From c8f1117a8dd75475e5beddc9e00c819de8ec8fdb Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 23 Mar 2025 13:16:12 +0200
Subject: [PATCH] Refactor dependency iteration in SystemScheduler to be more
 reusable

---
 source/game/systemscheduler.cpp | 74 ++++++++++++++++++---------------
 source/game/systemscheduler.h   |  2 +
 2 files changed, 43 insertions(+), 33 deletions(-)

diff --git a/source/game/systemscheduler.cpp b/source/game/systemscheduler.cpp
index 1cc78a4..0a15a30 100644
--- a/source/game/systemscheduler.cpp
+++ b/source/game/systemscheduler.cpp
@@ -70,6 +70,46 @@ int SystemScheduler::get_data_order(const GraphNode &node1, const GraphNode &nod
 	int data_order = 0;
 	const Reflection::ClassBase *ordered_data = nullptr;
 	const Reflection::ClassBase *unordered_data = nullptr;
+	for_common_deps(node1, node2, [&](const Reflection::ClassBase *type, int flags1, int flags2){
+		bool unbuffered = (flags1|flags2)&System::UNBUFFERED;
+		flags1 &= ~System::UNBUFFERED;
+		flags2 &= ~System::UNBUFFERED;
+
+		int order = 0;
+		// Read-only access to fresh data comes after any writes
+		if(flags1==System::READ_FRESH && (flags2&System::WRITE))
+			order = 1;
+		else if(flags2==System::READ_FRESH && (flags1&System::WRITE))
+			order = -1;
+		// Reads can happen concurrently to other access with buffering
+		else if(!(flags1&flags2&System::WRITE) && !unbuffered)
+			order = 0;
+		// Chained updates always come after non-chained writes
+		else if(flags1==System::CHAINED_UPDATE && (flags2==System::WRITE || flags2==System::UPDATE))
+			order = 1;
+		else if(flags2==System::CHAINED_UPDATE && (flags1==System::WRITE || flags1==System::UPDATE))
+			order = -1;
+		else
+			unordered_data = type;
+
+		if(order && data_order && order!=data_order)
+			throw scheduling_error(format("Ambiguous data ordering between %s and %s, accessing %s and %s",
+				node1.type->get_name(), node2.type->get_name(), ordered_data->get_name(), type->get_name()));
+
+		data_order = order;
+		ordered_data = type;
+	});
+
+	if(!data_order && unordered_data)
+		throw scheduling_error(format("Ambiguous data ordering between %s and %s, accessing %s",
+			node1.type->get_name(), node2.type->get_name(), unordered_data->get_name()));
+
+	return data_order;
+}
+
+template<typename F>
+void SystemScheduler::for_common_deps(const GraphNode &node1, const GraphNode &node2, const F &func)
+{
 	for(const System::Dependency &d1: node1.system->get_dependencies())
 	{
 		int flags1 = d1.get_flags()&System::DATA_MASK;
@@ -90,41 +130,9 @@ int SystemScheduler::get_data_order(const GraphNode &node1, const GraphNode &nod
 			else
 				continue;
 
-			bool unbuffered = (flags1|flags2)&System::UNBUFFERED;
-			flags1 &= ~System::UNBUFFERED;
-			flags2 &= ~System::UNBUFFERED;
-
-			int order = 0;
-			// Read-only access to fresh data comes after any writes
-			if(flags1==System::READ_FRESH && (flags2&System::WRITE))
-				order = 1;
-			else if(flags2==System::READ_FRESH && (flags1&System::WRITE))
-				order = -1;
-			// Reads can happen concurrently to other access with buffering
-			else if(!(flags1&flags2&System::WRITE) && !unbuffered)
-				order = 0;
-			// Chained updates always come after non-chained writes
-			else if(flags1==System::CHAINED_UPDATE && (flags2==System::WRITE || flags2==System::UPDATE))
-				order = 1;
-			else if(flags2==System::CHAINED_UPDATE && (flags1==System::WRITE || flags1==System::UPDATE))
-				order = -1;
-			else
-				unordered_data = common_type;
-
-			if(order && data_order && order!=data_order)
-				throw scheduling_error(format("Ambiguous data ordering between %s and %s, accessing %s and %s",
-					node1.type->get_name(), node2.type->get_name(), ordered_data->get_name(), common_type->get_name()));
-
-			data_order = order;
-			ordered_data = common_type;
+			func(common_type, flags1, flags2);
 		}
 	}
-
-	if(!data_order && unordered_data)
-		throw scheduling_error(format("Ambiguous data ordering between %s and %s, accessing %s",
-			node1.type->get_name(), node2.type->get_name(), unordered_data->get_name()));
-
-	return data_order;
 }
 
 void SystemScheduler::run(Time::TimeDelta dt)
diff --git a/source/game/systemscheduler.h b/source/game/systemscheduler.h
index 9101f81..f7c1ebd 100644
--- a/source/game/systemscheduler.h
+++ b/source/game/systemscheduler.h
@@ -44,6 +44,8 @@ private:
 	static int get_order(const GraphNode &, const GraphNode &);
 	static int get_explicit_order(const GraphNode &, const GraphNode &);
 	static int get_data_order(const GraphNode &, const GraphNode &);
+	template<typename F>
+	static void for_common_deps(const GraphNode &, const GraphNode &, const F &);
 
 public:
 	const std::vector<GraphNode> &get_graph() const { return nodes; }
-- 
2.45.2