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use std::cell::UnsafeCell;
use std::fmt;
use std::future::Future;
use std::marker::PhantomData;
use std::mem::forget;
use std::ops::{Deref, DerefMut};
use std::pin::Pin;
use std::process::abort;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Arc, Condvar, Mutex};
use std::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
#[inline(always)]
pub fn abort_on_panic(f: impl FnOnce()) {
struct Bomb;
impl Drop for Bomb {
#[inline(always)]
fn drop(&mut self) {
abort();
}
}
let bomb = Bomb;
f();
forget(bomb);
}
#[macro_export]
macro_rules! defer {
($($body:tt)*) => {
let _guard = {
struct Guard<F: FnOnce()>(Option<F>);
impl<F: FnOnce()> Drop for Guard<F> {
#[inline(always)]
fn drop(&mut self) {
(self.0).take().map(|f| f());
}
}
Guard(Some(|| {
let _: () = { $($body)* };
}))
};
};
}
#[macro_export]
macro_rules! ready {
($e:expr $(,)?) => {
match $e {
Poll::Ready(t) => t,
Poll::Pending => return Poll::Pending,
}
};
}
#[derive(Debug)]
pub struct Yields(pub usize);
impl Future for Yields {
type Output = ();
#[inline(always)]
fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<()> {
if self.0 == 0 {
Poll::Ready(())
} else {
self.0 -= 1;
cx.waker().wake_by_ref();
Poll::Pending
}
}
}
pub struct SimpleLock<T: ?Sized> {
locked: AtomicBool,
value: UnsafeCell<T>,
}
unsafe impl<T: ?Sized + Send> Send for SimpleLock<T> {}
unsafe impl<T: ?Sized + Send> Sync for SimpleLock<T> {}
impl<T> SimpleLock<T> {
#[inline(always)]
pub fn new(value: T) -> SimpleLock<T> {
SimpleLock {
locked: AtomicBool::new(false),
value: UnsafeCell::new(value),
}
}
}
impl<T: ?Sized + Default> Default for SimpleLock<T> {
#[inline(always)]
fn default() -> SimpleLock<T> {
SimpleLock::new(T::default())
}
}
impl<T: ?Sized> SimpleLock<T> {
#[inline(always)]
pub fn try_lock(&self) -> Option<SimpleLockGuard<T>> {
if self.locked.swap(true, Ordering::Acquire) {
None
} else {
Some(SimpleLockGuard {
parent: self,
_marker: PhantomData,
})
}
}
#[inline(always)]
pub fn is_locked(&self) -> bool {
self.locked.load(Ordering::Relaxed)
}
}
impl<T: ?Sized + fmt::Debug> fmt::Debug for SimpleLock<T> {
#[inline(always)]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self.try_lock() {
Some(guard) => f.debug_tuple("SimpleLock").field(&&*guard).finish(),
None => f.write_str("SimpleLock(<locked>)"),
}
}
}
pub struct SimpleLockGuard<'a, T: 'a + ?Sized> {
parent: &'a SimpleLock<T>,
_marker: PhantomData<*mut ()>,
}
impl<T: ?Sized> Drop for SimpleLockGuard<'_, T> {
#[inline(always)]
fn drop(&mut self) {
self.parent.locked.store(false, Ordering::Release);
}
}
impl<T: ?Sized> Deref for SimpleLockGuard<'_, T> {
type Target = T;
#[inline(always)]
fn deref(&self) -> &Self::Target {
unsafe { &*self.parent.value.get() }
}
}
impl<T: ?Sized> DerefMut for SimpleLockGuard<'_, T> {
#[inline(always)]
fn deref_mut(&mut self) -> &mut Self::Target {
unsafe { &mut *self.parent.value.get() }
}
}
impl<T: ?Sized + fmt::Debug> fmt::Debug for SimpleLockGuard<'_, T> {
#[inline(always)]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&**self, f)
}
}
#[inline(always)]
pub fn block_on<F: Future>(mut f: F) -> F::Output {
#[allow(clippy::mutex_atomic)]
#[derive(Default)]
struct Parker(Mutex<bool>, Condvar);
#[allow(clippy::mutex_atomic)]
impl Parker {
#[inline(always)]
fn unpark(self: &Parker) {
*self.0.lock().unwrap() = true;
self.1.notify_one();
}
#[inline(always)]
fn park(self: &Parker) {
let mut runnable = self.0.lock().unwrap();
while !*runnable {
runnable = self.1.wait(runnable).unwrap();
}
*runnable = false;
}
}
static VTABLE: RawWakerVTable = RawWakerVTable::new(
#[inline(always)]
|parker| unsafe {
let parker = Arc::from_raw(parker as *const Parker);
let cloned_parker = parker.clone();
forget(parker);
RawWaker::new(Arc::into_raw(cloned_parker) as *const (), &VTABLE)
},
#[inline(always)]
|parker| unsafe { Arc::from_raw(parker as *const Parker).unpark() },
#[inline(always)]
|parker| unsafe { (&*(parker as *const Parker)).unpark() },
#[inline(always)]
|parker| unsafe { drop(Arc::from_raw(parker as *const Parker)) },
);
let parker = Arc::new(Parker::default());
let waker = unsafe {
Waker::from_raw(RawWaker::new(
Arc::into_raw(parker.clone()) as *const (),
&VTABLE,
))
};
let mut f = unsafe { Pin::new_unchecked(&mut f) };
let mut cx = Context::from_waker(&waker);
loop {
match f.as_mut().poll(&mut cx) {
Poll::Pending => parker.park(),
Poll::Ready(val) => return val,
}
}
}