1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44

use std::sync::atomic::{AtomicI64, Ordering};

#[cfg(feature = "ser")]
use serde::ser::SerializeMap;
#[cfg(feature = "ser")]
use serde::{Serialize, Serializer};

/// Counters are integer values you can increment and decrement.
#[derive(Debug)]
pub struct Counter {
    value: AtomicI64,
}

impl Counter {
    pub(crate) fn new() -> Counter {
        Counter {
            value: AtomicI64::new(0),
        }
    }

    pub fn inc(&self, n: i64) {
        self.value.fetch_add(n, Ordering::Relaxed);
    }

    pub fn dec(&self, n: i64) {
        self.value.fetch_sub(n, Ordering::Relaxed);
    }

    pub fn value(&self) -> i64 {
        self.value.load(Ordering::Relaxed)
    }
}

#[cfg(feature = "ser")]
impl Serialize for Counter {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        let mut map = serializer.serialize_map(Some(1))?;
        map.serialize_entry("value", &self.value())?;
        map.end()
    }
}