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

1 files changed, 2 insertions, 2 deletions

diff --git a/core/io/resource.h b/core/io/resource.h
index a45bc6e1e4..a2cde87990 100644
--- a/core/io/resource.h
+++ b/core/io/resource.h
@@ -153,7 +153,7 @@ public:
 class ResourceCache {
 	friend class Resource;
 	friend class ResourceLoader; //need the lock
-	static RWLock lock;
+	static Mutex lock;
 	static HashMap<String, Resource *> resources;
 #ifdef TOOLS_ENABLED
 	static HashMap<String, HashMap<String, String>> resource_path_cache; // Each tscn has a set of resource paths and IDs.
@@ -166,7 +166,7 @@ class ResourceCache {
 public:
 	static void reload_externals();
 	static bool has(const String &p_path);
-	static Resource *get(const String &p_path);
+	static Ref<Resource> get_ref(const String &p_path);
 	static void dump(const char *p_file = nullptr, bool p_short = false);
 	static void get_cached_resources(List<Ref<Resource>> *p_resources);
 	static int get_cached_resource_count();