Materializer settings as attributes (#27499)

* Replace MaterializerSettings with Attributes #25559 
 * Field access to settings deprecated to make stages use attributes instead
 * Internal stages updated to use attributes
 * Docs on ActorMaterializerSettings updated to recommend away from using it
 * Verify all stages stopped after each testcase in FlowGroupBySpec
 * Subscription timeout attributes merged into one

akka-docs/src/test/scala/docs/stream/FlowErrorDocSpec.scala

@@ -5,12 +5,9 @@
 package docs.stream
 
 import scala.concurrent.Await
-import akka.stream.ActorMaterializer
-import akka.stream.ActorMaterializerSettings
 import akka.stream.Supervision
 import akka.stream.scaladsl._
 import akka.testkit.AkkaSpec
-import akka.stream.Attributes
 import akka.stream.ActorAttributes
 import scala.concurrent.duration._
 
@@ -35,9 +32,13 @@ class FlowErrorDocSpec extends AkkaSpec {
       case _: ArithmeticException => Supervision.Resume
       case _                      => Supervision.Stop
     }
-    implicit val materializer = ActorMaterializer(ActorMaterializerSettings(system).withSupervisionStrategy(decider))
     val source = Source(0 to 5).map(100 / _)
-    val result = source.runWith(Sink.fold(0)(_ + _))
+    val runnableGraph =
+      source.toMat(Sink.fold(0)(_ + _))(Keep.right)
+
+    val withCustomSupervision = runnableGraph.withAttributes(ActorAttributes.supervisionStrategy(decider))
+
+    val result = withCustomSupervision.run()
     // the element causing division by zero will be dropped
     // result here will be a Future completed with Success(228)
     //#resume

akka-docs/src/test/scala/docs/stream/IntegrationDocSpec.scala

@@ -409,13 +409,12 @@ class IntegrationDocSpec extends AkkaSpec(IntegrationDocSpec.config) {
     implicit val blockingExecutionContext = system.dispatchers.lookup("blocking-dispatcher")
     val service = new SometimesSlowService
 
-    implicit val materializer =
-      ActorMaterializer(ActorMaterializerSettings(system).withInputBuffer(initialSize = 4, maxSize = 4))
-
     Source(List("a", "B", "C", "D", "e", "F", "g", "H", "i", "J"))
       .map(elem => { println(s"before: $elem"); elem })
       .mapAsync(4)(service.convert)
-      .runForeach(elem => println(s"after: $elem"))
+      .to(Sink.foreach(elem => println(s"after: $elem")))
+      .withAttributes(Attributes.inputBuffer(initial = 4, max = 4))
+      .run()
     //#sometimes-slow-mapAsync
 
     probe.expectMsg("after: A")
@@ -441,13 +440,12 @@ class IntegrationDocSpec extends AkkaSpec(IntegrationDocSpec.config) {
     implicit val blockingExecutionContext = system.dispatchers.lookup("blocking-dispatcher")
     val service = new SometimesSlowService
 
-    implicit val materializer =
-      ActorMaterializer(ActorMaterializerSettings(system).withInputBuffer(initialSize = 4, maxSize = 4))
-
     Source(List("a", "B", "C", "D", "e", "F", "g", "H", "i", "J"))
       .map(elem => { println(s"before: $elem"); elem })
       .mapAsyncUnordered(4)(service.convert)
-      .runForeach(elem => println(s"after: $elem"))
+      .to(Sink.foreach(elem => println(s"after: $elem")))
+      .withAttributes(Attributes.inputBuffer(initial = 4, max = 4))
+      .run()
     //#sometimes-slow-mapAsyncUnordered
 
     probe.receiveN(10).toSet should be(

akka-docs/src/test/scala/docs/stream/StreamBuffersRateSpec.scala

@@ -32,14 +32,13 @@ class StreamBuffersRateSpec extends AkkaSpec {
   }
 
   "Demonstrate buffer sizes" in {
-    //#materializer-buffer
-    val materializer =
-      ActorMaterializer(ActorMaterializerSettings(system).withInputBuffer(initialSize = 64, maxSize = 64))
-    //#materializer-buffer
-
     //#section-buffer
     val section = Flow[Int].map(_ * 2).async.addAttributes(Attributes.inputBuffer(initial = 1, max = 1)) // the buffer size of this map is 1
     val flow = section.via(Flow[Int].map(_ / 2)).async // the buffer size of this map is the default
+    val runnableGraph =
+      Source(1 to 10).via(flow).to(Sink.foreach(elem => println(elem)))
+
+    val withOverriddenDefaults = runnableGraph.withAttributes(Attributes.inputBuffer(initial = 64, max = 64))
     //#section-buffer
   }
 

akka-docs/src/test/scala/docs/stream/cookbook/RecipeCollectingMetrics.scala

@@ -4,13 +4,7 @@
 
 package docs.stream.cookbook
 
-import akka.stream.{ ActorMaterializer, ActorMaterializerSettings }
-
-import scala.collection.immutable
-import scala.concurrent.Await
-
 class RecipeCollectingMetrics extends RecipeSpec {
-  implicit val m2 = ActorMaterializer(ActorMaterializerSettings(system).withInputBuffer(1, 1))
 
   "Recipe for periodically collecting metrics" must {
 
@@ -39,7 +33,7 @@ class RecipeCollectingMetrics extends RecipeSpec {
       //      }
       //      //#periodic-metrics-collection
       //
-      //      val reports = graph.run().get(futureSink)
+      //      val reports = graph.withAttributes(Attributes.inputBuffer(1, 1).run().get(futureSink)
       //      val manualLoad = new StreamTestKit.AutoPublisher(loadPub)
       //      val manualTick = new StreamTestKit.AutoPublisher(tickPub)
       //