Wray Ferrell wrote:
Having spent a few days looking at what APR has to offer, I noticed that there does not appear to be anyway to set a generic timer. The functions apr_thread_cond_timedwait put the thread to sleep while waiting for either the condition to be fullfilled or the timeout to occur. What I am looking for, and feel sure I overlooked, is the ability for a thread to set a timer with an expiration and a callback function.
For example, use a VOIP phone using the SIP protocol. The phone sends out an INVITE and then sets a timer with a callback function. If that timer pops the phone knows that no response to the initial INVITE has been recieved so the phone will re-transmit the INVITE. However this thread cannot sleep because it must still process data from the DSP, the user could decide to hangup, etc...
How would this be modeled in APR or is APR a purely event-driven model?
The first question to ask is: is this a facility that can be provided on all (or at least most) systems we support? Because if it isn't, it isn't a candidate for APR.
If it is, then we would certainly consider adding it. Don't think we do it right now, though.
OTOH, the thing I'm trying to resolve (slowly) is how to do cross-platform select() or poll() that works on more than just sockets (in particular, pipes, too). With that, you can get what you want using the time-out argument. Which is probably better and simpler anyway.
Cheers,
Ben.
-- http://www.apache-ssl.org/ben.html http://www.thebunker.net/
"There is no limit to what a man can do or how far he can go if he doesn't mind who gets the credit." - Robert Woodruff
