Proof of concept for a hot-reload test case

cmake/godotcpp.cmake

@@ -139,6 +139,9 @@ function(godotcpp_options)
     #TODO compiledb_file
 
     set(GODOTCPP_BUILD_PROFILE "" CACHE PATH "Path to a file containing a feature build profile")
+    if(GODOTCPP_BUILD_PROFILE AND EXISTS "${GODOTCPP_BUILD_PROFILE}")
+        set_property(SOURCE APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS "${GODOTCPP_BUILD_PROFILE}")
+    endif()
 
     set(GODOTCPP_USE_HOT_RELOAD "" CACHE BOOL "Enable the extra accounting required to support hot reload. (ON|OFF)")
 

test/build_profile.json

@@ -8,6 +8,11 @@
 		"OS",
 		"TileMap",
 		"TileSet",
-		"Viewport"
+		"Viewport",
+		"Engine",
+		"DirAccess",
+		"EditorInterface",
+		"GDExtensionManager",
+		"Thread"
 	]
 }

test/project/example.gdextension

@@ -2,6 +2,7 @@
 
 entry_symbol = "example_library_init"
 compatibility_minimum = "4.1"
+reloadable = true
 
 [libraries]
 

test/project/icon.png.import

@@ -18,13 +18,19 @@ dest_files=["res://.godot/imported/icon.png-487276ed1e3a0c39cad0279d744ee560.cte
 compress/mode=0
 compress/high_quality=false
 compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
 compress/hdr_compression=1
 compress/normal_map=0
 compress/channel_pack=0
 mipmaps/generate=false
 mipmaps/limit=-1
 roughness/mode=0
 roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
 process/fix_alpha_border=true
 process/premult_alpha=false
 process/normal_map_invert_y=false

test/project/project.godot

@@ -12,7 +12,7 @@ config_version=5
 
 config/name="GDExtension Test Project"
 run/main_scene="res://main.tscn"
-config/features=PackedStringArray("4.4")
+config/features=PackedStringArray("4.5")
 config/icon="res://icon.png"
 
 [native_extensions]

test/project/reload.gd

@@ -0,0 +1,26 @@
+@tool
+extends Example
+
+func _on_custom_signal( _msg, _value ) -> void:
+	print_rich("[color=green] ******** PASSED ******** [/color]")
+	get_tree().quit(0)
+
+
+func _on_timeout():
+	print_rich("[color=red] ******** FAILED ********[/color]")
+	get_tree().quit(1)
+
+
+func _ready() -> void:
+	# Dont quit if the reload test isn't specified on the command line.
+	if not 'test_reload' in OS.get_cmdline_args(): return
+
+	print("gdscript:Reload Test is Enabled")
+	# Connect to the custom signal of Example
+	custom_signal.connect(_on_custom_signal)
+
+	# Start 5s watchdog timer
+	var timer = get_tree().create_timer(10.0)
+	timer.timeout.connect(_on_timeout)
+
+	print("Awaiting Custom Signal (with 10s timeout)")

test/project/reload.gd.uid

@@ -0,0 +1 @@
+uid://c8v75k3p4pnjj

test/project/reload.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://b4wrd36npp8ov"]
+
+[ext_resource type="Script" uid="uid://c8v75k3p4pnjj" path="res://reload.gd" id="1_icw2l"]
+
+[node name="Reload" type="Example"]
+script = ExtResource("1_icw2l")

test/run-tests.ps1

@@ -0,0 +1,82 @@
+# Define Godot executable (uses environment variable if set, else defaults to 'godot')
+$GODOT = if ($env:GODOT) { $env:GODOT } else { 'godot' }
+
+$END_STRING = "==== TESTS FINISHED ===="
+$FAILURE_STRING = "******** FAILED ********"
+$HAS_FAILURE = 0
+
+# Function to filter spam from output
+function Filter-Output {
+    param([string[]]$Lines)
+    $Lines | ForEach-Object { $_.TrimEnd() } | Where-Object {
+        $_ -notmatch "Narrowing conversion" -and
+        $_ -notmatch "at:\s+GDScript::reload" -and
+        $_ -notmatch "\[\s*\d+%\s*\]" -and
+        $_ -notmatch "first_scan_filesystem" -and
+        $_ -notmatch "loading_editor_layout"
+    }
+}
+
+# Run Godot and capture output and exit code
+try {
+    $OUTPUT = & $GODOT --path project --debug --headless --quit 2>&1
+    $ERRCODE = $LASTEXITCODE
+}
+catch {
+    $OUTPUT = $_.Exception.Message
+    $ERRCODE = 1
+}
+
+# Output the results
+Write-Output $OUTPUT
+Write-Output ""
+
+# Check if tests completed
+if (-not ($OUTPUT -match [regex]::Escape($END_STRING))) {
+    $HAS_FAILURE += 1
+}
+
+# Check for test failures
+if ($OUTPUT -match [regex]::Escape($FAILURE_STRING)) {
+    $HAS_FAILURE += 1
+}
+
+# Lock file path (relative to project dir)
+$LOCK_PATH = "project/test_reload_lock"
+
+# Delete lock file before reload test if it exists
+Remove-Item -Path $LOCK_PATH -Force -ErrorAction SilentlyContinue
+
+# Run Godot and capture output and exit code
+try {
+    $OUTPUT = & $GODOT -e --path project --scene reload.tscn --headless --debug test_reload 2>&1
+    $ERRCODE = $LASTEXITCODE
+}
+catch {
+    $OUTPUT = $_.Exception.Message
+    $ERRCODE = 1
+}
+
+# Filter and output the results
+$FilteredOutput = Filter-Output -Lines ($OUTPUT -split "`n")
+Write-Output ($FilteredOutput -join "`n")
+Write-Output ""
+
+# Check for test failures
+if ($OUTPUT -match [regex]::Escape($FAILURE_STRING)) {
+    $HAS_FAILURE += 1
+}
+
+# Lock file path (relative to project dir)
+$LOCK_PATH = "project/test_reload_lock"
+
+# Delete lock file before reload test if it exists
+Remove-Item -Path $LOCK_PATH -Force -ErrorAction SilentlyContinue
+
+if ($HAS_FAILURE -gt 0 ){
+    Write-Output "ERROR: Tests failed to complete"
+    exit 1
+}
+
+# Success!
+exit 0

test/src/example.cpp

@@ -114,6 +114,9 @@ void Example::_notification(int p_what) {
 		rpc_config("test_rpc", opts);
 	}
 	//UtilityFunctions::print("Notification: ", String::num(p_what));
+	if (p_what == NOTIFICATION_EXTENSION_RELOADED) {
+		emit_custom_signal("NOTIFICATION_EXTENSION_RELOADED ", 0);
+	}
 }
 
 bool Example::_set(const StringName &p_name, const Variant &p_value) {

test/src/register_types.cpp

@@ -12,38 +12,118 @@
 #include <godot_cpp/godot.hpp>
 
 #include "example.h"
+#include "godot_cpp/classes/dir_access.hpp"
+#include "godot_cpp/classes/editor_interface.hpp"
+#include "godot_cpp/classes/file_access.hpp"
+#include "godot_cpp/classes/gd_extension_manager.hpp"
+#include "godot_cpp/classes/thread.hpp"
 #include "tests.h"
 
+#include <chrono>
+
 using namespace godot;
+using std::chrono_literals::operator""s;
 
-void initialize_example_module(ModuleInitializationLevel p_level) {
-	if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
+// Global flag to control the timer thread
+std::atomic keep_running(true);
+
+// Minimal static worker, no class needed
+static void timer_thread_function(int interval_ms);
+
+// Global thread ref
+static Ref<Thread> g_reload_thread;
+
+// Function to simulate extension reload
+void trigger_extension_reload() {
+	// Loop if the scene is not yet loaded.
+	if (const EditorInterface *ei = EditorInterface::get_singleton();
+			!ei->get_edited_scene_root()) {
 		return;
 	}
+	keep_running = false;
+
+	// Trigger the Reload
+	const auto gdextension_path = String{ "res://example.gdextension" };
+	if (GDExtensionManager *ext_manager = GDExtensionManager::get_singleton()) {
+		ext_manager->call_deferred("reload_extension", gdextension_path);
+		UtilityFunctions::print("Simulating GDExtension reload...");
+	}
+}
+
+void timer_thread_function(const int interval_ms) {
+	while (keep_running) {
+		OS::get_singleton()->delay_msec(interval_ms);
+		trigger_extension_reload();
+	}
+}
+
+void initialize_example_module(ModuleInitializationLevel p_level) {
+	if (p_level == MODULE_INITIALIZATION_LEVEL_SCENE) {
+		UtilityFunctions::print("Initializing Integration Testing Extension");
+		GDREGISTER_CLASS(ExampleRef);
+		GDREGISTER_CLASS(ExampleMin);
+		GDREGISTER_CLASS(Example);
+		GDREGISTER_VIRTUAL_CLASS(ExampleVirtual);
+		GDREGISTER_ABSTRACT_CLASS(ExampleAbstractBase);
+		GDREGISTER_CLASS(ExampleConcrete);
+		GDREGISTER_CLASS(ExampleBase);
+		GDREGISTER_CLASS(ExampleChild);
+		GDREGISTER_RUNTIME_CLASS(ExampleRuntime);
+		GDREGISTER_CLASS(ExamplePrzykład);
+		GDREGISTER_INTERNAL_CLASS(ExampleInternal);
+	} else if (p_level == MODULE_INITIALIZATION_LEVEL_EDITOR) {
+		if (OS::get_singleton()->get_cmdline_args().has("test_reload")) {
+			UtilityFunctions::print("Test Reload is enabled");
+			const String lock_path = "res://test_reload_lock";
+			if (FileAccess::file_exists(lock_path)) {
+				UtilityFunctions::print("Lock File Exists");
+			} else {
+				UtilityFunctions::print("Creating Timer Thread");
+				// Start reload thread with a 3s loop timer.
+				g_reload_thread.instantiate();
+				g_reload_thread->start(callable_mp_static(&timer_thread_function).bind(3000));
 
-	GDREGISTER_CLASS(ExampleRef);
-	GDREGISTER_CLASS(ExampleMin);
-	GDREGISTER_CLASS(Example);
-	GDREGISTER_VIRTUAL_CLASS(ExampleVirtual);
-	GDREGISTER_ABSTRACT_CLASS(ExampleAbstractBase);
-	GDREGISTER_CLASS(ExampleConcrete);
-	GDREGISTER_CLASS(ExampleBase);
-	GDREGISTER_CLASS(ExampleChild);
-	GDREGISTER_RUNTIME_CLASS(ExampleRuntime);
-	GDREGISTER_CLASS(ExamplePrzykład);
-	GDREGISTER_INTERNAL_CLASS(ExampleInternal);
+				// Create the lock file to prevent future inits from starting duplicates.
+				if (const Ref<FileAccess> lock_file = FileAccess::open(lock_path, FileAccess::WRITE); lock_file.is_valid()) {
+					UtilityFunctions::print("Creating Lock File");
+					lock_file->close();
+				} else {
+					UtilityFunctions::print("Warning: Failed to create lock file.");
+				}
+			}
+		}
+	}
 }
 
 void uninitialize_example_module(ModuleInitializationLevel p_level) {
-	if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
-		return;
+	if (p_level == MODULE_INITIALIZATION_LEVEL_SCENE) {
+		UtilityFunctions::print("Uninitializing Integration Testing Extension");
+	} else if (p_level == MODULE_INITIALIZATION_LEVEL_EDITOR) {
+		// Stop the timer thread when deinitializing
+		keep_running = false;
+
+		// Join reload thread if ever started
+		if (g_reload_thread.is_valid()) {
+			UtilityFunctions::print("Waiting for reload thread to finish...");
+			// Loop-check for race safety (up to ~3s max, your interval)
+			for (int i = 0; i < 10; ++i) { // Arbitrary retries; adjust if needed
+				if (g_reload_thread->is_alive()) {
+					OS::get_singleton()->delay_msec(300); // Short poll delay
+				} else {
+					break;
+				}
+			}
+			g_reload_thread->wait_to_finish(); // Blocks until done; safe even if not alive
+			g_reload_thread.unref();
+			UtilityFunctions::print("Reload thread joined.");
+		}
 	}
 }
 
 extern "C" {
 // Initialization.
 GDExtensionBool GDE_EXPORT example_library_init(GDExtensionInterfaceGetProcAddress p_get_proc_address, GDExtensionClassLibraryPtr p_library, GDExtensionInitialization *r_initialization) {
-	godot::GDExtensionBinding::InitObject init_obj(p_get_proc_address, p_library, r_initialization);
+	GDExtensionBinding::InitObject init_obj(p_get_proc_address, p_library, r_initialization);
 
 	init_obj.register_initializer(initialize_example_module);
 	init_obj.register_terminator(uninitialize_example_module);