From 39fc35f7cbbbb4f62308be6f676a17f85a7fbdd9 Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Sat, 16 May 2020 12:57:44 +0300
Subject: [PATCH] check if already in the mesh in handleGraft to support
 concurrent grafting

---
 gossipsub.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gossipsub.go b/gossipsub.go
index 27dac7c..2ef7b64 100644
--- a/gossipsub.go
+++ b/gossipsub.go
@@ -537,6 +537,12 @@ func (gs *GossipSubRouter) handleGraft(p peer.ID, ctl *pb.ControlMessage) []*pb.
 			continue
 		}
 
+		// check if it is already in the mesh; if so do nothing (we might have concurrent grafting)
+		_, inMesh := peers[p]
+		if inMesh {
+			continue
+		}
+
 		// we don't GRAFT to/from direct peers; complain loudly if this happens
 		_, direct := gs.direct[p]
 		if direct {