RPM build fix (reverted CI changes which will need to be un-reverted or made conditional) and vendor Rust dependencies to make builds much faster in any CI system.
This commit is contained in:
103
zeroidc/vendor/futures-core/src/future.rs
vendored
Normal file
103
zeroidc/vendor/futures-core/src/future.rs
vendored
Normal file
@@ -0,0 +1,103 @@
|
||||
//! Futures.
|
||||
|
||||
use core::ops::DerefMut;
|
||||
use core::pin::Pin;
|
||||
use core::task::{Context, Poll};
|
||||
|
||||
#[doc(no_inline)]
|
||||
pub use core::future::Future;
|
||||
|
||||
/// An owned dynamically typed [`Future`] for use in cases where you can't
|
||||
/// statically type your result or need to add some indirection.
|
||||
#[cfg(feature = "alloc")]
|
||||
pub type BoxFuture<'a, T> = Pin<alloc::boxed::Box<dyn Future<Output = T> + Send + 'a>>;
|
||||
|
||||
/// `BoxFuture`, but without the `Send` requirement.
|
||||
#[cfg(feature = "alloc")]
|
||||
pub type LocalBoxFuture<'a, T> = Pin<alloc::boxed::Box<dyn Future<Output = T> + 'a>>;
|
||||
|
||||
/// A future which tracks whether or not the underlying future
|
||||
/// should no longer be polled.
|
||||
///
|
||||
/// `is_terminated` will return `true` if a future should no longer be polled.
|
||||
/// Usually, this state occurs after `poll` (or `try_poll`) returned
|
||||
/// `Poll::Ready`. However, `is_terminated` may also return `true` if a future
|
||||
/// has become inactive and can no longer make progress and should be ignored
|
||||
/// or dropped rather than being `poll`ed again.
|
||||
pub trait FusedFuture: Future {
|
||||
/// Returns `true` if the underlying future should no longer be polled.
|
||||
fn is_terminated(&self) -> bool;
|
||||
}
|
||||
|
||||
impl<F: FusedFuture + ?Sized + Unpin> FusedFuture for &mut F {
|
||||
fn is_terminated(&self) -> bool {
|
||||
<F as FusedFuture>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
|
||||
impl<P> FusedFuture for Pin<P>
|
||||
where
|
||||
P: DerefMut + Unpin,
|
||||
P::Target: FusedFuture,
|
||||
{
|
||||
fn is_terminated(&self) -> bool {
|
||||
<P::Target as FusedFuture>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
|
||||
mod private_try_future {
|
||||
use super::Future;
|
||||
|
||||
pub trait Sealed {}
|
||||
|
||||
impl<F, T, E> Sealed for F where F: ?Sized + Future<Output = Result<T, E>> {}
|
||||
}
|
||||
|
||||
/// A convenience for futures that return `Result` values that includes
|
||||
/// a variety of adapters tailored to such futures.
|
||||
pub trait TryFuture: Future + private_try_future::Sealed {
|
||||
/// The type of successful values yielded by this future
|
||||
type Ok;
|
||||
|
||||
/// The type of failures yielded by this future
|
||||
type Error;
|
||||
|
||||
/// Poll this `TryFuture` as if it were a `Future`.
|
||||
///
|
||||
/// This method is a stopgap for a compiler limitation that prevents us from
|
||||
/// directly inheriting from the `Future` trait; in the future it won't be
|
||||
/// needed.
|
||||
fn try_poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<Self::Ok, Self::Error>>;
|
||||
}
|
||||
|
||||
impl<F, T, E> TryFuture for F
|
||||
where
|
||||
F: ?Sized + Future<Output = Result<T, E>>,
|
||||
{
|
||||
type Ok = T;
|
||||
type Error = E;
|
||||
|
||||
#[inline]
|
||||
fn try_poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
|
||||
self.poll(cx)
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
mod if_alloc {
|
||||
use super::*;
|
||||
use alloc::boxed::Box;
|
||||
|
||||
impl<F: FusedFuture + ?Sized + Unpin> FusedFuture for Box<F> {
|
||||
fn is_terminated(&self) -> bool {
|
||||
<F as FusedFuture>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "std")]
|
||||
impl<F: FusedFuture> FusedFuture for std::panic::AssertUnwindSafe<F> {
|
||||
fn is_terminated(&self) -> bool {
|
||||
<F as FusedFuture>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
}
|
||||
27
zeroidc/vendor/futures-core/src/lib.rs
vendored
Normal file
27
zeroidc/vendor/futures-core/src/lib.rs
vendored
Normal file
@@ -0,0 +1,27 @@
|
||||
//! Core traits and types for asynchronous operations in Rust.
|
||||
|
||||
#![cfg_attr(not(feature = "std"), no_std)]
|
||||
#![warn(missing_debug_implementations, missing_docs, rust_2018_idioms, unreachable_pub)]
|
||||
// It cannot be included in the published code because this lints have false positives in the minimum required version.
|
||||
#![cfg_attr(test, warn(single_use_lifetimes))]
|
||||
#![doc(test(
|
||||
no_crate_inject,
|
||||
attr(
|
||||
deny(warnings, rust_2018_idioms, single_use_lifetimes),
|
||||
allow(dead_code, unused_assignments, unused_variables)
|
||||
)
|
||||
))]
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
extern crate alloc;
|
||||
|
||||
pub mod future;
|
||||
#[doc(no_inline)]
|
||||
pub use self::future::{FusedFuture, Future, TryFuture};
|
||||
|
||||
pub mod stream;
|
||||
#[doc(no_inline)]
|
||||
pub use self::stream::{FusedStream, Stream, TryStream};
|
||||
|
||||
#[macro_use]
|
||||
pub mod task;
|
||||
235
zeroidc/vendor/futures-core/src/stream.rs
vendored
Normal file
235
zeroidc/vendor/futures-core/src/stream.rs
vendored
Normal file
@@ -0,0 +1,235 @@
|
||||
//! Asynchronous streams.
|
||||
|
||||
use core::ops::DerefMut;
|
||||
use core::pin::Pin;
|
||||
use core::task::{Context, Poll};
|
||||
|
||||
/// An owned dynamically typed [`Stream`] for use in cases where you can't
|
||||
/// statically type your result or need to add some indirection.
|
||||
#[cfg(feature = "alloc")]
|
||||
pub type BoxStream<'a, T> = Pin<alloc::boxed::Box<dyn Stream<Item = T> + Send + 'a>>;
|
||||
|
||||
/// `BoxStream`, but without the `Send` requirement.
|
||||
#[cfg(feature = "alloc")]
|
||||
pub type LocalBoxStream<'a, T> = Pin<alloc::boxed::Box<dyn Stream<Item = T> + 'a>>;
|
||||
|
||||
/// A stream of values produced asynchronously.
|
||||
///
|
||||
/// If `Future<Output = T>` is an asynchronous version of `T`, then `Stream<Item
|
||||
/// = T>` is an asynchronous version of `Iterator<Item = T>`. A stream
|
||||
/// represents a sequence of value-producing events that occur asynchronously to
|
||||
/// the caller.
|
||||
///
|
||||
/// The trait is modeled after `Future`, but allows `poll_next` to be called
|
||||
/// even after a value has been produced, yielding `None` once the stream has
|
||||
/// been fully exhausted.
|
||||
#[must_use = "streams do nothing unless polled"]
|
||||
pub trait Stream {
|
||||
/// Values yielded by the stream.
|
||||
type Item;
|
||||
|
||||
/// Attempt to pull out the next value of this stream, registering the
|
||||
/// current task for wakeup if the value is not yet available, and returning
|
||||
/// `None` if the stream is exhausted.
|
||||
///
|
||||
/// # Return value
|
||||
///
|
||||
/// There are several possible return values, each indicating a distinct
|
||||
/// stream state:
|
||||
///
|
||||
/// - `Poll::Pending` means that this stream's next value is not ready
|
||||
/// yet. Implementations will ensure that the current task will be notified
|
||||
/// when the next value may be ready.
|
||||
///
|
||||
/// - `Poll::Ready(Some(val))` means that the stream has successfully
|
||||
/// produced a value, `val`, and may produce further values on subsequent
|
||||
/// `poll_next` calls.
|
||||
///
|
||||
/// - `Poll::Ready(None)` means that the stream has terminated, and
|
||||
/// `poll_next` should not be invoked again.
|
||||
///
|
||||
/// # Panics
|
||||
///
|
||||
/// Once a stream has finished (returned `Ready(None)` from `poll_next`), calling its
|
||||
/// `poll_next` method again may panic, block forever, or cause other kinds of
|
||||
/// problems; the `Stream` trait places no requirements on the effects of
|
||||
/// such a call. However, as the `poll_next` method is not marked `unsafe`,
|
||||
/// Rust's usual rules apply: calls must never cause undefined behavior
|
||||
/// (memory corruption, incorrect use of `unsafe` functions, or the like),
|
||||
/// regardless of the stream's state.
|
||||
///
|
||||
/// If this is difficult to guard against then the [`fuse`] adapter can be used
|
||||
/// to ensure that `poll_next` always returns `Ready(None)` in subsequent
|
||||
/// calls.
|
||||
///
|
||||
/// [`fuse`]: https://docs.rs/futures/0.3/futures/stream/trait.StreamExt.html#method.fuse
|
||||
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>;
|
||||
|
||||
/// Returns the bounds on the remaining length of the stream.
|
||||
///
|
||||
/// Specifically, `size_hint()` returns a tuple where the first element
|
||||
/// is the lower bound, and the second element is the upper bound.
|
||||
///
|
||||
/// The second half of the tuple that is returned is an [`Option`]`<`[`usize`]`>`.
|
||||
/// A [`None`] here means that either there is no known upper bound, or the
|
||||
/// upper bound is larger than [`usize`].
|
||||
///
|
||||
/// # Implementation notes
|
||||
///
|
||||
/// It is not enforced that a stream implementation yields the declared
|
||||
/// number of elements. A buggy stream may yield less than the lower bound
|
||||
/// or more than the upper bound of elements.
|
||||
///
|
||||
/// `size_hint()` is primarily intended to be used for optimizations such as
|
||||
/// reserving space for the elements of the stream, but must not be
|
||||
/// trusted to e.g., omit bounds checks in unsafe code. An incorrect
|
||||
/// implementation of `size_hint()` should not lead to memory safety
|
||||
/// violations.
|
||||
///
|
||||
/// That said, the implementation should provide a correct estimation,
|
||||
/// because otherwise it would be a violation of the trait's protocol.
|
||||
///
|
||||
/// The default implementation returns `(0, `[`None`]`)` which is correct for any
|
||||
/// stream.
|
||||
#[inline]
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
(0, None)
|
||||
}
|
||||
}
|
||||
|
||||
impl<S: ?Sized + Stream + Unpin> Stream for &mut S {
|
||||
type Item = S::Item;
|
||||
|
||||
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
|
||||
S::poll_next(Pin::new(&mut **self), cx)
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
(**self).size_hint()
|
||||
}
|
||||
}
|
||||
|
||||
impl<P> Stream for Pin<P>
|
||||
where
|
||||
P: DerefMut + Unpin,
|
||||
P::Target: Stream,
|
||||
{
|
||||
type Item = <P::Target as Stream>::Item;
|
||||
|
||||
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
|
||||
self.get_mut().as_mut().poll_next(cx)
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
(**self).size_hint()
|
||||
}
|
||||
}
|
||||
|
||||
/// A stream which tracks whether or not the underlying stream
|
||||
/// should no longer be polled.
|
||||
///
|
||||
/// `is_terminated` will return `true` if a future should no longer be polled.
|
||||
/// Usually, this state occurs after `poll_next` (or `try_poll_next`) returned
|
||||
/// `Poll::Ready(None)`. However, `is_terminated` may also return `true` if a
|
||||
/// stream has become inactive and can no longer make progress and should be
|
||||
/// ignored or dropped rather than being polled again.
|
||||
pub trait FusedStream: Stream {
|
||||
/// Returns `true` if the stream should no longer be polled.
|
||||
fn is_terminated(&self) -> bool;
|
||||
}
|
||||
|
||||
impl<F: ?Sized + FusedStream + Unpin> FusedStream for &mut F {
|
||||
fn is_terminated(&self) -> bool {
|
||||
<F as FusedStream>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
|
||||
impl<P> FusedStream for Pin<P>
|
||||
where
|
||||
P: DerefMut + Unpin,
|
||||
P::Target: FusedStream,
|
||||
{
|
||||
fn is_terminated(&self) -> bool {
|
||||
<P::Target as FusedStream>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
|
||||
mod private_try_stream {
|
||||
use super::Stream;
|
||||
|
||||
pub trait Sealed {}
|
||||
|
||||
impl<S, T, E> Sealed for S where S: ?Sized + Stream<Item = Result<T, E>> {}
|
||||
}
|
||||
|
||||
/// A convenience for streams that return `Result` values that includes
|
||||
/// a variety of adapters tailored to such futures.
|
||||
pub trait TryStream: Stream + private_try_stream::Sealed {
|
||||
/// The type of successful values yielded by this future
|
||||
type Ok;
|
||||
|
||||
/// The type of failures yielded by this future
|
||||
type Error;
|
||||
|
||||
/// Poll this `TryStream` as if it were a `Stream`.
|
||||
///
|
||||
/// This method is a stopgap for a compiler limitation that prevents us from
|
||||
/// directly inheriting from the `Stream` trait; in the future it won't be
|
||||
/// needed.
|
||||
fn try_poll_next(
|
||||
self: Pin<&mut Self>,
|
||||
cx: &mut Context<'_>,
|
||||
) -> Poll<Option<Result<Self::Ok, Self::Error>>>;
|
||||
}
|
||||
|
||||
impl<S, T, E> TryStream for S
|
||||
where
|
||||
S: ?Sized + Stream<Item = Result<T, E>>,
|
||||
{
|
||||
type Ok = T;
|
||||
type Error = E;
|
||||
|
||||
fn try_poll_next(
|
||||
self: Pin<&mut Self>,
|
||||
cx: &mut Context<'_>,
|
||||
) -> Poll<Option<Result<Self::Ok, Self::Error>>> {
|
||||
self.poll_next(cx)
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "alloc")]
|
||||
mod if_alloc {
|
||||
use super::*;
|
||||
use alloc::boxed::Box;
|
||||
|
||||
impl<S: ?Sized + Stream + Unpin> Stream for Box<S> {
|
||||
type Item = S::Item;
|
||||
|
||||
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
|
||||
Pin::new(&mut **self).poll_next(cx)
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
(**self).size_hint()
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(feature = "std")]
|
||||
impl<S: Stream> Stream for std::panic::AssertUnwindSafe<S> {
|
||||
type Item = S::Item;
|
||||
|
||||
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<S::Item>> {
|
||||
unsafe { self.map_unchecked_mut(|x| &mut x.0) }.poll_next(cx)
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
self.0.size_hint()
|
||||
}
|
||||
}
|
||||
|
||||
impl<S: ?Sized + FusedStream + Unpin> FusedStream for Box<S> {
|
||||
fn is_terminated(&self) -> bool {
|
||||
<S as FusedStream>::is_terminated(&**self)
|
||||
}
|
||||
}
|
||||
}
|
||||
409
zeroidc/vendor/futures-core/src/task/__internal/atomic_waker.rs
vendored
Normal file
409
zeroidc/vendor/futures-core/src/task/__internal/atomic_waker.rs
vendored
Normal file
@@ -0,0 +1,409 @@
|
||||
use core::cell::UnsafeCell;
|
||||
use core::fmt;
|
||||
use core::sync::atomic::AtomicUsize;
|
||||
use core::sync::atomic::Ordering::{AcqRel, Acquire, Release};
|
||||
use core::task::Waker;
|
||||
|
||||
/// A synchronization primitive for task wakeup.
|
||||
///
|
||||
/// Sometimes the task interested in a given event will change over time.
|
||||
/// An `AtomicWaker` can coordinate concurrent notifications with the consumer
|
||||
/// potentially "updating" the underlying task to wake up. This is useful in
|
||||
/// scenarios where a computation completes in another thread and wants to
|
||||
/// notify the consumer, but the consumer is in the process of being migrated to
|
||||
/// a new logical task.
|
||||
///
|
||||
/// Consumers should call `register` before checking the result of a computation
|
||||
/// and producers should call `wake` after producing the computation (this
|
||||
/// differs from the usual `thread::park` pattern). It is also permitted for
|
||||
/// `wake` to be called **before** `register`. This results in a no-op.
|
||||
///
|
||||
/// A single `AtomicWaker` may be reused for any number of calls to `register` or
|
||||
/// `wake`.
|
||||
///
|
||||
/// # Memory ordering
|
||||
///
|
||||
/// Calling `register` "acquires" all memory "released" by calls to `wake`
|
||||
/// before the call to `register`. Later calls to `wake` will wake the
|
||||
/// registered waker (on contention this wake might be triggered in `register`).
|
||||
///
|
||||
/// For concurrent calls to `register` (should be avoided) the ordering is only
|
||||
/// guaranteed for the winning call.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// Here is a simple example providing a `Flag` that can be signalled manually
|
||||
/// when it is ready.
|
||||
///
|
||||
/// ```
|
||||
/// use futures::future::Future;
|
||||
/// use futures::task::{Context, Poll, AtomicWaker};
|
||||
/// use std::sync::Arc;
|
||||
/// use std::sync::atomic::AtomicBool;
|
||||
/// use std::sync::atomic::Ordering::Relaxed;
|
||||
/// use std::pin::Pin;
|
||||
///
|
||||
/// struct Inner {
|
||||
/// waker: AtomicWaker,
|
||||
/// set: AtomicBool,
|
||||
/// }
|
||||
///
|
||||
/// #[derive(Clone)]
|
||||
/// struct Flag(Arc<Inner>);
|
||||
///
|
||||
/// impl Flag {
|
||||
/// pub fn new() -> Self {
|
||||
/// Self(Arc::new(Inner {
|
||||
/// waker: AtomicWaker::new(),
|
||||
/// set: AtomicBool::new(false),
|
||||
/// }))
|
||||
/// }
|
||||
///
|
||||
/// pub fn signal(&self) {
|
||||
/// self.0.set.store(true, Relaxed);
|
||||
/// self.0.waker.wake();
|
||||
/// }
|
||||
/// }
|
||||
///
|
||||
/// impl Future for Flag {
|
||||
/// type Output = ();
|
||||
///
|
||||
/// fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
|
||||
/// // quick check to avoid registration if already done.
|
||||
/// if self.0.set.load(Relaxed) {
|
||||
/// return Poll::Ready(());
|
||||
/// }
|
||||
///
|
||||
/// self.0.waker.register(cx.waker());
|
||||
///
|
||||
/// // Need to check condition **after** `register` to avoid a race
|
||||
/// // condition that would result in lost notifications.
|
||||
/// if self.0.set.load(Relaxed) {
|
||||
/// Poll::Ready(())
|
||||
/// } else {
|
||||
/// Poll::Pending
|
||||
/// }
|
||||
/// }
|
||||
/// }
|
||||
/// ```
|
||||
pub struct AtomicWaker {
|
||||
state: AtomicUsize,
|
||||
waker: UnsafeCell<Option<Waker>>,
|
||||
}
|
||||
|
||||
// `AtomicWaker` is a multi-consumer, single-producer transfer cell. The cell
|
||||
// stores a `Waker` value produced by calls to `register` and many threads can
|
||||
// race to take the waker (to wake it) by calling `wake`.
|
||||
//
|
||||
// If a new `Waker` instance is produced by calling `register` before an
|
||||
// existing one is consumed, then the existing one is overwritten.
|
||||
//
|
||||
// While `AtomicWaker` is single-producer, the implementation ensures memory
|
||||
// safety. In the event of concurrent calls to `register`, there will be a
|
||||
// single winner whose waker will get stored in the cell. The losers will not
|
||||
// have their tasks woken. As such, callers should ensure to add synchronization
|
||||
// to calls to `register`.
|
||||
//
|
||||
// The implementation uses a single `AtomicUsize` value to coordinate access to
|
||||
// the `Waker` cell. There are two bits that are operated on independently.
|
||||
// These are represented by `REGISTERING` and `WAKING`.
|
||||
//
|
||||
// The `REGISTERING` bit is set when a producer enters the critical section. The
|
||||
// `WAKING` bit is set when a consumer enters the critical section. Neither bit
|
||||
// being set is represented by `WAITING`.
|
||||
//
|
||||
// A thread obtains an exclusive lock on the waker cell by transitioning the
|
||||
// state from `WAITING` to `REGISTERING` or `WAKING`, depending on the operation
|
||||
// the thread wishes to perform. When this transition is made, it is guaranteed
|
||||
// that no other thread will access the waker cell.
|
||||
//
|
||||
// # Registering
|
||||
//
|
||||
// On a call to `register`, an attempt to transition the state from WAITING to
|
||||
// REGISTERING is made. On success, the caller obtains a lock on the waker cell.
|
||||
//
|
||||
// If the lock is obtained, then the thread sets the waker cell to the waker
|
||||
// provided as an argument. Then it attempts to transition the state back from
|
||||
// `REGISTERING` -> `WAITING`.
|
||||
//
|
||||
// If this transition is successful, then the registering process is complete
|
||||
// and the next call to `wake` will observe the waker.
|
||||
//
|
||||
// If the transition fails, then there was a concurrent call to `wake` that was
|
||||
// unable to access the waker cell (due to the registering thread holding the
|
||||
// lock). To handle this, the registering thread removes the waker it just set
|
||||
// from the cell and calls `wake` on it. This call to wake represents the
|
||||
// attempt to wake by the other thread (that set the `WAKING` bit). The state is
|
||||
// then transitioned from `REGISTERING | WAKING` back to `WAITING`. This
|
||||
// transition must succeed because, at this point, the state cannot be
|
||||
// transitioned by another thread.
|
||||
//
|
||||
// # Waking
|
||||
//
|
||||
// On a call to `wake`, an attempt to transition the state from `WAITING` to
|
||||
// `WAKING` is made. On success, the caller obtains a lock on the waker cell.
|
||||
//
|
||||
// If the lock is obtained, then the thread takes ownership of the current value
|
||||
// in the waker cell, and calls `wake` on it. The state is then transitioned
|
||||
// back to `WAITING`. This transition must succeed as, at this point, the state
|
||||
// cannot be transitioned by another thread.
|
||||
//
|
||||
// If the thread is unable to obtain the lock, the `WAKING` bit is still. This
|
||||
// is because it has either been set by the current thread but the previous
|
||||
// value included the `REGISTERING` bit **or** a concurrent thread is in the
|
||||
// `WAKING` critical section. Either way, no action must be taken.
|
||||
//
|
||||
// If the current thread is the only concurrent call to `wake` and another
|
||||
// thread is in the `register` critical section, when the other thread **exits**
|
||||
// the `register` critical section, it will observe the `WAKING` bit and handle
|
||||
// the wake itself.
|
||||
//
|
||||
// If another thread is in the `wake` critical section, then it will handle
|
||||
// waking the task.
|
||||
//
|
||||
// # A potential race (is safely handled).
|
||||
//
|
||||
// Imagine the following situation:
|
||||
//
|
||||
// * Thread A obtains the `wake` lock and wakes a task.
|
||||
//
|
||||
// * Before thread A releases the `wake` lock, the woken task is scheduled.
|
||||
//
|
||||
// * Thread B attempts to wake the task. In theory this should result in the
|
||||
// task being woken, but it cannot because thread A still holds the wake lock.
|
||||
//
|
||||
// This case is handled by requiring users of `AtomicWaker` to call `register`
|
||||
// **before** attempting to observe the application state change that resulted
|
||||
// in the task being awoken. The wakers also change the application state before
|
||||
// calling wake.
|
||||
//
|
||||
// Because of this, the waker will do one of two things.
|
||||
//
|
||||
// 1) Observe the application state change that Thread B is woken for. In this
|
||||
// case, it is OK for Thread B's wake to be lost.
|
||||
//
|
||||
// 2) Call register before attempting to observe the application state. Since
|
||||
// Thread A still holds the `wake` lock, the call to `register` will result
|
||||
// in the task waking itself and get scheduled again.
|
||||
|
||||
/// Idle state
|
||||
const WAITING: usize = 0;
|
||||
|
||||
/// A new waker value is being registered with the `AtomicWaker` cell.
|
||||
const REGISTERING: usize = 0b01;
|
||||
|
||||
/// The waker currently registered with the `AtomicWaker` cell is being woken.
|
||||
const WAKING: usize = 0b10;
|
||||
|
||||
impl AtomicWaker {
|
||||
/// Create an `AtomicWaker`.
|
||||
pub const fn new() -> Self {
|
||||
// Make sure that task is Sync
|
||||
trait AssertSync: Sync {}
|
||||
impl AssertSync for Waker {}
|
||||
|
||||
Self { state: AtomicUsize::new(WAITING), waker: UnsafeCell::new(None) }
|
||||
}
|
||||
|
||||
/// Registers the waker to be notified on calls to `wake`.
|
||||
///
|
||||
/// The new task will take place of any previous tasks that were registered
|
||||
/// by previous calls to `register`. Any calls to `wake` that happen after
|
||||
/// a call to `register` (as defined by the memory ordering rules), will
|
||||
/// notify the `register` caller's task and deregister the waker from future
|
||||
/// notifications. Because of this, callers should ensure `register` gets
|
||||
/// invoked with a new `Waker` **each** time they require a wakeup.
|
||||
///
|
||||
/// It is safe to call `register` with multiple other threads concurrently
|
||||
/// calling `wake`. This will result in the `register` caller's current
|
||||
/// task being notified once.
|
||||
///
|
||||
/// This function is safe to call concurrently, but this is generally a bad
|
||||
/// idea. Concurrent calls to `register` will attempt to register different
|
||||
/// tasks to be notified. One of the callers will win and have its task set,
|
||||
/// but there is no guarantee as to which caller will succeed.
|
||||
///
|
||||
/// # Examples
|
||||
///
|
||||
/// Here is how `register` is used when implementing a flag.
|
||||
///
|
||||
/// ```
|
||||
/// use futures::future::Future;
|
||||
/// use futures::task::{Context, Poll, AtomicWaker};
|
||||
/// use std::sync::atomic::AtomicBool;
|
||||
/// use std::sync::atomic::Ordering::Relaxed;
|
||||
/// use std::pin::Pin;
|
||||
///
|
||||
/// struct Flag {
|
||||
/// waker: AtomicWaker,
|
||||
/// set: AtomicBool,
|
||||
/// }
|
||||
///
|
||||
/// impl Future for Flag {
|
||||
/// type Output = ();
|
||||
///
|
||||
/// fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
|
||||
/// // Register **before** checking `set` to avoid a race condition
|
||||
/// // that would result in lost notifications.
|
||||
/// self.waker.register(cx.waker());
|
||||
///
|
||||
/// if self.set.load(Relaxed) {
|
||||
/// Poll::Ready(())
|
||||
/// } else {
|
||||
/// Poll::Pending
|
||||
/// }
|
||||
/// }
|
||||
/// }
|
||||
/// ```
|
||||
pub fn register(&self, waker: &Waker) {
|
||||
match self
|
||||
.state
|
||||
.compare_exchange(WAITING, REGISTERING, Acquire, Acquire)
|
||||
.unwrap_or_else(|x| x)
|
||||
{
|
||||
WAITING => {
|
||||
unsafe {
|
||||
// Locked acquired, update the waker cell
|
||||
*self.waker.get() = Some(waker.clone());
|
||||
|
||||
// Release the lock. If the state transitioned to include
|
||||
// the `WAKING` bit, this means that at least one wake has
|
||||
// been called concurrently.
|
||||
//
|
||||
// Start by assuming that the state is `REGISTERING` as this
|
||||
// is what we just set it to. If this holds, we know that no
|
||||
// other writes were performed in the meantime, so there is
|
||||
// nothing to acquire, only release. In case of concurrent
|
||||
// wakers, we need to acquire their releases, so success needs
|
||||
// to do both.
|
||||
let res = self.state.compare_exchange(REGISTERING, WAITING, AcqRel, Acquire);
|
||||
|
||||
match res {
|
||||
Ok(_) => {
|
||||
// memory ordering: acquired self.state during CAS
|
||||
// - if previous wakes went through it syncs with
|
||||
// their final release (`fetch_and`)
|
||||
// - if there was no previous wake the next wake
|
||||
// will wake us, no sync needed.
|
||||
}
|
||||
Err(actual) => {
|
||||
// This branch can only be reached if at least one
|
||||
// concurrent thread called `wake`. In this
|
||||
// case, `actual` **must** be `REGISTERING |
|
||||
// `WAKING`.
|
||||
debug_assert_eq!(actual, REGISTERING | WAKING);
|
||||
|
||||
// Take the waker to wake once the atomic operation has
|
||||
// completed.
|
||||
let waker = (*self.waker.get()).take().unwrap();
|
||||
|
||||
// We need to return to WAITING state (clear our lock and
|
||||
// concurrent WAKING flag). This needs to acquire all
|
||||
// WAKING fetch_or releases and it needs to release our
|
||||
// update to self.waker, so we need a `swap` operation.
|
||||
self.state.swap(WAITING, AcqRel);
|
||||
|
||||
// memory ordering: we acquired the state for all
|
||||
// concurrent wakes, but future wakes might still
|
||||
// need to wake us in case we can't make progress
|
||||
// from the pending wakes.
|
||||
//
|
||||
// So we simply schedule to come back later (we could
|
||||
// also simply leave the registration in place above).
|
||||
waker.wake();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
WAKING => {
|
||||
// Currently in the process of waking the task, i.e.,
|
||||
// `wake` is currently being called on the old task handle.
|
||||
//
|
||||
// memory ordering: we acquired the state for all
|
||||
// concurrent wakes, but future wakes might still
|
||||
// need to wake us in case we can't make progress
|
||||
// from the pending wakes.
|
||||
//
|
||||
// So we simply schedule to come back later (we
|
||||
// could also spin here trying to acquire the lock
|
||||
// to register).
|
||||
waker.wake_by_ref();
|
||||
}
|
||||
state => {
|
||||
// In this case, a concurrent thread is holding the
|
||||
// "registering" lock. This probably indicates a bug in the
|
||||
// caller's code as racing to call `register` doesn't make much
|
||||
// sense.
|
||||
//
|
||||
// memory ordering: don't care. a concurrent register() is going
|
||||
// to succeed and provide proper memory ordering.
|
||||
//
|
||||
// We just want to maintain memory safety. It is ok to drop the
|
||||
// call to `register`.
|
||||
debug_assert!(state == REGISTERING || state == REGISTERING | WAKING);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Calls `wake` on the last `Waker` passed to `register`.
|
||||
///
|
||||
/// If `register` has not been called yet, then this does nothing.
|
||||
pub fn wake(&self) {
|
||||
if let Some(waker) = self.take() {
|
||||
waker.wake();
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns the last `Waker` passed to `register`, so that the user can wake it.
|
||||
///
|
||||
///
|
||||
/// Sometimes, just waking the AtomicWaker is not fine grained enough. This allows the user
|
||||
/// to take the waker and then wake it separately, rather than performing both steps in one
|
||||
/// atomic action.
|
||||
///
|
||||
/// If a waker has not been registered, this returns `None`.
|
||||
pub fn take(&self) -> Option<Waker> {
|
||||
// AcqRel ordering is used in order to acquire the value of the `task`
|
||||
// cell as well as to establish a `release` ordering with whatever
|
||||
// memory the `AtomicWaker` is associated with.
|
||||
match self.state.fetch_or(WAKING, AcqRel) {
|
||||
WAITING => {
|
||||
// The waking lock has been acquired.
|
||||
let waker = unsafe { (*self.waker.get()).take() };
|
||||
|
||||
// Release the lock
|
||||
self.state.fetch_and(!WAKING, Release);
|
||||
|
||||
waker
|
||||
}
|
||||
state => {
|
||||
// There is a concurrent thread currently updating the
|
||||
// associated task.
|
||||
//
|
||||
// Nothing more to do as the `WAKING` bit has been set. It
|
||||
// doesn't matter if there are concurrent registering threads or
|
||||
// not.
|
||||
//
|
||||
debug_assert!(
|
||||
state == REGISTERING || state == REGISTERING | WAKING || state == WAKING
|
||||
);
|
||||
None
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl Default for AtomicWaker {
|
||||
fn default() -> Self {
|
||||
Self::new()
|
||||
}
|
||||
}
|
||||
|
||||
impl fmt::Debug for AtomicWaker {
|
||||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||||
write!(f, "AtomicWaker")
|
||||
}
|
||||
}
|
||||
|
||||
unsafe impl Send for AtomicWaker {}
|
||||
unsafe impl Sync for AtomicWaker {}
|
||||
4
zeroidc/vendor/futures-core/src/task/__internal/mod.rs
vendored
Normal file
4
zeroidc/vendor/futures-core/src/task/__internal/mod.rs
vendored
Normal file
@@ -0,0 +1,4 @@
|
||||
#[cfg(not(futures_no_atomic_cas))]
|
||||
mod atomic_waker;
|
||||
#[cfg(not(futures_no_atomic_cas))]
|
||||
pub use self::atomic_waker::AtomicWaker;
|
||||
10
zeroidc/vendor/futures-core/src/task/mod.rs
vendored
Normal file
10
zeroidc/vendor/futures-core/src/task/mod.rs
vendored
Normal file
@@ -0,0 +1,10 @@
|
||||
//! Task notification.
|
||||
|
||||
#[macro_use]
|
||||
mod poll;
|
||||
|
||||
#[doc(hidden)]
|
||||
pub mod __internal;
|
||||
|
||||
#[doc(no_inline)]
|
||||
pub use core::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
|
||||
12
zeroidc/vendor/futures-core/src/task/poll.rs
vendored
Normal file
12
zeroidc/vendor/futures-core/src/task/poll.rs
vendored
Normal file
@@ -0,0 +1,12 @@
|
||||
/// Extracts the successful type of a `Poll<T>`.
|
||||
///
|
||||
/// This macro bakes in propagation of `Pending` signals by returning early.
|
||||
#[macro_export]
|
||||
macro_rules! ready {
|
||||
($e:expr $(,)?) => {
|
||||
match $e {
|
||||
$crate::task::Poll::Ready(t) => t,
|
||||
$crate::task::Poll::Pending => return $crate::task::Poll::Pending,
|
||||
}
|
||||
};
|
||||
}
|
||||
Reference in New Issue
Block a user