+str #15588,#17229 Java 6 Synchronous File Sink / Source

These are synchronous implementations, because we need to be Java 6
  compatible while developing on 2.3.x. However asynchronous
  implementations using AsynchronousFileChannel will come soon for JDK7
  users.

+ ActorPublisher/Subscriber now manage stopping of the actor
+ added documentation on configuring dispatcher for File IO
+ properly handle if source file does not exist
+ file sink / source come with default io dispatcher
> verified no actors are leaking
> exceptions are caught and onErrored properly
+ moved files to akka.stream.io
+ Added OutputStreamSink and InputStreamSource

akka-stream/src/main/scala/akka/stream/io/impl/IOSources.scala

@@ -0,0 +1,74 @@
+/**
+ * Copyright (C) 2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream.io.impl
+
+import java.io.{ File, InputStream }
+
+import akka.stream._
+import akka.stream.impl.StreamLayout.Module
+import akka.stream.impl.{ ErrorPublisher, SourceModule }
+import akka.util.ByteString
+import org.reactivestreams._
+
+import scala.concurrent.{ Future, Promise }
+
+/**
+ * INTERNAL API
+ * Creates simple synchronous (Java 6 compatible) Source backed by the given file.
+ */
+private[akka] final class SynchronousFileSource(f: File, chunkSize: Int, val attributes: OperationAttributes, shape: SourceShape[ByteString])
+  extends SourceModule[ByteString, Future[Long]](shape) {
+  override def create(context: MaterializationContext) = {
+    val mat = ActorFlowMaterializer.downcast(context.materializer)
+    val settings = mat.effectiveSettings(context.effectiveAttributes)
+
+    val bytesReadPromise = Promise[Long]()
+    val props = SynchronousFilePublisher.props(f, bytesReadPromise, chunkSize, settings.initialInputBufferSize, settings.maxInputBufferSize)
+    val dispatcher = IOSettings.fileIoDispatcher(context)
+
+    val ref = mat.actorOf(context, props.withDispatcher(dispatcher))
+
+    (akka.stream.actor.ActorPublisher[ByteString](ref), bytesReadPromise.future)
+  }
+
+  override protected def newInstance(shape: SourceShape[ByteString]): SourceModule[ByteString, Future[Long]] =
+    new SynchronousFileSource(f, chunkSize, attributes, shape)
+
+  override def withAttributes(attr: OperationAttributes): Module =
+    new SynchronousFileSource(f, chunkSize, attr, amendShape(attr))
+}
+
+/**
+ * INTERNAL API
+ * Source backed by the given input stream.
+ */
+private[akka] final class InputStreamSource(createInputStream: () ⇒ InputStream, chunkSize: Int, val attributes: OperationAttributes, shape: SourceShape[ByteString])
+  extends SourceModule[ByteString, Future[Long]](shape) {
+  override def create(context: MaterializationContext) = {
+    val mat = ActorFlowMaterializer.downcast(context.materializer)
+    val settings = mat.effectiveSettings(context.effectiveAttributes)
+    val bytesReadPromise = Promise[Long]()
+
+    val pub = try {
+      val is = createInputStream() // can throw, i.e. FileNotFound
+
+      val props = InputStreamPublisher.props(is, bytesReadPromise, chunkSize, settings.initialInputBufferSize, settings.maxInputBufferSize)
+
+      val ref = mat.actorOf(context, props)
+      akka.stream.actor.ActorPublisher[ByteString](ref)
+    } catch {
+      case ex: Exception ⇒
+        bytesReadPromise.failure(ex)
+        ErrorPublisher(ex, attributes.nameOrDefault("inputStreamSource")).asInstanceOf[Publisher[ByteString]]
+    }
+
+    (pub, bytesReadPromise.future)
+  }
+
+  override protected def newInstance(shape: SourceShape[ByteString]): SourceModule[ByteString, Future[Long]] =
+    new InputStreamSource(createInputStream, chunkSize, attributes, shape)
+
+  override def withAttributes(attr: OperationAttributes): Module =
+    new InputStreamSource(createInputStream, chunkSize, attr, amendShape(attr))
+}