Implement support for RID

Add `RenderingServer` to minimal classes, to be able to test the RID impl against an actual server
Add `Engine` to minimal classes, to be able to disable error printing in itests

Author: lilizoey

godot-codegen/src/lib.rs

@@ -268,6 +268,7 @@ const SELECTED_CLASSES: &[&str] = &[
     "CollisionObject2D",
     "CollisionShape2D",
     "Control",
+    "Engine",
     "FileAccess",
     "HTTPRequest",
     "Image",
@@ -286,6 +287,7 @@ const SELECTED_CLASSES: &[&str] = &[
     "PathFollow2D",
     "PhysicsBody2D",
     "RefCounted",
+    "RenderingServer",
     "Resource",
     "ResourceLoader",
     "RigidBody2D",

godot-core/src/builtin/mod.rs

@@ -45,6 +45,7 @@ pub use others::*;
 pub use packed_array::*;
 pub use projection::*;
 pub use quaternion::*;
+pub use rid::*;
 pub use string::*;
 pub use string_name::*;
 pub use transform2d::*;
@@ -92,6 +93,7 @@ mod others;
 mod packed_array;
 mod projection;
 mod quaternion;
+mod rid;
 mod string;
 mod string_name;
 mod transform2d;

godot-core/src/builtin/others.rs

@@ -17,7 +17,6 @@ impl_builtin_stub!(Rect2, OpaqueRect2);
 impl_builtin_stub!(Rect2i, OpaqueRect2i);
 impl_builtin_stub!(Plane, OpaquePlane);
 impl_builtin_stub!(Aabb, OpaqueAabb);
-impl_builtin_stub!(Rid, OpaqueRid);
 impl_builtin_stub!(Callable, OpaqueCallable);
 impl_builtin_stub!(Signal, OpaqueSignal);
 

godot-core/src/builtin/rid.rs

@@ -0,0 +1,80 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+use std::num::NonZeroU64;
+
+use godot_ffi as sys;
+use sys::{ffi_methods, GodotFfi};
+
+/// A RID ("resource ID") is an opaque handle that refers to a Godot `Resource`.
+///
+/// RIDs do not grant access to the resource itself. Instead, they can be used in lower-level resource APIs
+/// such as the [servers]. See also [Godot API docs for `RID`][docs].
+///
+/// RIDs should be largely safe to work with. Certain calls to servers may fail, however doing so will
+/// trigger an error from Godot, and will not cause any UB.
+///
+/// # Safety Caveat:
+///
+/// In Godot 3, RID was not as safe as described here. We believe that this is fixed in Godot 4, but this has
+/// not been extensively tested as of yet. Some confirmed UB from Godot 3 does not occur anymore, but if you
+/// find anything suspicious or outright UB please open an issue.
+///
+/// [servers]: https://docs.godotengine.org/en/stable/tutorials/optimization/using_servers.html
+/// [docs]: https://docs.godotengine.org/en/stable/classes/class_rid.html
+
+// Using normal rust repr to take advantage advantage of the nullable pointer optimization. As this enum is
+// eligible for it, it is also guaranteed to have it. Meaning the layout of this type is identical to `u64`.
+// See: https://doc.rust-lang.org/nomicon/ffi.html#the-nullable-pointer-optimization
+// Cannot use `#[repr(C)]` as it does not use the nullable pointer optimization.
+#[derive(Copy, Clone, Eq, PartialEq, Hash, Ord, PartialOrd, Debug)]
+pub enum Rid {
+    /// A valid RID may refer to some resource, but is not guaranteed to do so.
+    Valid(NonZeroU64),
+    /// An invalid RID will never refer to a resource. Internally it is represented as a 0.
+    Invalid,
+}
+
+impl Rid {
+    /// Create a new RID.
+    #[inline]
+    pub const fn new(id: u64) -> Self {
+        match NonZeroU64::new(id) {
+            Some(id) => Self::Valid(id),
+            None => Self::Invalid,
+        }
+    }
+
+    /// Convert this RID into a [`u64`].
+    ///
+    /// _Godot equivalent: `Rid.get_id()`_
+    #[inline]
+    pub const fn to_u64(self) -> u64 {
+        match self {
+            Rid::Valid(id) => id.get(),
+            Rid::Invalid => 0,
+        }
+    }
+
+    /// Convert this RID into a [`NonZeroU64`].
+    #[inline]
+    pub const fn to_non_zero_u64(self) -> Option<NonZeroU64> {
+        match self {
+            Rid::Valid(id) => Some(id),
+            Rid::Invalid => None,
+        }
+    }
+
+    /// Returns `true` if this is a valid RID.
+    #[inline]
+    pub const fn is_valid(&self) -> bool {
+        matches!(self, Rid::Valid(_))
+    }
+}
+
+impl GodotFfi for Rid {
+    ffi_methods! { type sys::GDExtensionTypePtr = *mut Self; .. }
+}

godot-core/src/builtin/variant/impls.rs

@@ -159,7 +159,6 @@ mod impls {
     impl_variant_metadata!(Rect2i, /* rect2i_to_variant, rect2i_from_variant, */ Rect2i);
     impl_variant_metadata!(Plane, /* plane_to_variant, plane_from_variant, */ Plane);
     impl_variant_metadata!(Aabb, /* aabb_to_variant, aabb_from_variant, */ Aabb);
-    impl_variant_metadata!(Rid, /* rid_to_variant, rid_from_variant, */ Rid);
     impl_variant_metadata!(Callable, /* callable_to_variant, callable_from_variant, */ Callable);
     impl_variant_metadata!(Signal, /* signal_to_variant, signal_from_variant, */ Signal);
     impl_variant_traits!(PackedByteArray, packed_byte_array_to_variant, packed_byte_array_from_variant, PackedByteArray);
@@ -172,6 +171,7 @@ mod impls {
     impl_variant_traits!(PackedVector3Array, packed_vector3_array_to_variant, packed_vector3_array_from_variant, PackedVector3Array);
     impl_variant_traits!(PackedColorArray, packed_color_array_to_variant, packed_color_array_from_variant, PackedColorArray);
     impl_variant_traits!(Projection, projection_to_variant, projection_from_variant, Projection);
+    impl_variant_traits!(Rid, rid_to_variant, rid_from_variant, Rid);
     impl_variant_traits!(Transform2D, transform_2d_to_variant, transform_2d_from_variant, Transform2D);
     impl_variant_traits!(Transform3D, transform_3d_to_variant, transform_3d_from_variant, Transform3D);
     impl_variant_traits!(Dictionary, dictionary_to_variant, dictionary_from_variant, Dictionary);

itest/rust/src/lib.rs

@@ -4,7 +4,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-use godot::engine::Node;
+use godot::engine::{Engine, Node};
 use godot::init::{gdextension, ExtensionLibrary};
 use godot::obj::Gd;
 use godot::sys;
@@ -23,6 +23,7 @@ mod node_test;
 mod object_test;
 mod packed_array_test;
 mod quaternion_test;
+mod rid_test;
 mod singleton_test;
 mod string_test;
 mod transform2d_test;
@@ -55,6 +56,15 @@ pub(crate) fn expect_panic(context: &str, code: impl FnOnce() + std::panic::Unwi
     );
 }
 
+/// Disable printing errors from Godot. Ideally we should catch and handle errors, ensuring they happen when
+/// expected. But that isn't possible, so for now we can just disable printing the error to avoid spamming
+/// the terminal when tests should error.
+pub(crate) fn suppress_godot_print(mut f: impl FnMut()) {
+    Engine::singleton().set_print_error_messages(false);
+    f();
+    Engine::singleton().set_print_error_messages(true);
+}
+
 // ----------------------------------------------------------------------------------------------------------------------------------------------
 // Entry point + #[itest] test registration
 

itest/rust/src/rid_test.rs

@@ -0,0 +1,127 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+use std::{collections::HashSet, thread};
+
+use godot::{
+    engine::RenderingServer,
+    prelude::{inner::InnerRid, Color, Rid, Vector2},
+};
+
+use crate::{itest, suppress_godot_print};
+
+#[itest]
+fn rid_equiv() {
+    let invalid: Rid = Rid::Invalid;
+    let valid: Rid = Rid::new((10 << 32) | 20);
+    assert!(!InnerRid::from_outer(&invalid).is_valid());
+    assert!(InnerRid::from_outer(&valid).is_valid());
+
+    assert_eq!(InnerRid::from_outer(&invalid).get_id(), 0);
+    assert_eq!(InnerRid::from_outer(&valid).get_id(), (10 << 32) | 20);
+}
+
+#[itest]
+fn canvas_set_parent() {
+    // This originally caused UB, but still testing it here in case it breaks.
+    let mut server = RenderingServer::singleton();
+    let canvas = server.canvas_create();
+    let viewport = server.viewport_create();
+
+    suppress_godot_print(|| server.canvas_item_set_parent(viewport, canvas));
+    suppress_godot_print(|| server.canvas_item_set_parent(viewport, viewport));
+
+    server.free_rid(canvas);
+    server.free_rid(viewport);
+}
+
+#[itest]
+fn multi_thread_test() {
+    let threads = (0..10)
+        .map(|_| {
+            thread::spawn(|| {
+                let mut server = RenderingServer::singleton();
+                (0..1000).map(|_| server.canvas_item_create()).collect()
+            })
+        })
+        .collect::<Vec<_>>();
+
+    let mut rids: Vec<Rid> = vec![];
+
+    for thread in threads.into_iter() {
+        rids.append(&mut thread.join().unwrap());
+    }
+
+    let set = rids.iter().cloned().collect::<HashSet<_>>();
+    assert_eq!(set.len(), rids.len());
+
+    let mut server = RenderingServer::singleton();
+
+    for rid in rids.iter() {
+        server.canvas_item_add_circle(*rid, Vector2::ZERO, 1.0, Color::from_rgb(1.0, 0.0, 0.0));
+    }
+
+    for rid in rids.iter() {
+        server.free_rid(*rid);
+    }
+}
+
+/// Check that godot does not crash upon receiving various RIDs that may be edge cases. As it could do in Godot 3.
+#[itest]
+fn strange_rids() {
+    let mut server = RenderingServer::singleton();
+    let mut rids: Vec<u64> = vec![
+        // Invalid RID.
+        0,
+        // Normal RID, should work without issue.
+        1,
+        10,
+        // Testing the boundaries of various ints.
+        u8::MAX as u64,
+        u16::MAX as u64,
+        u32::MAX as u64,
+        u64::MAX,
+        i8::MIN as u64,
+        i8::MAX as u64,
+        i16::MIN as u64,
+        i16::MAX as u64,
+        i32::MIN as u64,
+        i32::MAX as u64,
+        i64::MIN as u64,
+        i64::MAX as u64,
+        // Biggest RIDs possible in Godot (ignoring local indices).
+        0xFFFFFFFF << 32,
+        0x7FFFFFFF << 32,
+        // Godot's servers treats RIDs as two u32s, so testing what happens round the region where
+        // one u32 overflows into the next.
+        u32::MAX as u64 + 1,
+        u32::MAX as u64 + 2,
+        u32::MAX as u64 - 1,
+        u32::MAX as u64 - 2,
+        // A couple random RIDs.
+        1234567891011121314,
+        14930753991246632225,
+        8079365198791785081,
+        10737267678893224303,
+        12442588258967011829,
+        4275912429544145425,
+    ];
+    // Checking every number with exactly 2 bits = 1.
+    // An approximation of exhaustively checking every number.
+    for i in 0..64 {
+        for j in 0..63 {
+            if j >= i {
+                rids.push((1 << i) | (1 << (j + 1)))
+            } else {
+                rids.push((1 << i) | (1 << j))
+            }
+        }
+    }
+
+    for id in rids.iter() {
+        suppress_godot_print(|| server.canvas_item_clear(Rid::new(*id)))
+    }
+}