From 4b973f451e4c5d929baeac7e86ebd3cb3e4c60a8 Mon Sep 17 00:00:00 2001 From: Fabio Alessandrelli Date: Fri, 29 Mar 2024 22:35:03 +0100 Subject: [PATCH] [MP] Gracefully handle cache confirmation of deleted nodes It's possible that after sending a cached node reference (e.g. RPC or static MultiplayerSynchronizer) the reference node is removed from tree before the remote peer(s) can confirm the referenced path. To better detect that case, and avoid spamming errors when it happens, this commit modifies the multiplayer API caching protocol, to send the received ID instead of the Node path when sending the confirmation packet. **This is a breaking change** because it makes the runtime multiplayer protocol incompatible with previous versions of Godot. --- modules/multiplayer/scene_cache_interface.cpp | 38 ++++++++++--------- modules/multiplayer/scene_cache_interface.h | 3 +- 2 files changed, 22 insertions(+), 19 deletions(-) diff --git a/modules/multiplayer/scene_cache_interface.cpp b/modules/multiplayer/scene_cache_interface.cpp index 33b05d4cc21d..c08ccbe4cc3c 100644 --- a/modules/multiplayer/scene_cache_interface.cpp +++ b/modules/multiplayer/scene_cache_interface.cpp @@ -52,6 +52,9 @@ void SceneCacheInterface::_remove_node_cache(ObjectID p_oid) { if (!nc) { return; } + if (nc->cache_id) { + assigned_ids.erase(nc->cache_id); + } for (KeyValue &E : nc->recv_ids) { PeerInfo *pinfo = peers_info.getptr(E.key); ERR_CONTINUE(!pinfo); @@ -117,16 +120,12 @@ void SceneCacheInterface::process_simplify_path(int p_from, const uint8_t *p_pac NodeCache &cache = _track(node); cache.recv_ids.insert(p_from, id); - // Encode path to send ack. - CharString pname = String(path).utf8(); - int len = encode_cstring(pname.get_data(), nullptr); - + // Send ack. Vector packet; - - packet.resize(1 + 1 + len); + packet.resize(1 + 1 + 4); packet.write[0] = SceneMultiplayer::NETWORK_COMMAND_CONFIRM_PATH; packet.write[1] = valid_rpc_checksum; - encode_cstring(pname.get_data(), &packet.write[2]); + encode_uint32(id, &packet.write[2]); Ref multiplayer_peer = multiplayer->get_multiplayer_peer(); ERR_FAIL_COND(multiplayer_peer.is_null()); @@ -137,26 +136,26 @@ 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."); + ERR_FAIL_COND_MSG(p_packet_len != 6, "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]; + int id = decode_uint32(&p_packet[2]); - String paths; - paths.parse_utf8((const char *)&p_packet[2], p_packet_len - 2); - - const NodePath path = paths; + const ObjectID *oid = assigned_ids.getptr(id); + if (oid == nullptr) { + return; // May be trying to confirm a node that was removed. + } 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); + const Node *node = Object::cast_to(ObjectDB::get_instance(*oid)); + ERR_FAIL_NULL(node); // Bug. + ERR_PRINT("The rpc node checksum failed. Make sure to have the same methods on both nodes. Node path: " + node->get_path()); } - Node *node = root_node->get_node(path); - ERR_FAIL_NULL(node); - - NodeCache *cache = nodes_cache.getptr(node->get_instance_id()); - ERR_FAIL_NULL_MSG(cache, "Invalid packet received. Tries to confirm a node which was not requested."); + NodeCache *cache = nodes_cache.getptr(*oid); + ERR_FAIL_NULL(cache); // Bug. bool *confirmed = cache->confirmed_peers.getptr(p_from); ERR_FAIL_NULL_MSG(confirmed, "Invalid packet received. Tries to confirm a node which was not requested."); @@ -216,6 +215,7 @@ int SceneCacheInterface::make_object_cache(Object *p_obj) { NodeCache &cache = _track(node); if (cache.cache_id == 0) { cache.cache_id = last_send_cache_id++; + assigned_ids[cache.cache_id] = p_obj->get_instance_id(); } return cache.cache_id; } @@ -227,6 +227,7 @@ bool SceneCacheInterface::send_object_cache(Object *p_obj, int p_peer_id, int &r NodeCache &cache = _track(node); if (cache.cache_id == 0) { cache.cache_id = last_send_cache_id++; + assigned_ids[cache.cache_id] = p_obj->get_instance_id(); } r_id = cache.cache_id; @@ -289,5 +290,6 @@ void SceneCacheInterface::clear() { } peers_info.clear(); nodes_cache.clear(); + assigned_ids.clear(); last_send_cache_id = 1; } diff --git a/modules/multiplayer/scene_cache_interface.h b/modules/multiplayer/scene_cache_interface.h index ab4a20c078dc..73d6bde6effc 100644 --- a/modules/multiplayer/scene_cache_interface.h +++ b/modules/multiplayer/scene_cache_interface.h @@ -44,7 +44,7 @@ class SceneCacheInterface : public RefCounted { //path sent caches struct NodeCache { - int cache_id; + int cache_id = 0; HashMap recv_ids; // peer id, remote cache id HashMap confirmed_peers; // peer id, confirmed }; @@ -55,6 +55,7 @@ class SceneCacheInterface : public RefCounted { }; HashMap nodes_cache; + HashMap assigned_ids; HashMap peers_info; int last_send_cache_id = 1;