hiasync 0.1.4

Supports only single-threaded asynchronous runtime
Documentation 
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use crate::{Join, JoinHandle, SchedInfo};
use std::cell::RefCell;
use std::future::Future;
use std::pin::Pin;
use std::rc::{Rc, Weak};
use std::task::{Context, Poll};

#[derive(Copy, Clone)]
pub(crate) enum TaskState {
    Pending,
    Running,
}

pub(crate) trait Task {
    fn get_id(&self) -> u64;
    fn get_status(&self) -> TaskState;
    fn set_running(&mut self);
    fn run(&mut self, ctx: &mut Context<'_>) -> Poll<()>;
}

pub(crate) struct TaskImpl<T: Future> {
    id: u64,
    stat: TaskState,
    future: T,
    handle: Weak<dyn Join<T::Output>>,
}

impl<T: Future + 'static> TaskImpl<T> {
    pub(crate) fn with_info(
        future: T,
        info: &Rc<RefCell<SchedInfo>>,
    ) -> (Box<dyn Task>, JoinHandle<T>) {
        let id = info.borrow_mut().new_task_id();
        let handle = JoinHandle::new(info.clone(), id);
        let task = Box::new(TaskImpl {
            id,
            stat: TaskState::Pending,
            future,
            handle: handle.weak(),
        });
        (task, handle)
    }

    pub(crate) fn with_join(
        future: T,
        info: &Rc<RefCell<SchedInfo>>,
        handle: Weak<dyn Join<T::Output>>,
    ) -> Box<dyn Task> {
        let id = info.borrow_mut().new_task_id();
        Box::new(TaskImpl {
            stat: TaskState::Pending,
            id,
            future,
            handle,
        })
    }
}

impl<T: Future> Task for TaskImpl<T> {
    fn get_id(&self) -> u64 {
        self.id
    }

    fn get_status(&self) -> TaskState {
        self.stat
    }

    fn set_running(&mut self) {
        self.stat = TaskState::Running;
        // 这个设置通知JoinHandle, 避免调用abort导致资源泄露.
        if let Some(handle) = self.handle.upgrade() {
            handle.set_running(self.id);
        }
    }

    fn run(&mut self, ctx: &mut Context<'_>) -> Poll<()> {
        let pin = unsafe { Pin::new_unchecked(&mut self.future) };
        match pin.poll(ctx) {
            Poll::Pending => Poll::Pending,
            Poll::Ready(output) => {
                if let Some(handle) = self.handle.upgrade() {
                    handle.set_finished(output, self.id);
                }
                Poll::Ready(())
            }
        }
    }
}