Cyrus IMAP Server: Prot Events

From an email exchange between Ken Murchison and Lawrence Greenfield, dated 03 Feb 2002 (slightly redacted and formatted for your viewing pleasure):

From: Ken Murchison
To: Lawrence Greenfield
Subject: Re: prot events

Lawrence Greenfield wrote:

Can you give me some details on how the event API in the prot layer works? I’m a little unclear about the memory management, what should be returned from the event callback,

Either the event pointer (if the event is still active), or NULL (if the event has been removed by the callback).

and how to reschedule an event.

Simply set the ‘mark’ time in the event to the wall time you want it to run again.

(I’d like to make an event called every X seconds of idle time; I know the API can’t do exactly that but I suspect I can fake it well enough.)

Look at backend_timeout() in proxyd.c and/or drac_ping() in contrib/drac_auth.patch, they do exactly this.

The API is pretty simple:

  • use prot_addwaitevent() to add an event (linked list) callback onto a stream. takes the stream, the ‘mark’ time at which to run the event (NOT an interval, but the future clock value), the function pointer, and a rock to pass to the callback as args, and returns a pointer to the event (to use for future removal).

  • use prot_removewaitevent() to remove an event. takes the stream and a pointer to the event as args.

  • the event callback gets the stream, a pointer to the event and the rock as args. To reschedule an event, simply set the ‘mark’ time and return the event pointer. If the callback removes the event, then return NULL.

If you see and flaws in this API, feel free to go ahead and change it.