Downgrade to OkHttp 4.11.0

build.gradle

@@ -51,7 +51,7 @@ subprojects {
     apply plugin: 'com.diffplug.spotless'
 
     if (project.name != 'micrometer-bom') {
-        if (project.name.contains('samples') || project.name.contains('benchmarks')) {
+        if ((project.name.contains('samples') && !project.name.contains('kotlin')) || project.name.contains('benchmarks')) {
             apply plugin: 'java'
         } else {
             apply plugin: 'java-library'

gradle/libs.versions.toml

@@ -58,7 +58,7 @@ mockito = "5.5.0"
 mongo = "4.8.2"
 netty = "4.1.104.Final"
 newrelic-api = "5.14.0"
-okhttp = "5.0.0-alpha.11" # TODO is compiling against an alpha version intentional?
+okhttp = "4.11.0"
 postgre = "42.5.4"
 prometheus = "0.16.0"
 reactor = "2020.0.39"
@@ -198,3 +198,7 @@ plugin-javaformat = { module = "io.spring.javaformat:spring-javaformat-gradle-pl
 plugin-japicmp = { module = "me.champeau.gradle:japicmp-gradle-plugin", version = "0.4.2" }
 plugin-downloadTask = { module = "de.undercouch:gradle-download-task", version = "5.5.0" }
 plugin-spotless = { module = "com.diffplug.spotless:spotless-plugin-gradle", version = "6.22.0" }
+
+[plugins]
+kotlin19 = { id = "org.jetbrains.kotlin.jvm", version = "1.9.22" }
+kotlin17 = { id = "org.jetbrains.kotlin.jvm", version = "1.7.22" }

micrometer-core/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id "org.jetbrains.kotlin.jvm" version "1.7.22"
+    alias(libs.plugins.kotlin17)
     id 'me.champeau.mrjar' version "0.1.1"
 }
 
@@ -82,6 +82,7 @@ dependencies {
     optionalApi 'io.micrometer:context-propagation'
 
     // kotlin
+    optionalApi enforcedPlatform('org.jetbrains.kotlin:kotlin-bom')
     optionalApi 'org.jetbrains.kotlin:kotlin-reflect'
     optionalApi 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
     optionalApi 'org.jetbrains.kotlinx:kotlinx-coroutines-core'

micrometer-core/src/main/java/io/micrometer/core/instrument/AbstractTimerBuilder.java

@@ -199,7 +199,8 @@ public B maximumExpectedValue(@Nullable Duration max) {
      * over time to give greater weight to recent samples (exception: histogram counts are
      * cumulative for those systems that expect cumulative histogram buckets). Samples are
      * accumulated to such statistics in ring buffers which rotate after this expiry, with
-     * a buffer length of {@link #distributionStatisticBufferLength(Integer)}.
+     * a buffer length of {@link #distributionStatisticBufferLength(Integer)}, hence
+     * complete expiry happens after this expiry * buffer length.
      * @param expiry The amount of time samples are accumulated to a histogram before it
      * is reset and rotated.
      * @return This builder.

micrometer-core/src/main/java/io/micrometer/core/instrument/distribution/DistributionStatisticConfig.java

@@ -214,7 +214,8 @@ public Double getMaximumExpectedValueAsDouble() {
      * greater weight to recent samples (exception: histogram counts are cumulative for
      * those systems that expect cumulative histogram buckets). Samples are accumulated to
      * such statistics in ring buffers which rotate after this expiry, with a buffer
-     * length of {@link #bufferLength}.
+     * length of {@link #bufferLength}, hence complete expiry happens after this expiry *
+     * buffer length.
      * @return The amount of time samples are accumulated to a histogram before it is
      * reset and rotated.
      */
@@ -426,7 +427,8 @@ public Builder maximumExpectedValue(@Nullable Double max) {
          * greater weight to recent samples (exception: histogram counts are cumulative
          * for those systems that expect cumulative histogram buckets). Samples are
          * accumulated to such statistics in ring buffers which rotate after this expiry,
-         * with a buffer length of {@link #bufferLength}.
+         * with a buffer length of {@link #bufferLength}, hence complete expiry happens
+         * after this expiry * buffer length.
          * @param expiry The amount of time samples are accumulated to decaying
          * distribution statistics before they are reset and rotated.
          * @return This builder.

samples/micrometer-samples-kotlin/build.gradle

@@ -0,0 +1,19 @@
+plugins {
+    // test with the highest version of Kotlin supported because we compile with oldest version supported
+    alias(libs.plugins.kotlin19)
+}
+
+dependencies {
+    // libraries that have Kotlin dependencies
+    implementation project(":micrometer-core")
+    implementation libs.kotlinxCoroutines
+    // force the stdlib versions to match the plugin version for this sample
+    implementation enforcedPlatform('org.jetbrains.kotlin:kotlin-bom')
+    implementation libs.okhttp
+
+    testRuntimeOnly libs.contextPropagation
+
+    testImplementation libs.junitJupiter
+    testImplementation libs.assertj
+    testImplementation project(":micrometer-test")
+}

samples/micrometer-samples-kotlin/src/test/kotlin/io/micrometer/samples/kotlin/KotlinCoroutinesTests.kt

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2024 VMware, Inc.
+ *
+ * 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
+ *
+ * https://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 io.micrometer.samples.kotlin
+
+import io.micrometer.core.instrument.kotlin.asContextElement
+import io.micrometer.core.instrument.kotlin.currentObservation
+import io.micrometer.observation.Observation
+import io.micrometer.observation.ObservationRegistry
+import kotlinx.coroutines.*
+import org.assertj.core.api.BDDAssertions
+import org.junit.jupiter.api.Test
+
+internal class KotlinCoroutinesTests {
+
+    val observationRegistry = ObservationRegistry.create()
+
+    @Test
+    fun `should return current observation from context`(): Unit = runBlocking {
+        observationRegistry.observationConfig().observationHandler { true }
+        val nextObservation = Observation.start("name", observationRegistry)
+        val inScope = nextObservation.openScope()
+        var observationInGlobalScopeLaunch: Observation? = null
+        var observationInGlobalScopeAsync: Observation? = null
+        val asContextElement = observationRegistry.asContextElement()
+
+        @OptIn(DelicateCoroutinesApi::class)
+        GlobalScope.launch(asContextElement) {
+            observationInGlobalScopeLaunch = coroutineContext.currentObservation()
+        }
+        @OptIn(DelicateCoroutinesApi::class)
+        GlobalScope.async(asContextElement) {
+            observationInGlobalScopeAsync = coroutineContext.currentObservation()
+        }.await()
+
+        inScope.close()
+
+        BDDAssertions.then(observationInGlobalScopeLaunch).isSameAs(nextObservation)
+        BDDAssertions.then(observationInGlobalScopeAsync).isSameAs(nextObservation)
+    }
+}

samples/micrometer-samples-kotlin/src/test/kotlin/io/micrometer/samples/kotlin/OkHttpClientTimingInstrumentationVerificationTests.kt

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2024 VMware, Inc.
+ *
+ * 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
+ *
+ * https://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 io.micrometer.samples.kotlin
+
+import io.micrometer.core.instrument.HttpClientTimingInstrumentationVerificationTests
+import io.micrometer.core.instrument.binder.okhttp3.OkHttpMetricsEventListener
+import io.micrometer.core.instrument.binder.okhttp3.OkHttpObservationDocumentation
+import io.micrometer.core.instrument.binder.okhttp3.OkHttpObservationInterceptor
+import io.micrometer.observation.docs.ObservationDocumentation
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import java.io.IOException
+import java.net.URI
+
+internal class OkHttpClientTimingInstrumentationVerificationTests :
+    HttpClientTimingInstrumentationVerificationTests<OkHttpClient>() {
+
+    override fun sendHttpRequest(
+        instrumentedClient: OkHttpClient,
+        method: HttpMethod,
+        body: ByteArray?,
+        baseUri: URI,
+        templatedPath: String,
+        vararg pathVariables: String?,
+    ) {
+        val request: Request = Request.Builder().method(method.name, body?.toRequestBody())
+            .url(baseUri.toString() + substitutePathVariables(templatedPath, *pathVariables))
+            .header(OkHttpMetricsEventListener.URI_PATTERN, templatedPath)
+            .build()
+        try {
+            instrumentedClient.newCall(request).execute().use { }
+        } catch (e: IOException) {
+            throw RuntimeException(e)
+        }
+    }
+
+    override fun clientInstrumentedWithMetrics(): OkHttpClient {
+        return OkHttpClient.Builder()
+            .eventListener(OkHttpMetricsEventListener.builder(registry, timerName()).build())
+            .build()
+    }
+
+    override fun clientInstrumentedWithObservations(): OkHttpClient {
+        return OkHttpClient.Builder()
+            .addInterceptor(OkHttpObservationInterceptor.builder(observationRegistry, timerName()).build())
+            .build()
+    }
+
+    override fun observationDocumentation(): ObservationDocumentation {
+        return OkHttpObservationDocumentation.DEFAULT
+    }
+}

settings.gradle

@@ -25,7 +25,7 @@ gradleEnterprise {
 
 include 'micrometer-commons', 'micrometer-core', 'micrometer-observation'
 
-['core', 'boot2', 'boot2-reactive', 'spring-integration', 'hazelcast', 'hazelcast3', 'javalin', 'jersey3'].each { sample ->
+['core', 'boot2', 'boot2-reactive', 'spring-integration', 'hazelcast', 'hazelcast3', 'javalin', 'jersey3', 'kotlin'].each { sample ->
     include "micrometer-samples-$sample"
     project(":micrometer-samples-$sample").projectDir = new File(rootProject.projectDir, "samples/micrometer-samples-$sample")
 }