From 05463873a21004b27a275a78e43d84c5cb69add1 Mon Sep 17 00:00:00 2001
From: Giovanni Petrantoni <giovanni@fragcolor.xyz>
Date: Wed, 12 Aug 2020 18:25:57 +0900
Subject: [PATCH] restore explicit peering

---
 libp2p/protocols/pubsub/gossipsub.nim | 39 ++++++++++++++++++---------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/libp2p/protocols/pubsub/gossipsub.nim b/libp2p/protocols/pubsub/gossipsub.nim
index 06d3f812c..2e0d26c62 100644
--- a/libp2p/protocols/pubsub/gossipsub.nim
+++ b/libp2p/protocols/pubsub/gossipsub.nim
@@ -100,7 +100,7 @@ type
     expire*: Moment # updated on disconnect, to retain scores until expire
 
   GossipSubParams* = object
-    explicit*: bool
+    explicit: bool
     pruneBackoff*: Duration
     floodPublish*: bool
     gossipFactor*: float64
@@ -122,13 +122,14 @@ type
     behaviourPenaltyWeight*: float64
     behaviourPenaltyDecay*: float64
 
+    directPeers*: seq[PeerId]
+
   GossipSub* = ref object of FloodSub
     mesh*: PeerTable                           # peers that we send messages to when we are subscribed to the topic
     fanout*: PeerTable                         # peers that we send messages to when we're not subscribed to the topic
     gossipsub*: PeerTable                      # peers that are subscribed to a topic
     explicit*: PeerTable                       # directpeers that we keep alive explicitly
-    explicitPeers*: HashSet[PeerID]            # explicit (always connected/forward) peers
-    backingOff*: HashSet[PeerID]            # explicit (always connected/forward) peers
+    backingOff*: HashSet[PeerID]               # explicit (always connected/forward) peers
     lastFanoutPubSub*: Table[string, Moment]   # last publish time for fanout topics
     gossip*: Table[string, seq[ControlIHave]]  # pending gossip
     control*: Table[string, ControlMessage]    # pending control messages
@@ -140,6 +141,7 @@ type
     peerStats: Table[PubSubPeer, PeerStats]
     parameters*: GossipSubParams
     topicParams*: Table[string, TopicParams]
+    directPeersLoop: Future[void]
 
     heartbeatEvents*: seq[AsyncEvent]
 
@@ -369,7 +371,7 @@ proc rebalanceMesh(g: GossipSub, topic: string) {.async.} =
       # avoid negative score peers
       x.score >= 0.0 and
       # don't pick explicit peers
-      x.peerId notin g.explicitPeers and
+      x.peerId notin g.parameters.directPeers and
       # and avoid peers we are backing off
       x.peerId notin g.backingOff
 
@@ -427,7 +429,7 @@ proc rebalanceMesh(g: GossipSub, topic: string) {.async.} =
         # avoid negative score peers
         x.score >= median.score and
         # don't pick explicit peers
-        x.peerId notin g.explicitPeers and
+        x.peerId notin g.parameters.directPeers and
         # and avoid peers we are backing off
         x.peerId notin g.backingOff
       
@@ -658,6 +660,8 @@ method unsubscribePeer*(g: GossipSub, peer: PeerID) =
 
   for t in toSeq(g.gossipsub.keys):
     g.gossipsub.removePeer(t, pubSubPeer)
+    # also try to remove from explicit table here
+    g.explicit.removePeer(t, pubSubPeer)
 
     when defined(libp2p_expensive_metrics):
       libp2p_gossipsub_peers_per_topic_gossipsub
@@ -678,12 +682,6 @@ method unsubscribePeer*(g: GossipSub, peer: PeerID) =
     when defined(libp2p_expensive_metrics):
       libp2p_gossipsub_peers_per_topic_fanout
         .set(g.fanout.peers(t).int64, labelValues = [t])
-
-    # TODO
-    # if peer.peerInfo.maintain:
-    #   for t in toSeq(g.explicit.keys):
-    #     g.explicit.removePeer(t, peer)
-    #   g.explicitPeers.excl(peer.id)
     
     # don't retain bad score peers
     if pubSubPeer.score < 0.0:
@@ -717,7 +715,7 @@ method subscribeTopic*(g: GossipSub,
     trace "peer subscribed to topic"
     # subscribe remote peer to the topic
     discard g.gossipsub.addPeer(topic, peer)
-    if peerId in g.explicitPeers:
+    if peerId in g.parameters.directPeers:
       discard g.explicit.addPeer(topic, peer)
   else:
     trace "peer unsubscribed from topic"
@@ -725,7 +723,7 @@ method subscribeTopic*(g: GossipSub,
     g.gossipsub.removePeer(topic, peer)
     g.mesh.removePeer(topic, peer)
     g.fanout.removePeer(topic, peer)
-    if peerId in g.explicitPeers:
+    if peerId in g.parameters.directPeers:
       g.explicit.removePeer(topic, peer)
 
     when defined(libp2p_expensive_metrics):
@@ -1044,6 +1042,18 @@ method publish*(g: GossipSub,
                                       msg = msg.shortLog()
   return published
 
+proc maintainDirectPeers(g: GossipSub) {.async.} =
+  while g.heartbeatRunning:
+    for id in g.parameters.directPeers:
+      let peer = g.peers.getOrDefault(id)
+      if peer == nil:
+        # this creates a new peer and assigns the current switch to it
+        # as a result the next time we try to Send we will as well try to open a connection
+        # see pubsubpeer.nim send and such
+        discard g.getOrCreatePeer(id, g.codec)
+
+    await sleepAsync(1.minutes)
+
 method start*(g: GossipSub) {.async.} =
   trace "gossipsub start"
 
@@ -1054,6 +1064,7 @@ method start*(g: GossipSub) {.async.} =
     # setup the heartbeat interval
     g.heartbeatRunning = true
     g.heartbeatFut = g.heartbeat()
+    g.directPeersLoop = g.maintainDirectPeers()
 
 method stop*(g: GossipSub) {.async.} =
   trace "gossipsub stop"
@@ -1067,6 +1078,8 @@ method stop*(g: GossipSub) {.async.} =
     if not g.heartbeatFut.finished:
       trace "awaiting last heartbeat"
       await g.heartbeatFut
+    await g.directPeersLoop.cancelAndWait()
+    
 
 method initPubSub*(g: GossipSub) =
   procCall FloodSub(g).initPubSub()