Merge pull request #85939 from adamscott/single-threaded-godot-4

Add `THREADS_ENABLED` macro in order to compile Godot to run on the main thread

1 files changed, 62 insertions, 2 deletions

diff --git a/core/os/thread.h b/core/os/thread.h
index cc954678f9..a0ecc24c91 100644
--- a/core/os/thread.h
+++ b/core/os/thread.h
@@ -53,6 +53,8 @@
 
 class String;
 
+#ifdef THREADS_ENABLED
+
 class Thread {
 public:
 	typedef void (*Callback)(void *p_userdata);
@@ -86,6 +88,8 @@ public:
 private:
 	friend class Main;
 
+	static PlatformFunctions platform_functions;
+
 	ID id = UNASSIGNED_ID;
 	static SafeNumeric<uint64_t> id_counter;
 	static thread_local ID caller_id;
@@ -93,8 +97,6 @@ private:
 
 	static void callback(ID p_caller_id, const Settings &p_settings, Thread::Callback p_callback, void *p_userdata);
 
-	static PlatformFunctions platform_functions;
-
 	static void make_main_thread() { caller_id = MAIN_ID; }
 	static void release_main_thread() { caller_id = UNASSIGNED_ID; }
 
@@ -125,6 +127,64 @@ public:
 	~Thread();
 };
 
+#else // No threads.
+
+class Thread {
+public:
+	typedef void (*Callback)(void *p_userdata);
+
+	typedef uint64_t ID;
+
+	enum : ID {
+		UNASSIGNED_ID = 0,
+		MAIN_ID = 1
+	};
+
+	enum Priority {
+		PRIORITY_LOW,
+		PRIORITY_NORMAL,
+		PRIORITY_HIGH
+	};
+
+	struct Settings {
+		Priority priority;
+		Settings() { priority = PRIORITY_NORMAL; }
+	};
+
+	struct PlatformFunctions {
+		Error (*set_name)(const String &) = nullptr;
+		void (*set_priority)(Thread::Priority) = nullptr;
+		void (*init)() = nullptr;
+		void (*wrapper)(Thread::Callback, void *) = nullptr;
+		void (*term)() = nullptr;
+	};
+
+private:
+	friend class Main;
+
+	static PlatformFunctions platform_functions;
+
+	static void make_main_thread() {}
+	static void release_main_thread() {}
+
+public:
+	static void _set_platform_functions(const PlatformFunctions &p_functions);
+
+	_FORCE_INLINE_ ID get_id() const { return 0; }
+	_FORCE_INLINE_ static ID get_caller_id() { return MAIN_ID; }
+	_FORCE_INLINE_ static ID get_main_id() { return MAIN_ID; }
+
+	_FORCE_INLINE_ static bool is_main_thread() { return true; }
+
+	static Error set_name(const String &p_name) { return ERR_UNAVAILABLE; }
+
+	void start(Thread::Callback p_callback, void *p_user, const Settings &p_settings = Settings()) {}
+	bool is_started() const { return false; }
+	void wait_to_finish() {}
+};
+
+#endif // THREADS_ENABLED
+
 #endif // THREAD_H
 
 #endif // PLATFORM_THREAD_OVERRIDE