feat(metrics): add support of f32 for Gauge and Counter (#216)

Signed-off-by: Léo Gillot-Lamure <[email protected]>
Signed-off-by: Max Inden <[email protected]>
Co-authored-by: Max Inden <[email protected]>

Author: navaati

CHANGELOG.md

@@ -6,15 +6,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.23.0] - unreleased
 
+### Changed
+
+- `ConstCounter::new` now requires specifying the type of literal arguments, like this: `ConstCounter::new(42u64);`.
+  See [PR 173].
+
 - Update `prost` dependencies to `v0.12`.
   See [PR 198].
 
 [PR 198]: https://github.com/prometheus/client_rust/pull/198
 
-- Add `EncodeGaugeValue` `i32` and `f32`, `EncodeCounterValue` `u32` and `f32` and `EncodeExemplarValue` `f32` and `u32` implementations.
-  See [PR 173].
+### Added
+
+- Support `i32`/`f32` for `Gauge` and `u32`/`f32` for `Counter`/`CounterWithExemplar`.
+  See [PR 173] and [PR 216].
 
 [PR 173]: https://github.com/prometheus/client_rust/pull/173
+[PR 216]: https://github.com/prometheus/client_rust/pull/216
 
 ## [0.22.3]
 

src/encoding/text.rs

@@ -717,9 +717,10 @@ mod tests {
         let mut registry = Registry::default();
         registry.register("my_counter", "My counter", counter);
 
+        let counter_f32 = Counter::<f32, AtomicU32>::default();
+        registry.register("f32_counter", "Counter::<f32, AtomicU32>", counter_f32);
         let counter_u32 = Counter::<u32, AtomicU32>::default();
         registry.register("u32_counter", "Counter::<u32, AtomicU32>", counter_u32);
-
         let mut encoded = String::new();
 
         encode(&mut encoded, &registry).unwrap();
@@ -783,6 +784,9 @@ mod tests {
         let gauge = Gauge::<u32, AtomicU32>::default();
         registry.register("u32_gauge", "Gauge::<u32, AtomicU32>", gauge);
 
+        let gauge_f32 = Gauge::<f32, AtomicU32>::default();
+        registry.register("f32_gauge", "Gauge::<f32, AtomicU32>", gauge_f32);
+
         let gauge_i32 = Gauge::<i32, AtomicI32>::default();
         registry.register("i32_gauge", "Gauge::<i32, AtomicU32>", gauge_i32);
 

src/metrics/counter.rs

@@ -169,6 +169,31 @@ impl Atomic<f64> for AtomicU64 {
     }
 }
 
+impl Atomic<f32> for AtomicU32 {
+    fn inc(&self) -> f32 {
+        self.inc_by(1.0)
+    }
+
+    fn inc_by(&self, v: f32) -> f32 {
+        let mut old_u32 = self.load(Ordering::Relaxed);
+        let mut old_f32;
+        loop {
+            old_f32 = f32::from_bits(old_u32);
+            let new = f32::to_bits(old_f32 + v);
+            match self.compare_exchange_weak(old_u32, new, Ordering::Relaxed, Ordering::Relaxed) {
+                Ok(_) => break,
+                Err(x) => old_u32 = x,
+            }
+        }
+
+        old_f32
+    }
+
+    fn get(&self) -> f32 {
+        f32::from_bits(self.load(Ordering::Relaxed))
+    }
+}
+
 impl<N, A> TypedMetric for Counter<N, A> {
     const TYPE: MetricType = MetricType::Counter;
 }

src/metrics/gauge.rs

@@ -262,6 +262,54 @@ impl Atomic<f64> for AtomicU64 {
     }
 }
 
+impl Atomic<f32> for AtomicU32 {
+    fn inc(&self) -> f32 {
+        self.inc_by(1.0)
+    }
+
+    fn inc_by(&self, v: f32) -> f32 {
+        let mut old_u32 = self.load(Ordering::Relaxed);
+        let mut old_f32;
+        loop {
+            old_f32 = f32::from_bits(old_u32);
+            let new = f32::to_bits(old_f32 + v);
+            match self.compare_exchange_weak(old_u32, new, Ordering::Relaxed, Ordering::Relaxed) {
+                Ok(_) => break,
+                Err(x) => old_u32 = x,
+            }
+        }
+
+        old_f32
+    }
+
+    fn dec(&self) -> f32 {
+        self.dec_by(1.0)
+    }
+
+    fn dec_by(&self, v: f32) -> f32 {
+        let mut old_u32 = self.load(Ordering::Relaxed);
+        let mut old_f32;
+        loop {
+            old_f32 = f32::from_bits(old_u32);
+            let new = f32::to_bits(old_f32 - v);
+            match self.compare_exchange_weak(old_u32, new, Ordering::Relaxed, Ordering::Relaxed) {
+                Ok(_) => break,
+                Err(x) => old_u32 = x,
+            }
+        }
+
+        old_f32
+    }
+
+    fn set(&self, v: f32) -> f32 {
+        f32::from_bits(self.swap(f32::to_bits(v), Ordering::Relaxed))
+    }
+
+    fn get(&self) -> f32 {
+        f32::from_bits(self.load(Ordering::Relaxed))
+    }
+}
+
 impl<N, A> TypedMetric for Gauge<N, A> {
     const TYPE: MetricType = MetricType::Gauge;
 }