Merge pull request #622 from iRevive/sdk-common/component-registry

sdk-common: add `ComponentRegistry`

sdk/common/src/main/scala/org/typelevel/otel4s/sdk/internal/ComponentRegistry.scala

@@ -0,0 +1,129 @@
+/*
+ * Copyright 2023 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.otel4s
+package sdk
+package internal
+
+import cats.Applicative
+import cats.effect.kernel.Concurrent
+import cats.effect.std.AtomicCell
+import cats.syntax.functor._
+import org.typelevel.otel4s.sdk.common.InstrumentationScope
+
+/** A registry that caches components by `key`, `version`, and `schemaUrl`.
+  *
+  * @tparam F
+  *   the higher-kinded type of a polymorphic effect
+  *
+  * @tparam A
+  *   the type of the component
+  */
+private[sdk] sealed trait ComponentRegistry[F[_], A] {
+
+  /** Returns the component associated with the `name`, `version`, and
+    * `schemaUrl`.
+    *
+    * '''Note''': `attributes` are not part of component identity.
+    *
+    * Behavior is undefined when different `attributes` are provided where
+    * `name`, `version`, and `schemaUrl` are identical.
+    *
+    * @param name
+    *   the name to associate with a component
+    *
+    * @param version
+    *   the version to associate with a component
+    *
+    * @param schemaUrl
+    *   the schema URL to associate with a component
+    *
+    * @param attributes
+    *   the attributes to associate with a component
+    */
+  def get(
+      name: String,
+      version: Option[String],
+      schemaUrl: Option[String],
+      attributes: Attributes
+  ): F[A]
+
+  /** Returns the collection of the registered components.
+    */
+  def components: F[Vector[A]]
+
+}
+
+private[sdk] object ComponentRegistry {
+
+  /** Creates a [[ComponentRegistry]] that uses `buildComponent` to build a
+    * component if it is not already present in the cache.
+    *
+    * @param buildComponent
+    *   how to build a component
+    *
+    * @tparam F
+    *   the higher-kinded type of a polymorphic effect
+    *
+    * @tparam A
+    *   the type of the component
+    */
+  def create[F[_]: Concurrent, A](
+      buildComponent: InstrumentationScope => F[A]
+  ): F[ComponentRegistry[F, A]] =
+    for {
+      cache <- AtomicCell[F].of(Map.empty[Key, A])
+    } yield new Impl(cache, buildComponent)
+
+  private final case class Key(
+      name: String,
+      version: Option[String],
+      schemaUrl: Option[String]
+  )
+
+  private final class Impl[F[_]: Applicative, A](
+      cache: AtomicCell[F, Map[Key, A]],
+      buildComponent: InstrumentationScope => F[A]
+  ) extends ComponentRegistry[F, A] {
+
+    def get(
+        name: String,
+        version: Option[String],
+        schemaUrl: Option[String],
+        attributes: Attributes
+    ): F[A] =
+      cache.evalModify { cache =>
+        val key = Key(name, version, schemaUrl)
+
+        cache.get(key) match {
+          case Some(component) =>
+            Applicative[F].pure((cache, component))
+
+          case None =>
+            val scope =
+              InstrumentationScope(name, version, schemaUrl, attributes)
+
+            for {
+              component <- buildComponent(scope)
+            } yield (cache.updated(key, component), component)
+        }
+      }
+
+    def components: F[Vector[A]] =
+      cache.get.map(_.values.toVector)
+  }
+
+}

sdk/common/src/test/scala/org/typelevel/otel4s/sdk/internal/ComponentRegistrySuite.scala

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2023 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.otel4s.sdk.internal
+
+import cats.effect.IO
+import munit.CatsEffectSuite
+import org.typelevel.otel4s.Attribute
+import org.typelevel.otel4s.Attributes
+
+class ComponentRegistrySuite extends CatsEffectSuite {
+
+  private val name = "component"
+  private val version = "0.0.1"
+  private val schemaUrl = "https://otel4s.schema.com"
+  private val attributes = Attributes(Attribute("key", "value"))
+
+  registryTest("get cached values (by name only)") { registry =>
+    for {
+      v1 <- registry.get(name, None, None, Attributes.empty)
+      v2 <- registry.get(name, None, None, attributes)
+      v3 <- registry.get(name, Some(version), None, attributes)
+      v4 <- registry.get(name, Some(version), Some(schemaUrl), attributes)
+    } yield {
+      assertEquals(v1, v2)
+      assertNotEquals(v1, v3)
+      assertNotEquals(v2, v3)
+      assertNotEquals(v1, v4)
+      assertNotEquals(v2, v4)
+    }
+  }
+
+  registryTest("get cached values (by name and version)") { registry =>
+    for {
+      v1 <- registry.get(name, Some(version), None, Attributes.empty)
+      v2 <- registry.get(name, Some(version), None, attributes)
+      v3 <- registry.get(name, Some(version), Some(schemaUrl), attributes)
+    } yield {
+      assertEquals(v1, v2)
+      assertNotEquals(v1, v3)
+      assertNotEquals(v2, v3)
+    }
+  }
+
+  registryTest("get cached values (by name, version, and schema)") { registry =>
+    for {
+      v1 <- registry.get(name, Some(version), Some(schemaUrl), Attributes.empty)
+      v2 <- registry.get(name, Some(version), Some(schemaUrl), attributes)
+    } yield assertEquals(v1, v2)
+  }
+
+  private def registryTest(
+      name: String
+  )(body: ComponentRegistry[IO, TestComponent] => IO[Unit]): Unit =
+    test(name) {
+      for {
+        registry <- ComponentRegistry.create(_ => IO.pure(new TestComponent()))
+        _ <- body(registry)
+      } yield ()
+    }
+
+  private class TestComponent
+
+}