Added a flag on takeWhile to allow it to include the final element, #21330

akka-actor/src/main/scala/akka/pattern/BackoffSupervisor.scala

@@ -3,7 +3,6 @@
  */
 package akka.pattern
 
-
 import java.time.Instant
 
 import scala.concurrent.duration.{ Deadline, Duration, FiniteDuration }

akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowTakeWhileSpec.scala

@@ -43,6 +43,13 @@ class FlowTakeWhileSpec extends StreamSpec {
         .expectComplete()
     }
 
+    "emit the element that caused the predicate to return false and then no more with inclusive set" in assertAllStagesStopped {
+      Source(1 to 10).takeWhile(_ < 3, true).runWith(TestSink.probe[Int])
+        .request(4)
+        .expectNext(1, 2, 3)
+        .expectComplete()
+    }
+
   }
 
 }

akka-stream/src/main/scala/akka/stream/impl/fusing/Ops.scala

@@ -92,7 +92,7 @@ final case class Filter[T](p: T ⇒ Boolean) extends SimpleLinearGraphStage[T] {
 /**
  * INTERNAL API
  */
-final case class TakeWhile[T](p: T ⇒ Boolean) extends SimpleLinearGraphStage[T] {
+final case class TakeWhile[T](p: T ⇒ Boolean, inclusive: Boolean = false) extends SimpleLinearGraphStage[T] {
   override def initialAttributes: Attributes = DefaultAttributes.takeWhile
 
   override def toString: String = "TakeWhile"
@@ -109,6 +109,7 @@ final case class TakeWhile[T](p: T ⇒ Boolean) extends SimpleLinearGraphStage[T
           if (p(elem)) {
             push(out, elem)
           } else {
+            if (inclusive) push(out, elem)
             completeStage()
           }
         } catch {

akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala

@@ -777,9 +777,9 @@ final class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends
 
   /**
    * Terminate processing (and cancel the upstream publisher) after predicate
-   * returns false for the first time. Due to input buffering some elements may have been
-   * requested from upstream publishers that will then not be processed downstream
-   * of this step.
+   * returns false for the first time, including the first failed element iff inclusive is true
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
    *
    * The stream will be completed without producing any elements if predicate is false for
    * the first stream element.
@@ -788,13 +788,34 @@ final class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends
    *
    * '''Backpressures when''' downstream backpressures
    *
-   * '''Completes when''' predicate returned false or upstream completes
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
    *
    * '''Cancels when''' predicate returned false or downstream cancels
    *
    * See also [[Flow.limit]], [[Flow.limitWeighted]]
    */
-  def takeWhile(p: function.Predicate[Out]): javadsl.Flow[In, Out, Mat] = new Flow(delegate.takeWhile(p.test))
+  def takeWhile(p: function.Predicate[Out], inclusive: Boolean = false): javadsl.Flow[In, Out, Mat] = new Flow(delegate.takeWhile(p.test, inclusive))
+
+  /**
+   * Terminate processing (and cancel the upstream publisher) after predicate
+   * returns false for the first time, including the first failed element iff inclusive is true
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
+   *
+   * The stream will be completed without producing any elements if predicate is false for
+   * the first stream element.
+   *
+   * '''Emits when''' the predicate is true
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
+   *
+   * '''Cancels when''' predicate returned false or downstream cancels
+   *
+   * See also [[Flow.limit]], [[Flow.limitWeighted]]
+   */
+  def takeWhile(p: function.Predicate[Out]): javadsl.Flow[In, Out, Mat] = takeWhile(p, false)
 
   /**
    * Discard elements at the beginning of the stream while predicate is true.

akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala

@@ -608,9 +608,9 @@ class SubFlow[-In, +Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Flo
 
   /**
    * Terminate processing (and cancel the upstream publisher) after predicate
-   * returns false for the first time. Due to input buffering some elements may have been
-   * requested from upstream publishers that will then not be processed downstream
-   * of this step.
+   * returns false for the first time,
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
    *
    * The stream will be completed without producing any elements if predicate is false for
    * the first stream element.
@@ -619,12 +619,31 @@ class SubFlow[-In, +Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Flo
    *
    * '''Backpressures when''' downstream backpressures
    *
-   * '''Completes when''' predicate returned false or upstream completes
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
    *
    * '''Cancels when''' predicate returned false or downstream cancels
    */
-  def takeWhile(p: function.Predicate[Out]): SubFlow[In, Out, Mat] =
-    new SubFlow(delegate.takeWhile(p.test))
+  def takeWhile(p: function.Predicate[Out]): SubFlow[In, Out, Mat] = takeWhile(p, false)
+
+  /**
+   * Terminate processing (and cancel the upstream publisher) after predicate
+   * returns false for the first time, including the first failed element iff inclusive is true
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
+   *
+   * The stream will be completed without producing any elements if predicate is false for
+   * the first stream element.
+   *
+   * '''Emits when''' the predicate is true
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
+   *
+   * '''Cancels when''' predicate returned false or downstream cancels
+   */
+  def takeWhile(p: function.Predicate[Out], inclusive: Boolean): SubFlow[In, Out, Mat] =
+    new SubFlow(delegate.takeWhile(p.test, inclusive))
 
   /**
    * Discard elements at the beginning of the stream while predicate is true.

akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala

@@ -578,9 +578,9 @@ class SubSource[+Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Source
 
   /**
    * Terminate processing (and cancel the upstream publisher) after predicate
-   * returns false for the first time. Due to input buffering some elements may have been
-   * requested from upstream publishers that will then not be processed downstream
-   * of this step.
+   * returns false for the first time,
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
    *
    * The stream will be completed without producing any elements if predicate is false for
    * the first stream element.
@@ -589,12 +589,31 @@ class SubSource[+Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Source
    *
    * '''Backpressures when''' downstream backpressures
    *
-   * '''Completes when''' predicate returned false or upstream completes
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
    *
    * '''Cancels when''' predicate returned false or downstream cancels
    */
-  def takeWhile(p: function.Predicate[Out]): SubSource[Out, Mat] =
-    new SubSource(delegate.takeWhile(p.test))
+  def takeWhile(p: function.Predicate[Out]): SubSource[Out, Mat] = takeWhile(p, false)
+
+  /**
+   * Terminate processing (and cancel the upstream publisher) after predicate
+   * returns false for the first time, including the first failed element iff inclusive is true
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
+   *
+   * The stream will be completed without producing any elements if predicate is false for
+   * the first stream element.
+   *
+   * '''Emits when''' the predicate is true
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
+   *
+   * '''Cancels when''' predicate returned false or downstream cancels
+   */
+  def takeWhile(p: function.Predicate[Out], inclusive: Boolean): SubSource[Out, Mat] =
+    new SubSource(delegate.takeWhile(p.test, inclusive))
 
   /**
    * Discard elements at the beginning of the stream while predicate is true.

akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala

@@ -616,9 +616,9 @@ trait FlowOps[+Out, +Mat] {
 
   /**
    * Terminate processing (and cancel the upstream publisher) after predicate
-   * returns false for the first time. Due to input buffering some elements may have been
-   * requested from upstream publishers that will then not be processed downstream
-   * of this step.
+   * returns false for the first time,
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
    *
    * The stream will be completed without producing any elements if predicate is false for
    * the first stream element.
@@ -627,13 +627,34 @@ trait FlowOps[+Out, +Mat] {
    *
    * '''Backpressures when''' downstream backpressures
    *
-   * '''Completes when''' predicate returned false or upstream completes
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
    *
    * '''Cancels when''' predicate returned false or downstream cancels
    *
    * See also [[FlowOps.limit]], [[FlowOps.limitWeighted]]
    */
-  def takeWhile(p: Out ⇒ Boolean): Repr[Out] = via(TakeWhile(p))
+  def takeWhile(p: Out ⇒ Boolean): Repr[Out] = takeWhile(p, false)
+
+  /**
+   * Terminate processing (and cancel the upstream publisher) after predicate
+   * returns false for the first time, including the first failed element iff inclusive is true
+   * Due to input buffering some elements may have been requested from upstream publishers
+   * that will then not be processed downstream of this step.
+   *
+   * The stream will be completed without producing any elements if predicate is false for
+   * the first stream element.
+   *
+   * '''Emits when''' the predicate is true
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' predicate returned false (or 1 after predicate returns false if `inclusive` or upstream completes
+   *
+   * '''Cancels when''' predicate returned false or downstream cancels
+   *
+   * See also [[FlowOps.limit]], [[FlowOps.limitWeighted]]
+   */
+  def takeWhile(p: Out ⇒ Boolean, inclusive: Boolean): Repr[Out] = via(TakeWhile(p, inclusive))
 
   /**
    * Discard elements at the beginning of the stream while predicate is true.

project/MiMa.scala

@@ -994,7 +994,10 @@ object MiMa extends AutoPlugin {
         ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.cluster.ddata.protobuf.msg.ReplicatorMessages#UniqueAddressOrBuilder.hasUid2"),
         ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.cluster.ddata.protobuf.msg.ReplicatorMessages#UniqueAddressOrBuilder.getUid2"),
         ProblemFilters.exclude[IncompatibleMethTypeProblem]("akka.remote.RemoteWatcher.receiveHeartbeatRsp"),
-        ProblemFilters.exclude[IncompatibleResultTypeProblem]("akka.remote.RemoteWatcher.selfHeartbeatRspMsg")
+        ProblemFilters.exclude[IncompatibleResultTypeProblem]("akka.remote.RemoteWatcher.selfHeartbeatRspMsg"),
+
+        // #21330 takeWhile inclusive flag
+        ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.stream.scaladsl.FlowOps.takeWhile")
       )
     )
   }