product-os-async-executor 0.0.18

use std::prelude::v1::*;

use alloc::sync::Arc;
use std::pin::Pin;
use std::task::{Context, Poll};
use async_trait::async_trait;
use futures_task::SpawnError;

use crate::{Future, Timer};
use crate::{Executor, ExecutorPerform};


#[cfg(feature = "exec_async_std")]
/// Async-std-based executor implementation.
///
/// This executor uses the global async-std runtime and provides timer functionality.
pub struct AsyncStdExecutor {
    duration: Option<std::time::Duration>
}


#[cfg(feature = "exec_async_std")]
#[async_trait]
impl Executor<async_std::task::JoinHandle<()>> for AsyncStdExecutor {
    async fn context() -> Result<Self, SpawnError> where Self: Sized {
        // async-std doesn't have an explicit executor context like tokio
        // Just return an empty struct
        Ok(Self { duration: None })
    }

    async fn set_context(&mut self, _executor: async_std::task::JoinHandle<()>) {
        // async-std uses global executor, no context to set
    }

    async fn enter_context(&self) {
        // No-op for async-std
    }

    async fn get_executor(&self) -> &async_std::task::JoinHandle<()> {
        panic!("async-std does not support executor handles - use spawn_in_context instead")
    }

    fn context_sync() -> Result<Self, SpawnError> where Self: Sized {
        Ok(Self { duration: None })
    }

    fn set_context_sync(&mut self, _executor: async_std::task::JoinHandle<()>) {
        // async-std uses global executor, no context to set
    }

    fn enter_context_sync(&self) {
        // No-op for async-std
    }

    fn get_executor_sync(&self) -> &async_std::task::JoinHandle<()> {
        panic!("async-std does not support executor handles - use spawn_in_context_sync instead")
    }
}




#[cfg(feature = "exec_async_std")]
#[async_trait]
impl ExecutorPerform<async_std::task::JoinHandle<()>> for AsyncStdExecutor {
    async fn spawn_in_context<F>(future: F) -> Result<Arc<dyn crate::Task<F::Output, Output=F::Output>>, SpawnError> where F: Future + Send + 'static, F::Output: Send + 'static {
        let handle = async_std::task::spawn(future);
        Ok(Arc::new(Task::new(handle)))
    }

    async fn spawn_from_executor<E, F>(_executor: &E, future: F) -> Result<Arc<dyn crate::Task<F::Output, Output=F::Output>>, SpawnError>
        where
            E: Executor<async_std::task::JoinHandle<()>>,
            F: Future + Send + 'static,
            F::Output: Send + 'static
    {
        // async-std uses global executor, so just spawn directly
        let handle = async_std::task::spawn(future);
        Ok(Arc::new(Task::new(handle)))
    }

    async fn block_from_executor<E, F>(_executor: &E, future: F) -> F::Output
        where
            E: Executor<async_std::task::JoinHandle<()>>,
            F: Future + Send + 'static,
            F::Output: Send + 'static
    {
        // async-std provides block_on
        async_std::task::block_on(future)
    }

    fn spawn_in_context_sync<F>(future: F) -> Result<Arc<dyn crate::Task<F::Output, Output=F::Output>>, SpawnError> where F: Future + Send + 'static, F::Output: Send + 'static {
        let handle = async_std::task::spawn(future);
        Ok(Arc::new(Task::new(handle)))
    }

    fn spawn_from_executor_sync<E, F>(_executor: &E, future: F) -> Result<Arc<dyn crate::Task<F::Output, Output=F::Output>>, SpawnError> where E: Executor<async_std::task::JoinHandle<()>>, F: Future + Send + 'static, F::Output: Send + 'static {
        let handle = async_std::task::spawn(future);
        Ok(Arc::new(Task::new(handle)))
    }

    fn block_from_executor_sync<E, F>(_executor: &E, future: F) -> F::Output where E: Executor<async_std::task::JoinHandle<()>>, F: Future + Send + 'static, F::Output: Send + 'static {
        async_std::task::block_on(future)
    }
}




#[cfg(feature = "exec_async_std")]
#[async_trait]
impl Timer for AsyncStdExecutor {
    async fn once(duration_millis: u32) -> Self {
        let duration = std::time::Duration::from_millis(u64::from(duration_millis));
        Self {
            duration: Some(duration)
        }
    }

    async fn interval(duration_millis: u32) -> Self {
        let duration = std::time::Duration::from_millis(u64::from(duration_millis));
        Self {
            duration: Some(duration)
        }
    }

    async fn cancel(&mut self) {
        self.duration = None;
    }

    fn once_sync(duration_millis: u32) -> Self {
        let duration = std::time::Duration::from_millis(u64::from(duration_millis));
        Self {
            duration: Some(duration)
        }
    }

    fn interval_sync(duration_millis: u32) -> Self {
        let duration = std::time::Duration::from_millis(u64::from(duration_millis));
        Self {
            duration: Some(duration)
        }
    }

    fn cancel_sync(&mut self) {
        self.duration = None;
    }

    async fn tick(&mut self) -> u32 {
        match self.duration {
            None => panic!("Timer has been dropped"),
            Some(duration) => {
                async_std::task::sleep(duration).await;
                // Return duration in milliseconds
                u32::try_from(duration.as_millis()).unwrap_or(0)
            }
        }
    }
}

#[cfg(feature = "exec_async_std")]
impl Clone for AsyncStdExecutor {
    fn clone(&self) -> Self {
        Self { duration: None }
    }
}

#[cfg(feature = "exec_async_std")]
pub struct Task<T> {
    detached: bool,
    handle: async_std::task::JoinHandle<T>
}

#[cfg(feature = "exec_async_std")]
impl<T> Task<T> {
    pub const fn new(handle: async_std::task::JoinHandle<T>) -> Self {
        Self {
            detached: false,
            handle
        }
    }
}

#[cfg(feature = "exec_async_std")]
impl<T> Future for Task<T> {
    type Output = T;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let handle = &mut self.get_mut().handle;

        Poll::Ready(futures_util::ready!(Pin::new(handle).poll(cx)))
    }
}

#[cfg(feature = "exec_async_std")]
#[async_trait]
impl<T: Send + 'static> crate::Task<T> for Task<T> {
    async fn output(self) -> T {
        self.handle.await
    }

    fn detach(mut self) {
        self.detached = true;
    }

    fn drop(self) {
        if !self.detached { drop(self.handle) }
    }
}



#[cfg(all(feature = "hyper_executor", feature = "exec_async_std"))]
impl<F> hyper::rt::Executor<F> for AsyncStdExecutor
    where
        F: Future + Send + 'static,
        F::Output: Send + 'static
{
    fn execute(&self, fut: F) {
        let _ = Self::spawn_in_context_sync(fut);
    }
}