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use crate::future::Future;
use crate::runtime::task::{Cell, Harness, Header, Schedule, State};
use std::ptr::NonNull;
use std::task::{Poll, Waker};
/// Raw task handle
pub(super) struct RawTask {
ptr: NonNull<Header>,
}
pub(super) struct Vtable {
/// Polls the future.
pub(super) poll: unsafe fn(NonNull<Header>),
/// Deallocates the memory.
pub(super) dealloc: unsafe fn(NonNull<Header>),
/// Reads the task output, if complete.
pub(super) try_read_output: unsafe fn(NonNull<Header>, *mut (), &Waker),
/// Try to set the waker notified when the task is complete. Returns true if
/// the task has already completed. If this call returns false, then the
/// waker will not be notified.
pub(super) try_set_join_waker: unsafe fn(NonNull<Header>, &Waker) -> bool,
/// The join handle has been dropped.
pub(super) drop_join_handle_slow: unsafe fn(NonNull<Header>),
/// The task is remotely aborted.
pub(super) remote_abort: unsafe fn(NonNull<Header>),
/// Scheduler is being shutdown.
pub(super) shutdown: unsafe fn(NonNull<Header>),
}
/// Get the vtable for the requested `T` and `S` generics.
pub(super) fn vtable<T: Future, S: Schedule>() -> &'static Vtable {
&Vtable {
poll: poll::<T, S>,
dealloc: dealloc::<T, S>,
try_read_output: try_read_output::<T, S>,
try_set_join_waker: try_set_join_waker::<T, S>,
drop_join_handle_slow: drop_join_handle_slow::<T, S>,
remote_abort: remote_abort::<T, S>,
shutdown: shutdown::<T, S>,
}
}
impl RawTask {
pub(super) fn new<T, S>(task: T, scheduler: S) -> RawTask
where
T: Future,
S: Schedule,
{
let ptr = Box::into_raw(Cell::<_, S>::new(task, scheduler, State::new()));
let ptr = unsafe { NonNull::new_unchecked(ptr as *mut Header) };
RawTask { ptr }
}
pub(super) unsafe fn from_raw(ptr: NonNull<Header>) -> RawTask {
RawTask { ptr }
}
pub(super) fn header_ptr(&self) -> NonNull<Header> {
self.ptr
}
/// Returns a reference to the task's meta structure.
///
/// Safe as `Header` is `Sync`.
pub(super) fn header(&self) -> &Header {
unsafe { self.ptr.as_ref() }
}
/// Safety: mutual exclusion is required to call this function.
pub(super) fn poll(self) {
let vtable = self.header().vtable;
unsafe { (vtable.poll)(self.ptr) }
}
pub(super) fn dealloc(self) {
let vtable = self.header().vtable;
unsafe {
(vtable.dealloc)(self.ptr);
}
}
/// Safety: `dst` must be a `*mut Poll<super::Result<T::Output>>` where `T`
/// is the future stored by the task.
pub(super) unsafe fn try_read_output(self, dst: *mut (), waker: &Waker) {
let vtable = self.header().vtable;
(vtable.try_read_output)(self.ptr, dst, waker);
}
pub(super) fn try_set_join_waker(self, waker: &Waker) -> bool {
let vtable = self.header().vtable;
unsafe { (vtable.try_set_join_waker)(self.ptr, waker) }
}
pub(super) fn drop_join_handle_slow(self) {
let vtable = self.header().vtable;
unsafe { (vtable.drop_join_handle_slow)(self.ptr) }
}
pub(super) fn shutdown(self) {
let vtable = self.header().vtable;
unsafe { (vtable.shutdown)(self.ptr) }
}
pub(super) fn remote_abort(self) {
let vtable = self.header().vtable;
unsafe { (vtable.remote_abort)(self.ptr) }
}
}
impl Clone for RawTask {
fn clone(&self) -> Self {
RawTask { ptr: self.ptr }
}
}
impl Copy for RawTask {}
unsafe fn poll<T: Future, S: Schedule>(ptr: NonNull<Header>) {
let harness = Harness::<T, S>::from_raw(ptr);
harness.poll();
}
unsafe fn dealloc<T: Future, S: Schedule>(ptr: NonNull<Header>) {
let harness = Harness::<T, S>::from_raw(ptr);
harness.dealloc();
}
unsafe fn try_read_output<T: Future, S: Schedule>(
ptr: NonNull<Header>,
dst: *mut (),
waker: &Waker,
) {
let out = &mut *(dst as *mut Poll<super::Result<T::Output>>);
let harness = Harness::<T, S>::from_raw(ptr);
harness.try_read_output(out, waker);
}
unsafe fn try_set_join_waker<T: Future, S: Schedule>(ptr: NonNull<Header>, waker: &Waker) -> bool {
let harness = Harness::<T, S>::from_raw(ptr);
harness.try_set_join_waker(waker)
}
unsafe fn drop_join_handle_slow<T: Future, S: Schedule>(ptr: NonNull<Header>) {
let harness = Harness::<T, S>::from_raw(ptr);
harness.drop_join_handle_slow()
}
unsafe fn remote_abort<T: Future, S: Schedule>(ptr: NonNull<Header>) {
let harness = Harness::<T, S>::from_raw(ptr);
harness.remote_abort()
}
unsafe fn shutdown<T: Future, S: Schedule>(ptr: NonNull<Header>) {
let harness = Harness::<T, S>::from_raw(ptr);
harness.shutdown()
}
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