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//
// Copyright 2017 Garrett D'Amore <garrett@damore.org>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#include "core/nng_impl.h"
#include <stdlib.h>
#include <string.h>
extern void nni_timer_schedule(nni_timer_node *);
extern void nni_timer_cancel(nni_timer_node *);
extern int nni_timer_init(void);
extern void nni_timer_fini(void);
static void nni_timer_loop(void *);
struct nni_timer {
// We use two mutexes. One protects the list, and the other ensures
// that cancel is blocked if we are running a timeout calllback.
// The callback(s) are allowed to reschedule a timeout. The list
// mutex is *always* acquired before the run mutex.
nni_mtx t_list_mx;
nni_mtx t_run_mx;
nni_cv t_cv;
nni_list t_entries;
nni_thr t_thr;
int t_close;
};
typedef struct nni_timer nni_timer;
static nni_timer nni_global_timer;
int
nni_timer_sys_init(void)
{
int rv;
nni_timer *timer = &nni_global_timer;
memset(timer, 0, sizeof (*timer));
NNI_LIST_INIT(&timer->t_entries, nni_timer_node, t_node);
timer->t_close = 0;
if (((rv = nni_mtx_init(&timer->t_list_mx)) != 0) ||
((rv = nni_mtx_init(&timer->t_run_mx)) != 0) ||
((rv = nni_cv_init(&timer->t_cv, &timer->t_list_mx)) != 0) ||
((rv = nni_thr_init(&timer->t_thr, nni_timer_loop, timer)) != 0)) {
nni_timer_sys_fini();
return (rv);
}
nni_thr_run(&timer->t_thr);
return (0);
}
void
nni_timer_sys_fini(void)
{
nni_timer *timer = &nni_global_timer;
nni_mtx_lock(&timer->t_list_mx);
timer->t_close = 1;
nni_cv_wake(&timer->t_cv);
nni_mtx_unlock(&timer->t_list_mx);
nni_thr_fini(&timer->t_thr);
nni_cv_fini(&timer->t_cv);
nni_mtx_fini(&timer->t_list_mx);
nni_mtx_fini(&timer->t_run_mx);
}
void
nni_timer_cancel(nni_timer_node *node)
{
nni_timer *timer = &nni_global_timer;
nni_mtx_lock(&timer->t_list_mx);
nni_mtx_lock(&timer->t_run_mx);
if (node->t_sched) {
nni_list_remove(&timer->t_entries, node);
node->t_sched = 0;
}
nni_mtx_unlock(&timer->t_run_mx);
nni_mtx_unlock(&timer->t_list_mx);
}
void
nni_timer_schedule(nni_timer_node *node)
{
nni_timer *timer = &nni_global_timer;
nni_timer_node *srch;
int wake = 1;
nni_mtx_lock(&timer->t_list_mx);
srch = nni_list_first(&timer->t_entries);
while ((srch != NULL) && (srch->t_expire < node->t_expire)) {
srch = nni_list_next(&timer->t_entries, srch);
wake = 0;
}
if (srch != NULL) {
nni_list_insert_before(&timer->t_entries, node, srch);
} else {
nni_list_append(&timer->t_entries, node);
}
node->t_sched = 1;
if (wake) {
nni_cv_wake(&timer->t_cv);
}
nni_mtx_unlock(&timer->t_list_mx);
}
static void
nni_timer_loop(void *arg)
{
nni_timer *timer = arg;
nni_time now;
nni_time expire;
nni_timer_node *node;
for (;;) {
nni_mtx_lock(&timer->t_list_mx);
if (timer->t_close) {
nni_mtx_unlock(&timer->t_list_mx);
break;
}
now = nni_clock();
if ((node = nni_list_first(&timer->t_entries)) == NULL) {
nni_cv_wait(&timer->t_cv);
nni_mtx_unlock(&timer->t_list_mx);
continue;
}
if (now < node->t_expire) {
// End of run, we have to wait for next.
nni_cv_until(&timer->t_cv, node->t_expire);
nni_mtx_unlock(&timer->t_list_mx);
continue;
}
nni_list_remove(&timer->t_entries, node);
node->t_sched = 0;
// The lock ordering here is important. We acquire the run
// lock before dropping the list lock. One the run is done,
// we can drop the run lock too. The reason for the second
// lock is so that the callback can reschedule itself.
nni_mtx_lock(&timer->t_run_mx);
nni_mtx_unlock(&timer->t_list_mx);
node->t_cb(node->t_arg);
nni_mtx_unlock(&timer->t_run_mx);
}
}
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