Remake resource thread safety and API

* Ensures thread safety when resources are destroyed.
* Simplified API by always forcing `ResourceCache::get_ref`, which needs less hacks and is fully thread safe.
* Removed RWLock for resources because its not possible to use for the new logic. Should not be a problem.

Supersedes #57533

2 files changed, 12 insertions, 14 deletions

diff --git a/scene/debugger/scene_debugger.cpp b/scene/debugger/scene_debugger.cpp
index a54e728c1b..e9c33b1839 100644
--- a/scene/debugger/scene_debugger.cpp
+++ b/scene/debugger/scene_debugger.cpp
@@ -701,7 +701,7 @@ void LiveEditor::_res_set_func(int p_id, const StringName &p_prop, const Variant
 		return;
 	}
 
-	Ref<Resource> r = ResourceCache::get(resp);
+	Ref<Resource> r = ResourceCache::get_ref(resp);
 	if (!r.is_valid()) {
 		return;
 	}
@@ -728,7 +728,7 @@ void LiveEditor::_res_call_func(int p_id, const StringName &p_method, const Vari
 		return;
 	}
 
-	Ref<Resource> r = ResourceCache::get(resp);
+	Ref<Resource> r = ResourceCache::get_ref(resp);
 	if (!r.is_valid()) {
 		return;
 	}
diff --git a/scene/resources/resource_format_text.cpp b/scene/resources/resource_format_text.cpp
index 0320585b5a..5080517707 100644
--- a/scene/resources/resource_format_text.cpp
+++ b/scene/resources/resource_format_text.cpp
@@ -528,9 +528,9 @@ Error ResourceLoaderText::load() {
 
 		if (cache_mode == ResourceFormatLoader::CACHE_MODE_REPLACE && ResourceCache::has(path)) {
 			//reuse existing
-			Resource *r = ResourceCache::get(path);
-			if (r && r->get_class() == type) {
-				res = Ref<Resource>(r);
+			Ref<Resource> cache = ResourceCache::get_ref(path);
+			if (cache.is_valid() && cache->get_class() == type) {
+				res = cache;
 				res->reset_state();
 				do_assign = true;
 			}
@@ -539,10 +539,10 @@ Error ResourceLoaderText::load() {
 		MissingResource *missing_resource = nullptr;
 
 		if (res.is_null()) { //not reuse
-			if (cache_mode != ResourceFormatLoader::CACHE_MODE_IGNORE && ResourceCache::has(path)) { //only if it doesn't exist
+			Ref<Resource> cache = ResourceCache::get_ref(path);
+			if (cache_mode != ResourceFormatLoader::CACHE_MODE_IGNORE && cache.is_valid()) { //only if it doesn't exist
 				//cached, do not assign
-				Resource *r = ResourceCache::get(path);
-				res = Ref<Resource>(r);
+				res = cache;
 			} else {
 				//create
 
@@ -652,12 +652,10 @@ Error ResourceLoaderText::load() {
 			return error;
 		}
 
-		if (cache_mode == ResourceFormatLoader::CACHE_MODE_REPLACE && ResourceCache::has(local_path)) {
-			Resource *r = ResourceCache::get(local_path);
-			if (r->get_class() == res_type) {
-				r->reset_state();
-				resource = Ref<Resource>(r);
-			}
+		Ref<Resource> cache = ResourceCache::get_ref(local_path);
+		if (cache_mode == ResourceFormatLoader::CACHE_MODE_REPLACE && cache.is_valid() && cache->get_class() == res_type) {
+			cache->reset_state();
+			resource = cache;
 		}
 
 		MissingResource *missing_resource = nullptr;