116 lines
2.8 KiB
Rust
116 lines
2.8 KiB
Rust
use core::future::Future;
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use std::pin::Pin;
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use futures::future::join_all;
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use std::sync::Arc;
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use std::time::Duration;
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use tokio::sync::Mutex;
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use tokio::sync::{mpsc, watch};
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use crate::error::Error;
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type JobOutput = Result<(), Error>;
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type Job = Pin<Box<dyn Future<Output = JobOutput> + Send>>;
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pub struct BackgroundRunner {
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n_runners: usize,
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pub stop_signal: watch::Receiver<bool>,
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queue_in: mpsc::UnboundedSender<(Job, bool)>,
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queue_out: Mutex<mpsc::UnboundedReceiver<(Job, bool)>>,
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workers: Mutex<Vec<tokio::task::JoinHandle<()>>>,
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}
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impl BackgroundRunner {
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pub fn new(n_runners: usize, stop_signal: watch::Receiver<bool>) -> Arc<Self> {
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let (queue_in, queue_out) = mpsc::unbounded_channel();
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Arc::new(Self {
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n_runners,
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stop_signal,
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queue_in,
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queue_out: Mutex::new(queue_out),
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workers: Mutex::new(Vec::new()),
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})
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}
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pub async fn run(self: Arc<Self>) {
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let mut workers = self.workers.lock().await;
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for _i in 0..self.n_runners {
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workers.push(tokio::spawn(self.clone().runner()));
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}
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drop(workers);
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let mut stop_signal = self.stop_signal.clone();
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while let Some(exit_now) = stop_signal.recv().await {
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if exit_now {
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let mut workers = self.workers.lock().await;
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let workers_vec = workers.drain(..).collect::<Vec<_>>();
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join_all(workers_vec).await;
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return;
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}
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}
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}
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pub fn spawn<T>(&self, job: T)
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where
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T: Future<Output = JobOutput> + Send + 'static,
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{
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let boxed: Job = Box::pin(job);
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let _: Result<_, _> = self.queue_in.clone().send((boxed, false));
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}
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pub fn spawn_cancellable<T>(&self, job: T)
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where
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T: Future<Output = JobOutput> + Send + 'static,
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{
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let boxed: Job = Box::pin(job);
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let _: Result<_, _> = self.queue_in.clone().send((boxed, true));
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}
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pub async fn spawn_worker<F, T>(&self, worker: F)
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where
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F: FnOnce(watch::Receiver<bool>) -> T + Send + 'static,
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T: Future<Output = JobOutput> + Send + 'static,
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{
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let mut workers = self.workers.lock().await;
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let stop_signal = self.stop_signal.clone();
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workers.push(tokio::spawn(async move {
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if let Err(e) = worker(stop_signal).await {
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eprintln!("Worker stopped with error: {}", e);
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} else {
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println!("A worker exited successfully (which one?)");
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}
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}));
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}
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async fn runner(self: Arc<Self>) {
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let stop_signal = self.stop_signal.clone();
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loop {
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let must_exit: bool = *stop_signal.borrow();
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if let Some(job) = self.dequeue_job(must_exit).await {
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if let Err(e) = job.await {
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eprintln!("Job failed: {}", e)
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}
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} else {
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if must_exit {
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return;
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}
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tokio::time::delay_for(Duration::from_secs(1)).await;
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}
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}
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}
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async fn dequeue_job(&self, must_exit: bool) -> Option<Job> {
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let mut queue = self.queue_out.lock().await;
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while let Ok((job, cancellable)) = queue.try_recv() {
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if cancellable && must_exit {
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continue;
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} else {
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return Some(job);
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}
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}
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None
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}
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}
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