Detecting dropped messages

Richard van Harten · Post by **Richard van Harten** » 07 Dec 2009, 09:18

Hi,

We would like to detect dropped messages, currently we have no means to detect if and what kind of messages are being dropped. We can get the underlying socketchannel which however does not seem to expose any functionality to detect it either.

Any suggestions to make this possible?

Post by **Lapo** » 07 Dec 2009, 11:10

You mean via some sort of server side events?

Richard van Harten · Post by **Richard van Harten** » 08 Dec 2009, 01:56

That would be ideal yes, it would also be ideal to be able to clear the queue so we could send some resync message.

Post by **Lapo** » 08 Dec 2009, 14:31

This is not simple as it may seem:
- dropped messages event can happen in hundreds per second under certain conditions, for example when on the server side you are running out of bandwidth. Firing so many events would be useless.

- clearing the queues would be highly dangerous because you would be eliminating messages that the server needs to deliver

We have implemented a few ideas for the next major update of SFS. One of them allows to set message priorities so that the server will first drop messages of lower priority (e.g. the user count updates, keep alives etc...)

Another one is to provide a default policy for dropped packets and the allow the developer to provide its own via custom classes.

Richard van Harten · Post by **Richard van Harten** » 09 Dec 2009, 01:21

Sounds good to me! Could you give a rough estimate for this next update?

Post by **Lapo** » 09 Dec 2009, 08:19

Sorry, I am not able to do this at the moment.
This will be a major update requiring a lot of work. We'll provide more details in the first quarter of 2010.