binarybana commented on a change in pull request #5328:
URL: https://github.com/apache/incubator-tvm/pull/5328#discussion_r411067781
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File path: rust/tvm-rt/src/object.rs
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@@ -0,0 +1,268 @@
+use std::convert::TryFrom;
+use std::convert::TryInto;
+use std::ffi::CString;
+use std::ptr::NonNull;
+use tvm_sys::ffi::{self, TVMObjectFree, TVMObjectRetain,
TVMObjectTypeKey2Index};
+use tvm_sys::{TVMArgValue, TVMRetValue};
+
+type Deleter<T> = unsafe extern "C" fn(object: *mut T) -> ();
+
+#[derive(Debug)]
+#[repr(C)]
+pub struct Object {
+ pub type_index: u32,
+ pub ref_count: i32,
+ pub fdeleter: Deleter<Object>,
+}
+
+unsafe extern "C" fn delete<T: IsObject>(object: *mut Object) {
+ let typed_object: *mut T = std::mem::transmute(object);
+ T::typed_delete(typed_object);
+}
+
+fn derived_from(child_type_index: u32, parent_type_index: u32) -> bool {
+ let mut is_derived = 0;
+ crate::check_call!(ffi::TVMObjectDerivedFrom(
+ child_type_index,
+ parent_type_index,
+ &mut is_derived
+ ));
+ if is_derived == 0 {
+ false
+ } else {
+ true
+ }
+}
+
+impl Object {
+ fn new(type_index: u32, deleter: Deleter<Object>) -> Object {
+ Object {
+ type_index,
+ // Note: do not touch this field directly again, this is
+ // a critical section, we write a 1 to the atomic which will now
+ // be managed by the C++ atomics.
+ // In the future we should probably use C-atomcis.
+ ref_count: 1,
+ fdeleter: deleter,
+ }
+ }
+
+ fn get_type_index<T: IsObject>() -> u32 {
+ let type_key = T::TYPE_KEY;
+ let cstring = CString::new(type_key).expect("type key must not contain
null characters");
+ if type_key == "Object" {
+ return 0;
+ } else {
+ let mut index = 0;
+ unsafe {
+ let index_ptr = std::mem::transmute(&mut index);
+ if TVMObjectTypeKey2Index(cstring.as_ptr(), index_ptr) != 0 {
+ panic!(crate::get_last_error())
+ }
+ }
+ return index;
+ }
+ }
+
+ pub fn base_object<T: IsObject>() -> Object {
+ let index = Object::get_type_index::<T>();
+ Object::new(index, delete::<T>)
+ }
+}
+
+pub unsafe trait IsObject {
+ const TYPE_KEY: &'static str;
+
+ fn as_object<'s>(&'s self) -> &'s Object;
+
+ unsafe extern "C" fn typed_delete(object: *mut Self) {
+ // let object = Box::from_raw(object);
+ // drop(object)
+ }
+}
+
+unsafe impl IsObject for Object {
+ const TYPE_KEY: &'static str = "Object";
+
+ fn as_object<'s>(&'s self) -> &'s Object {
+ self
+ }
+}
+
+// unsafe impl<T: IsObject> IsObject for ObjectPtr<T> {
+// fn as_object<'s>(&'s self) -> &'s Object {
+// unsafe { self.ptr.as_ref().as_object() }
+// }
+// }
+
+#[repr(C)]
+pub struct ObjectPtr<T> {
+ ptr: NonNull<T>,
+}
+
+impl ObjectPtr<Object> {
+ fn from_raw(object_ptr: *mut Object) -> Option<ObjectPtr<Object>> {
+ let non_null = NonNull::new(object_ptr);
+ non_null.map(|ptr| ObjectPtr { ptr })
+ }
+}
+
+impl<T> Clone for ObjectPtr<T> {
+ fn clone(&self) -> Self {
+ unsafe {
+ let raw_ptr = std::mem::transmute(self.ptr);
+ assert_eq!(TVMObjectRetain(raw_ptr), 0);
+ ObjectPtr { ptr: self.ptr }
+ }
+ }
+}
+
+impl<T> Drop for ObjectPtr<T> {
+ fn drop(&mut self) {
+ unsafe {
+ let raw_ptr = std::mem::transmute(self.ptr);
+ assert_eq!(TVMObjectFree(raw_ptr), 0)
+ }
+ }
+}
+
+impl<T: IsObject> ObjectPtr<T> {
+ pub fn new(object: T) -> ObjectPtr<T> {
+ let object_ptr = Box::new(object);
+ let ptr = NonNull::from(Box::leak(object_ptr));
+ ObjectPtr { ptr }
+ }
+
+ pub fn count(&self) -> i32 {
+ // need to do atomic read in C++
+ // ABI compatible atomics is funky/hard.
Review comment:
My understanding was that for both Rust and C++, their atomic int types
are laid out in memory identical to their non atomic counterparts, but I guess
this is not the same as guaranteeing ABI compatibility...
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