Rollup merge of #110145 - WaffleLapkin:share_slice_of_bytes, r=Nilstrieb
Share slice of bytes r? `@Nilstrieb` cc `@noamtashma`
This commit is contained in:
commit
2a5c4baf68
10 changed files with 64 additions and 37 deletions
|
@ -1,5 +1,6 @@
|
|||
use std::{borrow::Borrow, ops::Deref};
|
||||
|
||||
use crate::sync::Lrc;
|
||||
// Use our fake Send/Sync traits when on not parallel compiler,
|
||||
// so that `OwnedSlice` only implements/requires Send/Sync
|
||||
// for parallel compiler builds.
|
||||
|
@ -7,7 +8,7 @@ use crate::sync::{Send, Sync};
|
|||
|
||||
/// An owned slice.
|
||||
///
|
||||
/// This is similar to `Box<[u8]>` but allows slicing and using anything as the
|
||||
/// This is similar to `Lrc<[u8]>` but allows slicing and using anything as the
|
||||
/// backing buffer.
|
||||
///
|
||||
/// See [`slice_owned`] for `OwnedSlice` construction and examples.
|
||||
|
@ -16,6 +17,7 @@ use crate::sync::{Send, Sync};
|
|||
///
|
||||
/// This is essentially a replacement for `owning_ref` which is a lot simpler
|
||||
/// and even sound! 🌸
|
||||
#[derive(Clone)]
|
||||
pub struct OwnedSlice {
|
||||
/// This is conceptually a `&'self.owner [u8]`.
|
||||
bytes: *const [u8],
|
||||
|
@ -31,7 +33,7 @@ pub struct OwnedSlice {
|
|||
// \/
|
||||
// ⊂(´・◡・⊂ )∘˚˳° (I am the phantom remnant of #97770)
|
||||
#[expect(dead_code)]
|
||||
owner: Box<dyn Send + Sync>,
|
||||
owner: Lrc<dyn Send + Sync>,
|
||||
}
|
||||
|
||||
/// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function.
|
||||
|
@ -72,10 +74,10 @@ where
|
|||
O: Send + Sync + 'static,
|
||||
F: FnOnce(&O) -> Result<&[u8], E>,
|
||||
{
|
||||
// We box the owner of the bytes, so it doesn't move.
|
||||
// We wrap the owner of the bytes in, so it doesn't move.
|
||||
//
|
||||
// Since the owner does not move and we don't access it in any way
|
||||
// before drop, there is nothing that can invalidate the bytes pointer.
|
||||
// before dropping, there is nothing that can invalidate the bytes pointer.
|
||||
//
|
||||
// Thus, "extending" the lifetime of the reference returned from `F` is fine.
|
||||
// We pretend that we pass it a reference that lives as long as the returned slice.
|
||||
|
@ -83,12 +85,39 @@ where
|
|||
// N.B. the HRTB on the `slicer` is important — without it the caller could provide
|
||||
// a short lived slice, unrelated to the owner.
|
||||
|
||||
let owner = Box::new(owner);
|
||||
let owner = Lrc::new(owner);
|
||||
let bytes = slicer(&*owner)?;
|
||||
|
||||
Ok(OwnedSlice { bytes, owner })
|
||||
}
|
||||
|
||||
impl OwnedSlice {
|
||||
/// Slice this slice by `slicer`.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// ```rust
|
||||
/// # use rustc_data_structures::owned_slice::{OwnedSlice, slice_owned};
|
||||
/// let vec = vec![1, 2, 3, 4];
|
||||
///
|
||||
/// // Identical to slicing via `&v[1..3]` but produces an owned slice
|
||||
/// let slice: OwnedSlice = slice_owned(vec, |v| &v[..]);
|
||||
/// assert_eq!(&*slice, [1, 2, 3, 4]);
|
||||
///
|
||||
/// let slice = slice.slice(|slice| &slice[1..][..2]);
|
||||
/// assert_eq!(&*slice, [2, 3]);
|
||||
/// ```
|
||||
///
|
||||
pub fn slice(self, slicer: impl FnOnce(&[u8]) -> &[u8]) -> OwnedSlice {
|
||||
// This is basically identical to `try_slice_owned`,
|
||||
// `slicer` can only return slices of its argument or some static data,
|
||||
// both of which are valid while `owner` is alive.
|
||||
|
||||
let bytes = slicer(&self);
|
||||
OwnedSlice { bytes, ..self }
|
||||
}
|
||||
}
|
||||
|
||||
impl Deref for OwnedSlice {
|
||||
type Target = [u8];
|
||||
|
||||
|
@ -108,11 +137,11 @@ impl Borrow<[u8]> for OwnedSlice {
|
|||
}
|
||||
}
|
||||
|
||||
// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Send`
|
||||
// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Send`
|
||||
#[cfg(parallel_compiler)]
|
||||
unsafe impl Send for OwnedSlice {}
|
||||
|
||||
// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Sync`
|
||||
// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Sync`
|
||||
#[cfg(parallel_compiler)]
|
||||
unsafe impl Sync for OwnedSlice {}
|
||||
|
||||
|
|
|
@ -26,7 +26,7 @@ fn static_storage() {
|
|||
}
|
||||
|
||||
#[test]
|
||||
fn slice_the_slice() {
|
||||
fn slice_owned_the_slice() {
|
||||
let slice = slice_owned(vec![1, 2, 3, 4, 5, 6], Vec::as_slice);
|
||||
let slice = slice_owned(slice, |s| &s[1..][..4]);
|
||||
let slice = slice_owned(slice, |s| s);
|
||||
|
@ -35,6 +35,16 @@ fn slice_the_slice() {
|
|||
assert_eq!(&*slice, &[1, 2, 3, 4, 5, 6][1..][..4][1..]);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn slice_the_slice() {
|
||||
let slice = slice_owned(vec![1, 2, 3, 4, 5, 6], Vec::as_slice)
|
||||
.slice(|s| &s[1..][..4])
|
||||
.slice(|s| s)
|
||||
.slice(|s| &s[1..]);
|
||||
|
||||
assert_eq!(&*slice, &[1, 2, 3, 4, 5, 6][1..][..4][1..]);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn try_and_fail() {
|
||||
let res = try_slice_owned(vec![0], |v| v.get(12..).ok_or(()));
|
||||
|
|
|
@ -40,7 +40,6 @@
|
|||
//! [^2] `MTLockRef` is a typedef.
|
||||
|
||||
pub use crate::marker::*;
|
||||
use crate::owned_slice::OwnedSlice;
|
||||
use std::collections::HashMap;
|
||||
use std::hash::{BuildHasher, Hash};
|
||||
use std::ops::{Deref, DerefMut};
|
||||
|
@ -92,6 +91,7 @@ mod mode {
|
|||
}
|
||||
|
||||
pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
|
||||
|
||||
cfg_if! {
|
||||
if #[cfg(not(parallel_compiler))] {
|
||||
pub unsafe auto trait Send {}
|
||||
|
@ -244,8 +244,6 @@ cfg_if! {
|
|||
r
|
||||
}
|
||||
|
||||
pub type MetadataRef = OwnedSlice;
|
||||
|
||||
pub use std::rc::Rc as Lrc;
|
||||
pub use std::rc::Weak as Weak;
|
||||
pub use std::cell::Ref as ReadGuard;
|
||||
|
@ -517,8 +515,6 @@ cfg_if! {
|
|||
}
|
||||
}
|
||||
|
||||
pub type MetadataRef = OwnedSlice;
|
||||
|
||||
/// This makes locks panic if they are already held.
|
||||
/// It is only useful when you are running in a single thread
|
||||
const ERROR_CHECKING: bool = false;
|
||||
|
|
Loading…
Add table
Add a link
Reference in a new issue