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 int wheel_timer_thread(struct thread *t)
  33 {
  34         struct listnode *node, *nextnode;
  35         unsigned long long curr_slot;
  36         unsigned int slots_to_skip = 1;
  37         struct timer_wheel *wheel;
  38         void *data;
  39
  40         wheel = THREAD_ARG(t);
  41         THREAD_OFF(wheel->timer);
  42
  43         wheel->curr_slot += wheel->slots_to_skip;
  44
  45         curr_slot = wheel->curr_slot % wheel->slots;
  46
  47         if (debug_timer_wheel)
  48                 zlog_debug("%s: Wheel Slot: %lld(%lld) count: %d",
  49                            __PRETTY_FUNCTION__, wheel->curr_slot, curr_slot,
  50                            listcount(wheel->wheel_slot_lists[curr_slot]));
  51
  52         for (ALL_LIST_ELEMENTS(wheel->wheel_slot_lists[curr_slot], node,
  53                                nextnode, data))
  54                 (*wheel->slot_run)(data);
  55
  56         while (list_isempty(wheel->wheel_slot_lists[(curr_slot + slots_to_skip)
  57                                                     % wheel->slots])
  58                && (curr_slot + slots_to_skip) % wheel->slots != curr_slot)
  59                 slots_to_skip++;
  60
  61         wheel->slots_to_skip = slots_to_skip;
  62         thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
  63                               wheel->nexttime * slots_to_skip, &wheel->timer);
  64
  65         return 0;
  66 }
  67
  68 struct timer_wheel *wheel_init(struct thread_master *master, int period,
  69                                size_t slots, unsigned int (*slot_key)(void *),
  70                                void (*slot_run)(void *))
  71 {
  72         struct timer_wheel *wheel;
  73         size_t i;
  74
  75         wheel = XCALLOC(MTYPE_TIMER_WHEEL, sizeof(struct timer_wheel));
  76
  77         wheel->slot_key = slot_key;
  78         wheel->slot_run = slot_run;
  79
  80         wheel->period = period;
  81         wheel->slots = slots;
  82         wheel->curr_slot = 0;
  83         wheel->master = master;
  84         wheel->nexttime = period / slots;
  85
  86         wheel->wheel_slot_lists = XCALLOC(MTYPE_TIMER_WHEEL_LIST,
  87                                           slots * sizeof(struct listnode *));
  88         for (i = 0; i < slots; i++)
  89                 wheel->wheel_slot_lists[i] = list_new();
  90
  91         thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
  92                               wheel->nexttime, &wheel->timer);
  93
  94         return wheel;
  95 }
  96
  97 void wheel_delete(struct timer_wheel *wheel)
  98 {
  99         int i;
 100
 101         for (i = 0; i < wheel->slots; i++) {
 102                 list_delete(wheel->wheel_slot_lists[i]);
 103         }
 104
 105         THREAD_OFF(wheel->timer);
 106         XFREE(MTYPE_TIMER_WHEEL_LIST, wheel->wheel_slot_lists);
 107         XFREE(MTYPE_TIMER_WHEEL, wheel);
 108 }
 109
 110 int wheel_stop(struct timer_wheel *wheel)
 111 {
 112         THREAD_OFF(wheel->timer);
 113         return 0;
 114 }
 115
 116 int wheel_start(struct timer_wheel *wheel)
 117 {
 118         if (!wheel->timer)
 119                 thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
 120                                       wheel->nexttime, &wheel->timer);
 121
 122         return 0;
 123 }
 124
 125 int wheel_add_item(struct timer_wheel *wheel, void *item)
 126 {
 127         long long slot;
 128
 129         slot = (*wheel->slot_key)(item);
 130
 131         if (debug_timer_wheel)
 132                 zlog_debug("%s: Inserting %p: %lld %lld", __PRETTY_FUNCTION__,
 133                            item, slot, slot % wheel->slots);
 134         listnode_add(wheel->wheel_slot_lists[slot % wheel->slots], item);
 135
 136         return 0;
 137 }
 138
 139 int wheel_remove_item(struct timer_wheel *wheel, void *item)
 140 {
 141         long long slot;
 142
 143         slot = (*wheel->slot_key)(item);
 144
 145         if (debug_timer_wheel)
 146                 zlog_debug("%s: Removing %p: %lld %lld", __PRETTY_FUNCTION__,
 147                            item, slot, slot % wheel->slots);
 148         listnode_delete(wheel->wheel_slot_lists[slot % wheel->slots], item);
 149
 150         return 0;
 151 }