Event Threading Model

The threading model in the stack requires the application to build an FdSet and call process on the stack. The select call needs a timeout value which the stack can also determine. The application may need to add its own file descriptors and timers as well.

Table of Contents buildFdSet getTimeTillNextProcess select process

buildFdSet

• anything in the stack or the application that uses a file descriptor needs to add itself to the FdSet
• this should start with an empty FdSet
• next call SipStack::buildFdSet and this will add the file descriptors for all of the transports, connections and the dns provider
• next add any application file descriptors

getTimeTillNextProcess

• determines the minimum time till any timer in the application or stack will fire
• if anything in the stack needs to process immediately, short circuit and return 0. (Currently, the dns provider short circuits with a value of 50ms?)

select

• call select either in the Application or in a StackThread and pass in the two things constructed above

process

• after select returns, pass the now marked up FdSet to SipStack::process
• process delegates to anything in the SipStack that needs cycles periodically
  • ask the StatisticsManager to generate its stats
  • ask the Transports to send/receive and accept new connections
  • give the dns provider / cache cycles
  • process App and Transaction Timers
  • handle all outstanding events affecting Transaction State
  • handle TU shutdown related events

 WARNING!!! Under windows the default FD_SETSIZE is 64 so using TCP/TLS transports is limited