2017-04-07 02:12:01 +00:00
|
|
|
// Copyright 2016 Mozilla
|
|
|
|
//
|
|
|
|
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
|
|
|
|
// this file except in compliance with the License. You may obtain a copy of the
|
|
|
|
// License at http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
// Unless required by applicable law or agreed to in writing, software distributed
|
|
|
|
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
|
|
|
|
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
|
|
|
|
// specific language governing permissions and limitations under the License.
|
|
|
|
|
|
|
|
use std::rc::Rc;
|
|
|
|
|
|
|
|
use std::sync::atomic::{
|
|
|
|
AtomicUsize,
|
|
|
|
Ordering,
|
|
|
|
};
|
|
|
|
|
|
|
|
#[derive(Clone)]
|
|
|
|
pub struct RcCounter {
|
|
|
|
c: Rc<AtomicUsize>,
|
|
|
|
}
|
|
|
|
|
2017-04-12 17:56:59 +00:00
|
|
|
/// A simple shared counter.
|
2017-04-07 02:12:01 +00:00
|
|
|
impl RcCounter {
|
2017-04-11 21:44:11 +00:00
|
|
|
pub fn with_initial(value: usize) -> Self {
|
|
|
|
RcCounter { c: Rc::new(AtomicUsize::new(value)) }
|
|
|
|
}
|
|
|
|
|
2017-04-07 02:12:01 +00:00
|
|
|
pub fn new() -> Self {
|
|
|
|
RcCounter { c: Rc::new(AtomicUsize::new(0)) }
|
|
|
|
}
|
|
|
|
|
2017-04-12 17:56:59 +00:00
|
|
|
/// Return the next value in the sequence.
|
|
|
|
///
|
|
|
|
/// ```
|
|
|
|
/// use mentat_core::counter::RcCounter;
|
|
|
|
///
|
|
|
|
/// let c = RcCounter::with_initial(3);
|
|
|
|
/// assert_eq!(c.next(), 3);
|
|
|
|
/// assert_eq!(c.next(), 4);
|
|
|
|
/// let d = c.clone();
|
|
|
|
/// assert_eq!(d.next(), 5);
|
|
|
|
/// assert_eq!(c.next(), 6);
|
|
|
|
/// ```
|
2017-04-07 02:12:01 +00:00
|
|
|
pub fn next(&self) -> usize {
|
|
|
|
self.c.fetch_add(1, Ordering::SeqCst)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
#[cfg(test)]
|
|
|
|
mod tests {
|
|
|
|
use super::RcCounter;
|
|
|
|
|
|
|
|
#[test]
|
|
|
|
fn test_rc_counter() {
|
|
|
|
let c = RcCounter::new();
|
|
|
|
assert_eq!(c.next(), 0);
|
|
|
|
assert_eq!(c.next(), 1);
|
|
|
|
|
|
|
|
let d = c.clone();
|
|
|
|
assert_eq!(d.next(), 2);
|
|
|
|
assert_eq!(c.next(), 3);
|
|
|
|
}
|
2018-01-20 03:21:04 +00:00
|
|
|
}
|