(g.mesh[topic])[rand(0..<g.mesh[topic].len)]
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g.mesh[topic].excl(id)
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let p = g.peers[id]
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# send a graft message to the peer
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await p.sendPrune(@[topic])
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trace "mesh balanced, got peers", peers = g.mesh[topic].len
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proc dropFanoutPeers(g: GossipSub) {.async.} =
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# drop peers that we haven't published to in
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# GossipSubFanoutTTL seconds
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var dropping = newSeq[string]()
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for topic, val in g.lastFanoutPubSub:
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if Moment.now > val:
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dropping.add(topic)
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g.fanout.del(topic)
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for topic in dropping:
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g.lastFanoutPubSub.del(topic)
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proc getGossipPeers(g: GossipSub): Table[string, ControlMessage] {.gcsafe.} =
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## gossip iHave messages to peers
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let topics = toHashSet(toSeq(g.mesh.keys)) + toHashSet(toSeq(g.fanout.keys))
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for topic in topics:
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let mesh: HashSet[string] =
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if topic in g.mesh:
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g.mesh[topic]
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else:
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initHashSet[string]()
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let fanout: HashSet[string] =
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if topic in g.fanout:
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g.fanout[topic]
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else:
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initHashSet[string]()
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let gossipPeers = mesh + fanout
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let mids = g.mcache.window(topic)
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let ihave = ControlIHave(topicID: topic,
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messageIDs: toSeq(mids))
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if topic notin g.gossipsub:
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trace "topic not in gossip array, skipping", topicID = topic
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continue
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while result.len < GossipSubD:
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if not (g.gossipsub[topic].len > 0):
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trace "no peers for topic, skipping", topicID = topic
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break
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let id = toSeq(g.gossipsub[topic]).sample()
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g.gossipsub[topic].excl(id)
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if id notin gossipPeers:
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if id notin result:
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result[id] = ControlMessage()
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result[id].ihave.add(ihave)
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proc heartbeat(g: GossipSub) {.async.} =
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await g.heartbeatLock.acquire()
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trace "running heartbeat"
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await sleepAsync(GossipSubHeartbeatInitialDelay)
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for t in g.mesh.keys:
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await g.rebalanceMesh(t)
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await g.dropFanoutPeers()
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let peers = g.getGossipPeers()
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for peer in peers.keys:
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await g.peers[peer].send(@[RPCMsg(control: some(peers[peer]))])
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g.mcache.shift() # shift the cache
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g.heartbeatLock.release()
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method subscribe*(g: GossipSub,
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topic: string,
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handler: TopicHandler) {.async.} =
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await procCall PubSub(g).subscribe(topic, handler)
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asyncCheck g.rebalanceMesh(topic)
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method unsubscribe*(g: GossipSub,
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topics: seq[TopicPair]) {.async.} =
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await procCall PubSub(g).unsubscribe(topics)
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for pair in topics:
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let topic = pair.topic
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if topic in g.mesh:
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let peers = g.mesh[topic]
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g.mesh.del(topic)
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for id in peers:
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let p = g.peers[id]
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await p.sendPrune(@[topic])
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method publish*(g: GossipSub,
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topic: string,
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data: seq[byte]) {.async.} =
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await procCall PubSub(g).publish(topic, data)
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trace "about to publish message on topic", name = topic,
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data = data.toHex()
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if data.len > 0 and topic.len > 0:
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var peers: HashSet[string]
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if topic in g.topics: # if we're subscribed to the topic attempt to build a mesh
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await g.rebalanceMesh(topic)
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peers = g.mesh[topic]
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else: # send to fanout peers
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await g.replenishFanout(topic)
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if topic in g.fanout:
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peers = g.fanout[topic]
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# set the fanout expiery time
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g.lastFanoutPubSub[topic] = Moment.fromNow(GossipSubFanoutTTL)
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let msg = newMessage(g.peerInfo, data, topic, g.sign)
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var sent: seq[Future[void]]
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for p in peers:
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if p == g.peerInfo.id:
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continue
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trace "publishing on topic", name = topic
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g.mcache.put(msg)
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sent.add(g.peers[p].send(@[RPCMsg(messages: @[msg])]))
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sent = await allFinished(sent)
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checkFutures(sent)
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method start*(g: GossipSub) {.async.} =
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## start pubsub
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## start long running/repeating procedures
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# setup the heartbeat interval
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g.heartbeatCancel = addInterval(GossipSubHeartbeatInterval,
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proc (arg: pointer = nil)
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{.gcsafe, locks: 0.} =
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asyncCheck g.heartbeat)
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method stop*(g: GossipSub) {.async.} =
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## stopt pubsub
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## stop long running tasks
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await g.heartbeatLock.acquire()
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# stop heartbeat interval
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if not g.heartbeatCancel.finished:
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g.heartbeatCancel.complete()
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g.heartbeatLock.release()
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method initPubSub(g: GossipSub) =
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procCall FloodSub(g).initPubSub()
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g.mcache = newMCache(GossipSubHistoryGossip, GossipSubHistoryLength)
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g.mesh = initTable[string, HashSet[string]]() # meshes - topic to peer
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g.fanout = initTable[string, HashSet[string]]() # fanout - topic to peer
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g.gossipsub = initTable[string, HashSet[string]]() # topic to peer map of all gossipsub peers
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g.lastFanoutPubSub = initTable[string, Moment]() # last publish time for fanout topics
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g.gossip = initTable[string, seq[ControlIHave]]() # pending gossip
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g.control = initTable[string, ControlMessage]() # pending control messages
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g.heartbeatLock = newAsyncLock()
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