From 8a31b41b4c6ad1deef5d544c4ac2a947821768fa Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Wed, 3 Jan 2018 11:25:20 +0200
Subject: [PATCH] use atomic counter for message seqnos; timestamp is
 insufficient

---
 floodsub.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/floodsub.go b/floodsub.go
index 5c56d1a..5a559b2 100644
--- a/floodsub.go
+++ b/floodsub.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/binary"
 	"fmt"
+	"sync/atomic"
 	"time"
 
 	pb "github.com/libp2p/go-floodsub/pb"
@@ -57,6 +58,9 @@ type PubSub struct {
 	seenMessages *timecache.TimeCache
 
 	ctx context.Context
+
+	// atomic counter for seqnos
+	counter uint64
 }
 
 type Message struct {
@@ -414,8 +418,10 @@ func (p *PubSub) GetTopics() []string {
 
 // Publish publishes data under the given topic
 func (p *PubSub) Publish(topic string, data []byte) error {
-	seqno := make([]byte, 8)
-	binary.BigEndian.PutUint64(seqno, uint64(time.Now().UnixNano()))
+	seqno := make([]byte, 16)
+	counter := atomic.AddUint64(&p.counter, 1)
+	binary.BigEndian.PutUint64(seqno[:8], uint64(time.Now().UnixNano()))
+	binary.BigEndian.PutUint64(seqno[8:], counter)
 
 	p.publish <- &Message{
 		&pb.Message{