From 1fd21c109e2492678a6f7169b7d33e29245f5160 Mon Sep 17 00:00:00 2001
From: Tiago Koji Castro Shibata <ticastro@microsoft.com>
Date: Sat, 4 Apr 2020 20:10:07 -0700
Subject: [PATCH] Fix race condition creating ConverterResourceStore (#3419)

---
 winml/lib/Api/LearningModelDevice.cpp | 8 ++------
 winml/lib/Api/LearningModelDevice.h   | 2 ++
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/winml/lib/Api/LearningModelDevice.cpp b/winml/lib/Api/LearningModelDevice.cpp
index ef0bf8e430..011ca06fdf 100644
--- a/winml/lib/Api/LearningModelDevice.cpp
+++ b/winml/lib/Api/LearningModelDevice.cpp
@@ -53,16 +53,12 @@ Windows::AI::MachineLearning::LearningModelDevice LearningModelDevice::CreateFro
 WINML_CATCH_ALL
 
 std::shared_ptr<::Windows::AI::MachineLearning::ConverterResourceStore> LearningModelDevice::TensorizerStore() {
-  if (m_tensorizerStore == nullptr) {
-    m_tensorizerStore = ::Windows::AI::MachineLearning::ConverterResourceStore::Create(5);
-  }
+  std::call_once(m_tensorizerStoreInitialized, [this](){ m_tensorizerStore = ::Windows::AI::MachineLearning::ConverterResourceStore::Create(5); });
   return m_tensorizerStore;
 }
 
 std::shared_ptr<::Windows::AI::MachineLearning::ConverterResourceStore> LearningModelDevice::DetensorizerStore() {
-  if (m_detensorizerStore == nullptr) {
-    m_detensorizerStore = ::Windows::AI::MachineLearning::ConverterResourceStore::Create(5);
-  }
+  std::call_once(m_detensorizerStoreInitialized, [this](){ m_detensorizerStore = ::Windows::AI::MachineLearning::ConverterResourceStore::Create(5); });
   return m_detensorizerStore;
 }
 
diff --git a/winml/lib/Api/LearningModelDevice.h b/winml/lib/Api/LearningModelDevice.h
index ce20a4b765..26639d7c7e 100644
--- a/winml/lib/Api/LearningModelDevice.h
+++ b/winml/lib/Api/LearningModelDevice.h
@@ -84,7 +84,9 @@ struct LearningModelDevice : LearningModelDeviceT<LearningModelDevice, IMetacomm
   bool m_isCpuDevice;
   bool m_areMetacommandsEnabled = true;
   std::shared_ptr<WinML::ConverterResourceStore> m_detensorizerStore;
+  std::once_flag m_detensorizerStoreInitialized;
   std::shared_ptr<WinML::ConverterResourceStore> m_tensorizerStore;
+  std::once_flag m_tensorizerStoreInitialized;
 
   std::unique_ptr<D3DDeviceCache> m_deviceCache;
 };