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/*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*/
/*
* Copyright 2015, Joyent, Inc.
*/
#include <stddef.h>
#include <libvarpd_svp.h>
/*
* svp timer backend
*
* This implements all of the logic of maintaining a timer for the svp backend.
* We have a timer that fires at a one second tick. We maintain all of our
* events in avl tree, sorted by the tick that they need to be processed at.
*
* For more information, see the big theory statement in
* lib/varpd/svp/common/libvarpd_svp.c.
*/
int svp_tickrate = 1;
static svp_event_t svp_timer_event;
static mutex_t svp_timer_lock = ERRORCHECKMUTEX;
static cond_t svp_timer_cv = DEFAULTCV;
static avl_tree_t svp_timer_tree;
static uint64_t svp_timer_nticks;
static int
svp_timer_comparator(const void *l, const void *r)
{
const svp_timer_t *lt, *rt;
lt = l;
rt = r;
if (lt->st_expire > rt->st_expire)
return (1);
else if (lt->st_expire < rt->st_expire)
return (-1);
/*
* Multiple timers can have the same delivery time, so sort within that
* by the address of the timer itself.
*/
if ((uintptr_t)lt > (uintptr_t)rt)
return (1);
else if ((uintptr_t)lt < (uintptr_t)rt)
return (-1);
return (0);
}
/* ARGSUSED */
static void
svp_timer_tick(port_event_t *pe, void *arg)
{
mutex_enter(&svp_timer_lock);
svp_timer_nticks++;
for (;;) {
svp_timer_t *t;
t = avl_first(&svp_timer_tree);
if (t == NULL || t->st_expire > svp_timer_nticks)
break;
avl_remove(&svp_timer_tree, t);
/*
* We drop this while performing an operation so that way state
* can advance in the face of a long-running callback.
*/
t->st_delivering = B_TRUE;
mutex_exit(&svp_timer_lock);
t->st_func(t->st_arg);
mutex_enter(&svp_timer_lock);
t->st_delivering = B_FALSE;
(void) cond_broadcast(&svp_timer_cv);
if (t->st_oneshot == B_FALSE) {
t->st_expire += t->st_value;
avl_add(&svp_timer_tree, t);
}
}
mutex_exit(&svp_timer_lock);
}
void
svp_timer_add(svp_timer_t *stp)
{
if (stp->st_value == 0)
libvarpd_panic("tried to add svp timer with zero value");
mutex_enter(&svp_timer_lock);
stp->st_delivering = B_FALSE;
stp->st_expire = svp_timer_nticks + stp->st_value;
avl_add(&svp_timer_tree, stp);
mutex_exit(&svp_timer_lock);
}
void
svp_timer_remove(svp_timer_t *stp)
{
mutex_enter(&svp_timer_lock);
/*
* If the event in question is not currently being delivered, then we
* can stop it before it next fires. If it is currently being delivered,
* we need to wait for that to finish. Because we hold the timer lock,
* we know that it cannot be rearmed. Therefore, we make sure the one
* shot is set to zero, and wait until it's no longer set to delivering.
*/
if (stp->st_delivering == B_FALSE) {
avl_remove(&svp_timer_tree, stp);
mutex_exit(&svp_timer_lock);
return;
}
stp->st_oneshot = B_TRUE;
while (stp->st_delivering == B_TRUE)
(void) cond_wait(&svp_timer_cv, &svp_timer_lock);
mutex_exit(&svp_timer_lock);
}
int
svp_timer_init(void)
{
int ret;
svp_timer_event.se_func = svp_timer_tick;
svp_timer_event.se_arg = NULL;
avl_create(&svp_timer_tree, svp_timer_comparator, sizeof (svp_timer_t),
offsetof(svp_timer_t, st_link));
if ((ret = svp_event_timer_init(&svp_timer_event)) != 0) {
avl_destroy(&svp_timer_tree);
}
return (ret);
}
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