Hi,
On Thu, Jun 9, 2016 at 12:54 PM, Pavel Rappo <pavel.ra...@oracle.com> wrote:
> Hi,
>
> Could you please review the following change for JDK-8157273?
>
> http://cr.openjdk.java.net/~prappo/8157273/webrev.01/
>
> This change addresses some WebSocket API refinements and enhancements from
> [1].
>
> Currently WebSocket API allows only one scheduled but not yet sent message
> (i.e.
> an outstanding send operation) at a time. This design was influenced by
> java.nio.channels.AsynchronousChannel:
>
> * <p> Asynchronous channels are safe for use by multiple concurrent
> threads.
> * Some channel implementations may support concurrent reading and
> writing, but
> * may not allow more than one read and one write operation to be
> outstanding at
> * any given time.
>
> Although it is both easy to understand and implement, this was found to not
> work
> well with WebSocket API.
>
> 1. In WebSocket API it's not always easily known (in some modes of operation)
> for an app when the previous send operation has completed. Thus maintaining a
> non-overlapping sends is a burden on the user.
>
> 2. In contract with AsynchronousChannel, WebSocket does not allow "short
> writes"
> (i.e. a situation when a Future returned by the send operation may complete
> normally after the message has been written only partially.)
> The CompletableFuture in WebSocket completes only after an error or when the
> whole message has been written. Therefore, there's no inherent risk in
> serializing sends in WebSocket.
> The result on the wire will always be some permutation of messages, and not
> their chunks.
I'm not sure I understand all this.
I thought the idea was that you always want *at most* one outstanding write.
Multiple writes should be chained via CS.
Concurrent writes are handled by applications.
Are you saying that with this change, you allow infinite buffering ?
To be clear, do you want to allow this (pseudocode):
ByteBuffer buffer = ...;
while (true) {
int read = readFromHugeFile(buffer);
ws.sendBinary(buffer, read < 0);
}
Thanks !
--
Simone Bordet
----
http://cometd.org
http://webtide.com
Developer advice, training, services and support
from the Jetty & CometD experts.
