Improve resource load cache

-Added a new method in Resource: reset_state , used for reloading the same resource from disk
-Added a new cache mode "replace" in ResourceLoader, which reuses existing loaded sub-resources but resets their data from disk (or replaces them if they chaged type)
-Because the correct sub-resource paths are always loaded now, this fixes bugs with subresource folding or subresource ordering when saving.

16 files changed, 115 insertions, 70 deletions

diff --git a/core/core_bind.cpp b/core/core_bind.cpp
index 456a97e5e5..f568ee754d 100644
--- a/core/core_bind.cpp
+++ b/core/core_bind.cpp
@@ -86,9 +86,9 @@ RES _ResourceLoader::load_threaded_get(const String &p_path) {
 	return res;
 }
 
-RES _ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache) {
+RES _ResourceLoader::load(const String &p_path, const String &p_type_hint, CacheMode p_cache_mode) {
 	Error err = OK;
-	RES ret = ResourceLoader::load(p_path, p_type_hint, p_no_cache, &err);
+	RES ret = ResourceLoader::load(p_path, p_type_hint, ResourceFormatLoader::CacheMode(p_cache_mode), &err);
 
 	ERR_FAIL_COND_V_MSG(err != OK, ret, "Error loading resource: '" + p_path + "'.");
 	return ret;
@@ -135,7 +135,7 @@ void _ResourceLoader::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("load_threaded_get_status", "path", "progress"), &_ResourceLoader::load_threaded_get_status, DEFVAL(Array()));
 	ClassDB::bind_method(D_METHOD("load_threaded_get", "path"), &_ResourceLoader::load_threaded_get);
 
-	ClassDB::bind_method(D_METHOD("load", "path", "type_hint", "no_cache"), &_ResourceLoader::load, DEFVAL(""), DEFVAL(false));
+	ClassDB::bind_method(D_METHOD("load", "path", "type_hint", "no_cache"), &_ResourceLoader::load, DEFVAL(""), DEFVAL(CACHE_MODE_REUSE));
 	ClassDB::bind_method(D_METHOD("get_recognized_extensions_for_type", "type"), &_ResourceLoader::get_recognized_extensions_for_type);
 	ClassDB::bind_method(D_METHOD("set_abort_on_missing_resources", "abort"), &_ResourceLoader::set_abort_on_missing_resources);
 	ClassDB::bind_method(D_METHOD("get_dependencies", "path"), &_ResourceLoader::get_dependencies);
@@ -146,6 +146,10 @@ void _ResourceLoader::_bind_methods() {
 	BIND_ENUM_CONSTANT(THREAD_LOAD_IN_PROGRESS);
 	BIND_ENUM_CONSTANT(THREAD_LOAD_FAILED);
 	BIND_ENUM_CONSTANT(THREAD_LOAD_LOADED);
+
+	BIND_ENUM_CONSTANT(CACHE_MODE_IGNORE);
+	BIND_ENUM_CONSTANT(CACHE_MODE_REUSE);
+	BIND_ENUM_CONSTANT(CACHE_MODE_REPLACE);
 }
 
 ////// _ResourceSaver //////
diff --git a/core/core_bind.h b/core/core_bind.h
index 3305c93089..44e620085a 100644
--- a/core/core_bind.h
+++ b/core/core_bind.h
@@ -56,13 +56,19 @@ public:
 		THREAD_LOAD_LOADED
 	};
 
+	enum CacheMode {
+		CACHE_MODE_IGNORE, //resource and subresources do not use path cache, no path is set into resource.
+		CACHE_MODE_REUSE, //resource and subresources use patch cache, reuse existing loaded resources instead of loading from disk when available
+		CACHE_MODE_REPLACE, //resource and and subresource use path cache, but replace existing loaded resources when available with information from disk
+	};
+
 	static _ResourceLoader *get_singleton() { return singleton; }
 
 	Error load_threaded_request(const String &p_path, const String &p_type_hint = "", bool p_use_sub_threads = false);
 	ThreadLoadStatus load_threaded_get_status(const String &p_path, Array r_progress = Array());
 	RES load_threaded_get(const String &p_path);
 
-	RES load(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false);
+	RES load(const String &p_path, const String &p_type_hint = "", CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	Vector<String> get_recognized_extensions_for_type(const String &p_type);
 	void set_abort_on_missing_resources(bool p_abort);
 	PackedStringArray get_dependencies(const String &p_path);
@@ -73,6 +79,7 @@ public:
 };
 
 VARIANT_ENUM_CAST(_ResourceLoader::ThreadLoadStatus);
+VARIANT_ENUM_CAST(_ResourceLoader::CacheMode);
 
 class _ResourceSaver : public Object {
 	GDCLASS(_ResourceSaver, Object);
diff --git a/core/crypto/crypto.cpp b/core/crypto/crypto.cpp
index 99f4fb232d..f43f3e3290 100644
--- a/core/crypto/crypto.cpp
+++ b/core/crypto/crypto.cpp
@@ -141,7 +141,7 @@ void Crypto::_bind_methods() {
 
 /// Resource loader/saver
 
-RES ResourceFormatLoaderCrypto::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
+RES ResourceFormatLoaderCrypto::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	String el = p_path.get_extension().to_lower();
 	if (el == "crt") {
 		X509Certificate *cert = X509Certificate::create();
diff --git a/core/crypto/crypto.h b/core/crypto/crypto.h
index 30d2129e3d..9438fcfea5 100644
--- a/core/crypto/crypto.h
+++ b/core/crypto/crypto.h
@@ -116,7 +116,7 @@ public:
 
 class ResourceFormatLoaderCrypto : public ResourceFormatLoader {
 public:
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;
diff --git a/core/io/image_loader.cpp b/core/io/image_loader.cpp
index 8ca1cb3beb..7de038e6fe 100644
--- a/core/io/image_loader.cpp
+++ b/core/io/image_loader.cpp
@@ -122,7 +122,7 @@ void ImageLoader::cleanup() {
 
 /////////////////
 
-RES ResourceFormatLoaderImage::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
+RES ResourceFormatLoaderImage::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	FileAccess *f = FileAccess::open(p_path, FileAccess::READ);
 	if (!f) {
 		if (r_error) {
diff --git a/core/io/image_loader.h b/core/io/image_loader.h
index bf67e1486f..a5d588e0b5 100644
--- a/core/io/image_loader.h
+++ b/core/io/image_loader.h
@@ -72,7 +72,7 @@ public:
 
 class ResourceFormatLoaderImage : public ResourceFormatLoader {
 public:
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;
diff --git a/core/io/resource.cpp b/core/io/resource.cpp
index 801ec9432d..8560e2abc7 100644
--- a/core/io/resource.cpp
+++ b/core/io/resource.cpp
@@ -114,20 +114,18 @@ bool Resource::editor_can_reload_from_file() {
 	return true; //by default yes
 }
 
-void Resource::reload_from_file() {
-	String path = get_path();
-	if (!path.is_resource_file()) {
-		return;
+void Resource::reset_state() {
+}
+Error Resource::copy_from(const Ref<Resource> &p_resource) {
+	ERR_FAIL_COND_V(p_resource.is_null(), ERR_INVALID_PARAMETER);
+	if (get_class() != p_resource->get_class()) {
+		return ERR_INVALID_PARAMETER;
 	}
 
-	Ref<Resource> s = ResourceLoader::load(ResourceLoader::path_remap(path), get_class(), true);
-
-	if (!s.is_valid()) {
-		return;
-	}
+	reset_state(); //may want to reset state
 
 	List<PropertyInfo> pi;
-	s->get_property_list(&pi);
+	p_resource->get_property_list(&pi);
 
 	for (List<PropertyInfo>::Element *E = pi.front(); E; E = E->next()) {
 		if (!(E->get().usage & PROPERTY_USAGE_STORAGE)) {
@@ -137,8 +135,23 @@ void Resource::reload_from_file() {
 			continue; //do not change path
 		}
 
-		set(E->get().name, s->get(E->get().name));
+		set(E->get().name, p_resource->get(E->get().name));
 	}
+	return OK;
+}
+void Resource::reload_from_file() {
+	String path = get_path();
+	if (!path.is_resource_file()) {
+		return;
+	}
+
+	Ref<Resource> s = ResourceLoader::load(ResourceLoader::path_remap(path), get_class(), ResourceFormatLoader::CACHE_MODE_IGNORE);
+
+	if (!s.is_valid()) {
+		return;
+	}
+
+	copy_from(s);
 }
 
 Ref<Resource> Resource::duplicate_for_local_scene(Node *p_for_scene, Map<Ref<Resource>, Ref<Resource>> &remap_cache) {
diff --git a/core/io/resource.h b/core/io/resource.h
index d0cd6ea3ac..ae18ac0c8a 100644
--- a/core/io/resource.h
+++ b/core/io/resource.h
@@ -90,6 +90,8 @@ public:
 	static Node *(*_get_local_scene_func)(); //used by editor
 
 	virtual bool editor_can_reload_from_file();
+	virtual void reset_state(); //for resources that use variable amount of properties, either via _validate_property or _get_property_list, this function needs to be implemented to correctly clear state
+	virtual Error copy_from(const Ref<Resource> &p_resource);
 	virtual void reload_from_file();
 
 	void register_owner(Object *p_owner);
diff --git a/core/io/resource_format_binary.cpp b/core/io/resource_format_binary.cpp
index fad58d65fd..fb6ad7d65e 100644
--- a/core/io/resource_format_binary.cpp
+++ b/core/io/resource_format_binary.cpp
@@ -313,17 +313,12 @@ Error ResourceLoaderBinary::parse_variant(Variant &r_v) {
 					uint32_t index = f->get_32();
 					String path = res_path + "::" + itos(index);
 
-					if (use_nocache) {
-						if (!internal_index_cache.has(path)) {
-							WARN_PRINT(String("Couldn't load resource (no cache): " + path).utf8().get_data());
-						}
-						r_v = internal_index_cache[path];
+					//always use internal cache for loading internal resources
+					if (!internal_index_cache.has(path)) {
+						WARN_PRINT(String("Couldn't load resource (no cache): " + path).utf8().get_data());
+						r_v = Variant();
 					} else {
-						RES res = ResourceLoader::load(path);
-						if (res.is_null()) {
-							WARN_PRINT(String("Couldn't load resource: " + path).utf8().get_data());
-						}
-						r_v = res;
+						r_v = internal_index_cache[path];
 					}
 
 				} break;
@@ -645,7 +640,7 @@ Error ResourceLoaderBinary::load() {
 			}
 
 		} else {
-			Error err = ResourceLoader::load_threaded_request(path, external_resources[i].type, use_sub_threads, local_path);
+			Error err = ResourceLoader::load_threaded_request(path, external_resources[i].type, use_sub_threads, ResourceFormatLoader::CACHE_MODE_REUSE, local_path);
 			if (err != OK) {
 				if (!ResourceLoader::get_abort_on_missing_resources()) {
 					ResourceLoader::notify_dependency_error(local_path, path, external_resources[i].type);
@@ -675,7 +670,7 @@ Error ResourceLoaderBinary::load() {
 				path = res_path + "::" + path;
 			}
 
-			if (!use_nocache) {
+			if (cache_mode == ResourceFormatLoader::CACHE_MODE_REUSE) {
 				if (ResourceCache::has(path)) {
 					//already loaded, don't do anything
 					stage++;
@@ -684,7 +679,7 @@ Error ResourceLoaderBinary::load() {
 				}
 			}
 		} else {
-			if (!use_nocache && !ResourceCache::has(res_path)) {
+			if (cache_mode != ResourceFormatLoader::CACHE_MODE_IGNORE && !ResourceCache::has(res_path)) {
 				path = res_path;
 			}
 		}
@@ -695,26 +690,40 @@ Error ResourceLoaderBinary::load() {
 
 		String t = get_unicode_string();
 
-		Object *obj = ClassDB::instance(t);
-		if (!obj) {
-			error = ERR_FILE_CORRUPT;
-			ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource of unrecognized type in file: " + t + ".");
-		}
+		RES res;
 
-		Resource *r = Object::cast_to<Resource>(obj);
-		if (!r) {
-			String obj_class = obj->get_class();
-			error = ERR_FILE_CORRUPT;
-			memdelete(obj); //bye
-			ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource type in resource field not a resource, type is: " + obj_class + ".");
+		if (cache_mode == ResourceFormatLoader::CACHE_MODE_REPLACE && ResourceCache::has(path)) {
+			//use the existing one
+			Resource *r = ResourceCache::get(path);
+			if (r->get_class() == t) {
+				r->reset_state();
+				res = Ref<Resource>(r);
+			}
 		}
 
-		RES res = RES(r);
+		if (res.is_null()) {
+			//did not replace
 
-		if (path != String()) {
-			r->set_path(path);
+			Object *obj = ClassDB::instance(t);
+			if (!obj) {
+				error = ERR_FILE_CORRUPT;
+				ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource of unrecognized type in file: " + t + ".");
+			}
+
+			Resource *r = Object::cast_to<Resource>(obj);
+			if (!r) {
+				String obj_class = obj->get_class();
+				error = ERR_FILE_CORRUPT;
+				memdelete(obj); //bye
+				ERR_FAIL_V_MSG(ERR_FILE_CORRUPT, local_path + ":Resource type in resource field not a resource, type is: " + obj_class + ".");
+			}
+
+			res = RES(r);
+			if (path != String() && cache_mode != ResourceFormatLoader::CACHE_MODE_IGNORE) {
+				r->set_path(path, cache_mode == ResourceFormatLoader::CACHE_MODE_REPLACE); //if got here because the resource with same path has different type, replace it
+			}
+			r->set_subindex(subindex);
 		}
-		r->set_subindex(subindex);
 
 		if (!main) {
 			internal_index_cache[path] = res;
@@ -961,7 +970,7 @@ ResourceLoaderBinary::~ResourceLoaderBinary() {
 	}
 }
 
-RES ResourceFormatLoaderBinary::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
+RES ResourceFormatLoaderBinary::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	if (r_error) {
 		*r_error = ERR_FILE_CANT_OPEN;
 	}
@@ -972,7 +981,7 @@ RES ResourceFormatLoaderBinary::load(const String &p_path, const String &p_origi
 	ERR_FAIL_COND_V_MSG(err != OK, RES(), "Cannot open file '" + p_path + "'.");
 
 	ResourceLoaderBinary loader;
-	loader.use_nocache = p_no_cache;
+	loader.cache_mode = p_cache_mode;
 	loader.use_sub_threads = p_use_sub_threads;
 	loader.progress = r_progress;
 	String path = p_original_path != "" ? p_original_path : p_path;
diff --git a/core/io/resource_format_binary.h b/core/io/resource_format_binary.h
index 428725f1d2..3592bbdbc4 100644
--- a/core/io/resource_format_binary.h
+++ b/core/io/resource_format_binary.h
@@ -78,7 +78,7 @@ class ResourceLoaderBinary {
 	Map<String, String> remaps;
 	Error error = OK;
 
-	bool use_nocache = false;
+	ResourceFormatLoader::CacheMode cache_mode = ResourceFormatLoader::CACHE_MODE_REUSE;
 
 	friend class ResourceFormatLoaderBinary;
 
@@ -103,7 +103,7 @@ public:
 
 class ResourceFormatLoaderBinary : public ResourceFormatLoader {
 public:
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const;
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
diff --git a/core/io/resource_importer.cpp b/core/io/resource_importer.cpp
index d86877ee14..3e460726f6 100644
--- a/core/io/resource_importer.cpp
+++ b/core/io/resource_importer.cpp
@@ -116,7 +116,7 @@ Error ResourceFormatImporter::_get_path_and_type(const String &p_path, PathAndTy
 	return OK;
 }
 
-RES ResourceFormatImporter::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
+RES ResourceFormatImporter::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	PathAndType pat;
 	Error err = _get_path_and_type(p_path, pat);
 
@@ -128,7 +128,7 @@ RES ResourceFormatImporter::load(const String &p_path, const String &p_original_
 		return RES();
 	}
 
-	RES res = ResourceLoader::_load(pat.path, p_path, pat.type, p_no_cache, r_error, p_use_sub_threads, r_progress);
+	RES res = ResourceLoader::_load(pat.path, p_path, pat.type, p_cache_mode, r_error, p_use_sub_threads, r_progress);
 
 #ifdef TOOLS_ENABLED
 	if (res.is_valid()) {
diff --git a/core/io/resource_importer.h b/core/io/resource_importer.h
index d31273e3cb..bda8b74b73 100644
--- a/core/io/resource_importer.h
+++ b/core/io/resource_importer.h
@@ -57,7 +57,7 @@ class ResourceFormatImporter : public ResourceFormatLoader {
 
 public:
 	static ResourceFormatImporter *get_singleton() { return singleton; }
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const;
 	virtual bool recognize_path(const String &p_path, const String &p_for_type = String()) const;
diff --git a/core/io/resource_loader.cpp b/core/io/resource_loader.cpp
index d66511a39f..588af0f0ae 100644
--- a/core/io/resource_loader.cpp
+++ b/core/io/resource_loader.cpp
@@ -113,9 +113,9 @@ void ResourceFormatLoader::get_recognized_extensions(List<String> *p_extensions)
 	}
 }
 
-RES ResourceFormatLoader::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
+RES ResourceFormatLoader::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	if (get_script_instance() && get_script_instance()->has_method("load")) {
-		Variant res = get_script_instance()->call("load", p_path, p_original_path, p_use_sub_threads);
+		Variant res = get_script_instance()->call("load", p_path, p_original_path, p_use_sub_threads, p_cache_mode);
 
 		if (res.get_type() == Variant::INT) {
 			if (r_error) {
@@ -164,7 +164,7 @@ Error ResourceFormatLoader::rename_dependencies(const String &p_path, const Map<
 
 void ResourceFormatLoader::_bind_methods() {
 	{
-		MethodInfo info = MethodInfo(Variant::NIL, "load", PropertyInfo(Variant::STRING, "path"), PropertyInfo(Variant::STRING, "original_path"));
+		MethodInfo info = MethodInfo(Variant::NIL, "load", PropertyInfo(Variant::STRING, "path"), PropertyInfo(Variant::STRING, "original_path"), PropertyInfo(Variant::BOOL, "use_sub_threads"), PropertyInfo(Variant::INT, "cache_mode"));
 		info.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
 		ClassDB::add_virtual_method(get_class_static(), info);
 	}
@@ -178,7 +178,7 @@ void ResourceFormatLoader::_bind_methods() {
 
 ///////////////////////////////////
 
-RES ResourceLoader::_load(const String &p_path, const String &p_original_path, const String &p_type_hint, bool p_no_cache, Error *r_error, bool p_use_sub_threads, float *r_progress) {
+RES ResourceLoader::_load(const String &p_path, const String &p_original_path, const String &p_type_hint, ResourceFormatLoader::CacheMode p_cache_mode, Error *r_error, bool p_use_sub_threads, float *r_progress) {
 	bool found = false;
 
 	// Try all loaders and pick the first match for the type hint
@@ -187,7 +187,7 @@ RES ResourceLoader::_load(const String &p_path, const String &p_original_path, c
 			continue;
 		}
 		found = true;
-		RES res = loader[i]->load(p_path, p_original_path != String() ? p_original_path : p_path, r_error, p_use_sub_threads, r_progress, p_no_cache);
+		RES res = loader[i]->load(p_path, p_original_path != String() ? p_original_path : p_path, r_error, p_use_sub_threads, r_progress, p_cache_mode);
 		if (res.is_null()) {
 			continue;
 		}
@@ -214,7 +214,7 @@ void ResourceLoader::_thread_load_function(void *p_userdata) {
 		//this is an actual thread, so wait for Ok fom semaphore
 		thread_load_semaphore->wait(); //wait until its ok to start loading
 	}
-	load_task.resource = _load(load_task.remapped_path, load_task.remapped_path != load_task.local_path ? load_task.local_path : String(), load_task.type_hint, false, &load_task.error, load_task.use_sub_threads, &load_task.progress);
+	load_task.resource = _load(load_task.remapped_path, load_task.remapped_path != load_task.local_path ? load_task.local_path : String(), load_task.type_hint, load_task.cache_mode, &load_task.error, load_task.use_sub_threads, &load_task.progress);
 
 	load_task.progress = 1.0; //it was fully loaded at this point, so force progress to 1.0
 
@@ -267,7 +267,7 @@ void ResourceLoader::_thread_load_function(void *p_userdata) {
 	thread_load_mutex->unlock();
 }
 
-Error ResourceLoader::load_threaded_request(const String &p_path, const String &p_type_hint, bool p_use_sub_threads, const String &p_source_resource) {
+Error ResourceLoader::load_threaded_request(const String &p_path, const String &p_type_hint, bool p_use_sub_threads, ResourceFormatLoader::CacheMode p_cache_mode, const String &p_source_resource) {
 	String local_path;
 	if (p_path.is_rel_path()) {
 		local_path = "res://" + p_path;
@@ -314,6 +314,7 @@ Error ResourceLoader::load_threaded_request(const String &p_path, const String &
 		load_task.remapped_path = _path_remap(local_path, &load_task.xl_remapped);
 		load_task.local_path = local_path;
 		load_task.type_hint = p_type_hint;
+		load_task.cache_mode = p_cache_mode;
 		load_task.use_sub_threads = p_use_sub_threads;
 
 		{ //must check if resource is already loaded before attempting to load it in a thread
@@ -501,7 +502,7 @@ RES ResourceLoader::load_threaded_get(const String &p_path, Error *r_error) {
 	return resource;
 }
 
-RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
+RES ResourceLoader::load(const String &p_path, const String &p_type_hint, ResourceFormatLoader::CacheMode p_cache_mode, Error *r_error) {
 	if (r_error) {
 		*r_error = ERR_CANT_OPEN;
 	}
@@ -513,7 +514,7 @@ RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p
 		local_path = ProjectSettings::get_singleton()->localize_path(p_path);
 	}
 
-	if (!p_no_cache) {
+	if (p_cache_mode == ResourceFormatLoader::CACHE_MODE_IGNORE) {
 		thread_load_mutex->lock();
 
 		//Is it already being loaded? poll until done
@@ -561,6 +562,7 @@ RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p
 		load_task.local_path = local_path;
 		load_task.remapped_path = _path_remap(local_path, &load_task.xl_remapped);
 		load_task.type_hint = p_type_hint;
+		load_task.cache_mode = p_cache_mode; //ignore
 		load_task.loader_id = Thread::get_caller_id();
 
 		thread_load_tasks[local_path] = load_task;
@@ -581,7 +583,7 @@ RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p
 
 		print_verbose("Loading resource: " + path);
 		float p;
-		RES res = _load(path, local_path, p_type_hint, p_no_cache, r_error, false, &p);
+		RES res = _load(path, local_path, p_type_hint, p_cache_mode, r_error, false, &p);
 
 		if (res.is_null()) {
 			print_verbose("Failed loading resource: " + path);
diff --git a/core/io/resource_loader.h b/core/io/resource_loader.h
index dbf6be46c5..38a756c52f 100644
--- a/core/io/resource_loader.h
+++ b/core/io/resource_loader.h
@@ -38,11 +38,18 @@
 class ResourceFormatLoader : public Reference {
 	GDCLASS(ResourceFormatLoader, Reference);
 
+public:
+	enum CacheMode {
+		CACHE_MODE_IGNORE, //resource and subresources do not use path cache, no path is set into resource.
+		CACHE_MODE_REUSE, //resource and subresources use patch cache, reuse existing loaded resources instead of loading from disk when available
+		CACHE_MODE_REPLACE, //resource and and subresource use path cache, but replace existing loaded resources when available with information from disk
+	};
+
 protected:
 	static void _bind_methods();
 
 public:
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual bool exists(const String &p_path) const;
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions) const;
@@ -99,7 +106,7 @@ private:
 	friend class ResourceFormatImporter;
 	friend class ResourceInteractiveLoader;
 	//internal load function
-	static RES _load(const String &p_path, const String &p_original_path, const String &p_type_hint, bool p_no_cache, Error *r_error, bool p_use_sub_threads, float *r_progress);
+	static RES _load(const String &p_path, const String &p_original_path, const String &p_type_hint, ResourceFormatLoader::CacheMode p_cache_mode, Error *r_error, bool p_use_sub_threads, float *r_progress);
 
 	static ResourceLoadedCallback _loaded_callback;
 
@@ -114,6 +121,7 @@ private:
 		String type_hint;
 		float progress = 0.0;
 		ThreadLoadStatus status = THREAD_LOAD_IN_PROGRESS;
+		ResourceFormatLoader::CacheMode cache_mode = ResourceFormatLoader::CACHE_MODE_REUSE;
 		Error error = OK;
 		RES resource;
 		bool xl_remapped = false;
@@ -136,11 +144,11 @@ private:
 	static float _dependency_get_progress(const String &p_path);
 
 public:
-	static Error load_threaded_request(const String &p_path, const String &p_type_hint = "", bool p_use_sub_threads = false, const String &p_source_resource = String());
+	static Error load_threaded_request(const String &p_path, const String &p_type_hint = "", bool p_use_sub_threads = false, ResourceFormatLoader::CacheMode p_cache_mode = ResourceFormatLoader::CACHE_MODE_REUSE, const String &p_source_resource = String());
 	static ThreadLoadStatus load_threaded_get_status(const String &p_path, float *r_progress = nullptr);
 	static RES load_threaded_get(const String &p_path, Error *r_error = nullptr);
 
-	static RES load(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false, Error *r_error = nullptr);
+	static RES load(const String &p_path, const String &p_type_hint = "", ResourceFormatLoader::CacheMode p_cache_mode = ResourceFormatLoader::CACHE_MODE_REUSE, Error *r_error = nullptr);
 	static bool exists(const String &p_path, const String &p_type_hint = "");
 
 	static void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions);
diff --git a/core/io/translation_loader_po.cpp b/core/io/translation_loader_po.cpp
index ce2c3eb1cd..0e11ff514a 100644
--- a/core/io/translation_loader_po.cpp
+++ b/core/io/translation_loader_po.cpp
@@ -277,7 +277,7 @@ RES TranslationLoaderPO::load_translation(FileAccess *f, Error *r_error) {
 	return translation;
 }
 
-RES TranslationLoaderPO::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, bool p_no_cache) {
+RES TranslationLoaderPO::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
 	if (r_error) {
 		*r_error = ERR_CANT_OPEN;
 	}
diff --git a/core/io/translation_loader_po.h b/core/io/translation_loader_po.h
index a524972588..36d33fcac3 100644
--- a/core/io/translation_loader_po.h
+++ b/core/io/translation_loader_po.h
@@ -38,7 +38,7 @@
 class TranslationLoaderPO : public ResourceFormatLoader {
 public:
 	static RES load_translation(FileAccess *f, Error *r_error = nullptr);
-	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, bool p_no_cache = false);
+	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual void get_recognized_extensions(List<String> *p_extensions) const;
 	virtual bool handles_type(const String &p_type) const;
 	virtual String get_resource_type(const String &p_path) const;