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/*
* Ouroboros - Copyright (C) 2016 - 2018
*
* Timerwheel
*
* Dimitri Staessens <dimitri.staessens@ugent.be>
* Sander Vrijders <sander.vrijders@ugent.be>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1 as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., http://www.fsf.org/about/contact/.
*/
#define _POSIX_C_SOURCE 200112L
#include "config.h"
#include <ouroboros/time_utils.h>
#include <ouroboros/errno.h>
#include <ouroboros/list.h>
#include <pthread.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#define FRAC 10 /* accuracy of the timer */
#define tw_used(tw) ((tw->head + tw->elements - tw->tail) & (tw->elements - 1));
#define tw_free(tw) (tw_used(tw) + 1 < tw->elements)
#define tw_empty(tw) (tw->head == tw->tail)
struct tw_f {
struct list_head next;
void (* func)(void *);
void * arg;
};
struct tw_el {
struct list_head funcs;
struct timespec expiry;
};
struct timerwheel {
struct tw_el * wheel;
struct timespec intv;
size_t pos;
pthread_mutex_t lock;
time_t resolution;
size_t elements;
};
static void tw_el_fini(struct tw_el * e)
{
struct list_head * p;
struct list_head * h;
list_for_each_safe(p, h, &e->funcs) {
struct tw_f * f = list_entry(p, struct tw_f, next);
list_del(&f->next);
}
}
void timerwheel_move(struct timerwheel * tw)
{
struct timespec now = {0, 0};
long ms = tw->resolution * tw->elements;
struct timespec total = {ms / 1000,
(ms % 1000) * MILLION};
struct list_head * p;
struct list_head * h;
clock_gettime(CLOCK_MONOTONIC, &now);
pthread_mutex_lock(&tw->lock);
while (ts_diff_us(&tw->wheel[tw->pos].expiry, &now) > 0) {
list_for_each_safe(p, h, &tw->wheel[tw->pos].funcs) {
struct tw_f * f = list_entry(p, struct tw_f, next);
list_del(&f->next);
f->func(f->arg);
free(f);
}
ts_add(&tw->wheel[tw->pos].expiry,
&total,
&tw->wheel[tw->pos].expiry);
tw->pos = (tw->pos + 1) & (tw->elements - 1);
}
pthread_mutex_unlock(&tw->lock);
}
struct timerwheel * timerwheel_create(time_t resolution,
time_t max_delay)
{
struct timespec now = {0, 0};
struct timespec res_ts = {resolution / 1000,
(resolution % 1000) * MILLION};
size_t i;
struct timerwheel * tw;
assert(resolution != 0);
tw = malloc(sizeof(*tw));
if (tw == NULL)
return NULL;
if (pthread_mutex_init(&tw->lock, NULL))
return NULL;
tw->elements = 1;
while (tw->elements < (size_t) max_delay / resolution)
tw->elements <<= 1;
tw->wheel = malloc(sizeof(*tw->wheel) * tw->elements);
if (tw->wheel == NULL)
goto fail_wheel_malloc;
tw->resolution = resolution;
tw->intv.tv_sec = (tw->resolution / FRAC) / 1000;
tw->intv.tv_nsec = ((tw->resolution / FRAC) % 1000) * MILLION;
if (pthread_mutex_init(&tw->lock, NULL))
goto fail_lock_init;
tw->pos = 0;
clock_gettime(CLOCK_MONOTONIC, &now);
now.tv_nsec -= (now.tv_nsec % MILLION);
for (i = 0; i < tw->elements; ++i) {
list_head_init(&tw->wheel[i].funcs);
tw->wheel[i].expiry = now;
ts_add(&now, &res_ts, &now);
}
return tw;
fail_lock_init:
free(tw->wheel);
fail_wheel_malloc:
free(tw);
return NULL;
}
void timerwheel_destroy(struct timerwheel * tw)
{
unsigned long i;
for (i = 0; i < tw->elements; ++i)
tw_el_fini(&tw->wheel[i]);
pthread_mutex_destroy(&tw->lock);
free(tw->wheel);
free(tw);
}
struct tw_f * timerwheel_start(struct timerwheel * tw,
void (* func)(void *),
void * arg,
time_t delay)
{
int pos;
struct tw_f * f = malloc(sizeof(*f));
if (f == NULL)
return NULL;
f->func = func;
f->arg = arg;
assert(delay < tw->elements * tw->resolution);
pthread_mutex_lock(&tw->lock);
pos = (tw->pos + delay / tw->resolution) & (tw->elements - 1);
list_add(&f->next, &tw->wheel[pos].funcs);
pthread_mutex_unlock(&tw->lock);
return f;
}
int timerwheel_restart(struct timerwheel * tw,
struct tw_f * f,
time_t delay)
{
int pos;
assert(tw);
assert(delay < tw->elements * tw->resolution);
pthread_mutex_lock(&tw->lock);
list_del(&f->next);
pos = (tw->pos + delay / tw->resolution) & (tw->elements - 1);
list_add(&f->next, &tw->wheel[pos].funcs);
pthread_mutex_unlock(&tw->lock);
return 0;
}
void timerwheel_stop(struct timerwheel * tw,
struct tw_f * f)
{
assert(tw);
pthread_mutex_lock(&tw->lock);
list_del(&f->next);
free(f);
pthread_mutex_unlock(&tw->lock);
}
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