lib/wheel.c

   1 /*
   2  * Timer Wheel
   3  * Copyright (C) 2016 Cumulus Networks, Inc.
   4  * Donald Sharp
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20 #include "zebra.h"
  21 #include "linklist.h"
  22 #include "thread.h"
  23 #include "memory.h"
  24 #include "wheel.h"
  25 #include "log.h"
  26
  27 DEFINE_MTYPE_STATIC(LIB, TIMER_WHEEL, "Timer Wheel");
  28 DEFINE_MTYPE_STATIC(LIB, TIMER_WHEEL_LIST, "Timer Wheel Slot List");
  29
  30 static int debug_timer_wheel = 0;
  31
  32 static void wheel_timer_thread(struct thread *t);
  33
  34 static void wheel_timer_thread_helper(struct thread *t)
  35 {
  36         struct listnode *node, *nextnode;
  37         unsigned long long curr_slot;
  38         unsigned int slots_to_skip = 1;
  39         struct timer_wheel *wheel;
  40         void *data;
  41
  42         wheel = THREAD_ARG(t);
  43
  44         wheel->curr_slot += wheel->slots_to_skip;
  45
  46         curr_slot = wheel->curr_slot % wheel->slots;
  47
  48         if (debug_timer_wheel)
  49                 zlog_debug("%s: Wheel Slot: %lld(%lld) count: %d", __func__,
  50                            wheel->curr_slot, curr_slot,
  51                            listcount(wheel->wheel_slot_lists[curr_slot]));
  52
  53         for (ALL_LIST_ELEMENTS(wheel->wheel_slot_lists[curr_slot], node,
  54                                nextnode, data))
  55                 (*wheel->slot_run)(data);
  56
  57         while (list_isempty(wheel->wheel_slot_lists[(curr_slot + slots_to_skip)
  58                                                     % wheel->slots])
  59                && (curr_slot + slots_to_skip) % wheel->slots != curr_slot)
  60                 slots_to_skip++;
  61
  62         wheel->slots_to_skip = slots_to_skip;
  63         thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
  64                               wheel->nexttime * slots_to_skip, &wheel->timer);
  65 }
  66
  67 static void wheel_timer_thread(struct thread *t)
  68 {
  69         struct timer_wheel *wheel;
  70
  71         wheel = THREAD_ARG(t);
  72
  73         thread_execute(wheel->master, wheel_timer_thread_helper, wheel, 0);
  74 }
  75
  76 struct timer_wheel *wheel_init(struct thread_master *master, int period,
  77                                size_t slots, unsigned int (*slot_key)(const void *),
  78                                void (*slot_run)(void *),
  79                                const char *run_name)
  80 {
  81         struct timer_wheel *wheel;
  82         size_t i;
  83
  84         wheel = XCALLOC(MTYPE_TIMER_WHEEL, sizeof(struct timer_wheel));
  85
  86         wheel->name = XSTRDUP(MTYPE_TIMER_WHEEL, run_name);
  87         wheel->slot_key = slot_key;
  88         wheel->slot_run = slot_run;
  89
  90         wheel->period = period;
  91         wheel->slots = slots;
  92         wheel->curr_slot = 0;
  93         wheel->master = master;
  94         wheel->nexttime = period / slots;
  95
  96         wheel->wheel_slot_lists = XCALLOC(MTYPE_TIMER_WHEEL_LIST,
  97                                           slots * sizeof(struct list *));
  98         for (i = 0; i < slots; i++)
  99                 wheel->wheel_slot_lists[i] = list_new();
 100
 101         thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
 102                               wheel->nexttime, &wheel->timer);
 103
 104         return wheel;
 105 }
 106
 107 void wheel_delete(struct timer_wheel *wheel)
 108 {
 109         int i;
 110
 111         for (i = 0; i < wheel->slots; i++) {
 112                 list_delete(&wheel->wheel_slot_lists[i]);
 113         }
 114
 115         THREAD_OFF(wheel->timer);
 116         XFREE(MTYPE_TIMER_WHEEL_LIST, wheel->wheel_slot_lists);
 117         XFREE(MTYPE_TIMER_WHEEL, wheel->name);
 118         XFREE(MTYPE_TIMER_WHEEL, wheel);
 119 }
 120
 121 int wheel_stop(struct timer_wheel *wheel)
 122 {
 123         THREAD_OFF(wheel->timer);
 124         return 0;
 125 }
 126
 127 int wheel_start(struct timer_wheel *wheel)
 128 {
 129         if (!wheel->timer)
 130                 thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
 131                                       wheel->nexttime, &wheel->timer);
 132
 133         return 0;
 134 }
 135
 136 int wheel_add_item(struct timer_wheel *wheel, void *item)
 137 {
 138         long long slot;
 139
 140         slot = (*wheel->slot_key)(item);
 141
 142         if (debug_timer_wheel)
 143                 zlog_debug("%s: Inserting %p: %lld %lld", __func__, item, slot,
 144                            slot % wheel->slots);
 145         listnode_add(wheel->wheel_slot_lists[slot % wheel->slots], item);
 146
 147         return 0;
 148 }
 149
 150 int wheel_remove_item(struct timer_wheel *wheel, void *item)
 151 {
 152         long long slot;
 153
 154         slot = (*wheel->slot_key)(item);
 155
 156         if (debug_timer_wheel)
 157                 zlog_debug("%s: Removing %p: %lld %lld", __func__, item, slot,
 158                            slot % wheel->slots);
 159         listnode_delete(wheel->wheel_slot_lists[slot % wheel->slots], item);
 160
 161         return 0;
 162 }