From a75ac39172c057ab3bcad5bdec32ae38d606c6eb Mon Sep 17 00:00:00 2001
From: Niels Dekker <N.Dekker@lumc.nl>
Date: Mon, 2 Oct 2023 17:05:53 +0200
Subject: [PATCH] ENH: Add
 `MersenneTwisterRandomVariateGenerator::ResetNextSeed()`

Allows generating a reproducible sequence of pseudo-random numbers.
---
 .../itkMersenneTwisterRandomVariateGenerator.h    |  5 +++++
 .../itkMersenneTwisterRandomVariateGenerator.cxx  | 10 ++++++++++
 ...MersenneTwisterRandomVariateGeneratorGTest.cxx | 15 +++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/Modules/Core/Common/include/itkMersenneTwisterRandomVariateGenerator.h b/Modules/Core/Common/include/itkMersenneTwisterRandomVariateGenerator.h
index 41eeaa135701..1e1d626a3d96 100644
--- a/Modules/Core/Common/include/itkMersenneTwisterRandomVariateGenerator.h
+++ b/Modules/Core/Common/include/itkMersenneTwisterRandomVariateGenerator.h
@@ -160,6 +160,11 @@ class ITKCommon_EXPORT MersenneTwisterRandomVariateGenerator : public RandomVari
   static Pointer
   GetInstance();
 
+  /** Resets the internal data that is used to calculate the next seed. (Does not reset the initial seed.) Allows
+   * generating a reproducible sequence of pseudo-random numbers. */
+  static void
+  ResetNextSeed();
+
   /** Length of state vector */
   static constexpr IntegerType StateVectorLength = 624;
 
diff --git a/Modules/Core/Common/src/itkMersenneTwisterRandomVariateGenerator.cxx b/Modules/Core/Common/src/itkMersenneTwisterRandomVariateGenerator.cxx
index 12d1380ec32c..7edab3c47fdf 100644
--- a/Modules/Core/Common/src/itkMersenneTwisterRandomVariateGenerator.cxx
+++ b/Modules/Core/Common/src/itkMersenneTwisterRandomVariateGenerator.cxx
@@ -81,6 +81,16 @@ MersenneTwisterRandomVariateGenerator::GetInstance()
   return m_PimplGlobals->m_StaticInstance;
 }
 
+
+void
+MersenneTwisterRandomVariateGenerator::ResetNextSeed()
+{
+  itkInitGlobalsMacro(PimplGlobals);
+  const std::lock_guard<std::recursive_mutex> lockGuard(m_PimplGlobals->m_StaticInstanceLock);
+  m_PimplGlobals->m_StaticDiffer = 0;
+}
+
+
 MersenneTwisterRandomVariateGenerator::MersenneTwisterRandomVariateGenerator()
 {
   SetSeed(121212);
diff --git a/Modules/Core/Common/test/itkMersenneTwisterRandomVariateGeneratorGTest.cxx b/Modules/Core/Common/test/itkMersenneTwisterRandomVariateGeneratorGTest.cxx
index 867e6dd3cac4..b99b11dc5c83 100644
--- a/Modules/Core/Common/test/itkMersenneTwisterRandomVariateGeneratorGTest.cxx
+++ b/Modules/Core/Common/test/itkMersenneTwisterRandomVariateGeneratorGTest.cxx
@@ -59,3 +59,18 @@ TEST(MersenneTwisterRandomVariateGenerator, GetIntegerVariateReturnsSameAsStdMt1
     EXPECT_EQ(generator->GetIntegerVariate(), stdMt19937());
   }
 }
+
+
+TEST(MersenneTwisterRandomVariateGenerator, ResetNextSeed)
+{
+  using GeneratorType = itk::Statistics::MersenneTwisterRandomVariateGenerator;
+
+  const auto globalGenerator = GeneratorType::GetInstance();
+  ASSERT_NE(globalGenerator, nullptr);
+
+  GeneratorType::ResetNextSeed();
+  const auto nextSeed = globalGenerator->GetNextSeed();
+
+  GeneratorType::ResetNextSeed();
+  EXPECT_EQ(globalGenerator->GetNextSeed(), nextSeed);
+}