From adb3811847f33a57c2728305f16ea73dc8ffec42 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 13 Nov 2017 22:51:42 -0500
Subject: [PATCH] Ensures deterministic initial state for the atomic flag.

---
 Concurrency/BestEffortUpdater.cpp | 5 +++++
 Concurrency/BestEffortUpdater.hpp | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/Concurrency/BestEffortUpdater.cpp b/Concurrency/BestEffortUpdater.cpp
index 551730f0b..a3ea15067 100644
--- a/Concurrency/BestEffortUpdater.cpp
+++ b/Concurrency/BestEffortUpdater.cpp
@@ -12,6 +12,11 @@
 
 using namespace Concurrency;
 
+BestEffortUpdater::BestEffortUpdater() {
+	// ATOMIC_FLAG_INIT isn't necessarily safe to use, so establish default state by other means.
+	update_is_ongoing_.clear();
+}
+
 void BestEffortUpdater::update() {
 	// Perform an update only if one is not currently ongoing.
 	if(!update_is_ongoing_.test_and_set()) {
diff --git a/Concurrency/BestEffortUpdater.hpp b/Concurrency/BestEffortUpdater.hpp
index 9157723d6..6fb21edc3 100644
--- a/Concurrency/BestEffortUpdater.hpp
+++ b/Concurrency/BestEffortUpdater.hpp
@@ -25,6 +25,8 @@ namespace Concurrency {
 */
 class BestEffortUpdater {
 	public:
+		BestEffortUpdater();
+
 		/// A delegate receives timing cues.
 		struct Delegate {
 			virtual void update(BestEffortUpdater *updater, int cycles, bool did_skip_previous_update) = 0;