From af90dd3663be70cf783c5f4c594d6ccd5d30b7dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20Bl=C3=BChdorn?=
 <johannes.bluehdorn@scicomp.uni-kl.de>
Date: Mon, 29 Jul 2024 21:14:04 +0200
Subject: [PATCH] Use a custom thread id to resolve ambiguity.

---
 .../tools/helpers/externalFunctionHelper.hpp     |  7 +++++--
 .../parallel/openmp/openMPThreadInformation.hpp  | 16 +++++++++++++++-
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/codi/tools/helpers/externalFunctionHelper.hpp b/include/codi/tools/helpers/externalFunctionHelper.hpp
index 3b1eb30f..3607c0e9 100644
--- a/include/codi/tools/helpers/externalFunctionHelper.hpp
+++ b/include/codi/tools/helpers/externalFunctionHelper.hpp
@@ -599,8 +599,11 @@ namespace codi {
           Synchronization::synchronize();
 
           // Push the delete handle on at most one thread's tape.
-          typename ExternalFunction<Tape>::DeleteFunction delFunc =
-              0 == ThreadInformation::getThreadId() ? EvalData::delFunc : nullptr;
+          typename ExternalFunction<Tape>::DeleteFunction delFunc = nullptr;
+          Synchronization::serialize([&]() {
+            delFunc = EvalData::delFunc;
+          });
+
           Type::getTape().pushExternalFunction(ExternalFunction<Tape>::create(
               EvalData::evalRevFuncStatic, data, delFunc, EvalData::evalForwFuncStatic, EvalData::evalPrimFuncStatic));
 
diff --git a/include/codi/tools/parallel/openmp/openMPThreadInformation.hpp b/include/codi/tools/parallel/openmp/openMPThreadInformation.hpp
index d8c03d80..01203024 100644
--- a/include/codi/tools/parallel/openmp/openMPThreadInformation.hpp
+++ b/include/codi/tools/parallel/openmp/openMPThreadInformation.hpp
@@ -37,6 +37,7 @@
 #include <omp.h>
 
 #include "../threadInformationInterface.hpp"
+#include "openMPAtomic.hpp"
 
 /** \copydoc codi::Namespace */
 namespace codi {
@@ -48,13 +49,26 @@ namespace codi {
     public:
 
       /// \copydoc ThreadInformationInterface::getMaxThreads()
+      /// <br><br> Implementation: Limit applies to all threads, also those due to nesting.
       static CODI_INLINE int getMaxThreads() {
         return 512;
       }
 
       /// \copydoc ThreadInformationInterface::getThreadId()
+      /// <br><br> Implementation: Returns custom IDs to account for nesting, in particular not omp_get_thread_num().
       static CODI_INLINE int getThreadId() {
-        return omp_get_thread_num();
+        static OpenMPAtomic<int> nextThreadId = 0;
+
+        static int myThreadId = -1;
+        CODI_OMP_THREADPRIVATE(myThreadId)
+
+        if (myThreadId == -1) {
+          myThreadId = nextThreadId++;
+        }
+
+        codiAssert(myThreadId < getMaxThreads());
+
+        return myThreadId;
       }
   };
 }