Time-out handler

The structures described can do operations on state blocks, if the appropriate methods are called. However they are not ``active'', which means that they cannot detect time-outs by themselves.

As said in section , a module polls the RSVP state periodically in order to deal with the time-outs; the Java object performing these operation is Timer.

All the state blocks are examined every 10ms. Each state block has a time stamp. If this time stamp is earlier than the current time, it means that the state block has expired and it should be deleted.

This module is run as a concurrent thread. We therefore have two threads: the main one dealing with the incoming RSVP messages, and the time-out module dealing with the expiration of the different state blocks. Each time this module does operations on the states, it has to wait for the appropriate semaphores and it releases them afterwards.