From 154b6dc461815a79a958fc8f9d9ca3a2b0cf6827 Mon Sep 17 00:00:00 2001
From: dmcdiar <dmcdiar@amazon.com>
Date: Mon, 20 Sep 2021 12:13:29 -0700
Subject: [PATCH] Added a mutex to protect the mesh and BLAS lists in the
 RayTracingFeatureProcessor

Signed-off-by: dmcdiar <dmcdiar@amazon.com>
---
 .../Code/Source/RayTracing/RayTracingFeatureProcessor.cpp   | 6 ++++++
 .../Code/Source/RayTracing/RayTracingFeatureProcessor.h     | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.cpp b/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.cpp
index d10da818ee..a17ecaf1aa 100644
--- a/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.cpp
+++ b/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.cpp
@@ -89,6 +89,9 @@ namespace AZ
             RHI::Ptr<RHI::Device> device = RHI::RHISystemInterface::Get()->GetDevice();
             uint32_t objectIndex = objectId.GetIndex();
 
+            // lock the mutex to protect the mesh and BLAS lists
+            AZStd::unique_lock<AZStd::mutex> lock(m_mutex);
+
             MeshMap::iterator itMesh = m_meshes.find(objectIndex);
             if (itMesh == m_meshes.end())
             {
@@ -169,6 +172,9 @@ namespace AZ
                 return;
             }
 
+            // lock the mutex to protect the mesh and BLAS lists
+            AZStd::unique_lock<AZStd::mutex> lock(m_mutex);
+
             MeshMap::iterator itMesh = m_meshes.find(objectId.GetIndex());
             if (itMesh != m_meshes.end())
             {
diff --git a/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.h b/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.h
index ee0a27b814..be75f0fac9 100644
--- a/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.h
+++ b/Gems/Atom/Feature/Common/Code/Source/RayTracing/RayTracingFeatureProcessor.h
@@ -223,6 +223,9 @@ namespace AZ
             // cached TransformServiceFeatureProcessor
             TransformServiceFeatureProcessor* m_transformServiceFeatureProcessor = nullptr;
 
+            // mutex for the mesh and BLAS lists
+            AZStd::mutex m_mutex;
+
             // structure for data in the m_meshInfoBuffer, shaders that use the buffer must match this type
             struct MeshInfo
             {