Introduce Type::GetConfigTypesSortedByLoadDependencies()

lib/base/initialize.hpp

@@ -23,6 +23,7 @@ enum class InitializePriority {
 	RegisterBuiltinTypes,
 	RegisterFunctions,
 	RegisterTypes,
+	SortTypes,
 	EvaluateConfigFragments,
 	Default,
 	FreezeNamespaces,

lib/base/type.cpp

@@ -1,9 +1,15 @@
 /* Icinga 2 | (c) 2012 Icinga GmbH | GPLv2+ */
 
 #include "base/type.hpp"
+#include "base/atomic.hpp"
+#include "base/configobject.hpp"
+#include "base/debug.hpp"
 #include "base/scriptglobal.hpp"
 #include "base/namespace.hpp"
 #include "base/objectlock.hpp"
+#include <algorithm>
+#include <functional>
+#include <unordered_map>
 
 using namespace icinga;
 
@@ -32,6 +38,59 @@ INITIALIZE_ONCE_WITH_PRIORITY([]() {
 	Type::Register(type);
 }, InitializePriority::RegisterTypeType);
 
+static std::vector<Type::Ptr> l_SortedByLoadDependencies;
+static Atomic l_SortingByLoadDependenciesDone (false);
+
+typedef std::unordered_map<Type*, bool> Visited; // https://stackoverflow.com/a/8942986
+
+INITIALIZE_ONCE_WITH_PRIORITY([] {
+	auto types (Type::GetAllTypes());
+
+	types.erase(std::remove_if(types.begin(), types.end(), [](auto& type) {
+		return !ConfigObject::TypeInstance->IsAssignableFrom(type);
+	}), types.end());
+
+	// Depth-first search
+	std::unordered_set<Type*> unsorted;
+	Visited visited;
+	std::vector<Type::Ptr> sorted;
+
+	for (auto type : types) {
+		unsorted.emplace(type.get());
+	}
+
+	std::function<void(Type*)> visit ([&visit, &unsorted, &visited, &sorted](Type* type) {
+		if (unsorted.find(type) == unsorted.end()) {
+			return;
+		}
+
+		bool& alreadyVisited (visited.at(type));
+		VERIFY(!alreadyVisited);
+		alreadyVisited = true;
+
+		for (auto dep : type->GetLoadDependencies()) {
+			visit(dep);
+		}
+
+		unsorted.erase(type);
+		sorted.emplace_back(type);
+	});
+
+	while (!unsorted.empty()) {
+		for (auto& type : types) {
+			visited[type.get()] = false;
+		}
+
+		visit(*unsorted.begin());
+	}
+
+	VERIFY(sorted.size() == types.size());
+	VERIFY(sorted[0]->GetLoadDependencies().empty());
+
+	std::swap(sorted, l_SortedByLoadDependencies);
+	l_SortingByLoadDependenciesDone.store(true);
+}, InitializePriority::SortTypes);
+
 String Type::ToString() const
 {
 	return "type '" + GetName() + "'";
@@ -72,6 +131,12 @@ std::vector<Type::Ptr> Type::GetAllTypes()
 	return types;
 }
 
+const std::vector<Type::Ptr>& Type::GetConfigTypesSortedByLoadDependencies()
+{
+	VERIFY(l_SortingByLoadDependenciesDone.load());
+	return l_SortedByLoadDependencies;
+}
+
 String Type::GetPluralName() const
 {
 	String name = GetName();

lib/base/type.hpp

@@ -82,6 +82,7 @@ public:
 	static void Register(const Type::Ptr& type);
 	static Type::Ptr GetByName(const String& name);
 	static std::vector<Type::Ptr> GetAllTypes();
+	static const std::vector<Ptr>& GetConfigTypesSortedByLoadDependencies();
 
 	void SetField(int id, const Value& value, bool suppress_events = false, const Value& cookie = Empty) override;
 	Value GetField(int id) const override;