[Metrics-API] Mark no-op structs as pub(crate) (#2203)

Co-authored-by: Cijo Thomas <[email protected]>

Author: utpilla

opentelemetry-sdk/src/metrics/meter.rs

@@ -4,7 +4,6 @@ use std::{borrow::Cow, sync::Arc};
 use opentelemetry::{
     global,
     metrics::{
-        noop::{NoopAsyncInstrument, NoopSyncInstrument},
         AsyncInstrumentBuilder, Counter, Gauge, Histogram, HistogramBuilder, InstrumentBuilder,
         InstrumentProvider, MetricsError, ObservableCounter, ObservableGauge,
         ObservableUpDownCounter, Result, UpDownCounter,
@@ -18,6 +17,8 @@ use crate::metrics::{
     pipeline::{Pipelines, Resolver},
 };
 
+use super::noop::{NoopAsyncInstrument, NoopSyncInstrument};
+
 // maximum length of instrument name
 const INSTRUMENT_NAME_MAX_LENGTH: usize = 255;
 // maximum length of instrument unit name

opentelemetry-sdk/src/metrics/meter_provider.rs

@@ -9,13 +9,15 @@ use std::{
 
 use opentelemetry::{
     global,
-    metrics::{noop::NoopMeter, Meter, MeterProvider, MetricsError, Result},
+    metrics::{Meter, MeterProvider, MetricsError, Result},
     KeyValue,
 };
 
 use crate::{instrumentation::Scope, Resource};
 
-use super::{meter::SdkMeter, pipeline::Pipelines, reader::MetricReader, view::View};
+use super::{
+    meter::SdkMeter, noop::NoopMeter, pipeline::Pipelines, reader::MetricReader, view::View,
+};
 
 /// Handles the creation and coordination of [Meter]s.
 ///

opentelemetry-sdk/src/metrics/mod.rs

@@ -47,6 +47,7 @@ pub(crate) mod internal;
 pub(crate) mod manual_reader;
 pub(crate) mod meter;
 mod meter_provider;
+pub(crate) mod noop;
 pub(crate) mod periodic_reader;
 pub(crate) mod pipeline;
 pub mod reader;

opentelemetry-sdk/src/metrics/noop.rs

@@ -0,0 +1,78 @@
+use opentelemetry::{
+    metrics::{
+        AsyncInstrument, InstrumentProvider, SyncCounter, SyncGauge, SyncHistogram,
+        SyncUpDownCounter,
+    },
+    KeyValue,
+};
+
+/// A no-op instance of a `Meter`
+#[derive(Debug, Default)]
+pub(crate) struct NoopMeter {
+    _private: (),
+}
+
+impl NoopMeter {
+    /// Create a new no-op meter core.
+    pub(crate) fn new() -> Self {
+        NoopMeter { _private: () }
+    }
+}
+
+impl InstrumentProvider for NoopMeter {}
+
+/// A no-op sync instrument
+#[derive(Debug, Default)]
+pub(crate) struct NoopSyncInstrument {
+    _private: (),
+}
+
+impl NoopSyncInstrument {
+    /// Create a new no-op sync instrument
+    pub(crate) fn new() -> Self {
+        NoopSyncInstrument { _private: () }
+    }
+}
+
+impl<T> SyncCounter<T> for NoopSyncInstrument {
+    fn add(&self, _value: T, _attributes: &[KeyValue]) {
+        // Ignored
+    }
+}
+
+impl<T> SyncUpDownCounter<T> for NoopSyncInstrument {
+    fn add(&self, _value: T, _attributes: &[KeyValue]) {
+        // Ignored
+    }
+}
+
+impl<T> SyncHistogram<T> for NoopSyncInstrument {
+    fn record(&self, _value: T, _attributes: &[KeyValue]) {
+        // Ignored
+    }
+}
+
+impl<T> SyncGauge<T> for NoopSyncInstrument {
+    fn record(&self, _value: T, _attributes: &[KeyValue]) {
+        // Ignored
+    }
+}
+
+/// A no-op async instrument.
+#[derive(Debug, Default)]
+pub(crate) struct NoopAsyncInstrument {
+    _private: (),
+}
+
+impl NoopAsyncInstrument {
+    /// Create a new no-op async instrument
+    pub(crate) fn new() -> Self {
+        NoopAsyncInstrument { _private: () }
+    }
+}
+
+impl<T> AsyncInstrument<T> for NoopAsyncInstrument {
+    fn observe(&self, _value: T, _attributes: &[KeyValue]) {
+        // Ignored
+    }
+}

opentelemetry/src/global/metrics.rs

@@ -7,7 +7,7 @@ type GlobalMeterProvider = Arc<dyn MeterProvider + Send + Sync>;
 
 /// The global `MeterProvider` singleton.
 static GLOBAL_METER_PROVIDER: Lazy<RwLock<GlobalMeterProvider>> =
-    Lazy::new(|| RwLock::new(Arc::new(metrics::noop::NoopMeterProvider::new())));
+    Lazy::new(|| RwLock::new(Arc::new(crate::metrics::noop::NoopMeterProvider::new())));
 
 /// Sets the given [`MeterProvider`] instance as the current global meter
 /// provider.

opentelemetry/src/metrics/mod.rs

@@ -9,7 +9,7 @@ use thiserror::Error;
 
 mod instruments;
 mod meter;
-pub mod noop;
+pub(crate) mod noop;
 
 use crate::{Array, ExportError, KeyValue, Value};
 pub use instruments::{

opentelemetry/src/metrics/noop.rs

@@ -39,13 +39,13 @@ impl MeterProvider for NoopMeterProvider {
 
 /// A no-op instance of a `Meter`
 #[derive(Debug, Default)]
-pub struct NoopMeter {
+pub(crate) struct NoopMeter {
     _private: (),
 }
 
 impl NoopMeter {
     /// Create a new no-op meter core.
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Self {
         NoopMeter { _private: () }
     }
 }
@@ -54,13 +54,13 @@ impl InstrumentProvider for NoopMeter {}
 
 /// A no-op sync instrument
 #[derive(Debug, Default)]
-pub struct NoopSyncInstrument {
+pub(crate) struct NoopSyncInstrument {
     _private: (),
 }
 
 impl NoopSyncInstrument {
     /// Create a new no-op sync instrument
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Self {
         NoopSyncInstrument { _private: () }
     }
 }
@@ -91,13 +91,13 @@ impl<T> SyncGauge<T> for NoopSyncInstrument {
 
 /// A no-op async instrument.
 #[derive(Debug, Default)]
-pub struct NoopAsyncInstrument {
+pub(crate) struct NoopAsyncInstrument {
     _private: (),
 }
 
 impl NoopAsyncInstrument {
     /// Create a new no-op async instrument
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Self {
         NoopAsyncInstrument { _private: () }
     }
 }