message from Emmanuel
---------- Forwarded message ----------
From: Emmanuel Lécharny <[EMAIL PROTECTED]>
Date: Fri, Sep 5, 2008 at 3:07 PM
Subject: Re: PorotocolCodecFilter potential pbs and improvement
To: Maarten Bosteels <[EMAIL PROTECTED]>
Hi Maarten,
mor einline
Maarten Bosteels wrote:
>
> Side note: I think it would be great if we had a list with such
> guarantees made by MINA.
> An example of another guarantee that should be in that list:
> ProtocolDecoder.decoder(IoSession session, IoBuffer in,
> ProtocolDecoderOutput out)
> will NEVER be called simultaneously for the same IoSession
>
That would imply some kind of synchornization on the session, I guess.
Something we can add.
>>
>> synchronized (factory) {
>> ProtocolDecoder decoder = (ProtocolDecoder)
>> session.getAttribute(DECODER);
>>
>> if ( decoder == null ) {
>> // No existing instance ? Create it and stores it into the
>> session
>> decoder = factory.getDecoder(session);
>> session.setAttribute(DECODER, decoder);
>> }
>> return decoder;
>> }
>>
>>
>
> But why synchronize on the factory instead of on the session ?
>
Well, because it would imply we synchronize all the other part of the
server where we access the session, a little bit overkilling, IMHO.
>
>
>>
>> Now, I think we can d something slightly better : we have two methods -
>> getDecoder0(IoSession) and getDecoder(IoSession) - doing the exact same
>> thing (returning the session decoder), except the fact that getDecoder0()
>> inject the decoder into the session, if it was not already done. It makes me
>> think that we might want to do taht during the createSession() event
>> processing, instead of doing it while processing the first message
>> received.
>>
>> We will just have to implement the sessionCreated() method, and then we can
>> remove the getDecoder0() method, using the getDecoder() method instead,
>> without any synchronization.
>>
>> thoughts ?
>>
>
> I think that will be a nice improvement: simpler and more thread-safe,
> don't see any downsides.
>
Here is a proposal :
/**
* Associate a decoder and encoder instances to the newly created session.
*
* @param nextFilter The next filter to invoke when having processed
the current
* method
* @param session The newly created session
* @throws Exception if we can't create instances of the decoder or encoder
*/
@Override
public void sessionCreated(NextFilter nextFilter, IoSession session)
throws Exception {
// Creates the decoder and stores it into the newly created session
ProtocolDecoder decoder = factory.getDecoder(session);
session.setAttribute(DECODER, decoder);
// Creates the encoder and stores it into the newly created session
ProtocolEncoder encoder = factory.getEncoder(session);
session.setAttribute(ENCODER, encoder);
// Call the next filter
nextFilter.sessionCreated(session);
}
--
--
cordialement, regards,
Emmanuel Lécharny
www.nextury.com
directory.apache.org
