From 9303b0225e4092c9e28207010ec611f655ac0765 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alf-Andr=C3=A9=20Walla?= <fwsgonzo@hotmail.com>
Date: Sat, 26 Oct 2024 13:32:08 +0200
Subject: [PATCH] Implement hot-reloading support for ELFScript

---
 src/elf/script_elf.cpp | 17 ++++++++++++++---
 src/elf/script_elf.h   |  5 +++++
 src/sandbox.cpp        | 16 ++++++++++++++--
 src/sandbox.h          |  1 +
 4 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/elf/script_elf.cpp b/src/elf/script_elf.cpp
index 3a9c81c..f2f3d79 100644
--- a/src/elf/script_elf.cpp
+++ b/src/elf/script_elf.cpp
@@ -271,7 +271,15 @@ String ELFScript::get_elf_programming_language() const {
 
 void ELFScript::set_file(const String &p_path) {
 	path = p_path;
-	source_code = FileAccess::get_file_as_bytes(path);
+	PackedByteArray new_source_code = FileAccess::get_file_as_bytes(path);
+	if (new_source_code == source_code) {
+		if constexpr (VERBOSE_ELFSCRIPT) {
+			printf("ELFScript::set_file: No changes in %s\n", path.utf8().ptr());
+		}
+		return;
+	}
+	source_code = std::move(new_source_code);
+
 	global_name = "Sandbox_" + path.get_basename().replace("res://", "").replace("/", "_").replace("-", "_").capitalize().replace(" ", "");
 	Sandbox::BinaryInfo info = Sandbox::get_program_info_from_binary(source_code);
 	info.functions.sort();
@@ -279,8 +287,11 @@ void ELFScript::set_file(const String &p_path) {
 	this->elf_programming_language = info.language;
 	this->elf_api_version = info.version;
 
-	for (ELFScriptInstance *instance : instances) {
-		instance->reload(this);
+	if constexpr (VERBOSE_ELFSCRIPT) {
+		printf("ELFScript::set_file: %s Sandbox instances: %d\n", path.utf8().ptr(), sandbox_map[path].size());
+	}
+	for (Sandbox *sandbox : sandbox_map[path]) {
+		sandbox->set_program(Ref<ELFScript>(this));
 	}
 }
 
diff --git a/src/elf/script_elf.h b/src/elf/script_elf.h
index 6d907df..7dc72a9 100644
--- a/src/elf/script_elf.h
+++ b/src/elf/script_elf.h
@@ -26,6 +26,8 @@ class ELFScript : public ScriptExtension {
 	mutable HashSet<ELFScriptInstance *> instances;
 	friend class ELFScriptInstance;
 
+	static inline HashMap<String, HashSet<Sandbox *>> sandbox_map;
+
 public:
 	PackedStringArray functions;
 	String get_elf_programming_language() const;
@@ -47,6 +49,9 @@ class ELFScript : public ScriptExtension {
 	/// @return An ELF program as a byte array.
 	const PackedByteArray &get_content();
 
+	void register_instance(Sandbox *p_sandbox) { sandbox_map[path].insert(p_sandbox); }
+	void unregister_instance(Sandbox *p_sandbox) { sandbox_map[path].erase(p_sandbox); }
+
 	virtual bool _editor_can_reload_from_file() override;
 	virtual void _placeholder_erased(void *p_placeholder) override;
 	virtual bool _can_instantiate() const override;
diff --git a/src/sandbox.cpp b/src/sandbox.cpp
index f5c9838..2711652 100644
--- a/src/sandbox.cpp
+++ b/src/sandbox.cpp
@@ -209,6 +209,7 @@ Sandbox::~Sandbox() {
 		ERR_PRINT("Sandbox instance destroyed while a VM call is in progress.");
 	}
 	this->m_global_instance_count -= 1;
+	this->set_program_data_internal(nullptr);
 	try {
 		if (this->m_machine != dummy_machine)
 			delete this->m_machine;
@@ -244,7 +245,7 @@ void Sandbox::set_program(Ref<ELFScript> program) {
 		property_values.push_back(value);
 	}
 
-	this->m_program_data = program;
+	this->set_program_data_internal(program);
 	this->m_program_bytes = {};
 
 	// Unload program and reset the machine
@@ -273,6 +274,17 @@ void Sandbox::set_program(Ref<ELFScript> program) {
 		}
 	}
 }
+void Sandbox::set_program_data_internal(Ref<ELFScript> program) {
+	if (this->m_program_data.is_valid()) {
+		//printf("Sandbox %p: Program *unset* from %s\n", this, this->m_program_data->get_path().utf8().ptr());
+		this->m_program_data->unregister_instance(this);
+	}
+	this->m_program_data = program;
+	if (this->m_program_data.is_valid()) {
+		//printf("Sandbox %p: Program set to %s\n", this, this->m_program_data->get_path().utf8().ptr());
+		this->m_program_data->register_instance(this);
+	}
+}
 Ref<ELFScript> Sandbox::get_program() {
 	return m_program_data;
 }
@@ -284,7 +296,7 @@ void Sandbox::load_buffer(const PackedByteArray &buffer) {
 		return;
 	}
 
-	this->m_program_data.unref();
+	this->set_program_data_internal(nullptr);
 	this->m_program_bytes = buffer;
 	this->load(&this->m_program_bytes);
 }
diff --git a/src/sandbox.h b/src/sandbox.h
index d4788cd..166e95e 100644
--- a/src/sandbox.h
+++ b/src/sandbox.h
@@ -441,6 +441,7 @@ class Sandbox : public Node {
 	void constructor_initialize();
 	void full_reset();
 	void reset_machine();
+	void set_program_data_internal(Ref<ELFScript> program);
 	bool load(const PackedByteArray *vbuf, const std::vector<std::string> *argv = nullptr);
 	void read_program_properties(bool editor) const;
 	void handle_exception(gaddr_t);