Merge pull request #120 from libp2p/feat/801

Introduce EvtPeerConnectednessChanged event

Author: aarshkshah1992

core/event/network.go

@@ -0,0 +1,16 @@
+package event
+
+import (
+	"github.com/libp2p/go-libp2p-core/network"
+	"github.com/libp2p/go-libp2p-core/peer"
+)
+
+// EvtPeerConnectednessChanged should be emitted every time we form a connection with a peer or drop our last
+// connection with the peer. Essentially, it is emitted in two cases:
+// a) We form a/any connection with a peer.
+// b) We go from having a connection/s with a peer to having no connection with the peer.
+// It contains the Id of the remote peer and the new connectedness state.
+type EvtPeerConnectednessChanged struct {
+	Peer          peer.ID
+	Connectedness network.Connectedness
+}