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// Copyright 2019 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use std::sync::{Arc, Mutex};
/// RingBufferStopCallback wraps a callback. The callback will be invoked when last instance of
/// RingBufferStopCallback and its clones is dropped.
///
/// The callback might not be invoked in certain cases. Don't depend this for safety.
#[derive(Clone)]
pub struct RingBufferStopCallback {
inner: Arc<Mutex<RingBufferStopCallbackInner>>,
}
impl RingBufferStopCallback {
/// Create new callback from closure.
pub fn new<C: 'static + FnMut() + Send>(cb: C) -> RingBufferStopCallback {
RingBufferStopCallback {
inner: Arc::new(Mutex::new(RingBufferStopCallbackInner {
callback: Box::new(cb),
})),
}
}
}
struct RingBufferStopCallbackInner {
callback: Box<FnMut() + Send>,
}
impl Drop for RingBufferStopCallbackInner {
fn drop(&mut self) {
(self.callback)();
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::sync::{Arc, Mutex};
fn task(_: RingBufferStopCallback) {}
#[test]
fn simple_raii_callback() {
let a = Arc::new(Mutex::new(0));
let ac = a.clone();
let cb = RingBufferStopCallback::new(move || {
*ac.lock().unwrap() = 1;
});
task(cb.clone());
task(cb.clone());
task(cb);
assert_eq!(*a.lock().unwrap(), 1);
}
}
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