Add build(), build_freezable() and build_frozen() methods to `r…

…ecorder::Builder` (#4)

Co-authored-by: Kai Ren <tyranron@gmail.com>

CHANGELOG.md

@@ -6,6 +6,20 @@ All user visible changes to this project will be documented in this file. This p
 
 
 
+## [0.3.1] · 2023-01-??
+[0.3.1]: /../../tree/v0.3.1
+
+[Diff](/../../compare/v0.3.0...v0.3.1)
+
+### Added
+
+- `build()`, `build_freezable()` and `build_frozen()` methods to `recorder::Builder`, allowing to build the resulting `metrics::Recorder` without installing it as `metrics::recorder()`. ([#4])
+
+[#3]: /../../pull/4
+
+
+
+
 ## [0.3.0] · 2022-12-11
 [0.3.0]: /../../tree/v0.3.0
 

src/recorder/mod.rs

@@ -720,6 +720,107 @@ impl<S, L> Builder<S, L> {
         })
     }
 
+    /// Builds a [`Recorder`] out of this [`Builder`] and returns it being
+    /// wrapped into all the provided [`metrics::Layer`]s.
+    ///
+    /// # Usage
+    ///
+    /// Use this method if you want to:
+    /// - either install the built [`Recorder`] as [`metrics::recorder()`]
+    ///   manually;
+    /// - or to compose the built [`Recorder`] with some other
+    ///   [`metrics::Recorder`]s (like being able to write into multiple
+    ///   [`prometheus::Registry`]s via [`metrics::layer::Fanout`], for
+    ///   example).
+    ///
+    /// Otherwise, consider using the [`build_and_install()`] method instead.
+    ///
+    /// [`build_and_install()`]: Builder::build_and_install
+    /// [`metrics::layer::Fanout`]: metrics_util::layers::Fanout
+    /// [`metrics::Layer`]: Layer
+    pub fn build(self) -> <L as Layer<Recorder<S>>>::Output
+    where
+        S: failure::Strategy,
+        L: Layer<Recorder<S>>,
+    {
+        let Self { storage, failure_strategy, layers } = self;
+        let rec = Recorder {
+            metrics: Arc::new(metrics_util::registry::Registry::new(
+                storage.clone(),
+            )),
+            storage,
+            failure_strategy,
+        };
+        layers.layer(rec)
+    }
+
+    /// Builds a [`FreezableRecorder`] out of this [`Builder`] and returns it
+    /// being wrapped into all the provided [`metrics::Layer`]s.
+    ///
+    /// # Usage
+    ///
+    /// Use this method if you want to:
+    /// - either install the built [`FreezableRecorder`] as
+    ///   [`metrics::recorder()`] manually;
+    /// - or to compose the built [`FreezableRecorder`] with some other
+    ///   [`metrics::Recorder`]s (like being able to write into multiple
+    ///   [`prometheus::Registry`]s via [`metrics::layer::Fanout`], for
+    ///   example).
+    ///
+    /// Otherwise, consider using the [`build_freezable_and_install()`] method
+    /// instead.
+    ///
+    /// [`build_freezable_and_install()`]: Builder::build_freezable_and_install
+    /// [`metrics::layer::Fanout`]: metrics_util::layers::Fanout
+    /// [`metrics::Layer`]: Layer
+    /// [`FreezableRecorder`]: Freezable
+    pub fn build_freezable(self) -> <L as Layer<freezable::Recorder<S>>>::Output
+    where
+        S: failure::Strategy,
+        L: Layer<freezable::Recorder<S>>,
+    {
+        let Self { storage, failure_strategy, layers } = self;
+        let rec = freezable::Recorder::wrap(Recorder {
+            metrics: Arc::new(metrics_util::registry::Registry::new(
+                storage.clone(),
+            )),
+            storage,
+            failure_strategy,
+        });
+        layers.layer(rec)
+    }
+
+    /// Builds a [`FrozenRecorder`] out of this [`Builder`] and returns it being
+    /// wrapped into all the provided [`metrics::Layer`]s.
+    ///
+    /// # Usage
+    ///
+    /// Use this method if you want to:
+    /// - either install the built [`FrozenRecorder`] as [`metrics::recorder()`]
+    ///   manually;
+    /// - or to compose the built [`FrozenRecorder`] with some other
+    ///   [`metrics::Recorder`]s (like being able to write into multiple
+    ///   [`prometheus::Registry`]s via [`metrics::layer::Fanout`], for
+    ///   example).
+    ///
+    /// Otherwise, consider using the [`build_frozen_and_install()`] method
+    /// instead.
+    ///
+    /// [`build_frozen_and_install()`]: Builder::build_frozen_and_install
+    /// [`metrics::layer::Fanout`]: metrics_util::layers::Fanout
+    /// [`metrics::Layer`]: Layer
+    /// [`FrozenRecorder`]: Frozen
+    pub fn build_frozen(self) -> <L as Layer<frozen::Recorder<S>>>::Output
+    where
+        S: failure::Strategy,
+        L: Layer<frozen::Recorder<S>>,
+    {
+        let Self { storage, failure_strategy, layers } = self;
+        let rec =
+            frozen::Recorder { storage: (&storage).into(), failure_strategy };
+        layers.layer(rec)
+    }
+
     /// Builds a [`Recorder`] out of this [`Builder`] and tries to install it as
     /// [`metrics::recorder()`].
     ///