From 173111c64c3e5f0883255be660026c363f582f32 Mon Sep 17 00:00:00 2001
From: Peter Johnson <johnson.peter@gmail.com>
Date: Sun, 19 Jul 2015 16:36:08 -0700
Subject: [PATCH] ConcurrentQueue: Make mutex mutable.

---
 src/support/ConcurrentQueue.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/support/ConcurrentQueue.h b/src/support/ConcurrentQueue.h
index b2d108457a..fa310c5ec7 100644
--- a/src/support/ConcurrentQueue.h
+++ b/src/support/ConcurrentQueue.h
@@ -64,7 +64,7 @@ class ConcurrentQueue {
 
  private:
   std::queue<T> queue_;
-  std::mutex mutex_;
+  mutable std::mutex mutex_;
   std::condition_variable cond_;
 };