From 63df436e5f165605a5aebcace9012551470da5d0 Mon Sep 17 00:00:00 2001
From: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
Date: Sun, 15 Feb 2015 11:57:51 -0800
Subject: [PATCH] core: Make global random generator thread-local

Change-Id: Ib17ea05592445cf99af9726ef7799ead813ca0fe
Refs: #2489
---
 core/random.cpp         | 28 ++++++++++++++-------
 tests/core/random.t.cpp | 55 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+), 9 deletions(-)
 create mode 100644 tests/core/random.t.cpp

diff --git a/core/random.cpp b/core/random.cpp
index 51b137e5..c398f8df 100644
--- a/core/random.cpp
+++ b/core/random.cpp
@@ -1,12 +1,12 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014,  Regents of the University of California,
- *                      Arizona Board of Regents,
- *                      Colorado State University,
- *                      University Pierre & Marie Curie, Sorbonne University,
- *                      Washington University in St. Louis,
- *                      Beijing Institute of Technology,
- *                      The University of Memphis
+ * Copyright (c) 2014-2015,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
  *
  * This file is part of NFD (Named Data Networking Forwarding Daemon).
  * See AUTHORS.md for complete list of NFD authors and contributors.
@@ -24,15 +24,25 @@
  */
 
 #include "random.hpp"
+#include <boost/thread/tss.hpp>
 
 namespace nfd {
 
-static boost::random::mt19937 g_rng;
+static boost::thread_specific_ptr<boost::random::mt19937> g_rng;
 
 boost::random::mt19937&
 getGlobalRng()
 {
-  return g_rng;
+  if (g_rng.get() == nullptr) {
+    g_rng.reset(new boost::random::mt19937());
+  }
+  return *g_rng;
+}
+
+void
+resetGlobalRng()
+{
+  g_rng.reset();
 }
 
 } // namespace nfd
diff --git a/tests/core/random.t.cpp b/tests/core/random.t.cpp
new file mode 100644
index 00000000..279424e7
--- /dev/null
+++ b/tests/core/random.t.cpp
@@ -0,0 +1,55 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "core/random.hpp"
+
+#include "tests/test-common.hpp"
+
+#include <boost/thread.hpp>
+
+namespace nfd {
+namespace tests {
+
+BOOST_FIXTURE_TEST_SUITE(CoreRandom, BaseFixture)
+
+BOOST_AUTO_TEST_CASE(ThreadLocalRandon)
+{
+  boost::random::mt19937* s1 = &getGlobalRng();
+  boost::random::mt19937* s2 = nullptr;
+  boost::thread t([&s2] {
+      s2 = &getGlobalRng();
+    });
+
+  t.join();
+
+  BOOST_CHECK(s1 != nullptr);
+  BOOST_CHECK(s2 != nullptr);
+  BOOST_CHECK(s1 != s2);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace tests
+} // namespace nfd