I'm thinking again about this. Why wouldn't it be possible to make functions
using SIGEV_THREAD (such as timer_settime) create a pthread behind
the scenes (only the first time a SIGEV_THREAD is setup)? The underlying
watchdog would go to a handler that posts a semaphore/condition variable
that the helper thread is waiting on. When this thread unblocks, it calls the
user handler directly.
The thread would be created per-process in KERNEL mode, so that shouldn't
be a problem (inside same address space as user handler). I suspect the
unblocking of the thread should also be possible in multi-process somehow
(named semaphore?).
This is essentially what I'm doing myself around a call to timer_settime.
Best,
Matias
I think a proper approach would be to see how Linux/GLIBC accomplish this. I
think that would give you some ideas for proper implementation.
