From 35cdd195130be61fae88c6ba952364038c313903 Mon Sep 17 00:00:00 2001
From: Lukas Markeffsky <@>
Date: Wed, 31 Jan 2024 23:54:22 +0100
Subject: [PATCH] write root target backref only once
---
src/lib.rs | 28 +++++++++++++++++-----------
1 file changed, 17 insertions(+), 11 deletions(-)
diff --git a/src/lib.rs b/src/lib.rs
index 94d7a35..46b9828 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,7 +5,7 @@ use core::marker::PhantomPinned;
use core::mem::{self, MaybeUninit};
use core::ops::{Deref, DerefMut};
use core::pin::Pin;
-use core::ptr::NonNull;
+use core::ptr::{self, NonNull};
pub trait Reclaim: Sized {
fn reclaim(self, unclaimed: Unclaimed<Self>);
@@ -80,7 +80,15 @@ impl<T> Root<T> {
panic!("unclaimed called multiple times");
}
self.state.set(STATE_UNCLAIMED);
+
let ptr = unsafe { NonNull::from(self.get_unchecked_mut()) };
+ let ptr_erased = ptr.cast::<Root<Erased>>();
+
+ unsafe {
+ let target_root = ptr::addr_of_mut!((*(*ptr.as_ptr()).target.as_mut_ptr()).root);
+ target_root.write(Cell::new(Some(ptr_erased)));
+ }
+
Unclaimed { ptr }
}
}
@@ -126,20 +134,18 @@ pub struct Unclaimed<T> {
impl<T> Unclaimed<T> {
pub fn claim(self, value: T) -> Xrc<T> {
- let root_erased = self.ptr.cast::<Root<Erased>>();
- let target = unsafe {
- (*self.ptr.as_ptr()).target.write(ProjectTarget {
- root: Cell::new(Some(root_erased)),
- value,
- })
- };
-
unsafe {
(*self.ptr.as_ptr()).state.set(STATE_SHARED_INIT);
}
- // shared reborrow
- let ptr = NonNull::from(&*target);
+ unsafe {
+ let target_value = ptr::addr_of_mut!((*(*self.ptr.as_ptr()).target.as_mut_ptr()).value);
+ target_value.write(value);
+ }
+
+ // shared read-only reborrow
+ let target = unsafe { (*self.ptr.as_ptr()).target.assume_init_ref() };
+ let ptr = NonNull::from(target);
Xrc { ptr }
}
}
--
GitLab