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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.

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Adam Ierymenko
2022-06-08 07:32:16 -04:00
parent 373ca30269
commit d5ca4e5f52
12611 changed files with 2898014 additions and 284 deletions
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409
zeroidc/vendor/futures-core/src/task/__internal/atomic_waker.rs vendored Normal file
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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 {}

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zeroidc/vendor/futures-core/src/task/__internal/mod.rs vendored Normal file
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#[cfg(not(futures_no_atomic_cas))]
mod atomic_waker;
#[cfg(not(futures_no_atomic_cas))]
pub use self::atomic_waker::AtomicWaker;

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zeroidc/vendor/futures-core/src/task/mod.rs vendored Normal file
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//! Task notification.
#[macro_use]
mod poll;
#[doc(hidden)]
pub mod __internal;
#[doc(no_inline)]
pub use core::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};

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zeroidc/vendor/futures-core/src/task/poll.rs vendored Normal file
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/// 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,
}
};
}