Add blanket implementations of Recorder for some pointer-like types

metrics-util/src/layers/router.rs

@@ -191,7 +191,7 @@ mod tests {
         predicate::{always, eq},
         Sequence,
     };
-    use std::borrow::Cow;
+    use std::{borrow::Cow, sync::Arc};
 
     use super::RouterBuilder;
     use crate::MetricKindMask;
@@ -292,4 +292,49 @@ mod tests {
         let _ = recorder.register_counter(&all_override, &METADATA);
         let _ = recorder.register_histogram(&all_override, &METADATA);
     }
+
+    #[test]
+    fn test_same_recorder_multiple_routes() {
+        let default_counter: Key = "default".into();
+        let foo_counter: Key = "foo.counter".into();
+        let bar_counter: Key = "bar.counter".into();
+
+        let mut default_mock = MockTestRecorder::new();
+        let mut foo_bar_mock = MockTestRecorder::new();
+
+        let mut seq = Sequence::new();
+
+        static METADATA: metrics::Metadata =
+            metrics::Metadata::new(module_path!(), metrics::Level::INFO, Some(module_path!()));
+
+        foo_bar_mock
+            .expect_register_counter()
+            .times(1)
+            .in_sequence(&mut seq)
+            .with(eq(foo_counter.clone()), always())
+            .returning(|_, _| Counter::noop());
+        foo_bar_mock
+            .expect_register_counter()
+            .times(1)
+            .in_sequence(&mut seq)
+            .with(eq(bar_counter.clone()), always())
+            .returning(|_, _| Counter::noop());
+        default_mock
+            .expect_register_counter()
+            .times(1)
+            .in_sequence(&mut seq)
+            .with(eq(default_counter.clone()), always())
+            .returning(|_, _| Counter::noop());
+
+        let foo_bar_mock = Arc::new(foo_bar_mock);
+
+        let mut builder = RouterBuilder::from_recorder(default_mock);
+        builder.add_route(MetricKindMask::COUNTER, "foo", foo_bar_mock.clone());
+        builder.add_route(MetricKindMask::COUNTER, "bar", foo_bar_mock);
+        let recorder = builder.build();
+
+        let _ = recorder.register_counter(&foo_counter, &METADATA);
+        let _ = recorder.register_counter(&bar_counter, &METADATA);
+        let _ = recorder.register_counter(&default_counter, &METADATA);
+    }
 }

metrics/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Added `Debug` derive to numerous types. ([#504](https://github.com/metrics-rs/metrics/pull/504))
+- Blanket implementations of `Recorder` over smart pointer representations (i.e. `Arc<T> where T: Recorder`). ([#512](https://github.com/metrics-rs/metrics/pull/512))
 
 ### Changed
 

metrics/src/recorder/mod.rs

@@ -26,23 +26,23 @@ pub trait Recorder {
     /// Describes a counter.
     ///
     /// Callers may provide the unit or a description of the counter being registered. Whether or
-    /// not a metric can be reregistered to provide a unit/description, if one was already passed
+    /// not a metric can be re-registered to provide a unit/description, if one was already passed
     /// or not, as well as how units/descriptions are used by the underlying recorder, is an
     /// implementation detail.
     fn describe_counter(&self, key: KeyName, unit: Option<Unit>, description: SharedString);
 
     /// Describes a gauge.
     ///
     /// Callers may provide the unit or a description of the gauge being registered. Whether or
-    /// not a metric can be reregistered to provide a unit/description, if one was already passed
+    /// not a metric can be re-registered to provide a unit/description, if one was already passed
     /// or not, as well as how units/descriptions are used by the underlying recorder, is an
     /// implementation detail.
     fn describe_gauge(&self, key: KeyName, unit: Option<Unit>, description: SharedString);
 
     /// Describes a histogram.
     ///
     /// Callers may provide the unit or a description of the histogram being registered. Whether or
-    /// not a metric can be reregistered to provide a unit/description, if one was already passed
+    /// not a metric can be re-registered to provide a unit/description, if one was already passed
     /// or not, as well as how units/descriptions are used by the underlying recorder, is an
     /// implementation detail.
     fn describe_histogram(&self, key: KeyName, unit: Option<Unit>, description: SharedString);
@@ -57,6 +57,72 @@ pub trait Recorder {
     fn register_histogram(&self, key: &Key, metadata: &Metadata<'_>) -> Histogram;
 }
 
+// Blanket implementations.
+macro_rules! impl_recorder {
+    ($inner_ty:ident, $ptr_ty:ty) => {
+        impl<$inner_ty> $crate::Recorder for $ptr_ty
+        where
+            $inner_ty: $crate::Recorder + ?Sized,
+        {
+            fn describe_counter(
+                &self,
+                key: $crate::KeyName,
+                unit: Option<$crate::Unit>,
+                description: $crate::SharedString,
+            ) {
+                std::ops::Deref::deref(self).describe_counter(key, unit, description)
+            }
+
+            fn describe_gauge(
+                &self,
+                key: $crate::KeyName,
+                unit: Option<$crate::Unit>,
+                description: $crate::SharedString,
+            ) {
+                std::ops::Deref::deref(self).describe_gauge(key, unit, description)
+            }
+
+            fn describe_histogram(
+                &self,
+                key: $crate::KeyName,
+                unit: Option<$crate::Unit>,
+                description: $crate::SharedString,
+            ) {
+                std::ops::Deref::deref(self).describe_histogram(key, unit, description)
+            }
+
+            fn register_counter(
+                &self,
+                key: &$crate::Key,
+                metadata: &$crate::Metadata<'_>,
+            ) -> $crate::Counter {
+                std::ops::Deref::deref(self).register_counter(key, metadata)
+            }
+
+            fn register_gauge(
+                &self,
+                key: &$crate::Key,
+                metadata: &$crate::Metadata<'_>,
+            ) -> $crate::Gauge {
+                std::ops::Deref::deref(self).register_gauge(key, metadata)
+            }
+
+            fn register_histogram(
+                &self,
+                key: &$crate::Key,
+                metadata: &$crate::Metadata<'_>,
+            ) -> $crate::Histogram {
+                std::ops::Deref::deref(self).register_histogram(key, metadata)
+            }
+        }
+    };
+}
+
+impl_recorder!(T, &T);
+impl_recorder!(T, &mut T);
+impl_recorder!(T, std::boxed::Box<T>);
+impl_recorder!(T, std::sync::Arc<T>);
+
 /// Guard for setting a local recorder.
 ///
 /// When using a local recorder, we take a reference to the recorder and only hold it for as long as
@@ -151,6 +217,8 @@ mod tests {
         Arc,
     };
 
+    use crate::NoopRecorder;
+
     use super::{Recorder, RecorderOnceCell};
 
     #[test]
@@ -232,4 +300,17 @@ mod tests {
         drop(second_set_result);
         assert!(was_dropped.load(Ordering::SeqCst));
     }
+
+    #[test]
+    fn blanket_implementations() {
+        fn is_recorder<T: Recorder>(_recorder: T) {}
+
+        let mut local = NoopRecorder;
+
+        is_recorder(NoopRecorder);
+        is_recorder(Arc::new(NoopRecorder));
+        is_recorder(Box::new(NoopRecorder));
+        is_recorder(&local);
+        is_recorder(&mut local);
+    }
 }