archived-lcd4linux/plugin_loadavg.c

/* $Id: plugin_loadavg.c,v 1.7 2004/06/26 09:27:21 reinelt Exp $
 *
 * plugin for load average
 *
 * Copyright 2003 Michael Reinelt <reinelt@eunet.at>
 * Copyright 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net>
 *
 * This file is part of LCD4Linux.
 *
 * LCD4Linux 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.
 *
 * LCD4Linux 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; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 * $Log: plugin_loadavg.c,v $
 * Revision 1.7  2004/06/26 09:27:21  reinelt
 *
 * added '-W' to CFLAGS
 * changed all C++ comments to C ones ('//' => '/* */')
 * cleaned up a lot of signed/unsigned mistakes
 *
 * Revision 1.6  2004/03/11 06:39:59  reinelt
 * big patch from Martin:
 * - reuse filehandles
 * - memory leaks fixed
 * - earlier busy-flag checking with HD44780
 * - reuse memory for strings in RESULT and hash
 * - netdev_fast to wavid time-consuming regex
 *
 * Revision 1.5  2004/03/08 18:46:21  hejl
 * Fixed bug introduced with "caching" the loadavg values
 *
 * Revision 1.4  2004/03/03 03:47:04  reinelt
 * big patch from Martin Hejl:
 * - use qprintf() where appropriate
 * - save CPU cycles on gettimeofday()
 * - add quit() functions to free allocated memory
 * - fixed lots of memory leaks
 *
 * Revision 1.3  2004/01/30 07:12:35  reinelt
 * HD44780 busy-flag support from Martin Hejl
 * loadavg() uClibc replacement from Martin Heyl
 * round() uClibc replacement from Martin Hejl
 * warning in i2c_sensors fixed
 * [
 *
 * Revision 1.2  2004/01/29 04:40:02  reinelt
 * every .c file includes "config.h" now
 *
 * Revision 1.1  2004/01/15 04:29:45  reinelt
 * moved lcd4linux.conf.sample to *.old
 * lcd4linux.conf.sample with new layout
 * new plugins 'loadavg' and 'meminfo'
 * text widget have pre- and postfix
 *
 */

/* 
 * exported functions:
 *
 * int plugin_init_loadavg (void)
 *  adds functions for load average
 *
 */


#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>

#include "debug.h"
#include "plugin.h"

#ifndef HAVE_GETLOADAVG
static int fd = -2;

int getloadavg (double loadavg[], int nelem)
{
  char buf[65], *p;
  ssize_t nread;
  int i;
      
  if (fd == -2) fd = open ("/proc/loadavg", O_RDONLY);
  if (fd < 0) return -1;

  lseek(fd,0,SEEK_SET);
  nread = read (fd, buf, sizeof buf - 1);
  
  if (nread < 0) return -1;
  buf[nread - 1] = '\0';
  
  if (nelem > 3) nelem = 3;
  p = buf;
  for (i = 0; i < nelem; ++i) {
    char *endp;
    loadavg[i] = strtod (p, &endp);
    if (endp == NULL || endp == p)
      /* This should not happen.  The format of /proc/loadavg
	 must have changed.  Don't return with what we have,
	 signal an error.  */
      return -1;
    p = endp;
  }
  
  return i;
}

#endif


static void my_loadavg (RESULT *result, RESULT *arg1)
{
  static int nelem=-1;
  int index,age;
  static double loadavg[3];
  static struct timeval last_value;
  struct timeval now;
  
  gettimeofday(&now,NULL);
  
  age = (now.tv_sec - last_value.tv_sec)*1000 + (now.tv_usec - last_value.tv_usec)/1000;
  /* reread every 10 msec only */
  if (nelem==-1 || age==0 || age>10) {
  
    nelem=getloadavg(loadavg, 3);
    if (nelem<0) {
      error ("getloadavg() failed!");
      SetResult(&result, R_STRING, "");
      return;
    }
    last_value=now;
  }

  index=R2N(arg1);
  if (index<1 || index>nelem) {
    error ("loadavg(%d): index out of range!", index);
    SetResult(&result, R_STRING, "");
    return;
  }

  
  SetResult(&result, R_NUMBER, &(loadavg[index-1]));
  return;
  
}

int plugin_init_loadavg (void)
{
  AddFunction ("loadavg", 1, my_loadavg);
  return 0;
}

void plugin_exit_loadavg(void) 
{
#ifndef HAVE_GETLOADAVG   
  if (fd>0) close(fd);
  fd=-2;
#endif
}