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// Copyright 2016 Amanieu d'Antras
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// copied, modified, or distributed except according to those terms.
use core::sync::atomic::{AtomicBool, Ordering};
use std::time::Instant;
use std::{
io,
os::fortanix_sgx::{
thread::current as current_tcs,
usercalls::{
self,
raw::{Tcs, EV_UNPARK, WAIT_INDEFINITE},
},
},
thread,
};
// Helper type for putting a thread to sleep until some other thread wakes it up
pub struct ThreadParker {
parked: AtomicBool,
tcs: Tcs,
}
impl super::ThreadParkerT for ThreadParker {
type UnparkHandle = UnparkHandle;
const IS_CHEAP_TO_CONSTRUCT: bool = true;
#[inline]
fn new() -> ThreadParker {
ThreadParker {
parked: AtomicBool::new(false),
tcs: current_tcs(),
}
}
#[inline]
unsafe fn prepare_park(&self) {
self.parked.store(true, Ordering::Relaxed);
}
#[inline]
unsafe fn timed_out(&self) -> bool {
self.parked.load(Ordering::Relaxed)
}
#[inline]
unsafe fn park(&self) {
while self.parked.load(Ordering::Acquire) {
let result = usercalls::wait(EV_UNPARK, WAIT_INDEFINITE);
debug_assert_eq!(result.expect("wait returned error") & EV_UNPARK, EV_UNPARK);
}
}
#[inline]
unsafe fn park_until(&self, _timeout: Instant) -> bool {
panic!("timeout not supported in SGX");
}
#[inline]
unsafe fn unpark_lock(&self) -> UnparkHandle {
// We don't need to lock anything, just clear the state
self.parked.store(false, Ordering::Release);
UnparkHandle(self.tcs)
}
}
pub struct UnparkHandle(Tcs);
impl super::UnparkHandleT for UnparkHandle {
#[inline]
unsafe fn unpark(self) {
let result = usercalls::send(EV_UNPARK, Some(self.0));
if cfg!(debug_assertions) {
if let Err(error) = result {
// `InvalidInput` may be returned if the thread we send to has
// already been unparked and exited.
if error.kind() != io::ErrorKind::InvalidInput {
panic!("send returned an unexpected error: {:?}", error);
}
}
}
}
}
#[inline]
pub fn thread_yield() {
thread::yield_now();
}