Provide a method to reset a counter

src/metrics/counter.rs

@@ -84,6 +84,11 @@ impl<N, A: Atomic<N>> Counter<N, A> {
  self.value.inc_by(v)
  }
 
+ /// Resets the [`Counter`] to `0`, returning the previous value.
+ pub fn reset(&self) -> N {
+ self.value.reset()
+ }
+
  /// Get the current value of the [`Counter`].
  pub fn get(&self) -> N {
  self.value.get()
@@ -110,6 +115,9 @@ pub trait Atomic<N> {
  /// Increase the value.
  fn inc_by(&self, v: N) -> N;
 
+ /// Reset the value to `0`.
+ fn reset(&self) -> N;
+
  /// Get the the value.
  fn get(&self) -> N;
 }
@@ -124,6 +132,10 @@ impl Atomic<u64> for AtomicU64 {
  self.fetch_add(v, Ordering::Relaxed)
  }
 
+ fn reset(&self) -> u64 {
+ self.swap(Default::default(), Ordering::Relaxed)
+ }
+
  fn get(&self) -> u64 {
  self.load(Ordering::Relaxed)
  }
@@ -138,6 +150,10 @@ impl Atomic<u32> for AtomicU32 {
  self.fetch_add(v, Ordering::Relaxed)
  }
 
+ fn reset(&self) -> u32 {
+ self.swap(Default::default(), Ordering::Relaxed)
+ }
+
  fn get(&self) -> u32 {
  self.load(Ordering::Relaxed)
  }
@@ -164,6 +180,10 @@ impl Atomic<f64> for AtomicU64 {
  old_f64
  }
 
+ fn reset(&self) -> f64 {
+ f64::from_bits(self.swap(Default::default(), Ordering::Relaxed))
+ }
+
  fn get(&self) -> f64 {
  f64::from_bits(self.load(Ordering::Relaxed))
  }
@@ -231,6 +251,14 @@ mod tests {
  assert_eq!(1, counter.get());
  }
 
+ #[test]
+ fn inc_reset_and_get() {
+ let counter: Counter = Counter::default();
+ assert_eq!(0, counter.inc());
+ assert_eq!(1, counter.reset());
+ assert_eq!(0, counter.get());
+ }
+
  #[cfg(not(any(target_arch = "mips", target_arch = "powerpc")))]
  #[test]
  fn f64_stored_in_atomic_u64() {