From 06b0999ba09f2042d61239982e7ac95abbb00ecb Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Wed, 10 Oct 2018 17:17:27 +0300
Subject: [PATCH] randomsub implementation

---
 randomsub.go | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 randomsub.go

diff --git a/randomsub.go b/randomsub.go
new file mode 100644
index 0000000..86e691f
--- /dev/null
+++ b/randomsub.go
@@ -0,0 +1,108 @@
+package floodsub
+
+import (
+	"context"
+
+	pb "github.com/libp2p/go-floodsub/pb"
+
+	host "github.com/libp2p/go-libp2p-host"
+	peer "github.com/libp2p/go-libp2p-peer"
+	protocol "github.com/libp2p/go-libp2p-protocol"
+)
+
+const (
+	RandomSubID = protocol.ID("/randomsub/1.0.0")
+)
+
+var (
+	RandomSubD = 6
+)
+
+// NewRandomSub returns a new PubSub object using RandomSubRouter as the router
+func NewRandomSub(ctx context.Context, h host.Host, opts ...Option) (*PubSub, error) {
+	rt := &RandomSubRouter{
+		peers: make(map[peer.ID]protocol.ID),
+	}
+	return NewPubSub(ctx, h, rt, opts...)
+}
+
+// RandomSubRouter is a router that implements a random propagation strategy.
+// For each message, it selects RandomSubD peers and forwards the message to them.
+type RandomSubRouter struct {
+	p     *PubSub
+	peers map[peer.ID]protocol.ID
+}
+
+func (rs *RandomSubRouter) Protocols() []protocol.ID {
+	return []protocol.ID{RandomSubID, RandomSubID}
+}
+
+func (rs *RandomSubRouter) Attach(p *PubSub) {
+	rs.p = p
+}
+
+func (rs *RandomSubRouter) AddPeer(p peer.ID, proto protocol.ID) {
+	rs.peers[p] = proto
+}
+
+func (rs *RandomSubRouter) RemovePeer(p peer.ID) {
+	delete(rs.peers, p)
+}
+
+func (rs *RandomSubRouter) HandleRPC(rpc *RPC) {}
+
+func (rs *RandomSubRouter) Publish(from peer.ID, msg *pb.Message) {
+	tosend := make(map[peer.ID]struct{})
+	rspeers := make(map[peer.ID]struct{})
+	src := peer.ID(msg.GetFrom())
+
+	for _, topic := range msg.GetTopicIDs() {
+		tmap, ok := rs.p.topics[topic]
+		if !ok {
+			continue
+		}
+
+		for p := range tmap {
+			if p == from || p == src {
+				continue
+			}
+
+			if rs.peers[p] == FloodSubID {
+				tosend[p] = struct{}{}
+			} else {
+				rspeers[p] = struct{}{}
+			}
+		}
+	}
+
+	if len(rspeers) > RandomSubD {
+		xpeers := peerMapToList(rspeers)
+		shufflePeers(xpeers)
+		xpeers = xpeers[:RandomSubD]
+		for _, p := range xpeers {
+			tosend[p] = struct{}{}
+		}
+	} else {
+		for p := range rspeers {
+			tosend[p] = struct{}{}
+		}
+	}
+
+	out := rpcWithMessages(msg)
+	for p := range tosend {
+		mch, ok := rs.p.peers[p]
+		if !ok {
+			continue
+		}
+
+		select {
+		case mch <- out:
+		default:
+			log.Infof("dropping message to peer %s: queue full", p)
+		}
+	}
+}
+
+func (rs *RandomSubRouter) Join(topic string) {}
+
+func (rs *RandomSubRouter) Leave(topic string) {}