1 // Copyright 2018 The ChromiumOS Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 use std::mem; 6 use std::sync::Arc; 7 8 use anyhow::Context; 9 use base::Event; 10 use base::EventType; 11 use sync::Mutex; 12 13 use super::Error; 14 use super::EventHandler; 15 use super::EventLoop; 16 use super::Result; 17 18 /// Async Job Queue can schedule async jobs. 19 pub struct AsyncJobQueue { 20 jobs: Mutex<Vec<Box<dyn FnMut() + Send>>>, 21 evt: Event, 22 } 23 24 impl AsyncJobQueue { 25 /// Init job queue on event loop. init(event_loop: &EventLoop) -> Result<Arc<AsyncJobQueue>>26 pub fn init(event_loop: &EventLoop) -> Result<Arc<AsyncJobQueue>> { 27 let evt = Event::new().map_err(Error::CreateEvent)?; 28 let queue = Arc::new(AsyncJobQueue { 29 jobs: Mutex::new(Vec::new()), 30 evt, 31 }); 32 let handler: Arc<dyn EventHandler> = queue.clone(); 33 event_loop.add_event(&queue.evt, EventType::Read, Arc::downgrade(&handler))?; 34 Ok(queue) 35 } 36 37 /// Queue a new job. It will be invoked on event loop. queue_job<T: Fn() + 'static + Send>(&self, cb: T) -> Result<()>38 pub fn queue_job<T: Fn() + 'static + Send>(&self, cb: T) -> Result<()> { 39 self.jobs.lock().push(Box::new(cb)); 40 self.evt.signal().map_err(Error::WriteEvent) 41 } 42 } 43 44 impl EventHandler for AsyncJobQueue { on_event(&self) -> anyhow::Result<()>45 fn on_event(&self) -> anyhow::Result<()> { 46 // We want to read out the event. 47 self.evt.wait().context("read event failed")?; 48 49 let jobs = mem::take(&mut *self.jobs.lock()); 50 for mut cb in jobs { 51 cb(); 52 } 53 Ok(()) 54 } 55 } 56