Allow Singletons to use ExecutePhaseChange

docs/DevGuide/Parallelization.md

@@ -866,4 +866,4 @@ also be run. Which functions are run on each node and core is set by calling
 `Parallel::charmxx::register_init_node_and_proc` in `CkRegisterMainModule()`
 with function pointers to the functions to be called. For example:
 
-\snippet Test_AlgorithmPhaseControl.cpp charm_init_funcs_example
+\snippet Test_AlgorithmPhaseControlNodegroup.cpp charm_init_funcs_example

src/Parallel/PhaseControl/ContributeToPhaseChangeReduction.hpp

@@ -72,23 +72,27 @@ void contribute_to_phase_change_reduction(
                               PhaseControl::TaggedTupleCombine, Ts...>(nullptr),
                       cache.get_main_proxy().value());
   reduction_data_type reduction_data{data_for_reduction};
-  // Note that Singletons could be supported by directly calling the main
-  // entry function, but due to this and other peculiarities with
-  // Singletons, it is best to discourage their use.
-  static_assert(
-      not std::is_same_v<typename SenderComponent::chare_type,
-                         Parallel::Algorithms::Singleton>,
-      "Phase change reduction is not supported for singleton chares. "
-      "Consider constructing your chare as a length-1 array chare if you "
-      "need to contribute to phase change data");
-  Parallel::local_branch(
-      Parallel::get_parallel_component<SenderComponent>(cache))
-      ->contribute(static_cast<int>(reduction_data.size()),
-                   reduction_data.packed().get(),
-                   Parallel::charmxx::charm_reducer_functions.at(
-                       std::hash<Parallel::charmxx::ReducerFunctions>{}(
-                           &reduction_data_type::combine)),
-                   callback);
+
+  if constexpr (std::is_same_v<typename SenderComponent::chare_type,
+                               Parallel::Algorithms::Singleton>) {
+    Parallel::local(Parallel::get_parallel_component<SenderComponent>(cache))
+        ->contribute(static_cast<int>(reduction_data.size()),
+                     reduction_data.packed().get(),
+                     Parallel::charmxx::charm_reducer_functions.at(
+                         std::hash<Parallel::charmxx::ReducerFunctions>{}(
+                             &reduction_data_type::combine)),
+                     callback);
+
+  } else {
+    Parallel::local_branch(
+        Parallel::get_parallel_component<SenderComponent>(cache))
+        ->contribute(static_cast<int>(reduction_data.size()),
+                     reduction_data.packed().get(),
+                     Parallel::charmxx::charm_reducer_functions.at(
+                         std::hash<Parallel::charmxx::ReducerFunctions>{}(
+                             &reduction_data_type::combine)),
+                     callback);
+  }
 }
 /// @}
 }  // namespace Parallel

tests/Unit/Parallel/CMakeLists.txt

@@ -147,8 +147,11 @@ add_algorithm_test(
   "AlgorithmGlobalCache"
   INPUT_FILE "Test_AlgorithmGlobalCache.yaml")
 add_algorithm_test(
-  "AlgorithmPhaseControl"
-  INPUT_FILE "Test_AlgorithmPhaseControl.yaml")
+  "AlgorithmPhaseControlSingleton"
+  INPUT_FILE "Test_AlgorithmPhaseControlSingleton.yaml")
+add_algorithm_test(
+  "AlgorithmPhaseControlNodegroup"
+  INPUT_FILE "Test_AlgorithmPhaseControlNodegroup.yaml")
 add_algorithm_test(
   "DynamicInsertionState"
   INPUT_FILE "Test_DynamicInsertionState.yaml")

tests/Unit/Parallel/Test_AlgorithmPhaseControl.cpp → tests/Unit/Parallel/Test_AlgorithmPhaseControl.hpp

@@ -1,6 +1,8 @@
 // Distributed under the MIT License.
 // See LICENSE.txt for details.
 
+#pragma once
+
 #include "Framework/TestingFramework.hpp"
 
 #include <cstddef>
@@ -165,7 +167,7 @@ struct ComponentAlpha {
 
 template <typename Metavariables>
 struct ComponentBeta {
-  using chare_type = Parallel::Algorithms::Nodegroup;
+  using chare_type = typename Metavariables::component_beta_chare_type;
   using metavariables = Metavariables;
   using array_index = size_t;
 
@@ -274,7 +276,7 @@ struct TerminateAndRestart {
       const ArrayIndex& /*array_index*/, const ActionList /*meta*/,
       const ParallelComponent* const /*meta*/) {
     if (db::get<Tags::Step>(box) % interval == 0) {
-      if(db::get<Tags::Step>(box) < 15) {
+      if (db::get<Tags::Step>(box) < 15) {
         Parallel::simple_action<Actions::RestartMe<ParallelComponent>>(
             Parallel::get_parallel_component<OtherComponent>(cache));
 
@@ -335,9 +337,12 @@ struct Testing {
 //  7: Register |   none
 // 10:  none    |     Solve
 // 14:  none    |  Register and Solve
+template <typename ComponentBetaChareType>
 struct TestMetavariables {
-  using component_list = tmpl::list<ComponentAlpha<TestMetavariables>,
-                                    ComponentBeta<TestMetavariables>>;
+  using component_beta_chare_type = ComponentBetaChareType;
+  using component_list =
+      tmpl::list<ComponentAlpha<TestMetavariables<ComponentBetaChareType>>,
+                 ComponentBeta<TestMetavariables<ComponentBetaChareType>>>;
 
   struct factory_creation
       : tt::ConformsTo<Options::protocols::FactoryCreation> {
@@ -364,7 +369,8 @@ struct TestMetavariables {
   }
 
   static std::string expected_log(
-      tmpl::type_<ComponentAlpha<TestMetavariables>> /*meta*/) {
+      tmpl::type_<
+          ComponentAlpha<TestMetavariables<ComponentBetaChareType>>> /*meta*/) {
     return "Running phase: Initialization\n" +
            repeat("Running phase: Evolve\n", 2_st) +
            "Terminate and Restart\n"
@@ -397,7 +403,8 @@ struct TestMetavariables {
   }
 
   static std::string expected_log(
-      tmpl::type_<ComponentBeta<TestMetavariables>> /*meta*/) {
+      tmpl::type_<
+          ComponentBeta<TestMetavariables<ComponentBetaChareType>>> /*meta*/) {
     return "Running phase: Initialization\n" +
            repeat("Running phase: Evolve\n", 3_st) +  // steps 1-3 -> Solve
            "Running phase: Solve\n"
@@ -429,11 +436,3 @@ struct TestMetavariables {
   // NOLINTNEXTLINE(google-runtime-references)
   void pup(PUP::er& /*p*/) {}
 };
-
-// [charm_init_funcs_example]
-extern "C" void CkRegisterMainModule() {
-  Parallel::charmxx::register_main_module<TestMetavariables>();
-  Parallel::charmxx::register_init_node_and_proc(
-      {&register_factory_classes_with_charm<TestMetavariables>}, {});
-}
-// [charm_init_funcs_example]

tests/Unit/Parallel/Test_AlgorithmPhaseControlNodegroup.cpp

@@ -0,0 +1,17 @@
+// Distributed under the MIT License.
+// See LICENSE.txt for details.
+
+#include "Parallel/Test_AlgorithmPhaseControl.hpp"
+
+#include "Parallel/Algorithms/AlgorithmNodegroup.hpp"
+
+// [charm_init_funcs_example]
+extern "C" void CkRegisterMainModule() {
+  Parallel::charmxx::register_main_module<
+      TestMetavariables<Parallel::Algorithms::Nodegroup>>();
+  Parallel::charmxx::register_init_node_and_proc(
+      {&register_factory_classes_with_charm<
+          TestMetavariables<Parallel::Algorithms::Nodegroup>>},
+      {});
+}
+// [charm_init_funcs_example]

tests/Unit/Parallel/Test_AlgorithmPhaseControl.yaml → tests/Unit/Parallel/Test_AlgorithmPhaseControlNodegroup.yaml

@@ -4,8 +4,6 @@
 ---
 ---
 
-# note that this is a vector of pairs, so has the peculiar '- -' for the
-# elements
 PhaseChangeAndTriggers:
   - Trigger: RegisterTrigger
     PhaseChanges:

tests/Unit/Parallel/Test_AlgorithmPhaseControlSingleton.cpp

@@ -0,0 +1,15 @@
+// Distributed under the MIT License.
+// See LICENSE.txt for details.
+
+#include "Parallel/Test_AlgorithmPhaseControl.hpp"
+
+#include "Parallel/Algorithms/AlgorithmSingleton.hpp"
+
+extern "C" void CkRegisterMainModule() {
+  Parallel::charmxx::register_main_module<
+      TestMetavariables<Parallel::Algorithms::Singleton>>();
+  Parallel::charmxx::register_init_node_and_proc(
+      {&register_factory_classes_with_charm<
+          TestMetavariables<Parallel::Algorithms::Singleton>>},
+      {});
+}

tests/Unit/Parallel/Test_AlgorithmPhaseControlSingleton.yaml

@@ -0,0 +1,17 @@
+# Distributed under the MIT License.
+# See LICENSE.txt for details.
+
+---
+---
+
+PhaseChangeAndTriggers:
+  - Trigger: RegisterTrigger
+    PhaseChanges:
+      - VisitAndReturn(Register)
+  - Trigger: SolveTrigger
+    PhaseChanges:
+      - VisitAndReturn(Solve)
+
+ResourceInfo:
+  AvoidGlobalProc0: false
+  Singletons: Auto