125 lines
3 KiB
Rust
125 lines
3 KiB
Rust
use core::future::Future;
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use std::pin::Pin;
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use std::sync::Mutex;
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use arc_swap::ArcSwapOption;
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use std::sync::Arc;
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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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pub stop_signal: watch::Receiver<bool>,
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queue_in: ArcSwapOption<mpsc::UnboundedSender<(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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let mut workers = vec![];
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let queue_out = Arc::new(tokio::sync::Mutex::new(queue_out));
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for i in 0..n_runners {
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let queue_out = queue_out.clone();
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let stop_signal = stop_signal.clone();
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workers.push(tokio::spawn(async move {
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while let Some((job, cancellable)) = queue_out.lock().await.recv().await {
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if cancellable && *stop_signal.borrow() {
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continue;
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}
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if let Err(e) = job.await {
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error!("Job failed: {}", e)
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}
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}
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info!("Worker {} exiting", i);
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}));
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}
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Arc::new(Self {
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stop_signal,
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queue_in: ArcSwapOption::new(Some(Arc::new(queue_in))),
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workers: Mutex::new(workers),
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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 stop_signal = self.stop_signal.clone();
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loop {
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let exit_now = match stop_signal.changed().await {
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Ok(()) => *stop_signal.borrow(),
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Err(e) => {
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error!("Watch .changed() error: {}", e);
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true
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}
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};
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if exit_now {
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break;
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}
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}
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info!("Closing background job queue_in...");
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drop(self.queue_in.swap(None));
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info!("Waiting for all workers to terminate...");
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while let Some(task) = self.workers.lock().unwrap().pop() {
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if let Err(e) = task.await {
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warn!("Error awaiting task: {}", e);
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}
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}
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}
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// Spawn a task to be run in background
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pub async 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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match self.queue_in.load().as_ref() {
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Some(chan) => {
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let boxed: Job = Box::pin(job);
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chan.send((boxed, false)).map_err(|_| "send error").unwrap();
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}
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None => {
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warn!("Doing background job now because we are exiting...");
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if let Err(e) = job.await {
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warn!("Task failed: {}", e);
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}
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}
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}
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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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match self.queue_in.load().as_ref() {
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Some(chan) => {
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let boxed: Job = Box::pin(job);
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chan.send((boxed, false)).map_err(|_| "send error").unwrap();
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}
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None => (), // drop job if we are exiting
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}
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}
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pub fn spawn_worker<F, T>(&self, name: String, 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 = ()> + Send + 'static,
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{
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let mut workers = self.workers.lock().unwrap();
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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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worker(stop_signal).await;
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info!("Worker exited: {}", name);
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}));
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}
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}
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