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use std::{future::Future, marker::PhantomData, pin::Pin, task::Poll}; use crate::AsyncJob; use crate::Interval; use crate::{ async_job::JobFuture, timeprovider::{ChronoTimeProvider, TimeProvider}, Job, }; /// An asynchronous job scheduler, for use with `Future`s. /// /// The asynchronous scheduler works almost identically to the [synchronous one](crate::Scheduler), except that /// instead of taking functions or closures returning `()`, it takes functions or closures returning values implementing `Future<Output = ()>`. /// /// Unlike the synchronous version, there is no [`watch_thread`](crate::Scheduler::watch_thread) method, as it would tie /// this crate to a specific runtime, and also because it's trivial to implement by hand. For example, using tokio: /// /// ```no_run /// # use clokwerk::*; /// # use std::time::Duration; /// # let mut scheduler = AsyncScheduler::new(); /// tokio::spawn(async move { /// loop { /// scheduler.run_pending().await; /// tokio::time::sleep(Duration::from_millis(100)).await; /// } /// }); /// ``` /// For async_std: /// ```no_run /// # use clokwerk::*; /// # use std::time::Duration; /// # let mut scheduler = AsyncScheduler::new(); /// async_std::task::spawn(async move { /// loop { /// scheduler.run_pending().await; /// async_std::task::sleep(Duration::from_millis(100)).await; /// } /// }); /// ``` /// ### Usage examples /// The examples below are intended to demonstrate how to work with various types of Future. /// See [synchronous examples](crate::Scheduler) for more examples of how to schedule tasks. /// /// ```rust /// // Scheduler, trait for .seconds(), .minutes(), etc., and trait with job scheduling methods /// use clokwerk::{AsyncScheduler, TimeUnits, Job}; /// // Import week days and WeekDay /// use clokwerk::Interval::*; /// use std::time::Duration; /// # use std::future::Future; /// # use std::pin::Pin; /// # async fn some_async_fn() {} /// # fn returns_boxed_future() -> Box<dyn Future<Output=()> + Send> { Box::new(some_async_fn()) } /// # fn returns_pinned_boxed_future() -> Pin<Box<dyn Future<Output=()> + Send>> { Box::pin(some_async_fn()) } /// /// // Create a new scheduler /// let mut scheduler = AsyncScheduler::new(); /// // Add some tasks to it /// scheduler /// .every(10.minutes()) /// .plus(30.seconds()) /// .run(|| async { println!("Simplest is just using an async block"); }); /// scheduler /// .every(1.day()) /// .at("3:20 pm") /// .run(|| some_async_fn()); /// scheduler /// .every(Wednesday) /// .at("14:20:17") /// .run(some_async_fn); /// scheduler /// .every(Tuesday) /// .at("14:20:17") /// .and_every(Thursday) /// .at("15:00") /// .run(|| std::pin::Pin::from(returns_boxed_future())); /// scheduler /// .every(Weekday) /// .run(|| returns_pinned_boxed_future()); /// scheduler /// .every(1.day()) /// .at("3:20 pm") /// .run(returns_pinned_boxed_future).once(); /// # tokio_test::block_on(async move { /// // Manually run the scheduler forever /// loop { /// scheduler.run_pending().await; /// tokio::time::sleep(Duration::from_millis(10)).await; /// # break; /// } /// /// // Or spawn a task to run it forever /// tokio::spawn(async move { /// loop { /// scheduler.run_pending().await; /// tokio::time::sleep(Duration::from_millis(100)).await; /// } /// }); /// # }); /// ``` #[derive(Debug)] pub struct AsyncScheduler<Tz = chrono::Local, Tp = ChronoTimeProvider> where Tz: chrono::TimeZone, Tp: TimeProvider, { jobs: Vec<AsyncJob<Tz, Tp>>, tz: Tz, _tp: PhantomData<Tp>, } impl Default for AsyncScheduler { fn default() -> AsyncScheduler { AsyncScheduler::<chrono::Local> { jobs: vec![], tz: chrono::Local, _tp: PhantomData, } } } impl AsyncScheduler { /// Create a new scheduler. Dates and times will be interpretted using the local timezone pub fn new() -> Self { Self::default() } /// Create a new scheduler. Dates and times will be interpretted using the specified timezone. pub fn with_tz<Tz: chrono::TimeZone>(tz: Tz) -> AsyncScheduler<Tz> { AsyncScheduler { jobs: vec![], tz, _tp: PhantomData, } } /// Create a new scheduler. Dates and times will be interpretted using the specified timezone. /// In addition, you can provide an alternate time provider. This is mostly useful for writing /// tests. pub fn with_tz_and_provider<Tz: chrono::TimeZone, Tp: TimeProvider>( tz: Tz, ) -> AsyncScheduler<Tz, Tp> { AsyncScheduler { jobs: vec![], tz, _tp: PhantomData, } } } impl<Tz, Tp> AsyncScheduler<Tz, Tp> where Tz: chrono::TimeZone + Sync + Send, Tp: TimeProvider, { /// Add a new job to the scheduler to be run on the given interval /// ```rust /// # use clokwerk::*; /// # use clokwerk::Interval::*; /// # use std::future::Future; /// # use std::pin::Pin; /// # async fn some_async_fn() {} /// # fn returns_boxed_future() -> Box<dyn Future<Output=()> + Send> { Box::new(some_async_fn()) } /// # fn returns_pinned_boxed_future() -> Pin<Box<dyn Future<Output=()> + Send>> { Box::pin(some_async_fn()) } /// let mut scheduler = AsyncScheduler::new(); /// scheduler.every(10.minutes()).plus(30.seconds()).run(|| async { println!("Periodic task") }); /// scheduler.every(1.day()).at("3:20 pm").run(|| some_async_fn()); /// scheduler.every(Wednesday).at("14:20:17").run(|| Pin::from(returns_boxed_future())); /// scheduler.every(Weekday).run(|| returns_pinned_boxed_future()); /// ``` pub fn every(&mut self, ival: Interval) -> &mut AsyncJob<Tz, Tp> { let job = AsyncJob::<Tz, Tp>::new(ival, self.tz.clone()); self.jobs.push(job); let last_index = self.jobs.len() - 1; &mut self.jobs[last_index] } /// Run all jobs that should run at this time. /// /// This method returns a future that will poll each of the tasks until they are completed. /// ```no_run /// # use clokwerk::*; /// # use clokwerk::Interval::*; /// use std::time::Duration; /// # let mut scheduler = AsyncScheduler::new(); /// # async { /// loop { /// scheduler.run_pending().await; /// tokio::time::sleep(Duration::from_millis(100)).await; /// # break /// } /// # }; /// ``` /// Note that while all pending jobs will run asynchronously, a long-running task can still /// block future executions if you `await` the future returned by this method. /// If you are concerned that a task might run for a long time, there are several possible approaches: /// /// 1. Pass the result of `scheduler.run_pending()` to your runtime's `spawn` function. This might /// result in multiple invocations of the same task running concurrently. /// 2. Use `spawn` or `spawn_blocking` in your task itself. This has the same concurrent execution risk /// as approach 1, but limited to that specific task. /// 3. Use `tokio::time::timeout` or equivalent to prevent `scheduler.run_pending()` or the task itself /// from running more than an expected amount of time. E.g. /// ```no_run /// # use clokwerk::*; /// # use clokwerk::Interval::*; /// # async fn scrape_pages() {} /// use std::time::Duration; /// let mut scheduler = AsyncScheduler::new(); /// scheduler.every(10.minutes()).run(|| async { /// if let Err(_) = tokio::time::timeout(Duration::from_secs(10 * 60), scrape_pages()).await { /// eprintln!("Timed out scraping pages") /// } /// }); /// ``` pub fn run_pending(&mut self) -> AsyncSchedulerFuture { let now = Tp::now(&self.tz); let mut futures = vec![]; for job in &mut self.jobs { if job.is_pending(&now) { if let Some(future) = job.execute(&now) { futures.push(Some(future.into())); } } } AsyncSchedulerFuture { futures } } } pub struct AsyncSchedulerFuture { futures: Vec<Option<Pin<JobFuture>>>, } impl Future for AsyncSchedulerFuture { type Output = (); fn poll(self: Pin<&mut Self>, cx: &mut std::task::Context<'_>) -> Poll<Self::Output> { let mut all_done = true; for future in &mut self.get_mut().futures { if let Some(this_future) = future { if this_future.as_mut().poll(cx) == Poll::Ready(()) { future.take(); } else { all_done = false; } } } if all_done { Poll::Ready(()) } else { Poll::Pending } } }