/* $Id: plugin_diskstats.c 840 2007-09-09 12:17:42Z michael $
 * $URL: https://ssl.bulix.org/svn/lcd4linux/trunk/plugin_diskstats.c $
 *
 * plugin for /proc/diskstats parsing
 *
 * Copyright (C) 2003 Michael Reinelt <michael@reinelt.co.at>
 * Copyright (C) 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.
 *
 */

/* 
 * exported functions:
 *
 * int plugin_init_diskstats (void)
 *  adds functions to access /proc/stat
 *
 */


#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>

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


static HASH DISKSTATS;
static FILE *stream = NULL;


static int parse_diskstats(void)
{
    int age;

    /* reread every 10 msec only */
    age = hash_age(&DISKSTATS, NULL);
    if (age > 0 && age <= 10)
	return 0;

    if (stream == NULL)
	stream = fopen("/proc/diskstats", "r");
    if (stream == NULL) {
	error("fopen(/proc/diskstats) failed: %s", strerror(errno));
	return -1;
    }

    rewind(stream);

    while (!feof(stream)) {
	char buffer[1024];
	char dev[64];
	char *beg, *end;
	unsigned int num, len;

	if (fgets(buffer, sizeof(buffer), stream) == NULL)
	    break;

	/* fetch device name (3rd column) as key */
	num = 0;
	beg = buffer;
	end = beg;
	while (*beg) {
	    while (*beg == ' ')
		beg++;
	    end = beg + 1;
	    while (*end && *end != ' ')
		end++;
	    if (num++ == 2)
		break;
	    beg = end ? end + 1 : NULL;
	}
	len = end ? (unsigned) (end - beg) : strlen(beg);

	if (len >= sizeof(dev))
	    len = sizeof(dev) - 1;
	strncpy(dev, beg, len);
	dev[len] = '\0';

	hash_put_delta(&DISKSTATS, dev, buffer);

    }
    return 0;
}


static void my_diskstats(RESULT * result, RESULT * arg1, RESULT * arg2, RESULT * arg3)
{
    char *dev, *key;
    int delay;
    double value;

    if (parse_diskstats() < 0) {
	SetResult(&result, R_STRING, "");
	return;
    }

    dev = R2S(arg1);
    key = R2S(arg2);
    delay = R2N(arg3);

    value = hash_get_regex(&DISKSTATS, dev, key, delay);

    SetResult(&result, R_NUMBER, &value);
}


int plugin_init_diskstats(void)
{
    int i;
    char *header[] = { "major", "minor", "name",
	"reads", "read_merges", "read_sectors", "read_ticks",
	"writes", "write_merges", "write_sectors", "write_ticks",
	"in_flight", "io_ticks", "time_in_queue", ""
    };

    hash_create(&DISKSTATS);
    hash_set_delimiter(&DISKSTATS, " \n");
    for (i = 0; *header[i] != '\0'; i++) {
	hash_set_column(&DISKSTATS, i, header[i]);
    }

    AddFunction("diskstats", 3, my_diskstats);
    return 0;
}

void plugin_exit_diskstats(void)
{
    if (stream != NULL) {
	fclose(stream);
	stream = NULL;
    }
    hash_destroy(&DISKSTATS);
}