mirror of https://github.com/rust-lang/rust
42 lines
923 B
Rust
42 lines
923 B
Rust
use std::{ptr::NonNull, task::Poll};
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struct TaskRef;
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struct Header {
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vtable: &'static Vtable,
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}
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struct Vtable {
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poll: unsafe fn(TaskRef) -> Poll<()>,
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deallocate: unsafe fn(NonNull<Header>),
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}
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// in the "Header" type, which is a private type in maitake
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impl Header {
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pub(crate) const fn new_stub() -> Self {
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unsafe fn nop(_ptr: TaskRef) -> Poll<()> {
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Poll::Pending
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}
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unsafe fn nop_deallocate(ptr: NonNull<Header>) {
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unreachable!("stub task ({ptr:p}) should never be deallocated!");
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}
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Self { vtable: &Vtable { poll: nop, deallocate: nop_deallocate } }
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}
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}
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// This is a public type in `maitake`
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#[repr(transparent)]
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#[cfg_attr(loom, allow(dead_code))]
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pub struct TaskStub {
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hdr: Header,
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}
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impl TaskStub {
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/// Create a new unique stub [`Task`].
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pub const fn new() -> Self {
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Self { hdr: Header::new_stub() }
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}
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}
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