From 3631b836510e33aa0f3f8f64fd42e6bb6661191a Mon Sep 17 00:00:00 2001
From: Dustin Hiatt <dustin.hiatt@workiva.com>
Date: Mon, 9 Feb 2015 13:04:46 -0600
Subject: [PATCH] Added lock to protect the RNG.

---
 slice/skip/skip.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/slice/skip/skip.go b/slice/skip/skip.go
index b23b80a..b7f6ea1 100644
--- a/slice/skip/skip.go
+++ b/slice/skip/skip.go
@@ -59,6 +59,7 @@ package skip
 
 import (
 	"math/rand"
+	"sync"
 	"time"
 )
 
@@ -76,8 +77,13 @@ const p = .5 // the p level defines the probability that a node
 // randomly seeded generator.
 var generator = rand.New(rand.NewSource(time.Now().UnixNano()))
 
+// rnLock protects the RNG as the generator is not threadsafe.
+var rnLock sync.Mutex
+
 func generateLevel(maxLevel uint8) uint8 {
 	var level uint8
+	rnLock.Lock()
+	defer rnLock.Unlock()
 	for level = uint8(1); level < maxLevel-1; level++ {
 		if generator.Float64() >= p {
 			return level