godot/modules/mono/glue/GodotSharp/GodotSharp/Core/DelegateUtils.cs
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

451 lines
16 KiB
C#

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Godot.NativeInterop;
namespace Godot
{
internal static class DelegateUtils
{
// TODO: Move somewhere else once we need to for things other than delegates
internal static void FreeGCHandle(IntPtr delegateGCHandle)
=> GCHandle.FromIntPtr(delegateGCHandle).Free();
internal static bool DelegateEquals(IntPtr delegateGCHandleA, IntPtr delegateGCHandleB)
{
var @delegateA = (Delegate)GCHandle.FromIntPtr(delegateGCHandleA).Target;
var @delegateB = (Delegate)GCHandle.FromIntPtr(delegateGCHandleB).Target;
return @delegateA == @delegateB;
}
internal static unsafe void InvokeWithVariantArgs(IntPtr delegateGCHandle, godot_variant** args, uint argc, godot_variant* ret)
{
// TODO: Optimize
var @delegate = (Delegate)GCHandle.FromIntPtr(delegateGCHandle).Target;
var managedArgs = new object[argc];
var parameterInfos = @delegate.Method.GetParameters();
var paramsLength = parameterInfos.Length;
if (argc != paramsLength)
{
throw new InvalidOperationException(
$"The delegate expects {paramsLength} arguments, but received {argc}.");
}
for (uint i = 0; i < argc; i++)
{
managedArgs[i] = Marshaling.variant_to_mono_object_of_type(
args[i], parameterInfos[i].ParameterType);
}
object invokeRet = @delegate.DynamicInvoke(managedArgs);
*ret = Marshaling.mono_object_to_variant(invokeRet);
}
// TODO: Check if we should be using BindingFlags.DeclaredOnly (would give better reflection performance).
private enum TargetKind : uint
{
Static,
GodotObject,
CompilerGenerated
}
internal static bool TrySerializeDelegateWithGCHandle(IntPtr delegateGCHandle, Collections.Array serializedData)
=> TrySerializeDelegate((Delegate)GCHandle.FromIntPtr(delegateGCHandle).Target, serializedData);
private static bool TrySerializeDelegate(Delegate @delegate, Collections.Array serializedData)
{
if (@delegate is MulticastDelegate multicastDelegate)
{
bool someDelegatesSerialized = false;
Delegate[] invocationList = multicastDelegate.GetInvocationList();
if (invocationList.Length > 1)
{
var multiCastData = new Collections.Array();
foreach (Delegate oneDelegate in invocationList)
someDelegatesSerialized |= TrySerializeDelegate(oneDelegate, multiCastData);
if (!someDelegatesSerialized)
return false;
serializedData.Add(multiCastData);
return true;
}
}
if (TrySerializeSingleDelegate(@delegate, out byte[] buffer))
{
serializedData.Add(buffer);
return true;
}
return false;
}
private static bool TrySerializeSingleDelegate(Delegate @delegate, out byte[] buffer)
{
buffer = null;
object target = @delegate.Target;
switch (target)
{
case null:
{
using (var stream = new MemoryStream())
using (var writer = new BinaryWriter(stream))
{
writer.Write((ulong)TargetKind.Static);
SerializeType(writer, @delegate.GetType());
if (!TrySerializeMethodInfo(writer, @delegate.Method))
return false;
buffer = stream.ToArray();
return true;
}
}
// ReSharper disable once RedundantNameQualifier
case Godot.Object godotObject:
{
using (var stream = new MemoryStream())
using (var writer = new BinaryWriter(stream))
{
writer.Write((ulong)TargetKind.GodotObject);
// ReSharper disable once RedundantCast
writer.Write((ulong)godotObject.GetInstanceId());
SerializeType(writer, @delegate.GetType());
if (!TrySerializeMethodInfo(writer, @delegate.Method))
return false;
buffer = stream.ToArray();
return true;
}
}
default:
{
Type targetType = target.GetType();
if (targetType.IsDefined(typeof(CompilerGeneratedAttribute), true))
{
// Compiler generated. Probably a closure. Try to serialize it.
using (var stream = new MemoryStream())
using (var writer = new BinaryWriter(stream))
{
writer.Write((ulong)TargetKind.CompilerGenerated);
SerializeType(writer, targetType);
SerializeType(writer, @delegate.GetType());
if (!TrySerializeMethodInfo(writer, @delegate.Method))
return false;
FieldInfo[] fields = targetType.GetFields(BindingFlags.Instance | BindingFlags.Public);
writer.Write(fields.Length);
foreach (FieldInfo field in fields)
{
Type fieldType = field.GetType();
Variant.Type variantType = GD.TypeToVariantType(fieldType);
if (variantType == Variant.Type.Nil)
return false;
writer.Write(field.Name);
byte[] valueBuffer = GD.Var2Bytes(field.GetValue(target));
writer.Write(valueBuffer.Length);
writer.Write(valueBuffer);
}
buffer = stream.ToArray();
return true;
}
}
return false;
}
}
}
private static bool TrySerializeMethodInfo(BinaryWriter writer, MethodInfo methodInfo)
{
if (methodInfo == null)
return false;
SerializeType(writer, methodInfo.DeclaringType);
writer.Write(methodInfo.Name);
int flags = 0;
if (methodInfo.IsPublic)
flags |= (int)BindingFlags.Public;
else
flags |= (int)BindingFlags.NonPublic;
if (methodInfo.IsStatic)
flags |= (int)BindingFlags.Static;
else
flags |= (int)BindingFlags.Instance;
writer.Write(flags);
Type returnType = methodInfo.ReturnType;
bool hasReturn = methodInfo.ReturnType != typeof(void);
writer.Write(hasReturn);
if (hasReturn)
SerializeType(writer, returnType);
ParameterInfo[] parameters = methodInfo.GetParameters();
writer.Write(parameters.Length);
if (parameters.Length > 0)
{
for (int i = 0; i < parameters.Length; i++)
SerializeType(writer, parameters[i].ParameterType);
}
return true;
}
private static void SerializeType(BinaryWriter writer, Type type)
{
if (type == null)
{
int genericArgumentsCount = -1;
writer.Write(genericArgumentsCount);
}
else if (type.IsGenericType)
{
Type genericTypeDef = type.GetGenericTypeDefinition();
Type[] genericArgs = type.GetGenericArguments();
int genericArgumentsCount = genericArgs.Length;
writer.Write(genericArgumentsCount);
string assemblyQualifiedName = genericTypeDef.AssemblyQualifiedName;
Debug.Assert(assemblyQualifiedName != null);
writer.Write(assemblyQualifiedName);
for (int i = 0; i < genericArgs.Length; i++)
SerializeType(writer, genericArgs[i]);
}
else
{
int genericArgumentsCount = 0;
writer.Write(genericArgumentsCount);
string assemblyQualifiedName = type.AssemblyQualifiedName;
Debug.Assert(assemblyQualifiedName != null);
writer.Write(assemblyQualifiedName);
}
}
private static bool TryDeserializeDelegateWithGCHandle(Collections.Array serializedData, out IntPtr delegateGCHandle)
{
bool res = TryDeserializeDelegate(serializedData, out Delegate @delegate);
delegateGCHandle = GCHandle.ToIntPtr(GCHandle.Alloc(@delegate));
return res;
}
private static bool TryDeserializeDelegate(Collections.Array serializedData, out Delegate @delegate)
{
if (serializedData.Count == 1)
{
object elem = serializedData[0];
if (elem is Collections.Array multiCastData)
return TryDeserializeDelegate(multiCastData, out @delegate);
return TryDeserializeSingleDelegate((byte[])elem, out @delegate);
}
@delegate = null;
var delegates = new List<Delegate>(serializedData.Count);
foreach (object elem in serializedData)
{
if (elem is Collections.Array multiCastData)
{
if (TryDeserializeDelegate(multiCastData, out Delegate oneDelegate))
delegates.Add(oneDelegate);
}
else
{
if (TryDeserializeSingleDelegate((byte[])elem, out Delegate oneDelegate))
delegates.Add(oneDelegate);
}
}
if (delegates.Count <= 0)
return false;
@delegate = delegates.Count == 1 ? delegates[0] : Delegate.Combine(delegates.ToArray());
return true;
}
private static bool TryDeserializeSingleDelegate(byte[] buffer, out Delegate @delegate)
{
@delegate = null;
using (var stream = new MemoryStream(buffer, writable: false))
using (var reader = new BinaryReader(stream))
{
var targetKind = (TargetKind)reader.ReadUInt64();
switch (targetKind)
{
case TargetKind.Static:
{
Type delegateType = DeserializeType(reader);
if (delegateType == null)
return false;
if (!TryDeserializeMethodInfo(reader, out MethodInfo methodInfo))
return false;
@delegate = Delegate.CreateDelegate(delegateType, null, methodInfo);
return true;
}
case TargetKind.GodotObject:
{
ulong objectId = reader.ReadUInt64();
// ReSharper disable once RedundantNameQualifier
Godot.Object godotObject = GD.InstanceFromId(objectId);
if (godotObject == null)
return false;
Type delegateType = DeserializeType(reader);
if (delegateType == null)
return false;
if (!TryDeserializeMethodInfo(reader, out MethodInfo methodInfo))
return false;
@delegate = Delegate.CreateDelegate(delegateType, godotObject, methodInfo);
return true;
}
case TargetKind.CompilerGenerated:
{
Type targetType = DeserializeType(reader);
if (targetType == null)
return false;
Type delegateType = DeserializeType(reader);
if (delegateType == null)
return false;
if (!TryDeserializeMethodInfo(reader, out MethodInfo methodInfo))
return false;
int fieldCount = reader.ReadInt32();
object recreatedTarget = Activator.CreateInstance(targetType);
for (int i = 0; i < fieldCount; i++)
{
string name = reader.ReadString();
int valueBufferLength = reader.ReadInt32();
byte[] valueBuffer = reader.ReadBytes(valueBufferLength);
FieldInfo fieldInfo = targetType.GetField(name, BindingFlags.Instance | BindingFlags.Public);
fieldInfo?.SetValue(recreatedTarget, GD.Bytes2Var(valueBuffer));
}
@delegate = Delegate.CreateDelegate(delegateType, recreatedTarget, methodInfo);
return true;
}
default:
return false;
}
}
}
private static bool TryDeserializeMethodInfo(BinaryReader reader, out MethodInfo methodInfo)
{
methodInfo = null;
Type declaringType = DeserializeType(reader);
string methodName = reader.ReadString();
int flags = reader.ReadInt32();
bool hasReturn = reader.ReadBoolean();
Type returnType = hasReturn ? DeserializeType(reader) : typeof(void);
int parametersCount = reader.ReadInt32();
if (parametersCount > 0)
{
var parameterTypes = new Type[parametersCount];
for (int i = 0; i < parametersCount; i++)
{
Type parameterType = DeserializeType(reader);
if (parameterType == null)
return false;
parameterTypes[i] = parameterType;
}
methodInfo = declaringType.GetMethod(methodName, (BindingFlags)flags, null, parameterTypes, null);
return methodInfo != null && methodInfo.ReturnType == returnType;
}
methodInfo = declaringType.GetMethod(methodName, (BindingFlags)flags);
return methodInfo != null && methodInfo.ReturnType == returnType;
}
private static Type DeserializeType(BinaryReader reader)
{
int genericArgumentsCount = reader.ReadInt32();
if (genericArgumentsCount == -1)
return null;
string assemblyQualifiedName = reader.ReadString();
var type = Type.GetType(assemblyQualifiedName);
if (type == null)
return null; // Type not found
if (genericArgumentsCount != 0)
{
var genericArgumentTypes = new Type[genericArgumentsCount];
for (int i = 0; i < genericArgumentsCount; i++)
{
Type genericArgumentType = DeserializeType(reader);
if (genericArgumentType == null)
return null;
genericArgumentTypes[i] = genericArgumentType;
}
type = type.MakeGenericType(genericArgumentTypes);
}
return type;
}
}
}