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use crate::{Error, Result}; use parking_lot::Mutex; use std::{ fmt, sync::{ mpsc::{sync_channel, Receiver, SyncSender}, Arc, }, }; pub struct Wait<T> { recv: Receiver<Result<T>>, send: SyncSender<Result<T>>, task: Arc<Mutex<Option<Box<dyn NotifyReady + Send>>>>, } #[derive(Clone)] pub struct WaitHandle<T> { send: SyncSender<Result<T>>, task: Arc<Mutex<Option<Box<dyn NotifyReady + Send>>>>, } pub trait NotifyReady { fn notify(&self); } pub(crate) trait Cancellable: fmt::Debug { fn cancel(&self, error: Error); } impl<T> Cancellable for WaitHandle<T> { fn cancel(&self, error: Error) { self.error(error); } } impl<T> Wait<T> { pub(crate) fn new() -> (Self, WaitHandle<T>) { let (send, recv) = sync_channel(1); let wait = Self { recv, send, task: Arc::new(Mutex::new(None)), }; let wait_handle = wait.handle(); (wait, wait_handle) } fn handle(&self) -> WaitHandle<T> { WaitHandle { send: self.send.clone(), task: self.task.clone(), } } pub(crate) fn try_wait(&self) -> Option<Result<T>> { self.recv.try_recv().ok() } pub(crate) fn wait(&self) -> Result<T> { self.recv.recv().unwrap() } pub(crate) fn subscribe(&self, task: Box<dyn NotifyReady + Send>) { *self.task.lock() = Some(task); } pub(crate) fn has_subscriber(&self) -> bool { self.task.lock().is_some() } } impl<T> WaitHandle<T> { pub(crate) fn finish(&self, val: T) { let _ = self.send.send(Ok(val)); self.notify(); } pub(crate) fn error(&self, error: Error) { let _ = self.send.send(Err(error)); self.notify(); } fn notify(&self) { if let Some(task) = self.task.lock().take() { task.notify(); } } } impl<T> fmt::Debug for Wait<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "Wait") } } impl<T> fmt::Debug for WaitHandle<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "WaitHandle") } }