Merge pull request #760 from iRevive/core-trace/remove-histogram-doub…

…le-backend

core-trace: remove `Histogram.DoubleBackend`

build.sbt

@@ -1,4 +1,4 @@
-ThisBuild / tlBaseVersion := "0.9"
+ThisBuild / tlBaseVersion := "0.10"
 
 ThisBuild / organization := "org.typelevel"
 ThisBuild / organizationName := "Typelevel"

core/metrics/src/main/scala/org/typelevel/otel4s/metrics/Histogram.scala

@@ -18,11 +18,7 @@ package org.typelevel.otel4s
 package metrics
 
 import cats.Applicative
-import cats.Monad
-import cats.effect.kernel.Clock
 import cats.effect.kernel.Resource
-import cats.syntax.flatMap._
-import cats.syntax.functor._
 import org.typelevel.otel4s.meta.InstrumentMeta
 
 import scala.collection.immutable
@@ -135,28 +131,6 @@ object Histogram {
     ): Resource[F, Unit]
   }
 
-  abstract class DoubleBackend[F[_]: Monad: Clock] extends Backend[F, Double] {
-
-    final val unit: F[Unit] = Monad[F].unit
-
-    final def recordDuration(
-        timeUnit: TimeUnit,
-        attributes: immutable.Iterable[Attribute[_]]
-    ): Resource[F, Unit] =
-      Resource
-        .makeCase(Clock[F].monotonic) { case (start, ec) =>
-          for {
-            end <- Clock[F].monotonic
-            _ <- record(
-              (end - start).toUnit(timeUnit),
-              attributes ++ causeAttributes(ec)
-            )
-          } yield ()
-        }
-        .void
-
-  }
-
   def noop[F[_], A](implicit F: Applicative[F]): Histogram[F, A] =
     new Histogram[F, A] {
       val backend: Backend[F, A] =