From cde478bda6a7ca5239daf96d0fd3cb6344c064a6 Mon Sep 17 00:00:00 2001
From: rune-scape <allie.smith.epic@gmail.com>
Date: Fri, 29 Dec 2023 23:06:54 -0800
Subject: [PATCH] Hot-reload only changed scripts

---
 core/debugger/remote_debugger.cpp             | 31 +++++++++++++++----
 core/debugger/remote_debugger.h               |  1 +
 core/object/script_language.h                 |  1 +
 core/object/script_language_extension.h       |  1 +
 editor/debugger/editor_debugger_node.cpp      | 10 ++++--
 editor/debugger/editor_debugger_node.h        |  3 +-
 editor/debugger/script_editor_debugger.cpp    |  8 +++--
 editor/debugger/script_editor_debugger.h      |  3 +-
 editor/plugins/script_editor_plugin.cpp       | 26 ++++++++++++++--
 editor/plugins/script_editor_plugin.h         |  5 ++-
 editor/plugins/script_text_editor.cpp         |  2 +-
 modules/gdscript/gdscript.cpp                 | 29 +++++++++--------
 modules/gdscript/gdscript.h                   |  1 +
 .../gdscript_text_document.cpp                |  2 +-
 modules/mono/csharp_script.cpp                | 23 ++++++++++++--
 modules/mono/csharp_script.h                  |  1 +
 modules/mono/editor/editor_internal_calls.cpp |  4 +--
 17 files changed, 113 insertions(+), 38 deletions(-)

diff --git a/core/debugger/remote_debugger.cpp b/core/debugger/remote_debugger.cpp
index a817ea871d42..cde9e05d79e1 100644
--- a/core/debugger/remote_debugger.cpp
+++ b/core/debugger/remote_debugger.cpp
@@ -36,6 +36,7 @@
 #include "core/debugger/engine_profiler.h"
 #include "core/debugger/script_debugger.h"
 #include "core/input/input.h"
+#include "core/io/resource_loader.h"
 #include "core/object/script_language.h"
 #include "core/os/os.h"
 
@@ -515,8 +516,9 @@ void RemoteDebugger::debug(bool p_can_continue, bool p_is_error_breakpoint) {
 				_send_stack_vars(globals, globals_vals, 2);
 
 			} else if (command == "reload_scripts") {
+				script_paths_to_reload = data;
+			} else if (command == "reload_all_scripts") {
 				reload_all_scripts = true;
-
 			} else if (command == "breakpoint") {
 				ERR_FAIL_COND(data.size() < 3);
 				bool set = data[2];
@@ -591,19 +593,36 @@ void RemoteDebugger::poll_events(bool p_is_idle) {
 	}
 
 	// Reload scripts during idle poll only.
-	if (p_is_idle && reload_all_scripts) {
-		for (int i = 0; i < ScriptServer::get_language_count(); i++) {
-			ScriptServer::get_language(i)->reload_all_scripts();
+	if (p_is_idle) {
+		if (reload_all_scripts) {
+			for (int i = 0; i < ScriptServer::get_language_count(); i++) {
+				ScriptServer::get_language(i)->reload_all_scripts();
+			}
+			reload_all_scripts = false;
+		} else if (!script_paths_to_reload.is_empty()) {
+			Array scripts_to_reload;
+			for (int i = 0; i < script_paths_to_reload.size(); ++i) {
+				String path = script_paths_to_reload[i];
+				Error err = OK;
+				Ref<Script> script = ResourceLoader::load(path, "", ResourceFormatLoader::CACHE_MODE_REUSE, &err);
+				ERR_CONTINUE_MSG(err != OK, vformat("Could not reload script '%s': %s", path, error_names[err]));
+				ERR_CONTINUE_MSG(script.is_null(), vformat("Could not reload script '%s': Not a script!", path, error_names[err]));
+				scripts_to_reload.push_back(script);
+			}
+			for (int i = 0; i < ScriptServer::get_language_count(); i++) {
+				ScriptServer::get_language(i)->reload_scripts(scripts_to_reload, true);
+			}
 		}
-		reload_all_scripts = false;
+		script_paths_to_reload.clear();
 	}
 }
 
 Error RemoteDebugger::_core_capture(const String &p_cmd, const Array &p_data, bool &r_captured) {
 	r_captured = true;
 	if (p_cmd == "reload_scripts") {
+		script_paths_to_reload = p_data;
+	} else if (p_cmd == "reload_all_scripts") {
 		reload_all_scripts = true;
-
 	} else if (p_cmd == "breakpoint") {
 		ERR_FAIL_COND_V(p_data.size() < 3, ERR_INVALID_DATA);
 		bool set = p_data[2];
diff --git a/core/debugger/remote_debugger.h b/core/debugger/remote_debugger.h
index 7c399178c66f..519a90e7cc23 100644
--- a/core/debugger/remote_debugger.h
+++ b/core/debugger/remote_debugger.h
@@ -74,6 +74,7 @@ class RemoteDebugger : public EngineDebugger {
 	int warn_count = 0;
 	int last_reset = 0;
 	bool reload_all_scripts = false;
+	Array script_paths_to_reload;
 
 	// Make handlers and send_message thread safe.
 	Mutex mutex;
diff --git a/core/object/script_language.h b/core/object/script_language.h
index 69da50f0742f..5d7058ebb763 100644
--- a/core/object/script_language.h
+++ b/core/object/script_language.h
@@ -371,6 +371,7 @@ class ScriptLanguage : public Object {
 	virtual Vector<StackInfo> debug_get_current_stack_info() { return Vector<StackInfo>(); }
 
 	virtual void reload_all_scripts() = 0;
+	virtual void reload_scripts(const Array &p_scripts, bool p_soft_reload) = 0;
 	virtual void reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) = 0;
 	/* LOADER FUNCTIONS */
 
diff --git a/core/object/script_language_extension.h b/core/object/script_language_extension.h
index 852b2aebd882..2166cbe07dc1 100644
--- a/core/object/script_language_extension.h
+++ b/core/object/script_language_extension.h
@@ -562,6 +562,7 @@ class ScriptLanguageExtension : public ScriptLanguage {
 	}
 
 	EXBIND0(reload_all_scripts)
+	EXBIND2(reload_scripts, const Array &, bool)
 	EXBIND2(reload_tool_script, const Ref<Script> &, bool)
 	/* LOADER FUNCTIONS */
 
diff --git a/editor/debugger/editor_debugger_node.cpp b/editor/debugger/editor_debugger_node.cpp
index 8229abb5a027..05c769f36ca5 100644
--- a/editor/debugger/editor_debugger_node.cpp
+++ b/editor/debugger/editor_debugger_node.cpp
@@ -593,9 +593,15 @@ void EditorDebuggerNode::set_breakpoints(const String &p_path, Array p_lines) {
 	}
 }
 
-void EditorDebuggerNode::reload_scripts() {
+void EditorDebuggerNode::reload_all_scripts() {
 	_for_all(tabs, [&](ScriptEditorDebugger *dbg) {
-		dbg->reload_scripts();
+		dbg->reload_all_scripts();
+	});
+}
+
+void EditorDebuggerNode::reload_scripts(const Vector<String> &p_script_paths) {
+	_for_all(tabs, [&](ScriptEditorDebugger *dbg) {
+		dbg->reload_scripts(p_script_paths);
 	});
 }
 
diff --git a/editor/debugger/editor_debugger_node.h b/editor/debugger/editor_debugger_node.h
index 4338f144b879..d30f29c7c673 100644
--- a/editor/debugger/editor_debugger_node.h
+++ b/editor/debugger/editor_debugger_node.h
@@ -187,7 +187,8 @@ class EditorDebuggerNode : public MarginContainer {
 	bool is_skip_breakpoints() const;
 	void set_breakpoint(const String &p_path, int p_line, bool p_enabled);
 	void set_breakpoints(const String &p_path, Array p_lines);
-	void reload_scripts();
+	void reload_all_scripts();
+	void reload_scripts(const Vector<String> &p_script_paths);
 
 	// Remote inspector/edit.
 	void request_remote_tree();
diff --git a/editor/debugger/script_editor_debugger.cpp b/editor/debugger/script_editor_debugger.cpp
index 7077bce9f76f..665578342b0c 100644
--- a/editor/debugger/script_editor_debugger.cpp
+++ b/editor/debugger/script_editor_debugger.cpp
@@ -1518,8 +1518,12 @@ void ScriptEditorDebugger::set_breakpoint(const String &p_path, int p_line, bool
 	}
 }
 
-void ScriptEditorDebugger::reload_scripts() {
-	_put_msg("reload_scripts", Array(), debugging_thread_id != Thread::UNASSIGNED_ID ? debugging_thread_id : Thread::MAIN_ID);
+void ScriptEditorDebugger::reload_all_scripts() {
+	_put_msg("reload_all_scripts", Array(), debugging_thread_id != Thread::UNASSIGNED_ID ? debugging_thread_id : Thread::MAIN_ID);
+}
+
+void ScriptEditorDebugger::reload_scripts(const Vector<String> &p_script_paths) {
+	_put_msg("reload_scripts", Variant(p_script_paths).operator Array(), debugging_thread_id != Thread::UNASSIGNED_ID ? debugging_thread_id : Thread::MAIN_ID);
 }
 
 bool ScriptEditorDebugger::is_skip_breakpoints() {
diff --git a/editor/debugger/script_editor_debugger.h b/editor/debugger/script_editor_debugger.h
index 79224061ffd8..589e82ef25aa 100644
--- a/editor/debugger/script_editor_debugger.h
+++ b/editor/debugger/script_editor_debugger.h
@@ -300,7 +300,8 @@ class ScriptEditorDebugger : public MarginContainer {
 
 	void update_live_edit_root();
 
-	void reload_scripts();
+	void reload_all_scripts();
+	void reload_scripts(const Vector<String> &p_script_paths);
 
 	bool is_skip_breakpoints();
 
diff --git a/editor/plugins/script_editor_plugin.cpp b/editor/plugins/script_editor_plugin.cpp
index c1a65b7bb7ac..6bd320fb65bd 100644
--- a/editor/plugins/script_editor_plugin.cpp
+++ b/editor/plugins/script_editor_plugin.cpp
@@ -1001,7 +1001,10 @@ void ScriptEditor::_res_saved_callback(const Ref<Resource> &p_res) {
 	}
 
 	_update_script_names();
-	trigger_live_script_reload();
+	Ref<Script> scr = p_res;
+	if (scr.is_valid()) {
+		trigger_live_script_reload(scr->get_path());
+	}
 }
 
 void ScriptEditor::_scene_saved_callback(const String &p_path) {
@@ -1029,16 +1032,33 @@ void ScriptEditor::_scene_saved_callback(const String &p_path) {
 	}
 }
 
-void ScriptEditor::trigger_live_script_reload() {
+void ScriptEditor::trigger_live_script_reload(const String &p_script_path) {
+	if (!script_paths_to_reload.has(p_script_path)) {
+		script_paths_to_reload.append(p_script_path);
+	}
 	if (!pending_auto_reload && auto_reload_running_scripts) {
 		call_deferred(SNAME("_live_auto_reload_running_scripts"));
 		pending_auto_reload = true;
 	}
 }
 
+void ScriptEditor::trigger_live_script_reload_all() {
+	if (!pending_auto_reload && auto_reload_running_scripts) {
+		call_deferred(SNAME("_live_auto_reload_running_scripts"));
+		pending_auto_reload = true;
+		reload_all_scripts = true;
+	}
+}
+
 void ScriptEditor::_live_auto_reload_running_scripts() {
 	pending_auto_reload = false;
-	EditorDebuggerNode::get_singleton()->reload_scripts();
+	if (reload_all_scripts) {
+		EditorDebuggerNode::get_singleton()->reload_all_scripts();
+	} else {
+		EditorDebuggerNode::get_singleton()->reload_scripts(script_paths_to_reload);
+	}
+	reload_all_scripts = false;
+	script_paths_to_reload.clear();
 }
 
 bool ScriptEditor::_test_script_times_on_disk(Ref<Resource> p_for_script) {
diff --git a/editor/plugins/script_editor_plugin.h b/editor/plugins/script_editor_plugin.h
index 4a814ea1bcc6..68eb23c83810 100644
--- a/editor/plugins/script_editor_plugin.h
+++ b/editor/plugins/script_editor_plugin.h
@@ -382,6 +382,8 @@ class ScriptEditor : public PanelContainer {
 
 	bool pending_auto_reload;
 	bool auto_reload_running_scripts;
+	bool reload_all_scripts = false;
+	Vector<String> script_paths_to_reload;
 	void _live_auto_reload_running_scripts();
 
 	void _update_selected_editor_menu();
@@ -542,7 +544,8 @@ class ScriptEditor : public PanelContainer {
 	void clear_docs_from_script(const Ref<Script> &p_script);
 	void update_docs_from_script(const Ref<Script> &p_script);
 
-	void trigger_live_script_reload();
+	void trigger_live_script_reload(const String &p_script_path);
+	void trigger_live_script_reload_all();
 
 	bool can_take_away_focus() const;
 
diff --git a/editor/plugins/script_text_editor.cpp b/editor/plugins/script_text_editor.cpp
index eb934da4dd3d..a9f44a67f036 100644
--- a/editor/plugins/script_text_editor.cpp
+++ b/editor/plugins/script_text_editor.cpp
@@ -822,7 +822,7 @@ void ScriptEditor::_update_modified_scripts_for_external_editor(Ref<Script> p_fo
 			scr->set_last_modified_time(rel_scr->get_last_modified_time());
 			scr->update_exports();
 
-			trigger_live_script_reload();
+			trigger_live_script_reload(scr->get_path());
 		}
 	}
 }
diff --git a/modules/gdscript/gdscript.cpp b/modules/gdscript/gdscript.cpp
index a999acd1bd0d..c4dd79f26f39 100644
--- a/modules/gdscript/gdscript.cpp
+++ b/modules/gdscript/gdscript.cpp
@@ -2373,14 +2373,13 @@ struct GDScriptDepSort {
 void GDScriptLanguage::reload_all_scripts() {
 #ifdef DEBUG_ENABLED
 	print_verbose("GDScript: Reloading all scripts");
-	List<Ref<GDScript>> scripts;
+	Array scripts;
 	{
 		MutexLock lock(this->mutex);
 
 		SelfList<GDScript> *elem = script_list.first();
 		while (elem) {
-			// Scripts will reload all subclasses, so only reload root scripts.
-			if (elem->self()->is_root_script() && elem->self()->get_path().is_resource_file()) {
+			if (elem->self()->get_path().is_resource_file()) {
 				print_verbose("GDScript: Found: " + elem->self()->get_path());
 				scripts.push_back(Ref<GDScript>(elem->self())); //cast to gdscript to avoid being erased by accident
 			}
@@ -2401,19 +2400,11 @@ void GDScriptLanguage::reload_all_scripts() {
 #endif
 	}
 
-	//as scripts are going to be reloaded, must proceed without locking here
-
-	scripts.sort_custom<GDScriptDepSort>(); //update in inheritance dependency order
-
-	for (Ref<GDScript> &scr : scripts) {
-		print_verbose("GDScript: Reloading: " + scr->get_path());
-		scr->load_source_code(scr->get_path());
-		scr->reload(true);
-	}
+	reload_scripts(scripts, true);
 #endif
 }
 
-void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) {
+void GDScriptLanguage::reload_scripts(const Array &p_scripts, bool p_soft_reload) {
 #ifdef DEBUG_ENABLED
 
 	List<Ref<GDScript>> scripts;
@@ -2439,7 +2430,7 @@ void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_so
 	scripts.sort_custom<GDScriptDepSort>(); //update in inheritance dependency order
 
 	for (Ref<GDScript> &scr : scripts) {
-		bool reload = scr == p_script || to_reload.has(scr->get_base());
+		bool reload = p_scripts.has(scr) || to_reload.has(scr->get_base());
 
 		if (!reload) {
 			continue;
@@ -2462,7 +2453,7 @@ void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_so
 				}
 			}
 
-//same thing for placeholders
+			//same thing for placeholders
 #ifdef TOOLS_ENABLED
 
 			while (scr->placeholders.size()) {
@@ -2490,6 +2481,8 @@ void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_so
 
 	for (KeyValue<Ref<GDScript>, HashMap<ObjectID, List<Pair<StringName, Variant>>>> &E : to_reload) {
 		Ref<GDScript> scr = E.key;
+		print_verbose("GDScript: Reloading: " + scr->get_path());
+		scr->load_source_code(scr->get_path());
 		scr->reload(p_soft_reload);
 
 		//restore state if saved
@@ -2537,6 +2530,12 @@ void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_so
 #endif
 }
 
+void GDScriptLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) {
+	Array scripts;
+	scripts.push_back(p_script);
+	reload_scripts(scripts, p_soft_reload);
+}
+
 void GDScriptLanguage::frame() {
 	calls = 0;
 
diff --git a/modules/gdscript/gdscript.h b/modules/gdscript/gdscript.h
index 31811bba47a9..73df98dafa0d 100644
--- a/modules/gdscript/gdscript.h
+++ b/modules/gdscript/gdscript.h
@@ -581,6 +581,7 @@ class GDScriptLanguage : public ScriptLanguage {
 	virtual String debug_parse_stack_level_expression(int p_level, const String &p_expression, int p_max_subitems = -1, int p_max_depth = -1) override;
 
 	virtual void reload_all_scripts() override;
+	virtual void reload_scripts(const Array &p_scripts, bool p_soft_reload) override;
 	virtual void reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) override;
 
 	virtual void frame() override;
diff --git a/modules/gdscript/language_server/gdscript_text_document.cpp b/modules/gdscript/language_server/gdscript_text_document.cpp
index 0b1371851b4b..1d8ed872e567 100644
--- a/modules/gdscript/language_server/gdscript_text_document.cpp
+++ b/modules/gdscript/language_server/gdscript_text_document.cpp
@@ -114,7 +114,7 @@ void GDScriptTextDocument::didSave(const Variant &p_param) {
 		scr->update_exports();
 		ScriptEditor::get_singleton()->reload_scripts(true);
 		ScriptEditor::get_singleton()->update_docs_from_script(scr);
-		ScriptEditor::get_singleton()->trigger_live_script_reload();
+		ScriptEditor::get_singleton()->trigger_live_script_reload(scr->get_path());
 	}
 }
 
diff --git a/modules/mono/csharp_script.cpp b/modules/mono/csharp_script.cpp
index 8e1587997b97..c6c03cec7a14 100644
--- a/modules/mono/csharp_script.cpp
+++ b/modules/mono/csharp_script.cpp
@@ -720,11 +720,22 @@ void CSharpLanguage::reload_all_scripts() {
 #endif
 }
 
-void CSharpLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) {
-	(void)p_script; // UNUSED
-
+void CSharpLanguage::reload_scripts(const Array &p_scripts, bool p_soft_reload) {
 	CRASH_COND(!Engine::get_singleton()->is_editor_hint());
 
+	bool has_csharp_script = false;
+	for (int i = 0; i < p_scripts.size(); ++i) {
+		Ref<CSharpScript> cs_script = p_scripts[i];
+		if (cs_script.is_valid()) {
+			has_csharp_script = true;
+			break;
+		}
+	}
+
+	if (!has_csharp_script) {
+		return;
+	}
+
 #ifdef TOOLS_ENABLED
 	get_godotsharp_editor()->get_node(NodePath("HotReloadAssemblyWatcher"))->call("RestartTimer");
 #endif
@@ -736,6 +747,12 @@ void CSharpLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_soft
 #endif
 }
 
+void CSharpLanguage::reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) {
+	Array scripts;
+	scripts.push_back(p_script);
+	reload_scripts(scripts, p_soft_reload);
+}
+
 #ifdef GD_MONO_HOT_RELOAD
 bool CSharpLanguage::is_assembly_reloading_needed() {
 	ERR_FAIL_NULL_V(gdmono, false);
diff --git a/modules/mono/csharp_script.h b/modules/mono/csharp_script.h
index 401f5c62e558..18ff4db43aed 100644
--- a/modules/mono/csharp_script.h
+++ b/modules/mono/csharp_script.h
@@ -478,6 +478,7 @@ class CSharpLanguage : public ScriptLanguage {
 	/* TODO? */ void get_public_annotations(List<MethodInfo> *p_annotations) const override {}
 
 	void reload_all_scripts() override;
+	void reload_scripts(const Array &p_scripts, bool p_soft_reload) override;
 	void reload_tool_script(const Ref<Script> &p_script, bool p_soft_reload) override;
 
 	/* LOADER FUNCTIONS */
diff --git a/modules/mono/editor/editor_internal_calls.cpp b/modules/mono/editor/editor_internal_calls.cpp
index fc99f3ceda1d..8349719f2d9f 100644
--- a/modules/mono/editor/editor_internal_calls.cpp
+++ b/modules/mono/editor/editor_internal_calls.cpp
@@ -148,7 +148,7 @@ void godot_icall_Internal_ReloadAssemblies(bool p_soft_reload) {
 }
 
 void godot_icall_Internal_EditorDebuggerNodeReloadScripts() {
-	EditorDebuggerNode::get_singleton()->reload_scripts();
+	EditorDebuggerNode::get_singleton()->reload_all_scripts();
 }
 
 bool godot_icall_Internal_ScriptEditorEdit(Resource *p_resource, int32_t p_line, int32_t p_col, bool p_grab_focus) {
@@ -175,7 +175,7 @@ void godot_icall_Internal_EditorPlugin_AddControlToEditorRunBar(Control *p_contr
 void godot_icall_Internal_ScriptEditorDebugger_ReloadScripts() {
 	EditorDebuggerNode *ed = EditorDebuggerNode::get_singleton();
 	if (ed) {
-		ed->reload_scripts();
+		ed->reload_all_scripts();
 	}
 }