From 1be2e9cc28138ee3fcee51510fb0bef168fb01a1 Mon Sep 17 00:00:00 2001
From: Edward Moyse <edward.moyse@cern.ch>
Date: Fri, 30 Sep 2022 13:54:29 +0200
Subject: [PATCH] Merge branch 'TRandomTLS' into 'master'
RootUtils: add TRandomTLS class
See merge request atlas/athena!57115
(cherry picked from commit 0865f88d81f1125f99d36be649bc38c22135cbaa)
f29e6bbd RootUtils: add TRandomTLS class
---
Control/RootUtils/CMakeLists.txt | 8 ++-
Control/RootUtils/RootUtils/TRandomTLS.h | 74 ++++++++++++++++++++++
Control/RootUtils/test/TRandomTLS_test.cxx | 67 ++++++++++++++++++++
3 files changed, 148 insertions(+), 1 deletion(-)
create mode 100644 Control/RootUtils/RootUtils/TRandomTLS.h
create mode 100644 Control/RootUtils/test/TRandomTLS_test.cxx
diff --git a/Control/RootUtils/CMakeLists.txt b/Control/RootUtils/CMakeLists.txt
index c301bcad6f9c..52a1d7ba36d3 100644
--- a/Control/RootUtils/CMakeLists.txt
+++ b/Control/RootUtils/CMakeLists.txt
@@ -1,4 +1,4 @@
-# Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
+# Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
# Declare the package name:
atlas_subdir( RootUtils )
@@ -61,5 +61,11 @@ atlas_add_test( WithRootErrorHandler_test
INCLUDE_DIRS ${ROOT_INCLUDE_DIRS}
LINK_LIBRARIES ${ROOT_LIBRARIES} RootUtils )
+atlas_add_test( TRandomTLS_test
+ SOURCES test/TRandomTLS_test.cxx
+ INCLUDE_DIRS ${ROOT_INCLUDE_DIRS}
+ LINK_LIBRARIES ${ROOT_LIBRARIES} CxxUtils RootUtils
+ POST_EXEC_SCRIPT nopost.sh )
+
# Install files from the package:
atlas_install_python_modules( python/*.py POST_BUILD_CMD ${ATLAS_FLAKE8} )
diff --git a/Control/RootUtils/RootUtils/TRandomTLS.h b/Control/RootUtils/RootUtils/TRandomTLS.h
new file mode 100644
index 000000000000..96d5befd8a02
--- /dev/null
+++ b/Control/RootUtils/RootUtils/TRandomTLS.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration.
+ */
+/**
+ * @file RootUtils/TRandomTLS.h
+ * @author Frank Winklmeier
+ * @date Sept, 2022
+ * @brief Thread-local TRandom generator.
+ */
+
+#ifndef ROOTUTILS_TRANDOMTLS_H
+#define ROOTUTILS_TRANDOMTLS_H
+
+#include <atomic>
+
+#include "Rtypes.h"
+#include "boost/thread/tss.hpp"
+
+namespace RootUtils {
+
+ /**
+ * Thread-local TRandom generator.
+ *
+ * This class provides a thread-local TRandom instance of type T.
+ * For each new instance/thread the seed is incremented to ensure
+ * independent random numbers.
+ */
+ template <class T>
+ class TRandomTLS {
+ public:
+ /**
+ * Constructor
+ *
+ * @param seed The seed of the first TRandom instance. Additional instances
+ * are created with the seed incremented by one. If the seed is 0,
+ * it will not be incremented as ROOT then uses a time-based seed.
+ */
+ TRandomTLS(UInt_t seed = 4357) : m_seed(seed) {}
+
+ /// Destructor
+ ~TRandomTLS() = default;
+
+ /// Get thread-specific TRandom
+ T* get() const;
+ T* operator->() const { return get(); }
+ T& operator*() const { return *get(); }
+
+ private:
+ /// Thread-local TRandom
+ mutable boost::thread_specific_ptr<T> m_rand_tls;
+
+ /// TRandom seed (incremented for each new instance/thread)
+ mutable std::atomic<UInt_t> m_seed;
+ };
+
+
+ //
+ // Inline methods
+ //
+
+ template <class T>
+ inline T* TRandomTLS<T>::get() const
+ {
+ T* random = m_rand_tls.get();
+ if (!random) {
+ random = new T(m_seed > 0 ? m_seed++ : 0);
+ m_rand_tls.reset(random);
+ }
+ return random;
+ }
+
+} // namespace RootUtils
+
+#endif
diff --git a/Control/RootUtils/test/TRandomTLS_test.cxx b/Control/RootUtils/test/TRandomTLS_test.cxx
new file mode 100644
index 000000000000..b4ee35695d43
--- /dev/null
+++ b/Control/RootUtils/test/TRandomTLS_test.cxx
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration.
+ */
+
+#undef NDEBUG
+
+#include "CxxUtils/checker_macros.h"
+#include "RootUtils/TRandomTLS.h"
+#include "TRandom3.h"
+
+#include <cassert>
+#include <iostream>
+#include <mutex>
+#include <set>
+#include <thread>
+
+/// Helper class
+struct Test {
+ void rnd() const
+ {
+ const int v = m_rnd->Integer(1000);
+ std::scoped_lock lock(m_mutex);
+ m_values.insert(v);
+ }
+ RootUtils::TRandomTLS<TRandom3> m_rnd;
+ mutable std::mutex m_mutex;
+ mutable std::set<int> m_values ATLAS_THREAD_SAFE;
+};
+
+
+void test_compilation()
+{
+ RootUtils::TRandomTLS<TRandom3> rnd(42);
+ rnd->Rndm();
+ (*rnd).Rndm();
+ assert(rnd.get());
+}
+
+
+void test_unique()
+{
+ Test test;
+ std::vector<std::thread> threads;
+ constexpr int Nthreads = 4;
+
+ // Launch threads and wait
+ for (size_t i = 0; i < Nthreads; i++) {
+ threads.emplace_back(&Test::rnd, &test);
+ }
+ for (auto& th : threads) th.join();
+
+ // Each thread should have created a unique random number
+ assert(test.m_values.size() == Nthreads);
+
+ for (int v : test.m_values) {
+ std::cout << v << std::endl;
+ }
+}
+
+
+int main()
+{
+ test_compilation();
+ test_unique();
+
+ return 0;
+}
--
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