=str Optimize concat for javadsl.Source.empty.

hughsimpson · Dec 23, 2023 · 781b122 · 781b122
1 parent 873868c
commit 781b122
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diff --git a/stream-tests/src/test/java/org/apache/pekko/stream/javadsl/SourceTest.java b/stream-tests/src/test/java/org/apache/pekko/stream/javadsl/SourceTest.java
@@ -286,6 +286,17 @@ public void apply(String elem) {
     assertEquals(Arrays.asList("A", "B", "C", "D", "E", "F"), output);
   }
 
+  @Test
+  public void mustBeAbleToConcatEmptySource() {
+    Source.from(Arrays.asList("A", "B", "C"))
+        .concat(Source.empty())
+        .runWith(TestSink.probe(system), system)
+        .ensureSubscription()
+        .request(3)
+        .expectNext("A", "B", "C")
+        .expectComplete();
+  }
+
   @Test
   public void mustBeAbleToUseConcatAll() {
     final Source<Integer, NotUsed> sourceA = Source.from(Arrays.asList(1, 2, 3));

diff --git a/stream/src/main/scala/org/apache/pekko/stream/scaladsl/Flow.scala b/stream/src/main/scala/org/apache/pekko/stream/scaladsl/Flow.scala
@@ -3302,7 +3302,7 @@ trait FlowOps[+Out, +Mat] {
 
   private def internalConcat[U >: Out, Mat2](that: Graph[SourceShape[U], Mat2], detached: Boolean): Repr[U] =
     that match {
-      case source if source eq Source.empty => this.asInstanceOf[Repr[U]]
+      case source if TraversalBuilder.isEmptySource(source) => this.asInstanceOf[Repr[U]]
       case other =>
         TraversalBuilder.getSingleSource(other) match {
           case OptionVal.Some(singleSource) =>