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Use a different method to avoid thread_local on MacOS #1992

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51 changes: 35 additions & 16 deletions include/godot_cpp/classes/wrapped.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,11 +40,9 @@
#include <godot_cpp/godot.hpp>

#if defined(MACOS_ENABLED) && defined(HOT_RELOAD_ENABLED)
#include <map>
#include <mutex>
#define _GODOT_CPP_AVOID_THREAD_LOCAL
#define _GODOT_CPP_THREAD_LOCAL
#else
#define _GODOT_CPP_THREAD_LOCAL thread_local
#include <thread>
#endif

namespace godot {
Expand All @@ -65,21 +63,45 @@ class Wrapped {
template <typename T, std::enable_if_t<std::is_base_of<::godot::Wrapped, T>::value, bool>>
friend _ALWAYS_INLINE_ void _pre_initialize();

#ifdef _GODOT_CPP_AVOID_THREAD_LOCAL
static std::recursive_mutex _constructing_mutex;
struct ConstructInfo {
const StringName *extension_class_name = nullptr;
const GDExtensionInstanceBindingCallbacks *class_binding_callbacks = nullptr;
#ifdef HOT_RELOAD_ENABLED
GDExtensionObjectPtr recreate_owner = nullptr;
#endif
};

_GODOT_CPP_THREAD_LOCAL static const StringName *_constructing_extension_class_name;
_GODOT_CPP_THREAD_LOCAL static const GDExtensionInstanceBindingCallbacks *_constructing_class_binding_callbacks;

#ifdef HOT_RELOAD_ENABLED
_GODOT_CPP_THREAD_LOCAL static GDExtensionObjectPtr _constructing_recreate_owner;
#if defined(MACOS_ENABLED) && defined(HOT_RELOAD_ENABLED)
// On macOS, `thread_local` storage keeps the library from being unloaded,
// which breaks hot-reload. Instead we keep each thread's `ConstructInfo` in a
// map keyed by thread id.
class ConstructInfoStore {
std::mutex mutex;
std::map<std::thread::id, ConstructInfo> infos;

public:
ConstructInfo &get() {
std::lock_guard<std::mutex> lock(mutex);
return infos[std::this_thread::get_id()];
}
};

static ConstructInfo &_get_construct_info() {
static ConstructInfoStore store;
return store.get();
}
#else
static ConstructInfo &_get_construct_info() {
static thread_local ConstructInfo info;
return info;
}
#endif

template <typename T>
_ALWAYS_INLINE_ static void _set_construct_info() {
_constructing_extension_class_name = T::_get_extension_class_name();
_constructing_class_binding_callbacks = &T::_gde_binding_callbacks;
ConstructInfo &info = _get_construct_info();
info.extension_class_name = T::_get_extension_class_name();
info.class_binding_callbacks = &T::_gde_binding_callbacks;
}

protected:
Expand Down Expand Up @@ -124,9 +146,6 @@ class Wrapped {

template <typename T, std::enable_if_t<std::is_base_of<::godot::Wrapped, T>::value, bool>>
_ALWAYS_INLINE_ void _pre_initialize() {
#ifdef _GODOT_CPP_AVOID_THREAD_LOCAL
Wrapped::_constructing_mutex.lock();
#endif
Wrapped::_set_construct_info<T>();
}

Expand Down
5 changes: 1 addition & 4 deletions include/godot_cpp/core/class_db.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -136,10 +136,7 @@ class ClassDB {
static GDExtensionClassInstancePtr _recreate_instance_func(void *data, GDExtensionObjectPtr obj) {
if constexpr (!std::is_abstract_v<T>) {
#ifdef HOT_RELOAD_ENABLED
#ifdef _GODOT_CPP_AVOID_THREAD_LOCAL
std::lock_guard<std::recursive_mutex> lk(Wrapped::_constructing_mutex);
#endif
Wrapped::_constructing_recreate_owner = obj;
Wrapped::_get_construct_info().recreate_owner = obj;
T *new_instance = (T *)memalloc(sizeof(T));
memnew_placement(new_instance, T);
return new_instance;
Expand Down
35 changes: 11 additions & 24 deletions src/classes/wrapped.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,26 +40,11 @@

namespace godot {

#ifdef _GODOT_CPP_AVOID_THREAD_LOCAL
std::recursive_mutex Wrapped::_constructing_mutex;
#endif

_GODOT_CPP_THREAD_LOCAL const StringName *Wrapped::_constructing_extension_class_name = nullptr;
_GODOT_CPP_THREAD_LOCAL const GDExtensionInstanceBindingCallbacks *Wrapped::_constructing_class_binding_callbacks = nullptr;

#ifdef HOT_RELOAD_ENABLED
_GODOT_CPP_THREAD_LOCAL GDExtensionObjectPtr Wrapped::_constructing_recreate_owner = nullptr;
#endif

const StringName *Wrapped::_get_extension_class_name() {
return nullptr;
}

void Wrapped::_postinitialize() {
#ifdef _GODOT_CPP_AVOID_THREAD_LOCAL
Wrapped::_constructing_mutex.unlock();
#endif

#if GODOT_VERSION_MINOR >= 4
Object *obj = dynamic_cast<Object *>(this);
if (obj) {
Expand All @@ -74,10 +59,12 @@ void Wrapped::_postinitialize() {
}

Wrapped::Wrapped(const StringName &p_godot_class) {
ConstructInfo &info = _get_construct_info();

#ifdef HOT_RELOAD_ENABLED
if (unlikely(Wrapped::_constructing_recreate_owner)) {
_owner = Wrapped::_constructing_recreate_owner;
Wrapped::_constructing_recreate_owner = nullptr;
if (unlikely(info.recreate_owner)) {
_owner = info.recreate_owner;
info.recreate_owner = nullptr;
} else
#endif
{
Expand All @@ -90,14 +77,14 @@ Wrapped::Wrapped(const StringName &p_godot_class) {
#endif
}

if (_constructing_extension_class_name) {
::godot::gdextension_interface::object_set_instance(_owner, reinterpret_cast<GDExtensionConstStringNamePtr>(_constructing_extension_class_name), this);
_constructing_extension_class_name = nullptr;
if (info.extension_class_name) {
::godot::gdextension_interface::object_set_instance(_owner, reinterpret_cast<GDExtensionConstStringNamePtr>(info.extension_class_name), this);
info.extension_class_name = nullptr;
}

if (likely(_constructing_class_binding_callbacks)) {
::godot::gdextension_interface::object_set_instance_binding(_owner, ::godot::gdextension_interface::token, this, _constructing_class_binding_callbacks);
_constructing_class_binding_callbacks = nullptr;
if (likely(info.class_binding_callbacks)) {
::godot::gdextension_interface::object_set_instance_binding(_owner, ::godot::gdextension_interface::token, this, info.class_binding_callbacks);
info.class_binding_callbacks = nullptr;
} else {
CRASH_NOW_MSG("BUG: Godot Object created without binding callbacks. Did you forget to use memnew()?");
}
Expand Down
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