Experimental IOLocalContextStorage

build.sbt

@@ -26,7 +26,7 @@ ThisBuild / crossScalaVersions := Seq(Scala213, "3.3.0")
 ThisBuild / scalaVersion := Scala213 // the default Scala
 
 val CatsVersion = "2.9.0"
-val CatsEffectVersion = "3.5.1"
+val CatsEffectVersion = "3.6-02a43a6"
 val CatsMtlVersion = "1.3.1"
 val DisciplineMUnitVersion = "2.0.0-M3"
 val FS2Version = "3.7.0"
@@ -164,7 +164,7 @@ lazy val `java-common` = project
   .settings(
     name := "otel4s-java-common",
     libraryDependencies ++= Seq(
-      "org.typelevel" %%% "cats-effect-kernel" % CatsEffectVersion,
+      "org.typelevel" %%% "cats-effect" % CatsEffectVersion,
       "org.typelevel" %%% "cats-mtl" % CatsMtlVersion,
       "io.opentelemetry" % "opentelemetry-sdk" % OpenTelemetryVersion,
       "org.typelevel" %%% "discipline-munit" % MUnitDisciplineVersion % Test,
@@ -265,6 +265,7 @@ lazy val examples = project
     ),
     run / fork := true,
     javaOptions += "-Dotel.java.global-autoconfigure.enabled=true",
+    javaOptions += "-Dcats.effect.ioLocalPropagation=true",
     envVars ++= Map(
       "OTEL_PROPAGATORS" -> "b3multi",
       "OTEL_SERVICE_NAME" -> "Trace Example"

examples/src/main/scala/ContextStorageExample.scala

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2022 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.
+ */
+
+import cats.effect.IO
+import cats.effect.IOApp
+import cats.effect.Resource
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextKey
+import io.opentelemetry.context.ContextStorage
+
+import java.util.logging._
+
+object ContextStorageExample extends IOApp.Simple {
+
+  val key = ContextKey.named[String]("test")
+
+  val printKey =
+    IO(Option(Context.current().get(key))).flatMap(v => IO.println(v))
+
+  def run =
+    for {
+      _ <- IO {
+        val rootLog = Logger.getLogger("")
+        rootLog.setLevel(Level.FINE)
+        rootLog.getHandlers().head.setLevel(Level.FINE)
+      }
+      _ <- IO.println(ContextStorage.get.getClass())
+      _ <- Resource
+        .make(IO(Context.root().`with`(key, "hello").makeCurrent()))(scope =>
+          IO(scope.close())
+        )
+        .surround(printKey)
+      _ <- printKey
+    } yield ()
+}

java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider

@@ -0,0 +1 @@
+org.typelevel.otel4s.java.IOLocalContextStorageProvider

java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2022 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.java
+
+import cats.effect.IOLocal
+import cats.effect.unsafe.IOLocals
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextStorage
+import io.opentelemetry.context.Scope
+
+class IOLocalContextStorage(
+    _ioLocal: => IOLocal[Context]
+) extends ContextStorage {
+  private[this] lazy val ioLocal = _ioLocal
+  override def attach(toAttach: Context): Scope = {
+    val previous = current()
+    IOLocals.set(ioLocal, toAttach)
+    new Scope {
+      def close() = IOLocals.set(ioLocal, previous)
+    }
+  }
+
+  override def current(): Context =
+    IOLocals.get(ioLocal)
+
+}

java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2022 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.java
+
+import cats.effect.IOLocal
+import cats.effect.SyncIO
+import cats.syntax.all._
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextStorage
+import io.opentelemetry.context.ContextStorageProvider
+
+object IOLocalContextStorageProvider {
+  val localContext: IOLocal[Context] =
+    IOLocal[Context](Context.root())
+      .syncStep(100)
+      .flatMap(
+        _.leftMap(_ =>
+          new Error(
+            "Failed to initialize the local context of the IOLocalContextStorageProvider."
+          )
+        ).liftTo[SyncIO]
+      )
+      .unsafeRunSync()
+}
+
+class IOLocalContextStorageProvider extends ContextStorageProvider {
+  def get(): ContextStorage =
+    new IOLocalContextStorage(IOLocalContextStorageProvider.localContext)
+}