File: heavy-wq.c

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/*
 * This file is part of Quagga.
 *
 * Quagga 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, or (at your option) any
 * later version.
 *
 * Quagga 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 Quagga; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

/* This programme shows the effects of 'heavy' long-running functions
 * on the cooperative threading model.
 *
 * Run it with a config file containing 'password whatever', telnet to it
 * (it defaults to port 4000) and enter the 'clear foo string' command.
 * then type whatever and observe that the vty interface is unresponsive
 * for quite a period of time, due to the clear_something command
 * taking a very long time to complete.
 */
#include <zebra.h>

#include "thread.h"
#include "vty.h"
#include "command.h"
#include "memory.h"
#include "log.h"
#include "workqueue.h"
#include <math.h>

extern struct thread_master *master;
static struct work_queue *heavy_wq;

struct heavy_wq_node
{
  char *str;
  int i;
};

enum
{
  ITERS_FIRST = 0,
  ITERS_ERR = 100,
  ITERS_LATER = 400,
  ITERS_PRINT = 10,
  ITERS_MAX = 1000,
};

static void
heavy_wq_add (struct vty *vty, const char *str, int i)
{
  struct heavy_wq_node *hn;

  if ((hn = XCALLOC (MTYPE_PREFIX_LIST, sizeof(struct heavy_wq_node))) == NULL)
    {
      zlog_err ("%s: unable to allocate hn", __func__);
      return;
    }
  
  hn->i = i;
  if (!(hn->str = XSTRDUP (MTYPE_PREFIX_LIST_STR, str)))
    {
      zlog_err ("%s: unable to xstrdup", __func__);
      XFREE (MTYPE_PREFIX_LIST, hn);
      return;
    }
  
  work_queue_add (heavy_wq, hn);
  
  return;
}

static void
slow_func_err (struct work_queue *wq, struct work_queue_item *item)
{
  printf ("%s: running error function\n", __func__);
}

static void
slow_func_del (struct work_queue *wq, void *data)
{
  struct heavy_wq_node *hn = data;
  assert (hn && hn->str);
  printf ("%s: %s\n", __func__, hn->str);
  XFREE (MTYPE_PREFIX_LIST_STR, hn->str);
  hn->str = NULL;  
  XFREE(MTYPE_PREFIX_LIST, hn);
}

static wq_item_status
slow_func (struct work_queue *wq, void *data)
{
  struct heavy_wq_node *hn = data;
  double x = 1;
  int j;
  
  assert (hn && hn->str);
  
  for (j = 0; j < 300; j++)
    x += sin(x)*j;
  
  if ((hn->i % ITERS_LATER) == 0)
    return WQ_RETRY_LATER;
  
  if ((hn->i % ITERS_ERR) == 0)
    return WQ_RETRY_NOW;
  
  if ((hn->i % ITERS_PRINT) == 0)
    printf ("%s did %d, x = %g\n", hn->str, hn->i, x);

  return WQ_SUCCESS;
}

static void
clear_something (struct vty *vty, const char *str)
{
  int i;
  
  /* this could be like iterating through 150k of route_table 
   * or worse, iterating through a list of peers, to bgp_stop them with
   * each having 150k route tables to process...
   */
  for (i = ITERS_FIRST; i < ITERS_MAX; i++)
    heavy_wq_add (vty, str, i);
}

DEFUN (clear_foo,
       clear_foo_cmd,
       "clear foo .LINE",
       "clear command\n"
       "arbitrary string\n")
{
  char *str;
  if (!argc)
    {
      vty_out (vty, "%% string argument required%s", VTY_NEWLINE);
      return CMD_WARNING;
    }
  
  str = argv_concat (argv, argc, 0);
  
  clear_something (vty, str);
  XFREE (MTYPE_TMP, str);
  return CMD_SUCCESS;
}

static int
heavy_wq_init ()
{
  if (! (heavy_wq = work_queue_new (master, "heavy_work_queue")))
    {
      zlog_err ("%s: could not get new work queue!", __func__);
      return -1;
    }
  
  heavy_wq->spec.workfunc = &slow_func;
  heavy_wq->spec.errorfunc = &slow_func_err;
  heavy_wq->spec.del_item_data = &slow_func_del;
  heavy_wq->spec.max_retries = 3;
  heavy_wq->spec.hold = 1000;
  
  return 0;
}

void
test_init()
{
  install_element (VIEW_NODE, &clear_foo_cmd);
  heavy_wq_init();
}