From cc4047dab3166ec0b4392ba266272c638d78b331 Mon Sep 17 00:00:00 2001
From: Marco Garten <m.garten@hzdr.de>
Date: Thu, 18 Aug 2016 00:44:34 +0200
Subject: [PATCH] Modified UsesRNG trait, encapsulate RNGFactory

RNGFactory is only created when it is needed.
---
 .../ionization/byField/ADK/ADK_Impl.hpp       | 15 +++++++
 .../simulationControl/MySimulation.hpp        | 21 ++++++++-
 src/picongpu/include/traits/UsesRNG.hpp       | 43 +++++++++++++++++++
 3 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 src/picongpu/include/traits/UsesRNG.hpp

diff --git a/src/picongpu/include/particles/ionization/byField/ADK/ADK_Impl.hpp b/src/picongpu/include/particles/ionization/byField/ADK/ADK_Impl.hpp
index 5f4785c9d76..4ed3304e895 100644
--- a/src/picongpu/include/particles/ionization/byField/ADK/ADK_Impl.hpp
+++ b/src/picongpu/include/particles/ionization/byField/ADK/ADK_Impl.hpp
@@ -20,8 +20,11 @@
 
 #pragma once
 
+#include <boost/type_traits/integral_constant.hpp>
+
 #include "simulation_defines.hpp"
 #include "traits/Resolve.hpp"
+#include "traits/UsesRNG.hpp"
 #include "mappings/kernel/AreaMapping.hpp"
 
 #include "fields/FieldB.hpp"
@@ -42,6 +45,18 @@
 
 namespace picongpu
 {
+namespace traits
+{
+    /** specialization of the UsesRNG trait
+     * --> ionization module uses random number generation
+     */
+    template<typename T_IonizationAlgorithm, typename T_DestSpecies, typename T_SrcSpecies>
+    struct UsesRNG<particles::ionization::ADK_Impl<T_IonizationAlgorithm, T_DestSpecies, T_SrcSpecies> > :
+    public boost::true_type
+    {
+    };
+} // namespace traits
+
 namespace particles
 {
 namespace ionization
diff --git a/src/picongpu/include/simulationControl/MySimulation.hpp b/src/picongpu/include/simulationControl/MySimulation.hpp
index e7e48a53e2d..4adb20a7a12 100644
--- a/src/picongpu/include/simulationControl/MySimulation.hpp
+++ b/src/picongpu/include/simulationControl/MySimulation.hpp
@@ -26,6 +26,7 @@
 #include <string>
 #include <vector>
 #include <boost/lexical_cast.hpp>
+#include <boost/mpl/count.hpp>
 
 #include "pmacc_types.hpp"
 #include "simulationControl/SimulationHelper.hpp"
@@ -285,17 +286,33 @@ class MySimulation : public SimulationHelper<simDim>
 
         laser = new LaserPhysics(cellDescription->getGridLayout());
 
+        // Make a list of all species that can be ionized
+        typedef typename PMacc::particles::traits::FilterByFlag
+        <
+            VectorAllSpecies,
+            ionizer<>
+        >::type VectorSpeciesWithIonizer;
+
+        /* Make a list of `boost::true_type`s and `boost::false_type`s for species that use or do not use the RNG during ionization */
+        typedef typename PMacc::OperateOnSeq<VectorSpeciesWithIonizer,picongpu::traits::UsesRNG<picongpu::traits::GetIonizer<bmpl::_> > >::type VectorIonizersUsingRNG;
+        /* define a type that contains the number of `boost::true_type`s when `::value` is accessed */
+        typedef typename boost::mpl::count<VectorIonizersUsingRNG, boost::true_type>::type NumReqRNGs;
+
         // Initialize random number generator and synchrotron functions, if there are synchrotron photon species
         typedef typename PMacc::particles::traits::FilterByFlag<VectorAllSpecies,
-                                                                synchrotronPhotons<> >::type AllSynchrotronPhotonsSpecies;
-        if(!bmpl::empty<AllSynchrotronPhotonsSpecies>::value)
+
+        if(!bmpl::empty<AllSynchrotronPhotonsSpecies>::value || NumReqRNGs::value)
         {
             // create factory for the random number generator
             this->rngFactory = new RNGFactory(Environment<simDim>::get().SubGrid().getLocalDomain().size);
             // init factory
             PMacc::GridController<simDim>& gridCon = PMacc::Environment<simDim>::get().GridController();
             this->rngFactory->init(gridCon.getScalarPosition());
+        }
 
+        // Initialize synchrotron functions, if there are synchrotron photon species
+        if(!bmpl::empty<AllSynchrotronPhotonsSpecies>::value)
+        {
             this->synchrotronFunctions.init();
         }
 
diff --git a/src/picongpu/include/traits/UsesRNG.hpp b/src/picongpu/include/traits/UsesRNG.hpp
new file mode 100644
index 00000000000..528212d9718
--- /dev/null
+++ b/src/picongpu/include/traits/UsesRNG.hpp
@@ -0,0 +1,43 @@
+/**
+ * Copyright 2016 Marco Garten, Rene Widera
+ *
+ * This file is part of PIConGPU.
+ *
+ * PIConGPU 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.
+ *
+ * PIConGPU 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 PIConGPU.
+ * If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <boost/type_traits/integral_constant.hpp>
+
+namespace picongpu
+{
+namespace traits
+{
+
+/** Checks if an object requires the RNG
+ *
+ * @tparam T_Object any object (class or typename)
+ *
+ * This struct must inherit from (boost::true_type/false_type)
+ */
+template<typename T_Object>
+struct UsesRNG : public boost::false_type
+{
+};
+
+}// namespace traits
+
+}// namespace picongpu