Made static factory method of KamonHttpContextPropagation less erro…

…r-prone.

Runtime exceptions get easily neglected by mistake. Returning a `Try` instead makes it obvious that the instance create might fail.

Signed-off-by: Juergen Fickel <juergen.fickel@bosch.io>

internal/utils/tracing/src/main/java/org/eclipse/ditto/internal/utils/tracing/DittoTracing.java

@@ -153,7 +153,7 @@ public void init(final TracingConfig tracingConfig) {
                 final var propagationChannelName = tracingConfig.getPropagationChannel();
                 newStateConsumer.accept(
                         new TracingEnabledState(
-                                tryToGetKamonHttpContextPropagation(propagationChannelName),
+                                tryToGetKamonHttpContextPropagationOrThrow(propagationChannelName),
                                 tracingConfig.getTracingFilter()
                         )
                 );
@@ -165,13 +165,17 @@ public void init(final TracingConfig tracingConfig) {
             }
         }
 
-        private static KamonHttpContextPropagation tryToGetKamonHttpContextPropagation(
+        private static KamonHttpContextPropagation tryToGetKamonHttpContextPropagationOrThrow(
                 final CharSequence propagationChannelName
         ) {
-            try {
-                return KamonHttpContextPropagation.newInstanceForChannelName(propagationChannelName);
-            } catch (final IllegalArgumentException e) {
-                throw new DittoConfigError(e.getMessage(), e);
+            final var kamonHttpContextPropagationTry =
+                    KamonHttpContextPropagation.tryNewInstanceForChannelName(propagationChannelName);
+            if (kamonHttpContextPropagationTry.isSuccess()) {
+                return kamonHttpContextPropagationTry.get();
+            } else {
+                final var failed = kamonHttpContextPropagationTry.failed();
+                final var throwable = failed.get();
+                throw new DittoConfigError(throwable.getMessage(), throwable);
             }
         }
 

internal/utils/tracing/src/main/java/org/eclipse/ditto/internal/utils/tracing/span/KamonHttpContextPropagation.java

@@ -26,6 +26,7 @@
 import kamon.context.Propagation;
 import scala.Option;
 import scala.jdk.javaapi.CollectionConverters;
+import scala.util.Try;
 
 /**
  * This class provides the means to read {@link Context} from a Map of headers as well as propagating {@code Context}
@@ -47,13 +48,17 @@ private KamonHttpContextPropagation(
      * argument.
      *
      * @param propagationChannelName configured name of the HTTP propagation channel.
-     * @return the new instance.
+     * @return a {@code Try} with the new instance if successful or an {@code IllegalArgumentException} if
+     * {@code propagationChannelName} is undefined.
      * @throws NullPointerException if {@code propagationChannelName} is {@code null}.
-     * @throws IllegalArgumentException if {@code propagationChannelName} is undefined.
      */
-    public static KamonHttpContextPropagation newInstanceForChannelName(final CharSequence propagationChannelName) {
+    public static Try<KamonHttpContextPropagation> tryNewInstanceForChannelName(
+            final CharSequence propagationChannelName
+    ) {
         checkNotNull(propagationChannelName, "propagationChannelName");
-        return new KamonHttpContextPropagation(getHttpPropagationOrThrow(propagationChannelName.toString()));
+        return Try.apply(
+                () -> new KamonHttpContextPropagation(getHttpPropagationOrThrow(propagationChannelName.toString()))
+        );
     }
 
     private static Propagation<HttpPropagation.HeaderReader, HttpPropagation.HeaderWriter> getHttpPropagationOrThrow(
@@ -72,6 +77,15 @@ private static Propagation<HttpPropagation.HeaderReader, HttpPropagation.HeaderW
         }
     }
 
+    /**
+     * Returns an instance of {@code KamonHttpContextPropagation} for the default HTTP propagation channel.
+     *
+     * @return the instance.
+     */
+    static KamonHttpContextPropagation getInstanceForDefaultHttpChannel() {
+        return new KamonHttpContextPropagation(Kamon.defaultHttpPropagation());
+    }
+
     /**
      * Reads context information from the specified map of headers.
      *

internal/utils/tracing/src/test/java/org/eclipse/ditto/internal/utils/tracing/span/KamonHttpContextPropagationTest.java

@@ -46,7 +46,6 @@ public final class KamonHttpContextPropagationTest {
             KamonTracingInitResource.KamonTracingConfig.defaultValues()
     );
 
-    private static final String DEFAULT_CHANNEL_NAME = "default";
     private static final String CONTEXT_TAGS_KEY = "context-tags";
     private static final String TRACEPARENT_KEY = DittoHeaderDefinition.W3C_TRACEPARENT.getKey();
 
@@ -70,23 +69,26 @@ public static void beforeClass() {
     @Test
     public void newInstanceForNullChannelNameThrowsNullPointerException() {
         assertThatNullPointerException()
-                .isThrownBy(() -> KamonHttpContextPropagation.newInstanceForChannelName(null))
+                .isThrownBy(() -> KamonHttpContextPropagation.tryNewInstanceForChannelName(null))
                 .withMessage("The propagationChannelName must not be null!")
                 .withNoCause();
     }
 
     @Test
-    public void newInstanceForUnknownChannelNameThrowsIllegalArgumentException() {
+    public void newInstanceForUnknownChannelNameReturnsFailedWithIllegalArgumentException() {
         final var channelName = "zoeglfrex";
+        final var kamonHttpContextPropagationTry =
+                KamonHttpContextPropagation.tryNewInstanceForChannelName(channelName);
+
         assertThatIllegalArgumentException()
-                .isThrownBy(() -> KamonHttpContextPropagation.newInstanceForChannelName(channelName))
+                .isThrownBy(kamonHttpContextPropagationTry::get)
                 .withMessage("HTTP propagation for channel name <%s> is undefined.", channelName)
                 .withNoCause();
     }
 
     @Test
     public void getContextFromHeadersForNullHeadersThrowsNullPointerException() {
-        final var underTest = KamonHttpContextPropagation.newInstanceForChannelName(DEFAULT_CHANNEL_NAME);
+        final var underTest = KamonHttpContextPropagation.getInstanceForDefaultHttpChannel();
 
         assertThatNullPointerException()
                 .isThrownBy(() -> underTest.getContextFromHeaders(null))
@@ -96,7 +98,7 @@ public void getContextFromHeadersForNullHeadersThrowsNullPointerException() {
 
     @Test
     public void getContextFromEmptyMapReturnsEmptyContext() {
-        final var underTest = KamonHttpContextPropagation.newInstanceForChannelName(DEFAULT_CHANNEL_NAME);
+        final var underTest = KamonHttpContextPropagation.getInstanceForDefaultHttpChannel();
 
         final var context = underTest.getContextFromHeaders(Map.of());
 
@@ -111,7 +113,7 @@ public void getContextFromMapWithCustomHeadersReturnsExpectedContext() {
                 "marco", "polo"
         );
         final var spanId = spanIdFactory.generate();
-        final var underTest = KamonHttpContextPropagation.newInstanceForChannelName(DEFAULT_CHANNEL_NAME);
+        final var underTest = KamonHttpContextPropagation.getInstanceForDefaultHttpChannel();
 
         final var context = underTest.getContextFromHeaders(
                 Map.of(
@@ -143,7 +145,7 @@ private static String getAsTraceparentHeaderValue(final Identifier traceId, fina
 
     @Test
     public void propagateContextToHeadersWithNullContextThrowsNullPointerException() {
-        final var underTest = KamonHttpContextPropagation.newInstanceForChannelName(DEFAULT_CHANNEL_NAME);
+        final var underTest = KamonHttpContextPropagation.getInstanceForDefaultHttpChannel();
 
         assertThatNullPointerException()
                 .isThrownBy(() -> underTest.propagateContextToHeaders(null, Map.of()))
@@ -153,7 +155,7 @@ public void propagateContextToHeadersWithNullContextThrowsNullPointerException()
 
     @Test
     public void propagateContextToHeadersWithNullMapThrowsNullPointerException() {
-        final var underTest = KamonHttpContextPropagation.newInstanceForChannelName(DEFAULT_CHANNEL_NAME);
+        final var underTest = KamonHttpContextPropagation.getInstanceForDefaultHttpChannel();
 
         assertThatNullPointerException()
                 .isThrownBy(() -> underTest.propagateContextToHeaders(Context.Empty(), null))
@@ -170,7 +172,7 @@ public void propagateContextToMapReturnsExpectedMap() {
         );
         final var span = Kamon.spanBuilder(testName.getMethodName()).traceId(traceId).start();
         final var dittoHeaders = DittoHeaders.newBuilder().correlationId(testName.getMethodName()).build();
-        final var underTest = KamonHttpContextPropagation.newInstanceForChannelName(DEFAULT_CHANNEL_NAME);
+        final var underTest = KamonHttpContextPropagation.getInstanceForDefaultHttpChannel();
 
         final var headersWithPropagatedContext = underTest.propagateContextToHeaders(
                 Context.of(Span.Key(), span, TagSet.from(contextTags)),

internal/utils/tracing/src/test/java/org/eclipse/ditto/internal/utils/tracing/span/PreparedKamonSpanTest.java

@@ -55,7 +55,7 @@ public void setup() {
         underTest = PreparedKamonSpan.newInstance(
                 Map.of(),
                 SpanOperationName.of(testName.getMethodName()),
-                KamonHttpContextPropagation.newInstanceForChannelName("default")
+                KamonHttpContextPropagation.getInstanceForDefaultHttpChannel()
         );
     }
 

internal/utils/tracing/src/test/java/org/eclipse/ditto/internal/utils/tracing/span/StartedKamonSpanTest.java

@@ -74,7 +74,7 @@ public void setup() {
                 Kamon.spanBuilder(testName.getMethodName())
                         .asChildOf(Kamon.spanBuilder("/").traceId(traceId).start())
                         .start(),
-                KamonHttpContextPropagation.newInstanceForChannelName("default")
+                KamonHttpContextPropagation.getInstanceForDefaultHttpChannel()
         );
     }