/*
* thread_depress_priority
*
* Depress thread's priority to lowest possible for specified period.
* Intended for use when thread wants a lock but doesn't know which
* other thread is holding it. As with thread_switch, fixed
* priority threads get exactly what they asked for. Users access
* this by the SWITCH_OPTION_DEPRESS option to thread_switch. A Time
* of zero will result in no timeout being scheduled.
*/
void
thread_depress_priority(
thread_t thread,
mach_msg_timeout_t depress_time)
{
unsigned int ticks;
spl_t s;
/* convert from milliseconds to ticks */
ticks = convert_ipc_timeout_to_ticks(depress_time);
s = splsched();
thread_lock(thread);
/*
* If thread is already depressed, override previous depression.
*/
reset_timeout_check(&thread->depress_timer);
/*
* Save current priority, then set priority and
* sched_pri to their lowest possible values.
*/
thread->depress_priority = thread->priority;
thread->priority = 31;
thread->sched_pri = 31;
if (ticks != 0)
set_timeout(&thread->depress_timer, ticks);
thread_unlock(thread);
(void) splx(s);
}
void
thread_will_wait_with_timeout(
thread_t thread,
mach_msg_timeout_t msecs)
{
natural_t ticks = convert_ipc_timeout_to_ticks(msecs);
spl_t s;
s = splsched();
thread_lock(thread);
assert(thread->wait_result = -1); /* for later assertions */
thread->state |= TH_WAIT;
set_timeout(&thread->timer, ticks);
thread_unlock(thread);
splx(s);
}
