mirror_frr/lib/wheel.c

/*
 * Timer Wheel
 * Copyright (C) 2016 Cumulus Networks, Inc.
 * Donald Sharp
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include "zebra.h"
#include "linklist.h"
#include "thread.h"
#include "memory.h"
#include "wheel.h"
#include "log.h"

DEFINE_MTYPE_STATIC(LIB, TIMER_WHEEL,   "Timer Wheel")
DEFINE_MTYPE_STATIC(LIB, TIMER_WHEEL_LIST, "Timer Wheel Slot List")

static int debug_timer_wheel = 0;

static int
wheel_timer_thread (struct thread *t)
{
  struct listnode *node, *nextnode;
  unsigned long long curr_slot;
  unsigned int slots_to_skip = 1;
  struct timer_wheel *wheel;
  void *data;

  wheel = THREAD_ARG(t);
  THREAD_OFF(wheel->timer);

  wheel->curr_slot += wheel->slots_to_skip;

  curr_slot = wheel->curr_slot % wheel->slots;

  if (debug_timer_wheel)
    zlog_debug ("%s: Wheel Slot: %lld(%lld) count: %d",
		__PRETTY_FUNCTION__,
		wheel->curr_slot,
		curr_slot, listcount(wheel->wheel_slot_lists[curr_slot]));

  for (ALL_LIST_ELEMENTS (wheel->wheel_slot_lists[curr_slot], node, nextnode, data))
    (*wheel->slot_run)(data);

  while (list_isempty(wheel->wheel_slot_lists[(curr_slot + slots_to_skip) % wheel->slots]) &&
	 (curr_slot + slots_to_skip ) % wheel->slots != curr_slot)
    slots_to_skip++;

  wheel->slots_to_skip = slots_to_skip;
  thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
                        wheel->nexttime * slots_to_skip, &wheel->timer);

  return 0;
}

struct timer_wheel *
wheel_init (struct thread_master *master, int period, size_t slots,
	    unsigned int (*slot_key) (void *),
	    void (*slot_run) (void *))
{
  struct timer_wheel *wheel;
  size_t i;

  wheel = XCALLOC(MTYPE_TIMER_WHEEL, sizeof (struct timer_wheel));

  wheel->slot_key = slot_key;
  wheel->slot_run = slot_run;

  wheel->period = period;
  wheel->slots = slots;
  wheel->curr_slot = 0;
  wheel->master = master;
  wheel->nexttime = period / slots;

  wheel->wheel_slot_lists = XCALLOC(MTYPE_TIMER_WHEEL_LIST,
				    slots * sizeof (struct listnode *));
  for (i = 0; i < slots; i++)
    wheel->wheel_slot_lists[i] = list_new ();

  thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
                        wheel->nexttime, &wheel->timer);

  return wheel;
}

void
wheel_delete (struct timer_wheel *wheel)
{
  int i;

  for (i = 0; i < wheel->slots; i++)
    {
      list_delete(wheel->wheel_slot_lists[i]);
    }

  THREAD_OFF(wheel->timer);
  XFREE(MTYPE_TIMER_WHEEL_LIST, wheel->wheel_slot_lists);
  XFREE(MTYPE_TIMER_WHEEL, wheel);
}

int
wheel_stop (struct timer_wheel *wheel)
{
  THREAD_OFF(wheel->timer);
  return 0;
}

int
wheel_start (struct timer_wheel *wheel)
{
  if (!wheel->timer)
    thread_add_timer_msec(wheel->master, wheel_timer_thread, wheel,
                          wheel->nexttime, &wheel->timer);

  return 0;
}

int
wheel_add_item (struct timer_wheel *wheel, void *item)
{
  long long slot;

  slot = (*wheel->slot_key)(item);

  if (debug_timer_wheel)
    zlog_debug ("%s: Inserting %p: %lld %lld",
		__PRETTY_FUNCTION__, item,
		slot, slot % wheel->slots);
  listnode_add (wheel->wheel_slot_lists[slot % wheel->slots], item);

  return 0;
}

int
wheel_remove_item (struct timer_wheel *wheel, void *item)
{
  long long slot;

  slot = (*wheel->slot_key)(item);

  if (debug_timer_wheel)
    zlog_debug ("%s: Removing %p: %lld %lld",
		__PRETTY_FUNCTION__, item,
		slot, slot % wheel->slots);
  listnode_delete (wheel->wheel_slot_lists[slot % wheel->slots], item);

  return 0;
}