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

runtime/bin/socket_patch.dart

Index: runtime/bin/socket_patch.dart
diff --git a/runtime/bin/socket_patch.dart b/runtime/bin/socket_patch.dart
index 7dbc01ad4bac130ac2fa5df91ba11122161170df..a49895484054fc3427b3e85ad2b4c95c5189415f 100644
--- a/runtime/bin/socket_patch.dart
+++ b/runtime/bin/socket_patch.dart
@@ -211,6 +211,20 @@ class _NetworkInterface implements NetworkInterface {
 // implicit constructor.
 class _NativeSocketNativeWrapper extends NativeFieldWrapperClass1 {}
 
+class _ConnectingSocket {
+  final _NativeSocket socket;
+  final Timer timer;
+
+  _ConnectingSocket(this.socket, this.timer);
+
+  void abort() {
+    timer.cancel();
+    socket.close();
+    socket.setHandlers();
+    socket.setListening(read: false, write: false);
+  }
+}
+
 
 // The _NativeSocket class encapsulates an OS socket.
 class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
@@ -273,6 +287,10 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
   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>();
 
@@ -390,12 +408,17 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
         })
         .then((addresses) {
           assert(addresses is List);
+          assert(addresses.isNotEmpty);

[Bill Hesse, 2014/07/29 10:57:06]

This assert is covered by the check in the above function.

[Anders Johnsen, 2014/07/29 11:23:27]

Done.

           var completer = new Completer();
           var it = addresses.iterator;
-          void run(error) {
+          var error = null;
+          var connecting = new HashSet();
+          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;
@@ -404,27 +427,42 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
             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).
+              var duration = address.isLoopback ?
+                  _RETRY_DURATION_LOOPBACK :
+                  _RETRY_DURATION;
+              var timer = new Timer(duration, connectNext);
+              var connectingSocket = new _ConnectingSocket(socket, timer);
+              connecting.add(connectingSocket);

[Bill Hesse, 2014/07/29 10:57:06]

If you used a Map, rather than a Set, then this would just be connecting[socket]
= timer, and the connectingSocket class would disappear.  I don't think the
other code would get more complicated - abort could still be encapsulated as a
closure, binding connecting.

But you can keep it a set.

[Anders Johnsen, 2014/07/29 11:23:27]

Acknowledged.

               // 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(connectingSocket);
+                    for (var s in connecting) {
+                      s.abort();
+                    }
                   },
                   error: (e) {
-                    socket.close();
+                    connectingSocket.abort();
                     // Keep first error, if present.
-                    run(error != null ? error : e);
-                  }
-              );
+                    if (error == null) error = e;
+                    connecting.remove(connectingSocket);
+                    if (connecting.isEmpty) connectNext();
+                  });
               socket.setListening(read: false, write: true);
             }
           }
-          run(null);
+          connectNext();
           return completer.future;
         });
   }