/* * 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 < (time_t) 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 < (time_t) 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); }