From ef36883ca1733a68162b199518275871c888391e Mon Sep 17 00:00:00 2001
From: jsmall-nvidia <jsmall@nvidia.com>
Date: Wed, 4 Sep 2019 16:16:17 -0400
Subject: Allow multiple threads to call glslang (#1046)

* Allow multiple threads to be able to call into glslang by
* Having a single call to glslang::InitializeProcess() per process (in our case dll load)
* Explicitly call glslang::InitThread

* Fix problem with case in path for linux.

* Rename s_processInitializer to g_processInitializer.
Move into the function.
---
 source/slang-glslang/slang-glslang.cpp | 52 ++++++++++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/source/slang-glslang/slang-glslang.cpp b/source/slang-glslang/slang-glslang.cpp
index 68bf7b6a3..25b46bafe 100644
--- a/source/slang-glslang/slang-glslang.cpp
+++ b/source/slang-glslang/slang-glslang.cpp
@@ -12,6 +12,8 @@
 #include "SPIRV/doc.h"
 #include "SPIRV/disassemble.h"
 
+#include "OGLCompilersDLL/InitializeDll.h"
+
 #include "../../slang.h"
 
 #if 0
@@ -190,6 +192,42 @@ static int glslang_dissassembleSPIRV(glslang_CompileRequest* request)
     return 0;
 }
 
+// We need a per process initialization
+class ProcessInitializer
+{
+public:
+    ProcessInitializer()
+    {
+        m_isInitialized = false;
+    }
+
+    bool init()
+    {
+        std::lock_guard<std::mutex> guard(m_mutex);
+        if (!m_isInitialized)
+        {
+            if (!glslang::InitializeProcess())
+            {
+                return false;
+            }
+            m_isInitialized = true;
+        }
+        return true;
+    }
+
+    ~ProcessInitializer()
+    {
+        // We *assume* will only be called once dll is detatched and that will be on a single thread
+        if (m_isInitialized)
+        {
+            glslang::FinalizeProcess();
+        }
+    }
+
+    std::mutex m_mutex;
+    bool m_isInitialized = false;
+};
+
 extern "C"
 #ifdef _MSC_VER
 _declspec(dllexport)
@@ -198,7 +236,17 @@ __attribute__((__visibility__("default")))
 #endif
 int glslang_compile(glslang_CompileRequest* request)
 {
-    glslang::InitializeProcess();
+    static ProcessInitializer g_processInitializer;
+    if (!g_processInitializer.init())
+    {
+        // Failed
+        return 1;
+    }
+    if (!glslang::InitThread())
+    {
+        // Failed
+        return 1;
+    }
 
     int result = 0;
     switch(request->action)
@@ -216,7 +264,5 @@ int glslang_compile(glslang_CompileRequest* request)
         break;
     }
 
-    glslang::FinalizeProcess();
-
     return result;
 }
-- 
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