Express fold nodes using accumulator nodes

.amazonq/rules/memory-bank/structure.md

@@ -16,7 +16,7 @@ The main framework implementation containing the execution engine and core abstr
   - Algorithm declarations: `provider_node.cpp/hpp`, `declared_transform.cpp/hpp`, `declared_observer.cpp/hpp`, `declared_fold.cpp/hpp`, `declared_unfold.cpp/hpp`, `declared_predicate.cpp/hpp`, `declared_output.cpp/hpp`
   - Graph execution: `framework_graph.cpp/hpp`, `make_computational_edges.cpp/hpp`, `producer_catalog.cpp/hpp`
   - Data flow: `message.cpp/hpp`, `message_sender.cpp/hpp`, `consumer.cpp/hpp`
-  - Product management: `product_query.cpp/hpp`, `products_consumer.cpp/hpp`
+  - Product management: `product_selector.cpp/hpp`, `products_consumer.cpp/hpp`
   - Registration: `registrar.cpp/hpp`, `registration_api.cpp/hpp`, `node_catalog.cpp/hpp`
   - Utilities: `filter.cpp/hpp`, `glue.cpp/hpp`, `multiplexer.cpp/hpp`
   - `fold/`: Fold operation implementations

phlex/core/CMakeLists.txt

@@ -28,7 +28,6 @@ cet_make_library(
   provider_node.cpp
   registrar.cpp
   registration_api.cpp
-  store_counters.cpp
   LIBRARIES
   PUBLIC
   TBB::tbb
@@ -67,7 +66,6 @@ install(
     registrar.hpp
     registration_api.hpp
     source.hpp
-    store_counters.hpp
     upstream_predicates.hpp
   DESTINATION include/phlex/core
 )

phlex/core/concepts.hpp

@@ -1,6 +1,7 @@
 #ifndef PHLEX_CORE_CONCEPTS_HPP
 #define PHLEX_CORE_CONCEPTS_HPP
 
+#include "phlex/core/fold/send.hpp"
 #include "phlex/core/fwd.hpp"
 #include "phlex/metaprogramming/type_deduction.hpp"
 #include "phlex/model/fwd.hpp"
@@ -17,9 +18,7 @@ namespace phlex::experimental {
   concept is_bound_object = not std::same_as<T, void_tag>;
 
   template <typename T>
-  concept sendable = std::move_constructible<T> || requires(T& t) {
-    { send(t) } -> std::move_constructible;
-  };
+  concept sendable = requires { typename sendable_type<T>; };
 
   template <typename T, std::size_t N>
   concept at_least_n_input_parameters = number_parameters<T> >= N;

phlex/core/declared_fold.cpp

@@ -3,8 +3,10 @@
 namespace phlex::experimental {
   declared_fold::declared_fold(algorithm_name name,
                                std::vector<std::string> predicates,
-                               product_selectors input_products) :
-    products_consumer{std::move(name), std::move(predicates), std::move(input_products)}
+                               product_selectors input_products,
+                               std::string partition_layer) :
+    products_consumer{std::move(name), std::move(predicates), std::move(input_products)},
+    partition_layer_{std::move(partition_layer)}
   {
   }
 

phlex/core/declared_fold.hpp

@@ -6,13 +6,12 @@
 #include "phlex/concurrency.hpp"
 #include "phlex/core/concepts.hpp"
 #include "phlex/core/fold/send.hpp"
+#include "phlex/core/fold_join_node.hpp"
 #include "phlex/core/fwd.hpp"
 #include "phlex/core/input_arguments.hpp"
 #include "phlex/core/message.hpp"
-#include "phlex/core/multilayer_join_node.hpp"
 #include "phlex/core/product_selector.hpp"
 #include "phlex/core/products_consumer.hpp"
-#include "phlex/core/store_counters.hpp"
 #include "phlex/model/algorithm_name.hpp"
 #include "phlex/model/data_cell_index.hpp"
 #include "phlex/model/handle.hpp"
@@ -40,26 +39,44 @@ namespace phlex::experimental {
   public:
     declared_fold(algorithm_name name,
                   std::vector<std::string> predicates,
-                  product_selectors input_products);
+                  product_selectors input_products,
+                  std::string partition_layer);
     ~declared_fold() override;
 
     virtual tbb::flow::sender<message>& output_port() = 0;
-    virtual tbb::flow::receiver<flush_message>& flush_port() = 0;
     virtual product_specifications const& output() const = 0;
+    virtual tbb::flow::receiver<index_message>& partition_port() = 0;
     virtual std::size_t product_count() const = 0;
+    identifier const& partition_layer() const { return partition_layer_; }
+
+  private:
+    identifier partition_layer_;
   };
 
   using declared_fold_ptr = std::unique_ptr<declared_fold>;
   using declared_folds = simple_ptr_map<declared_fold_ptr>;
 
+  template <typename FoldResult, typename InitTuple, std::size_t... Is>
+  auto make_initializer(InitTuple args, std::index_sequence<Is...>)
+  {
+    // The compiler emits a warning if an empty args tuple is captured by reference and then not expanded inside the lambda expression.  We therefore only capture args in the lambda expression if sizeof...(Is) > 0.
+    if constexpr (sizeof...(Is) == 0) {
+      return [](data_cell_index const&) { return std::make_unique<FoldResult>(); };
+    } else {
+      return [args](data_cell_index const&) {
+        return std::make_unique<FoldResult>(std::get<Is>(args)...);
+      };
+    }
+  }
+
   // =====================================================================================
 
   template <typename AlgorithmBits, typename InitTuple>
-  class fold_node : public declared_fold, private count_stores {
+  class fold_node : public declared_fold {
     using all_parameter_types = typename AlgorithmBits::input_parameter_types;
+    using result_type = std::decay_t<std::tuple_element_t<0, all_parameter_types>>;
     using input_parameter_types = skip_first_type<all_parameter_types>; // Skip fold object
     static constexpr auto num_inputs = std::tuple_size_v<input_parameter_types>;
-    using result_type = std::decay_t<std::tuple_element_t<0, all_parameter_types>>;
 
     static constexpr std::size_t num_outputs = 1; // hard-coded for now
     using function_t = typename AlgorithmBits::bound_type;
@@ -73,138 +90,69 @@ namespace phlex::experimental {
               InitTuple initializer,
               product_selectors input_products,
               std::vector<std::string> output,
-              std::string partition) :
-      declared_fold{std::move(algo_name), std::move(predicates), std::move(input_products)},
-      initializer_{std::move(initializer)},
+              std::string partition_layer) :
+      declared_fold{std::move(algo_name),
+                    std::move(predicates),
+                    std::move(input_products),
+                    std::move(partition_layer)},
       output_{to_product_specifications(name(), std::move(output), make_type_ids<result_type>())},
-      partition_{std::move(partition)},
-      flush_receiver_{g,
-                      tbb::flow::unlimited,
-                      [this](flush_message const& msg) -> tbb::flow::continue_msg {
-                        auto const& [index, counts, original_message_id] = msg;
-                        if (index->layer_name() != partition_) {
-                          return {};
-                        }
-
-                        counter_for(index->hash()).set_flush_value(counts, original_message_id);
-                        emit_and_evict_if_done(index);
-                        return {};
-                      }},
-      join_{make_join_or_none<num_inputs>(
-        g, name().to_string(), layers())}, // FIXME: This should change to include result product!
+      join_{g,
+            name().to_string(),
+            this->partition_layer(),
+            layers(),
+            this->output(),
+            make_initializer<result_type>(
+              std::move(initializer), std::make_index_sequence<std::tuple_size_v<InitTuple>>{})},
       fold_{g,
             concurrency,
-            [this, ft = alg.release_algorithm()](messages_t<num_inputs> const& messages, auto&) {
-              // N.B. The assumption is that a fold will *never* need to cache
-              //      the product store it creates.  Any flush messages *do not* need
-              //      to be propagated to downstream nodes.
-              auto const& msg = most_derived(messages);
-              auto const& index = msg.store->index();
-
-              auto fold_index = index->parent(partition_);
-              if (not fold_index) {
-                return;
-              }
-
-              auto index_hash_for_counter = fold_index->hash();
+            [this, ft = alg.release_algorithm()](
+              accumulator_with_messages<result_type, num_inputs> const& accum_with_msgs, auto&) {
+              std::size_t const partition_hash = apply_fold(ft, accum_with_msgs);
 
-              call(ft, messages, std::make_index_sequence<num_inputs>{});
               ++calls_;
 
-              counter_for(index_hash_for_counter).increment(index->layer_hash());
-
-              emit_and_evict_if_done(fold_index);
+              join_.notify_result_repeater_port().try_put(partition_hash);
             }}
     {
-      if constexpr (num_inputs > 1ull) {
-        make_edge(join_, fold_);
-      }
+      make_edge(join_, fold_);
     }
 
   private:
-    void emit_and_evict_if_done(data_cell_index_ptr const& fold_index)
-    {
-      if (auto counter = done_with(fold_index->hash())) {
-        auto parent = std::make_shared<product_store>(fold_index, name());
-        commit(parent);
-        ++product_count_;
-        tbb::flow::output_port<0>(fold_).try_put(
-          {.store = parent, .id = counter->original_message_id()});
-      }
-    }
-
     tbb::flow::receiver<message>& port_for(product_selector const& input_product) override
     {
-      return receiver_for<num_inputs>(join_, input(), input_product, fold_);
+      return receiver_for(join_, input(), input_product);
     }
 
-    std::vector<tbb::flow::receiver<message>*> ports() override
-    {
-      return input_ports<num_inputs>(join_, fold_);
-    }
+    std::vector<tbb::flow::receiver<message>*> ports() override { return input_ports(join_); }
 
-    tbb::flow::receiver<flush_message>& flush_port() override { return flush_receiver_; }
-    tbb::flow::sender<message>& output_port() override { return tbb::flow::output_port<0>(fold_); }
+    tbb::flow::receiver<index_message>& partition_port() override { return join_.partition_port(); }
+    tbb::flow::sender<message>& output_port() override { return join_.output_port(); }
     product_specifications const& output() const override { return output_; }
 
-    template <std::size_t... Is>
-    void call(function_t const& ft,
-              messages_t<num_inputs> const& messages,
-              std::index_sequence<Is...>)
-    {
-      auto const parent_index = most_derived(messages).store->index()->parent(partition_);
-
-      // FIXME: Not the safest approach!
-      auto it = results_.find(parent_index->hash());
-      if (it == results_.end()) {
-        it = results_
-               .insert({parent_index->hash(),
-                        initialized_object(
-                          initializer_, std::make_index_sequence<std::tuple_size_v<InitTuple>>{})})
-               .first;
-      }
-
-      if constexpr (num_inputs == 1ull) {
-        std::invoke(ft, *it->second, std::get<Is>(input_).retrieve(messages)...);
-      } else {
-        std::invoke(ft, *it->second, std::get<Is>(input_).retrieve(std::get<Is>(messages))...);
-      }
-    }
-
     named_index_ports index_ports() final { return join_.index_ports(); }
     std::size_t num_calls() const final { return calls_.load(); }
-    std::size_t product_count() const final { return product_count_.load(); }
-
-    template <size_t... Is>
-    auto initialized_object(InitTuple const& init, std::index_sequence<Is...>) const
-    {
-      return std::unique_ptr<result_type>(new result_type{std::get<Is>(init)...});
-    }
+    std::size_t product_count() const final { return join_.emitted_result_count(); }
 
-    auto commit(product_store_ptr& store)
+    std::size_t apply_fold(
+      function_t const& ft,
+      accumulator_with_messages<result_type, num_inputs> const& accum_with_msgs)
     {
-      auto& result = results_.at(store->index()->hash());
-      if constexpr (requires { send(*result); }) {
-        store->add_product(output()[0], send(*result));
-      } else {
-        store->add_product(output()[0], std::move(*result));
-      }
-      // Reclaim some memory; it would be better to erase the entire entry from the map,
-      // but that is not thread-safe.
-      result.reset();
+      // We have to do awkward index management until we can use structured bindings with packs.
+      auto& accumulator = std::get<0>(accum_with_msgs);
+      [&]<std::size_t... Is>(std::index_sequence<Is...>) {
+        accumulator.partial_result->call(
+          ft, std::get<Is>(input_).retrieve(std::get<Is + 1>(accum_with_msgs))...);
+      }(std::make_index_sequence<num_inputs>{});
+      return accumulator.index->hash();
     }
 
-    InitTuple initializer_;
     input_retriever_types<input_parameter_types> input_{input_arguments<input_parameter_types>()};
     product_specifications output_;
-    identifier partition_;
-    tbb::flow::function_node<flush_message> flush_receiver_;
-    join_or_none_t<num_inputs> join_;
-    tbb::flow::multifunction_node<messages_t<num_inputs>, message_tuple<1>> fold_;
-    tbb::concurrent_unordered_map<data_cell_index::hash_type, std::unique_ptr<result_type>>
-      results_;
+    fold_join_node<result_type, num_inputs> join_;
+    tbb::flow::multifunction_node<accumulator_with_messages<result_type, num_inputs>,
+                                  message_tuple<1>>
+      fold_;
     std::atomic<std::size_t> calls_;
-    std::atomic<std::size_t> product_count_;
   };
 }
 

phlex/core/declared_observer.hpp

@@ -10,7 +10,6 @@
 #include "phlex/core/multilayer_join_node.hpp"
 #include "phlex/core/product_selector.hpp"
 #include "phlex/core/products_consumer.hpp"
-#include "phlex/core/store_counters.hpp"
 #include "phlex/metaprogramming/type_deduction.hpp"
 #include "phlex/model/algorithm_name.hpp"
 #include "phlex/model/data_cell_index.hpp"

phlex/core/declared_unfold.cpp

@@ -20,7 +20,7 @@ namespace phlex::experimental {
   product_store_const_ptr generator::make_child(std::size_t const i, products new_products)
   {
     auto child_index = parent_->index()->make_child(child_layer_name_, i);
-    ++child_counts_;
+    ++child_count_;
     return std::make_shared<product_store>(child_index, node_name_, std::move(new_products));
   }
 

phlex/core/declared_unfold.hpp

@@ -42,7 +42,7 @@ namespace phlex::experimental {
                        std::string const& child_layer_name);
 
     std::size_t child_layer_hash() const { return child_layer_hash_; }
-    std::size_t child_count() const { return child_counts_; }
+    std::size_t child_count() const { return child_count_; }
     product_store_const_ptr make_child(std::size_t i, products new_products);
 
   private:
@@ -52,7 +52,7 @@ namespace phlex::experimental {
     // NOLINTNEXTLINE(cppcoreguidelines-avoid-const-or-ref-data-members)
     std::string const& child_layer_name_;
     std::size_t child_layer_hash_;
-    std::size_t child_counts_ = 0;
+    std::size_t child_count_ = 0;
   };
 
   class PHLEX_CORE_EXPORT declared_unfold : public products_consumer {