godot/modules/mono/signal_awaiter_utils.cpp
Ignacio Roldán Etcheverry 483071716e C#: Move marshaling logic and generated glue to C#
We will be progressively moving most code to C#.
The plan is to only use Mono's embedding APIs to set things at launch.
This will make it much easier to later support CoreCLR too which
doesn't have rich embedding APIs.

Additionally the code in C# is more maintainable and makes it easier
to implement new features, e.g.: runtime codegen which we could use to
avoid using reflection for marshaling everytime a field, property or
method is accessed.

SOME NOTES ON INTEROP

We make the same assumptions as GDNative about the size of the Godot
structures we use. We take it a bit further by also assuming the layout
of fields in some cases, which is riskier but let's us squeeze out some
performance by avoiding unnecessary managed to native calls.

Code that deals with native structs is less safe than before as there's
no RAII and copy constructors in C#. It's like using the GDNative C API
directly. One has to take special care to free values they own.
Perhaps we could use roslyn analyzers to check this, but I don't know
any that uses attributes to determine what's owned or borrowed.

As to why we maily use pointers for native structs instead of ref/out:
- AFAIK (and confirmed with a benchmark) ref/out are pinned
  during P/Invoke calls and that has a cost.
- Native struct fields can't be ref/out in the first place.
- A `using` local can't be passed as ref/out, only `in`. Calling a
  method or property on an `in` value makes a silent copy, so we want
  to avoid `in`.

REGARDING THE BUILD SYSTEM

There's no longer a `mono_glue=yes/no` SCons options. We no longer
need to build with `mono_glue=no`, generate the glue and then build
again with `mono_glue=yes`. We build only once and generate the glue
(which is in C# now).
However, SCons no longer builds the C# projects for us. Instead one
must run `build_assemblies.py`, e.g.:
```sh
%godot_src_root%/modules/mono/build_scripts/build_assemblies.py \
        --godot-output-dir=%godot_src_root%/bin \
        --godot-target=release_debug`
```
We could turn this into a custom build target, but I don't know how
to do that with SCons (it's possible with Meson).

OTHER NOTES

Most of the moved code doesn't follow the C# naming convention and
still has the word Mono in the names despite no longer dealing with
Mono's embedding APIs. This is just temporary while transitioning,
to make it easier to understand what was moved where.
2021-08-20 10:24:56 +02:00

233 lines
8.5 KiB
C++

/*************************************************************************/
/* signal_awaiter_utils.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/*************************************************************************/
#include "signal_awaiter_utils.h"
#include "csharp_script.h"
#include "mono_gd/gd_mono_cache.h"
#include "mono_gd/gd_mono_class.h"
#include "mono_gd/gd_mono_marshal.h"
#include "mono_gd/gd_mono_utils.h"
Error gd_mono_connect_signal_awaiter(Object *p_source, const StringName &p_signal, Object *p_target, MonoObject *p_awaiter) {
ERR_FAIL_NULL_V(p_source, ERR_INVALID_DATA);
ERR_FAIL_NULL_V(p_target, ERR_INVALID_DATA);
// TODO: Use pooling for ManagedCallable instances.
SignalAwaiterCallable *awaiter_callable = memnew(SignalAwaiterCallable(p_target, p_awaiter, p_signal));
Callable callable = Callable(awaiter_callable);
return p_source->connect(p_signal, callable, Vector<Variant>(), Object::CONNECT_ONESHOT);
}
bool SignalAwaiterCallable::compare_equal(const CallableCustom *p_a, const CallableCustom *p_b) {
// Only called if both instances are of type SignalAwaiterCallable. Static cast is safe.
const SignalAwaiterCallable *a = static_cast<const SignalAwaiterCallable *>(p_a);
const SignalAwaiterCallable *b = static_cast<const SignalAwaiterCallable *>(p_b);
return a->awaiter_handle.handle == b->awaiter_handle.handle;
}
bool SignalAwaiterCallable::compare_less(const CallableCustom *p_a, const CallableCustom *p_b) {
if (compare_equal(p_a, p_b)) {
return false;
}
return p_a < p_b;
}
uint32_t SignalAwaiterCallable::hash() const {
uint32_t hash = signal.hash();
return hash_djb2_one_64(target_id, hash);
}
String SignalAwaiterCallable::get_as_text() const {
Object *base = ObjectDB::get_instance(target_id);
if (base) {
String class_name = base->get_class();
Ref<Script> script = base->get_script();
if (script.is_valid() && script->get_path().is_resource_file()) {
class_name += "(" + script->get_path().get_file() + ")";
}
return class_name + "::SignalAwaiterMiddleman::" + String(signal);
} else {
return "null::SignalAwaiterMiddleman::" + String(signal);
}
}
CallableCustom::CompareEqualFunc SignalAwaiterCallable::get_compare_equal_func() const {
return compare_equal_func_ptr;
}
CallableCustom::CompareLessFunc SignalAwaiterCallable::get_compare_less_func() const {
return compare_less_func_ptr;
}
ObjectID SignalAwaiterCallable::get_object() const {
return target_id;
}
StringName SignalAwaiterCallable::get_signal() const {
return signal;
}
void SignalAwaiterCallable::call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
r_call_error.error = Callable::CallError::CALL_ERROR_INVALID_METHOD; // Can't find anything better
r_return_value = Variant();
#ifdef DEBUG_ENABLED
ERR_FAIL_COND_MSG(target_id.is_valid() && !ObjectDB::get_instance(target_id),
"Resumed after await, but class instance is gone.");
#endif
MonoArray *signal_args = nullptr;
if (p_argcount > 0) {
signal_args = mono_array_new(mono_domain_get(), CACHED_CLASS_RAW(MonoObject), p_argcount);
for (int i = 0; i < p_argcount; i++) {
MonoObject *boxed = GDMonoMarshal::variant_to_mono_object(*p_arguments[i]);
mono_array_setref(signal_args, i, boxed);
}
}
MonoObject *awaiter = awaiter_handle.get_target();
if (!awaiter) {
r_call_error.error = Callable::CallError::CALL_ERROR_INSTANCE_IS_NULL;
return;
}
MonoException *exc = nullptr;
CACHED_METHOD_THUNK(SignalAwaiter, SignalCallback).invoke(awaiter, signal_args, &exc);
if (exc) {
GDMonoUtils::set_pending_exception(exc);
ERR_FAIL();
} else {
r_call_error.error = Callable::CallError::CALL_OK;
}
}
SignalAwaiterCallable::SignalAwaiterCallable(Object *p_target, MonoObject *p_awaiter, const StringName &p_signal) :
target_id(p_target->get_instance_id()),
awaiter_handle(MonoGCHandleData::new_strong_handle(p_awaiter)),
signal(p_signal) {
}
SignalAwaiterCallable::~SignalAwaiterCallable() {
awaiter_handle.release();
}
bool EventSignalCallable::compare_equal(const CallableCustom *p_a, const CallableCustom *p_b) {
const EventSignalCallable *a = static_cast<const EventSignalCallable *>(p_a);
const EventSignalCallable *b = static_cast<const EventSignalCallable *>(p_b);
if (a->owner != b->owner) {
return false;
}
if (a->event_signal != b->event_signal) {
return false;
}
return true;
}
bool EventSignalCallable::compare_less(const CallableCustom *p_a, const CallableCustom *p_b) {
if (compare_equal(p_a, p_b)) {
return false;
}
return p_a < p_b;
}
uint32_t EventSignalCallable::hash() const {
uint32_t hash = event_signal->field->get_name().hash();
return hash_djb2_one_64(owner->get_instance_id(), hash);
}
String EventSignalCallable::get_as_text() const {
String class_name = owner->get_class();
Ref<Script> script = owner->get_script();
if (script.is_valid() && script->get_path().is_resource_file()) {
class_name += "(" + script->get_path().get_file() + ")";
}
StringName signal = event_signal->field->get_name();
return class_name + "::EventSignalMiddleman::" + String(signal);
}
CallableCustom::CompareEqualFunc EventSignalCallable::get_compare_equal_func() const {
return compare_equal_func_ptr;
}
CallableCustom::CompareLessFunc EventSignalCallable::get_compare_less_func() const {
return compare_less_func_ptr;
}
ObjectID EventSignalCallable::get_object() const {
return owner->get_instance_id();
}
StringName EventSignalCallable::get_signal() const {
return event_signal->field->get_name();
}
void EventSignalCallable::call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
r_call_error.error = Callable::CallError::CALL_ERROR_INVALID_METHOD; // Can't find anything better
r_return_value = Variant();
ERR_FAIL_COND(p_argcount < event_signal->invoke_method->get_parameters_count());
CSharpInstance *csharp_instance = CAST_CSHARP_INSTANCE(owner->get_script_instance());
ERR_FAIL_NULL(csharp_instance);
MonoObject *owner_managed = csharp_instance->get_mono_object();
ERR_FAIL_NULL(owner_managed);
MonoObject *delegate_field_value = event_signal->field->get_value(owner_managed);
if (!delegate_field_value) {
r_call_error.error = Callable::CallError::CALL_OK;
return;
}
MonoException *exc = nullptr;
event_signal->invoke_method->invoke(delegate_field_value, p_arguments, &exc);
if (exc) {
GDMonoUtils::set_pending_exception(exc);
ERR_FAIL();
} else {
r_call_error.error = Callable::CallError::CALL_OK;
}
}
EventSignalCallable::EventSignalCallable(Object *p_owner, const CSharpScript::EventSignal *p_event_signal) :
owner(p_owner),
event_signal(p_event_signal) {
}