feat(utils): Add runBlocking that preserves Log4j's MDC context

As `kotlinx.coroutines.runBlocking` creates a new coroutine context, it
does not preserve Log4j's MDC context [1] which is stored in a
thread-local `ThreadContext`. Add a helper function as replacement for
`runBlocking` which always adds a `CoroutineThreadContext` which is
initialized from the current `ThreadContext` to the newly created
coroutine context.

Signed-off-by: Martin Nonnenmacher <martin.nonnenmacher@bosch.com>

utils/ort/build.gradle.kts

@@ -26,11 +26,11 @@ dependencies {
     api(projects.utils.commonUtils)
     api(projects.utils.spdxUtils)
 
+    api(libs.kotlinx.coroutines)
     api(libs.okhttp)
 
     implementation(libs.awsS3)
     implementation(libs.commonsCompress)
-    implementation(libs.kotlinx.coroutines)
 
     testImplementation(libs.mockk)
 }

utils/ort/src/main/kotlin/Utils.kt

@@ -24,6 +24,13 @@ import java.net.Authenticator
 import java.net.PasswordAuthentication
 import java.net.URI
 
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+
+import kotlinx.coroutines.CoroutineScope
+
+import org.apache.logging.log4j.kotlin.CoroutineThreadContext
+
 import org.ossreviewtoolkit.utils.common.toSafeUri
 import org.ossreviewtoolkit.utils.common.toUri
 import org.ossreviewtoolkit.utils.common.withoutPrefix
@@ -211,3 +218,13 @@ fun normalizeVcsUrl(vcsUrl: String): String {
 
     return url
 }
+
+/**
+ * A wrapper for [kotlinx.coroutines.runBlocking] which always adds a [CoroutineThreadContext] to the newly created
+ * coroutine context. This ensures that Log4j's MDC context is not lost when `runBlocking` is used.
+ *
+ * This function should be used instead of [kotlinx.coroutines.runBlocking] in all code that can be used as a library to
+ * preserve any MDC context set by a consumer.
+ */
+fun <T> runBlocking(context: CoroutineContext = EmptyCoroutineContext, block: suspend CoroutineScope.() -> T): T =
+    kotlinx.coroutines.runBlocking(context + CoroutineThreadContext()) { block() }

utils/ort/src/test/kotlin/UtilsTest.kt

@@ -24,6 +24,7 @@ import io.kotest.inspectors.forAll
 import io.kotest.matchers.collections.beEmpty
 import io.kotest.matchers.collections.shouldContainExactly
 import io.kotest.matchers.collections.shouldHaveSingleElement
+import io.kotest.matchers.nulls.beNull
 import io.kotest.matchers.nulls.shouldNotBeNull
 import io.kotest.matchers.should
 import io.kotest.matchers.shouldBe
@@ -40,6 +41,11 @@ import java.net.PasswordAuthentication
 import java.net.URI
 import java.nio.file.Paths
 
+import kotlin.coroutines.EmptyCoroutineContext
+
+import org.apache.logging.log4j.kotlin.CoroutineThreadContext
+import org.apache.logging.log4j.kotlin.withLoggingContext
+
 class UtilsTest : WordSpec({
     "filterVersionNames" should {
         "return an empty list for a blank version" {
@@ -472,4 +478,18 @@ class UtilsTest : WordSpec({
             }
         }
     }
+
+    "runBlocking" should {
+        "preserve Log4j's MDC context which kotlinx.coroutines.runBlocking does not" {
+            withLoggingContext(mapOf("key" to "value")) {
+                kotlinx.coroutines.runBlocking(EmptyCoroutineContext) {
+                    coroutineContext[CoroutineThreadContext.Key]?.contextData?.map?.get("key") should beNull()
+                }
+
+                runBlocking(EmptyCoroutineContext) {
+                    coroutineContext[CoroutineThreadContext.Key]?.contextData?.map?.get("key") shouldBe "value"
+                }
+            }
+        }
+    }
 })