Add support for cloning server-sockets.

sdk/lib/io/socket.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 
 /**
  * [InternetAddressType] is the type an [InternetAddress]. Currently,
  * IP version 4 (IPv4) and IP version 6 (IPv6) are supported.
@@ skipping 226 matching lines @@
   /**
    * Returns the address used by this socket.
    */
   InternetAddress get address;
 
   /**
    * Closes the socket. The returned future completes when the socket
    * is fully closed and is no longer bound.
    */
   Future<RawServerSocket> close();
+
+  /**
+   * Get the [RawServerSocketReference].
+   *
+   * WARNING: This feature is *highly experimental* and currently only works on
+   * Linux. The API is most likely going to change in the near future.
+   *
+   * The returned [RawServerSocketReference] can be used to create other
+   * [RawServerSocket]s listening on the same port,
+   * using [RawServerSocketReference.create].
+   * Incoming connections on the port will be distributed fairly between the
+   * active server sockets.
+   * The [RawServerSocketReference] can be distributed to other isolates through
+   * a [RawSendPort].
+   */
+  RawServerSocketReference get reference;
 }
 
 
+/**
+ * A [RawServerSocketReference].
+ *
+ * WARNING: This class is used with [RawServerSocket.reference] which is highly
+ * experimental.
+ */
+abstract class RawServerSocketReference {
+  /**
+   * Create a new [RawServerSocket], from this reference.
+   */
+  Future<RawServerSocket> create();
+}
+
+
 /**
  * A [ServerSocket] represents a listening socket, and provides a
  * stream of [Socket] objects, one for each connection made to the
  * listening socket.
  *
  * See [Socket] for more info.
  */
 abstract class ServerSocket implements Stream<Socket> {
   /**
    * Returns a future for a [:ServerSocket:]. When the future
@@ skipping 38 matching lines @@
   /**
    * Returns the address used by this socket.
    */
   InternetAddress get address;
 
   /**
    * Closes the socket. The returned future completes when the socket
    * is fully closed and is no longer bound.
    */
   Future<ServerSocket> close();
+
+  /**
+   * Get the [ServerSocketReference].
+   *
+   * WARNING: This feature is *highly experimental* and currently only works on
+   * Linux. The API is most likely going to change in the near future.
+   *
+   * The returned [ServerSocketReference] can be used to create other
+   * [ServerSocket]s listening on the same port,
+   * using [ServerSocketReference.create].
+   * Incoming connections on the port will be distributed fairly between the
+   * active server sockets.
+   * The [ServerSocketReference] can be distributed to other isolates through a
+   * [SendPort].
+   */
+  ServerSocketReference get reference;
 }
 
+
+/**
+ * A [ServerSocketReference].
+ *
+ * WARNING: This class is used with [ServerSocket.reference] which is highly
+ * experimental.
+ */
+abstract class ServerSocketReference {
+  /**
+   * Create a new [ServerSocket], from this reference.
+   */
+  Future<ServerSocket> create();
+}
+
+
 /**
  * The [SocketDirection] is used as a parameter to [Socket.close] and
  * [RawSocket.close] to close a socket in the specified direction(s).
  */
 class SocketDirection {
   static const SocketDirection RECEIVE = const SocketDirection._(0);
   static const SocketDirection SEND = const SocketDirection._(1);
   static const SocketDirection BOTH = const SocketDirection._(2);
   final _value;
 
@@ skipping 359 matching lines @@
     }
     if (address != null) {
       sb.write(", address = ${address.host}");
     }
     if (port != null) {
       sb.write(", port = $port");
     }
     return sb.toString();
   }
 }