simplify

src/encoding/text.rs

@@ -26,7 +26,7 @@
 
 use crate::metrics::counter::{self, Counter};
 use crate::metrics::exemplar::{CounterWithExemplar, Exemplar, HistogramWithExemplars};
-use crate::metrics::family::{Family, MetricConstructor};
+use crate::metrics::family::Family;
 use crate::metrics::gauge::{self, Gauge};
 use crate::metrics::histogram::Histogram;
 use crate::metrics::info::Info;
@@ -491,7 +491,7 @@ impl<S, M, C> EncodeMetric for Family<S, M, C>
 where
     S: Clone + std::hash::Hash + Eq + Encode,
     M: EncodeMetric + TypedMetric,
-    C: MetricConstructor<M>,
+    C: Fn() -> M,
 {
     fn encode(&self, mut encoder: Encoder) -> Result<(), std::io::Error> {
         let guard = self.read();

src/metrics/family.rs

@@ -97,7 +97,7 @@ use std::sync::{Arc, RwLock, RwLockReadGuard};
 /// # assert_eq!(expected, String::from_utf8(buffer).unwrap());
 /// ```
 // TODO: Consider exposing hash algorithm.
-pub struct Family<S, M, C: MetricConstructor<M> = fn() -> M> {
+pub struct Family<S, M, C: Fn() -> M = fn() -> M> {
     metrics: Arc<RwLock<HashMap<S, M>>>,
     /// Function that when called constructs a new metric.
     ///
@@ -110,16 +110,6 @@ pub struct Family<S, M, C: MetricConstructor<M> = fn() -> M> {
     constructor: C,
 }
 
-pub trait MetricConstructor<M> {
-    fn new(&self) -> M;
-}
-
-impl<M, F: Fn() -> M> MetricConstructor<M> for F {
-    fn new(&self) -> M {
-        self()
-    }
-}
-
 impl<S: Clone + std::hash::Hash + Eq, M: Default> Default for Family<S, M> {
     fn default() -> Self {
         Self {
@@ -129,7 +119,7 @@ impl<S: Clone + std::hash::Hash + Eq, M: Default> Default for Family<S, M> {
     }
 }
 
-impl<S: Clone + std::hash::Hash + Eq, M, C: MetricConstructor<M>> Family<S, M, C> {
+impl<S: Clone + std::hash::Hash + Eq, M, C: Fn() -> M> Family<S, M, C> {
     /// Create a metric family using a custom constructor to construct new
     /// metrics.
     ///
@@ -149,6 +139,19 @@ impl<S: Clone + std::hash::Hash + Eq, M, C: MetricConstructor<M>> Family<S, M, C
     /// Family::<Vec<(String, String)>, Histogram>::new_with_constructor(|| {
     ///     Histogram::new(exponential_buckets(1.0, 2.0, 10))
     /// });
+    ///
+    /// ```
+    /// // Set the generic constructor parameter to _ if the given constructor
+    /// captures variables.
+    ///
+    /// ```
+    /// # use open_metrics_client::metrics::family::Family;
+    /// # use open_metrics_client::metrics::histogram::{exponential_buckets, Histogram};
+    /// let start_parameter = 1.0;
+    /// let length_parameter = 10;
+    /// Family::<Vec<(String, String)>, Histogram, _>::new_with_constructor(|| {
+    ///     Histogram::new(exponential_buckets(start_parameter, 2.0, length_parameter))
+    /// });
     /// ```
     pub fn new_with_constructor(constructor: C) -> Self {
         Self {
@@ -158,7 +161,7 @@ impl<S: Clone + std::hash::Hash + Eq, M, C: MetricConstructor<M>> Family<S, M, C
     }
 }
 
-impl<S: Clone + std::hash::Hash + Eq, M, C: MetricConstructor<M>> Family<S, M, C> {
+impl<S: Clone + std::hash::Hash + Eq, M, C: Fn() -> M> Family<S, M, C> {
     /// Access a metric with the given label set, creating it if one does not
     /// yet exist.
     ///
@@ -185,7 +188,7 @@ impl<S: Clone + std::hash::Hash + Eq, M, C: MetricConstructor<M>> Family<S, M, C
         }
 
         let mut write_guard = self.metrics.write().unwrap();
-        write_guard.insert(label_set.clone(), self.constructor.new());
+        write_guard.insert(label_set.clone(), (self.constructor)());
 
         drop(write_guard);
 
@@ -202,7 +205,7 @@ impl<S: Clone + std::hash::Hash + Eq, M, C: MetricConstructor<M>> Family<S, M, C
     }
 }
 
-impl<S, M, C: MetricConstructor<M> + Clone> Clone for Family<S, M, C> {
+impl<S, M, C: Fn() -> M + Clone> Clone for Family<S, M, C> {
     fn clone(&self) -> Self {
         Family {
             metrics: self.metrics.clone(),
@@ -211,7 +214,7 @@ impl<S, M, C: MetricConstructor<M> + Clone> Clone for Family<S, M, C> {
     }
 }
 
-impl<S, M: TypedMetric, C: MetricConstructor<M>> TypedMetric for Family<S, M, C> {
+impl<S, M: TypedMetric, C: Fn() -> M> TypedMetric for Family<S, M, C> {
     const TYPE: MetricType = <M as TypedMetric>::TYPE;
 }
 
@@ -239,23 +242,9 @@ mod tests {
 
     #[test]
     fn histogram_family() {
-        Family::<(), Histogram>::new_with_constructor(|| {
-            Histogram::new(exponential_buckets(1.0, 2.0, 10))
+        let captured_var = vec![3.4, 5.5];
+        Family::<(), Histogram, _>::new_with_constructor(|| {
+            Histogram::new(exponential_buckets(captured_var[0], captured_var[1], 10))
         });
     }
-
-    #[test]
-    fn histogram_family_with_struct_constructor() {
-        struct CustomBuilder {
-            custom_start: f64,
-        }
-        impl MetricConstructor<Histogram> for CustomBuilder {
-            fn new(&self) -> Histogram {
-                Histogram::new(exponential_buckets(self.custom_start, 2.0, 10))
-            }
-        }
-
-        let custom_builder = CustomBuilder { custom_start: 1.0 };
-        Family::<(), Histogram, CustomBuilder>::new_with_constructor(custom_builder);
-    }
 }