Stabilize Gauge (#1701)

Author: utpilla

examples/metrics-basic/src/main.rs

@@ -108,8 +108,6 @@ async fn main() -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
     // Note that there is no ObservableHistogram instrument.
 
     // Create a Gauge Instrument.
-    // Note that the Gauge instrument is experimental, and can be changed/removed in the future releases.
-    #[cfg(feature = "otel_unstable")]
     {
         let gauge = meter
             .f64_gauge("my_gauge")

opentelemetry/CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - [#1623](https://github.com/open-telemetry/opentelemetry-rust/pull/1623) Add global::meter_provider_shutdown
 - [#1640](https://github.com/open-telemetry/opentelemetry-rust/pull/1640) Add `PropagationError`
+- [#1701](https://github.com/open-telemetry/opentelemetry-rust/pull/1701) `Gauge` no longer requires `otel-unstable` feature flag, as OpenTelemetry specification for `Gauge` instrumentation is stable.
 
 ### Removed
 

opentelemetry/src/metrics/meter.rs

@@ -3,10 +3,8 @@ use std::any::Any;
 use std::borrow::Cow;
 use std::sync::Arc;
 
-#[cfg(feature = "otel_unstable")]
-use crate::metrics::Gauge;
 use crate::metrics::{
-    AsyncInstrumentBuilder, Counter, Histogram, InstrumentBuilder, InstrumentProvider,
+    AsyncInstrumentBuilder, Counter, Gauge, Histogram, InstrumentBuilder, InstrumentProvider,
     ObservableCounter, ObservableGauge, ObservableUpDownCounter, Result, UpDownCounter,
 };
 use crate::KeyValue;
@@ -335,32 +333,23 @@ impl Meter {
         AsyncInstrumentBuilder::new(self, name.into())
     }
 
-    /// # Experimental
-    /// This method is experimental and can be changed/removed in future releases.
     /// creates an instrument builder for recording independent values.
-    #[cfg(feature = "otel_unstable")]
     pub fn u64_gauge(
         &self,
         name: impl Into<Cow<'static, str>>,
     ) -> InstrumentBuilder<'_, Gauge<u64>> {
         InstrumentBuilder::new(self, name.into())
     }
 
-    /// # Experimental
-    /// This method is experimental and can be changed/removed in future releases.
     /// creates an instrument builder for recording independent values.
-    #[cfg(feature = "otel_unstable")]
     pub fn f64_gauge(
         &self,
         name: impl Into<Cow<'static, str>>,
     ) -> InstrumentBuilder<'_, Gauge<f64>> {
         InstrumentBuilder::new(self, name.into())
     }
 
-    /// # Experimental
-    /// This method is experimental and can be changed/removed in future releases.
-    /// creates an instrument builder for recording indenpendent values.
-    #[cfg(feature = "otel_unstable")]
+    /// creates an instrument builder for recording independent values.
     pub fn i64_gauge(
         &self,
         name: impl Into<Cow<'static, str>>,