In Socket:connect, start connecting to next address, after 250 (25 for loopback).

runtime/bin/socket_patch.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.
 
 patch class RawServerSocket {
   /* patch */ static Future<RawServerSocket> bind(address,
                                                   int port,
                                                   {int backlog: 0,
                                                    bool v6Only: false}) {
     return _RawServerSocket.bind(address, port, backlog, v6Only);
@@ skipping 255 matching lines @@
   static const LIST_INTERFACES = 1;
   static const REVERSE_LOOKUP = 2;
 
   // Protocol flags.
   static const int PROTOCOL_IPV4 = 1 << 0;
   static const int PROTOCOL_IPV6 = 1 << 1;
 
   static const int NORMAL_TOKEN_BATCH_SIZE = 8;
   static const int LISTENING_TOKEN_BATCH_SIZE = 2;
 
+  static const Duration _RETRY_DURATION = const Duration(milliseconds: 250);
+  static const Duration _RETRY_DURATION_LOOPBACK =
+      const Duration(milliseconds: 25);
+
   // Use default Map so we keep order.
   static Map<int, _NativeSocket> _sockets = new Map<int, _NativeSocket>();
 
   // Socket close state
   bool isClosed = false;
   bool isClosing = false;
   bool isClosedRead = false;
   bool isClosedWrite = false;
   Completer closeCompleter = new Completer.sync();
 
@@ skipping 88 matching lines @@
             return map.values.toList();
           }
         });
   }
 
   static Future<_NativeSocket> connect(host, int port) {
     return new Future.value(host)
         .then((host) {
           if (host is _InternetAddress) return [host];
           return lookup(host)
-              .then((list) {
-                if (list.length == 0) {
+              .then((addresses) {
+                if (addresses.isEmpty) {
                   throw createError(response, "Failed host lookup: '$host'");
                 }
-                return list;
+                return addresses;
               });
         })
         .then((addresses) {
           assert(addresses is List);
           var completer = new Completer();
           var it = addresses.iterator;
-          void run(error) {
+          var error = null;
+          var connecting = new HashMap();
+          void connectNext() {
             if (!it.moveNext()) {
-              assert(error != null);
-              completer.completeError(error);
+              if (connecting.isEmpty) {
+                assert(error != null);
+                completer.completeError(error);
+              }
               return;
             }
             var address = it.current;
             var socket = new _NativeSocket.normal();
             socket.address = address;
             var result = socket.nativeCreateConnect(address._in_addr, port);
             if (result is OSError) {
               // Keep first error, if present.
-              run(error != null ? error :
-                  createError(result, "Connection failed", address, port));
+              if (error == null) {
+                error = createError(result, "Connection failed", address, port);
+              }
+              connectNext();
             } else {
               socket.port;  // Query the local port, for error messages.
+              // Set up timer for when we should retry the next address (if any).

[Søren Gjesse, 2014/08/04 09:21:37]

Long line.

[Anders Johnsen, 2014/08/05 09:14:55]

Done.

+              var duration = address.isLoopback ?
+                  _RETRY_DURATION_LOOPBACK :
+                  _RETRY_DURATION;
+              var timer = new Timer(duration, connectNext);
+              connecting[socket] = timer;
               // Setup handlers for receiving the first write event which
               // indicate that the socket is fully connected.
               socket.setHandlers(
                   write: () {
+                    timer.cancel();
                     socket.setListening(read: false, write: false);
                     completer.complete(socket);
+                    connecting.remove(socket);
+                    connecting.forEach((s, t) {
+                      t.cancel();
+                      s.close();

[Søren Gjesse, 2014/08/04 09:21:37]

Shouldn't s.destroy() be enough?

[Anders Johnsen, 2014/08/05 09:14:55]

There is no destroy on _NativeSocket. We need to clean it up nicely.

+                      s.setHandlers();
+                      s.setListening(read: false, write: false);
+                    });
                   },
                   error: (e) {
+                    timer.cancel();
                     socket.close();
                     // Keep first error, if present.
-                    run(error != null ? error : e);
-                  }
-              );
+                    if (error == null) error = e;
+                    connecting.remove(socket);
+                    if (connecting.isEmpty) connectNext();
+                  });
               socket.setListening(read: false, write: true);
             }
           }
-          run(null);
+          connectNext();
           return completer.future;
         });
   }
 
   static Future<_NativeSocket> bind(host,
                                     int port,
                                     int backlog,
                                     bool v6Only) {
     return new Future.value(host)
         .then((host) {
@@ skipping 1464 matching lines @@
                        String address,
                        List<int> in_addr,
                        int port) {
   return new Datagram(
       data,
       new _InternetAddress(address, null, in_addr),
       port);
 }
 
 String _socketsStats() => _SocketsObservatory.toJSON();