From 8034780ca48e13cdffbe3240f0acacb3fa73cc4f Mon Sep 17 00:00:00 2001
From: Olaoluwa Osuntokun <laolu32@gmail.com>
Date: Tue, 15 Aug 2017 17:56:19 -0700
Subject: [PATCH] autopilot: fix chanID collision test flake by instead using
 atomic counter

This commit fixes a prior occasional test flake caused by the collision
of the randomly selected 64-bit integers. In order to get around this,
we now instead have a atomic monotonically increasing counter for each
channel ID used within the tests.
---
 autopilot/graph.go | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/autopilot/graph.go b/autopilot/graph.go
index 27dae73d..d4d04603 100644
--- a/autopilot/graph.go
+++ b/autopilot/graph.go
@@ -3,8 +3,8 @@ package autopilot
 import (
 	"bytes"
 	"math/big"
-	prand "math/rand"
 	"net"
+	"sync/atomic"
 	"time"
 
 	"github.com/boltdb/bolt"
@@ -21,6 +21,8 @@ var (
 	}
 	_, _ = testSig.R.SetString("63724406601629180062774974542967536251589935445068131219452686511677818569431", 10)
 	_, _ = testSig.S.SetString("18801056069249825825291287104931333862866033135609736119018462340006816851118", 10)
+
+	chanIdCounter uint64 = 0
 )
 
 // databaseChannelGraph wraps a channeldb.ChannelGraph instance with the
@@ -297,7 +299,8 @@ func (m memChannelGraph) ForEachNode(cb func(Node) error) error {
 
 // randChanID generates a new random channel ID.
 func randChanID() lnwire.ShortChannelID {
-	return lnwire.NewShortChanIDFromInt(uint64(prand.Int63()))
+	id := atomic.AddUint64(&chanIdCounter, 1)
+	return lnwire.NewShortChanIDFromInt(id)
 }
 
 // randKey returns a random public key.