[MP] Optimize multiplayer NodePath caching

Only use paths during network transfer.
Use ObjectID instead of NodePaths for storing the Node <-> NetID
relations locally.

3 files changed, 36 insertions, 27 deletions

diff --git a/modules/multiplayer/scene_cache_interface.cpp b/modules/multiplayer/scene_cache_interface.cpp
index 8d102ca981..56cd0bec18 100644
--- a/modules/multiplayer/scene_cache_interface.cpp
+++ b/modules/multiplayer/scene_cache_interface.cpp
@@ -44,9 +44,8 @@ void SceneCacheInterface::on_peer_change(int p_id, bool p_connected) {
 		path_get_cache.erase(p_id);
 		// Cleanup sent cache.
 		// Some refactoring is needed to make this faster and do paths GC.
-		for (const KeyValue<NodePath, PathSentCache> &E : path_send_cache) {
-			PathSentCache *psc = path_send_cache.getptr(E.key);
-			psc->confirmed_peers.erase(p_id);
+		for (KeyValue<ObjectID, PathSentCache> &E : path_send_cache) {
+			E.value.confirmed_peers.erase(p_id);
 		}
 	}
 }
@@ -67,7 +66,7 @@ void SceneCacheInterface::process_simplify_path(int p_from, const uint8_t *p_pac
 	String paths;
 	paths.parse_utf8((const char *)(p_packet + ofs), p_packet_len - ofs);
 
-	NodePath path = paths;
+	const NodePath path = paths;
 
 	if (!path_get_cache.has(p_from)) {
 		path_get_cache[p_from] = PathGetCache();
@@ -81,7 +80,7 @@ void SceneCacheInterface::process_simplify_path(int p_from, const uint8_t *p_pac
 	}
 
 	PathGetCache::NodeInfo ni;
-	ni.path = path;
+	ni.path = node->get_path();
 
 	path_get_cache[p_from].nodes[id] = ni;
 
@@ -106,19 +105,24 @@ void SceneCacheInterface::process_simplify_path(int p_from, const uint8_t *p_pac
 
 void SceneCacheInterface::process_confirm_path(int p_from, const uint8_t *p_packet, int p_packet_len) {
 	ERR_FAIL_COND_MSG(p_packet_len < 3, "Invalid packet received. Size too small.");
+	Node *root_node = SceneTree::get_singleton()->get_root()->get_node(multiplayer->get_root_path());
+	ERR_FAIL_NULL(root_node);
 
 	const bool valid_rpc_checksum = p_packet[1];
 
 	String paths;
 	paths.parse_utf8((const char *)&p_packet[2], p_packet_len - 2);
 
-	NodePath path = paths;
+	const NodePath path = paths;
 
 	if (valid_rpc_checksum == false) {
 		ERR_PRINT("The rpc node checksum failed. Make sure to have the same methods on both nodes. Node path: " + path);
 	}
 
-	PathSentCache *psc = path_send_cache.getptr(path);
+	Node *node = root_node->get_node(path);
+	ERR_FAIL_NULL(node);
+
+	PathSentCache *psc = path_send_cache.getptr(node->get_instance_id());
 	ERR_FAIL_NULL_MSG(psc, "Invalid packet received. Tries to confirm a path which was not found in cache.");
 
 	HashMap<int, bool>::Iterator E = psc->confirmed_peers.find(p_from);
@@ -126,9 +130,9 @@ void SceneCacheInterface::process_confirm_path(int p_from, const uint8_t *p_pack
 	E->value = true;
 }
 
-Error SceneCacheInterface::_send_confirm_path(Node *p_node, NodePath p_path, PathSentCache *psc, const List<int> &p_peers) {
+Error SceneCacheInterface::_send_confirm_path(Node *p_node, PathSentCache *psc, const List<int> &p_peers) {
 	// Encode function name.
-	const CharString path = String(p_path).utf8();
+	const CharString path = String(multiplayer->get_root_path().rel_path_to(p_node->get_path())).utf8();
 	const int path_len = encode_cstring(path.get_data(), nullptr);
 
 	// Extract MD5 from rpc methods list.
@@ -163,8 +167,9 @@ Error SceneCacheInterface::_send_confirm_path(Node *p_node, NodePath p_path, Pat
 	return err;
 }
 
-bool SceneCacheInterface::is_cache_confirmed(NodePath p_path, int p_peer) {
-	const PathSentCache *psc = path_send_cache.getptr(p_path);
+bool SceneCacheInterface::is_cache_confirmed(Node *p_node, int p_peer) {
+	ERR_FAIL_NULL_V(p_node, false);
+	const PathSentCache *psc = path_send_cache.getptr(p_node->get_instance_id());
 	ERR_FAIL_NULL_V(psc, false);
 	HashMap<int, bool>::ConstIterator F = psc->confirmed_peers.find(p_peer);
 	ERR_FAIL_COND_V(!F, false); // Should never happen.
@@ -174,13 +179,13 @@ bool SceneCacheInterface::is_cache_confirmed(NodePath p_path, int p_peer) {
 int SceneCacheInterface::make_object_cache(Object *p_obj) {
 	Node *node = Object::cast_to<Node>(p_obj);
 	ERR_FAIL_NULL_V(node, -1);
-	NodePath for_path = multiplayer->get_root_path().rel_path_to(node->get_path());
+	const ObjectID oid = node->get_instance_id();
 	// See if the path is cached.
-	PathSentCache *psc = path_send_cache.getptr(for_path);
+	PathSentCache *psc = path_send_cache.getptr(oid);
 	if (!psc) {
 		// Path is not cached, create.
-		path_send_cache[for_path] = PathSentCache();
-		psc = path_send_cache.getptr(for_path);
+		path_send_cache[oid] = PathSentCache();
+		psc = path_send_cache.getptr(oid);
 		psc->id = last_send_cache_id++;
 	}
 	return psc->id;
@@ -189,11 +194,16 @@ int SceneCacheInterface::make_object_cache(Object *p_obj) {
 bool SceneCacheInterface::send_object_cache(Object *p_obj, int p_peer_id, int &r_id) {
 	Node *node = Object::cast_to<Node>(p_obj);
 	ERR_FAIL_NULL_V(node, false);
-
-	r_id = make_object_cache(p_obj);
-	ERR_FAIL_COND_V(r_id < 0, false);
-	NodePath for_path = multiplayer->get_root_path().rel_path_to(node->get_path());
-	PathSentCache *psc = path_send_cache.getptr(for_path);
+	const ObjectID oid = node->get_instance_id();
+	// See if the path is cached.
+	PathSentCache *psc = path_send_cache.getptr(oid);
+	if (!psc) {
+		// Path is not cached, create.
+		path_send_cache[oid] = PathSentCache();
+		psc = path_send_cache.getptr(oid);
+		psc->id = last_send_cache_id++;
+	}
+	r_id = psc->id;
 
 	bool has_all_peers = true;
 	List<int> peers_to_add; // If one is missing, take note to add it.
@@ -225,7 +235,7 @@ bool SceneCacheInterface::send_object_cache(Object *p_obj, int p_peer_id, int &r
 	}
 
 	if (peers_to_add.size()) {
-		_send_confirm_path(node, for_path, psc, peers_to_add);
+		_send_confirm_path(node, psc, peers_to_add);
 	}
 
 	return has_all_peers;
diff --git a/modules/multiplayer/scene_cache_interface.h b/modules/multiplayer/scene_cache_interface.h
index 7a7304fde8..e63beb5f84 100644
--- a/modules/multiplayer/scene_cache_interface.h
+++ b/modules/multiplayer/scene_cache_interface.h
@@ -58,12 +58,12 @@ private:
 		HashMap<int, NodeInfo> nodes;
 	};
 
-	HashMap<NodePath, PathSentCache> path_send_cache;
+	HashMap<ObjectID, PathSentCache> path_send_cache;
 	HashMap<int, PathGetCache> path_get_cache;
 	int last_send_cache_id = 1;
 
 protected:
-	Error _send_confirm_path(Node *p_node, NodePath p_path, PathSentCache *psc, const List<int> &p_peers);
+	Error _send_confirm_path(Node *p_node, PathSentCache *psc, const List<int> &p_peers);
 
 public:
 	void clear();
@@ -75,7 +75,7 @@ public:
 	bool send_object_cache(Object *p_obj, int p_target, int &p_id);
 	int make_object_cache(Object *p_obj);
 	Object *get_cached_object(int p_from, uint32_t p_cache_id);
-	bool is_cache_confirmed(NodePath p_path, int p_peer);
+	bool is_cache_confirmed(Node *p_path, int p_peer);
 
 	SceneCacheInterface(SceneMultiplayer *p_multiplayer) { multiplayer = p_multiplayer; }
 };
diff --git a/modules/multiplayer/scene_rpc_interface.cpp b/modules/multiplayer/scene_rpc_interface.cpp
index 48e1d13f9c..bf0a261bd8 100644
--- a/modules/multiplayer/scene_rpc_interface.cpp
+++ b/modules/multiplayer/scene_rpc_interface.cpp
@@ -443,15 +443,14 @@ void SceneRPCInterface::_send_rpc(Node *p_node, int p_to, uint16_t p_rpc_id, con
 		// Not all verified path, so send one by one.
 
 		// Append path at the end, since we will need it for some packets.
-		NodePath from_path = multiplayer->get_root_path().rel_path_to(p_node->get_path());
-		CharString pname = String(from_path).utf8();
+		CharString pname = String(multiplayer->get_root_path().rel_path_to(p_node->get_path())).utf8();
 		int path_len = encode_cstring(pname.get_data(), nullptr);
 		MAKE_ROOM(ofs + path_len);
 		encode_cstring(pname.get_data(), &(packet_cache.write[ofs]));
 
 		// Not all verified path, so check which needs the longer packet.
 		for (const int P : targets) {
-			bool confirmed = multiplayer->get_path_cache()->is_cache_confirmed(from_path, P);
+			bool confirmed = multiplayer->get_path_cache()->is_cache_confirmed(p_node, P);
 			if (confirmed) {
 				// This one confirmed path, so use id.
 				encode_uint32(psc_id, &(packet_cache.write[1]));