Add external gc

arangodb · goedderz · Apr 28, 2025 · Mar 21, 2025 · Mar 24, 2025 · Mar 24, 2025
commit d2643db94435b64b8cc9f9da0702b483e38660dc
diff --git a/...iners/Concurrent/ListOfThreadOwnedLists.h → lib/Containers/Concurrent/ListOfLists.h b/...iners/Concurrent/ListOfThreadOwnedLists.h → lib/Containers/Concurrent/ListOfLists.h
@@ -37,8 +37,13 @@ concept IteratorOverNodes = requires(List l, F f) {
 template<typename List, typename Item, typename F>
 concept IteratorOverSnapshots =
     IteratorOverNodes<List, F> && std::invocable<F, typename Item::Snapshot>;
+template<typename T>
+concept HasExernalGarbageCollection = requires(T t) {
+  t.garbage_collect_external();
+};
 
 template<UpdatesMetrics List, HasSnapshot Item>
+requires HasExernalGarbageCollection<List>
 struct ListOfLists {
   std::shared_ptr<Metrics> metrics;
 
@@ -80,7 +85,22 @@ struct ListOfLists {
     auto guard = std::lock_guard(_mutex);
     metrics = new_metrics;
   }
-  // void run_external_cleanup() noexcept;
+
+  /**
+     Runs an external clean up.
+   */
+  void run_external_cleanup() noexcept {
+    auto lists = [&] {
+      auto guard = std::lock_guard(_mutex);
+      return _lists;
+    }();
+
+    for (auto& weak_list : lists) {
+      if (auto list = weak_list.lock()) {
+        list->garbage_collect_external();
+      }
+    }
+  }
 };
 
 }  // namespace arangodb::containers
diff --git a/tests/Containers/Concurrent/ListOfListsTest.cpp b/tests/Containers/Concurrent/ListOfListsTest.cpp
@@ -20,7 +20,7 @@
 ///
 /// @author Julia Volmer
 ////////////////////////////////////////////////////////////////////////////////
-#include "Containers/Concurrent/ListOfThreadOwnedLists.h"
+#include "Containers/Concurrent/ListOfLists.h"
 
 #include <gtest/gtest.h>
 #include <memory>
@@ -48,6 +48,7 @@ struct MyMetrics : Metrics {
 struct MyNodeList {
   std::vector<MyData> data;
   std::shared_ptr<Metrics> metrics;
+  bool isGarbageCollected = false;
 
   MyNodeList(std::vector<MyData> data) : data{std::move(data)} {
     if (metrics) {
@@ -70,6 +71,8 @@ struct MyNodeList {
   auto set_metrics(std::shared_ptr<Metrics> new_metrics) -> void {
     metrics = new_metrics;
   }
+
+  auto garbage_collect_external() -> void { isGarbageCollected = true; }
 };
 
 using MyList = ListOfLists<MyNodeList, MyData>;
@@ -135,3 +138,18 @@ TEST(ListOfListsTest, uses_list_of_lists_metrics_for_all_lists) {
   EXPECT_EQ(newMetrics->lists, 2);
   EXPECT_EQ(dynamic_cast<MyMetrics*>(list.metrics.get())->lists, 2);
 }
+
+TEST(ListOfListsTest, executes_garbage_collection_on_each_list) {
+  MyList list;
+  auto first_inner_list =
+      std::make_shared<MyNodeList>(std::vector<MyData>{1, 2, 3});
+  auto second_inner_list =
+      std::make_shared<MyNodeList>(std::vector<MyData>{4, 5, 6});
+  list.add(first_inner_list);
+  list.add(second_inner_list);
+
+  list.run_external_cleanup();
+
+  EXPECT_TRUE(first_inner_list->isGarbageCollected);
+  EXPECT_TRUE(second_inner_list->isGarbageCollected);
+}