collectd-lvmcache

#!/usr/bin/env python3

import os
import sys
import time
import socket

hostname = os.environ['COLLECTD_HOSTNAME'] if 'COLLECTD_HOSTNAME' in os.environ else socket.getfqdn()
interval = float(os.environ['COLLECTD_INTERVAL']) if 'COLLECTD_INTERVAL' in os.environ else 1


def parse_dmsetup_status(line):
    value = line.split()
    status = {
        'device': value[0][:-1],
        'length': int(value[2]),
        'target': value[3],
        'metadata_blocksize': int(value[4]),
        'metadata_used': int(value[5].split('/')[0]),
        'metadata_total': int(value[5].split('/')[1]),
        'cache_blocksize': int(value[6]),
        'cache_used': int(value[7].split('/')[0]),
        'cache_total': int(value[7].split('/')[1]),
        'read_hits': int(value[8]),
        'read_misses': int(value[9]),
        'write_hits': int(value[10]),
        'write_misses': int(value[11]),
        'demotions': int(value[12]),
        'promotions': int(value[13]),
        'dirty': int(value[14]),
        'blocksize': 512,
    }
    return status


def calculate_size(data, key):
    if key == 'metadata_free':
        value = data['metadata_total']-data['metadata_used']
    elif key == 'cache_used':
        value = data['cache_used']-data['dirty']
    elif key == 'cache_free':
        value = data['cache_total']-data['cache_used']
    else:
        value = data[key]

    if key in ['metadata_free', 'metadata_used']:
        value = value * data['blocksize'] * data['metadata_blocksize']
    else:
        value = value * data['blocksize'] * data['cache_blocksize']
    return value


def main():
    if not os.path.exists("/sbin/dmsetup"):
        print("/sbin/dmsetup doesn't exist")
        sys.exit(1)

    while True:
        status = os.popen('sudo /sbin/dmsetup status --target cache').readlines()
        for s in status:
            data = parse_dmsetup_status(s.rstrip())
            for c in ['dirty', 'metadata_used', 'metadata_free', 'cache_used', 'cache_free']:
                print('PUTVAL "%s/lvmcache-%s/df_complex-%s" interval=%s N:%s' %
                      (hostname, data['device'], c, interval, calculate_size(data, c)))
            for c in ['read_hits', 'read_misses', 'write_hits', 'write_misses', 'demotions', 'promotions']:
                print('PUTVAL "%s/lvmcache-%s/cache_result-%s" interval=%s N:%s' %
                      (hostname, data['device'], c, interval, data[c]))
        sys.stdout.flush()
        time.sleep(interval)


if __name__ == '__main__':
    main()