Move JFR functionality into junit-platform-launcher (#4674)

* Avoid storing JFR events when they are disabled
* Only fill JFR events if they're about to be committed
* Move JFR event generating listeners into junit-platform-launcher
* Make JFR optional
* Remove unnecessary concurrency handling

Resolves #4579.

Author: marcphilipp

build.gradle.kts

@@ -22,7 +22,6 @@ val platformProjects by extra(listOf(
 		projects.junitPlatformConsole,
 		projects.junitPlatformConsoleStandalone,
 		projects.junitPlatformEngine,
-		projects.junitPlatformJfr,
 		projects.junitPlatformLauncher,
 		projects.junitPlatformReporting,
 		projects.junitPlatformSuite,

documentation/documentation.gradle.kts

@@ -81,12 +81,6 @@ dependencies {
 		because("Jimfs is used in src/test/java")
 	}
 
-	if (java.toolchain.implementation.orNull == JvmImplementation.J9) {
-		testRuntimeOnly(libs.jfrPolyfill) {
-			because("OpenJ9 does not include JFR")
-		}
-	}
-
 	standaloneConsoleLauncher(projects.junitPlatformConsoleStandalone)
 }
 

documentation/src/docs/asciidoc/release-notes/release-notes-6.0.0-M1.adoc

@@ -49,6 +49,10 @@ repository on GitHub.
   `--h` (rather than `-h`) or `-help` (rather than `--help`).
 * The `junit-platform-runner` module that provided the JUnit 4 based `JUnitPlatform`
   runner has been discontinued.
+* The `junit-platform-jfr` module that provided custom Java Flight Recorder (JFR) events
+  for test discovery and execution has been discontinued. Instead, the functionality is
+  now available directly in `junit-platform-launcher` without requiring an additional
+  dependency.
 * Support for Maven Surefire/Failsafe versions less than 3.0.0 has been dropped.
 * The following deprecated APIs have been removed:
   - `ReflectionSupport.loadClass(String)` method

documentation/src/docs/asciidoc/user-guide/appendix.adoc

@@ -65,10 +65,6 @@ Please refer to the corresponding sections for <<running-tests-build-maven-bom,
     directory. See <<running-tests-console-launcher>> for details.
   `junit-platform-engine`::
     Public API for test engines. See <<launcher-api-engines-custom>> for details.
-  `junit-platform-jfr`::
-    Provides a `LauncherDiscoveryListener` and `TestExecutionListener` for Java Flight
-	Recorder events on the JUnit Platform. See <<running-tests-listeners-flight-recorder>>
-	for details.
   `junit-platform-launcher`::
     Public API for configuring and launching test plans -- typically used by IDEs and
     build tools. See <<launcher-api>> for details.

documentation/src/docs/asciidoc/user-guide/running-tests.adoc

@@ -1119,9 +1119,7 @@ to a problem.
 In order to record Flight Recorder events generated while running tests, you need to:
 
 1. Ensure that you are using either Java 8 Update 262 or higher or Java 11 or later.
-2. Provide the `org.junit.platform.jfr` module (`junit-platform-jfr-{version}.jar`)
-   on the class-path or module-path at test runtime.
-3. Start flight recording when launching a test run. Flight Recorder can be started via
+2. Start flight recording when launching a test run. Flight Recorder can be started via
    java command line option:
 
    -XX:StartFlightRecording:filename=...

documentation/src/plantuml/component-diagram.puml

@@ -20,7 +20,6 @@ package org.junit.platform {
     [junit-platform-commons] as commons
     [junit-platform-console] as console
     [junit-platform-engine] as engine
-    [junit-platform-jfr] as jfr
     [junit-platform-launcher] as launcher
     [junit-platform-reporting] as reporting
     [junit-platform-suite] as suite

gradle/libs.versions.toml

@@ -42,7 +42,6 @@ groovy2-bom = { module = "org.codehaus.groovy:groovy-bom", version = "2.5.23" }
 hamcrest = { module = "org.hamcrest:hamcrest", version = "3.0" }
 jackson-dataformat-yaml = { module = "com.fasterxml.jackson.dataformat:jackson-dataformat-yaml", version.ref = "jackson" }
 jackson-module-kotlin = { module = "com.fasterxml.jackson.module:jackson-module-kotlin", version.ref = "jackson" }
-jfrPolyfill = { module = "org.gradle.jfr.polyfill:jfr-polyfill", version = "1.0.2" }
 jfrunit = { module = "org.moditect.jfrunit:jfrunit-core", version = "1.0.0.Alpha2" }
 jimfs = { module = "com.google.jimfs:jimfs", version = "1.3.0" }
 jmh-core = { module = "org.openjdk.jmh:jmh-core", version.ref = "jmh" }

gradle/plugins/common/src/main/kotlin/junitbuild.testing-conventions.gradle.kts

@@ -201,13 +201,9 @@ dependencies {
 	testImplementation(project(":junit-jupiter"))
 
 	testRuntimeOnly(project(":junit-platform-engine"))
-	testRuntimeOnly(project(":junit-platform-jfr"))
 	testRuntimeOnly(project(":junit-platform-reporting"))
 
 	testRuntimeOnly(bundleFromLibs("log4j"))
-	testRuntimeOnly(dependencyFromLibs("jfrPolyfill")) {
-		because("OpenJ9 does not include JFR")
-	}
 	testRuntimeOnly(dependencyFromLibs("openTestReporting-events")) {
 		because("it's required to run tests via IntelliJ which does not consumed the shadowed jar of junit-platform-reporting")
 	}

junit-platform-commons/src/main/java/module-info.java

@@ -50,7 +50,6 @@
 			org.junit.jupiter.params,
 			org.junit.platform.console,
 			org.junit.platform.engine,
-			org.junit.platform.jfr,
 			org.junit.platform.launcher,
 			org.junit.platform.reporting,
 			org.junit.platform.suite.api,