Add ability to send a ping interval on a WebSocket.

Add ability to send a ping interval on a WebSocket.

By enabling it, ping messages can be used to ensure if a websocket
connection is open. However, as it depends on the remote peer to support
ping/pong, it's disabled by default.

BUG=https://code.google.com/p/dart/issues/detail?id=7366
R=sgjesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=25410

[Anders Johnsen, 2013-07-24 08:34:27]

As it's not possible to easily create a negative test where we somehow make a
socket unresponsive, I've mainly tested it locally where the connection _is_
being closed by missing pong messages. Ideas for tests are welcome!

[Søren Gjesse, 2013-07-24 11:12:45]

LGTM!

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket.dart
File sdk/lib/io/websocket.dart (right):

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket.dart#new...
sdk/lib/io/websocket.dart:135: * answered, the `WebSocket` is assumed
disconnected and the connection is
add "by a pong message from the peer" after answered

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket.dart#new...
sdk/lib/io/websocket.dart:136: * closed. When a ping signal is sent, the pong
message must be received
Add information on the close status used.

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket_impl.dart
File sdk/lib/io/websocket_impl.dart (right):

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket_impl.dar...
sdk/lib/io/websocket_impl.dart:458: addFrame(_WebSocketOpcode.PING,
message.payload, sink);
Oops!

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket_impl.dar...
sdk/lib/io/websocket_impl.dart:772: pingInterval = _pingInterval;
This means that the next ping is sent "pingInterval" after pong is received.
This is OK, but maybe we should update the comment to be more precise about
that.

[Anders Johnsen, 2013-07-24 12:14:23]

PTAL, added missing test.

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket.dart
File sdk/lib/io/websocket.dart (right):

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket.dart#new...
sdk/lib/io/websocket.dart:135: * answered, the `WebSocket` is assumed
disconnected and the connection is
On 2013/07/24 11:12:45, Søren Gjesse wrote:
> add "by a pong message from the peer" after answered

Done.

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket.dart#new...
sdk/lib/io/websocket.dart:136: * closed. When a ping signal is sent, the pong
message must be received
On 2013/07/24 11:12:45, Søren Gjesse wrote:
> Add information on the close status used.

Done.

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket_impl.dart
File sdk/lib/io/websocket_impl.dart (right):

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket_impl.dar...
sdk/lib/io/websocket_impl.dart:458: addFrame(_WebSocketOpcode.PING,
message.payload, sink);
On 2013/07/24 11:12:45, Søren Gjesse wrote:
> Oops!

Yeah :) Copy paste at its worsts.

https://codereview.chromium.org/19970004/diff/1/sdk/lib/io/websocket_impl.dar...
sdk/lib/io/websocket_impl.dart:772: pingInterval = _pingInterval;
On 2013/07/24 11:12:45, Søren Gjesse wrote:
> This means that the next ping is sent "pingInterval" after pong is received.
> This is OK, but maybe we should update the comment to be more precise about
> that.

Done.

[Søren Gjesse, 2013-07-24 12:31:28]

https://codereview.chromium.org/19970004/diff/6001/tests/standalone/io/web_so...
File tests/standalone/io/web_socket_ping_test.dart (right):

https://codereview.chromium.org/19970004/diff/6001/tests/standalone/io/web_so...
tests/standalone/io/web_socket_ping_test.dart:17: server.transform(new
WebSocketTransformer()).listen((webSocket) {
Set a pingInterval on the server side as well.

[Søren Gjesse, 2013-07-24 12:31:51]

lgtm

[Anders Johnsen, 2013-07-24 12:51:02]

https://codereview.chromium.org/19970004/diff/6001/tests/standalone/io/web_so...
File tests/standalone/io/web_socket_ping_test.dart (right):

https://codereview.chromium.org/19970004/diff/6001/tests/standalone/io/web_so...
tests/standalone/io/web_socket_ping_test.dart:17: server.transform(new
WebSocketTransformer()).listen((webSocket) {
On 2013/07/24 12:31:28, Søren Gjesse wrote:
> Set a pingInterval on the server side as well.

Done.

[Anders Johnsen, 2013-07-24 12:52:01]

Committed patchset #3 manually as r25410 (presubmit successful).