1 // Copyright 2019 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::sync::Arc;
6 use std::sync::Mutex;
7
8 use base::error;
9
10 use crate::utils::FailHandle;
11
12 /// RingBufferStopCallback wraps a callback. The callback will be invoked when last instance of
13 /// RingBufferStopCallback and its clones is dropped.
14 ///
15 /// The callback might not be invoked in certain cases. Don't depend this for safety.
16 #[derive(Clone)]
17 pub struct RingBufferStopCallback {
18 _inner: Arc<Mutex<RingBufferStopCallbackInner>>,
19 }
20
21 impl RingBufferStopCallback {
22 /// Create new callback from closure.
new<C: 'static + FnMut() + Send>(cb: C) -> RingBufferStopCallback23 pub fn new<C: 'static + FnMut() + Send>(cb: C) -> RingBufferStopCallback {
24 RingBufferStopCallback {
25 _inner: Arc::new(Mutex::new(RingBufferStopCallbackInner {
26 callback: Box::new(cb),
27 })),
28 }
29 }
30 }
31
32 struct RingBufferStopCallbackInner {
33 callback: Box<dyn FnMut() + Send>,
34 }
35
36 impl Drop for RingBufferStopCallbackInner {
drop(&mut self)37 fn drop(&mut self) {
38 (self.callback)();
39 }
40 }
41
42 /// Helper function to wrap up a closure with fail handle. The fail handle will be triggered if the
43 /// closure returns an error.
fallible_closure<E: std::fmt::Display, C: FnMut() -> Result<(), E> + 'static + Send>( fail_handle: Arc<dyn FailHandle>, mut callback: C, ) -> impl FnMut() + 'static + Send44 pub fn fallible_closure<E: std::fmt::Display, C: FnMut() -> Result<(), E> + 'static + Send>(
45 fail_handle: Arc<dyn FailHandle>,
46 mut callback: C,
47 ) -> impl FnMut() + 'static + Send {
48 move || match callback() {
49 Ok(()) => {}
50 Err(e) => {
51 error!("callback failed {}", e);
52 fail_handle.fail();
53 }
54 }
55 }
56
57 #[cfg(test)]
58 mod tests {
59 use std::sync::Arc;
60 use std::sync::Mutex;
61
62 use super::*;
63
task(_: RingBufferStopCallback)64 fn task(_: RingBufferStopCallback) {}
65
66 #[test]
simple_raii_callback()67 fn simple_raii_callback() {
68 let a = Arc::new(Mutex::new(0));
69 let ac = a.clone();
70 let cb = RingBufferStopCallback::new(move || {
71 *ac.lock().unwrap() = 1;
72 });
73 task(cb.clone());
74 task(cb.clone());
75 task(cb);
76 assert_eq!(*a.lock().unwrap(), 1);
77 }
78 }
79