nicolargo / glances

glances/plugins/glances_plugin.py

# -*- coding: utf-8 -*-
#
# This file is part of Glances.
#
# Copyright (C) 2019 Nicolargo <nicolas@nicolargo.com>
#
# Glances is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Glances 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

"""
I am your father...

...for all Glances plugins.
"""

import re
import json
import copy
from operator import itemgetter

from glances.compat import iterkeys, itervalues, listkeys, map, mean, nativestr
from glances.actions import GlancesActions
from glances.history import GlancesHistory
from glances.logger import logger
from glances.events import glances_events
from glances.thresholds import glances_thresholds


class GlancesPlugin(object):
    """Main class for Glances plugin."""

    def __init__(self,
                 args=None,
                 config=None,
                 items_history_list=None,
                 stats_init_value={}):
        """Init the plugin of plugins class.

        All Glances' plugins should inherit from this class. Most of the
        methods are already implemented in the father classes.

        Your plugin should return a dict or a list of dicts (stored in the
        self.stats). As an example, you can have a look on the mem plugin
        (for dict) or network (for list of dicts).

        A plugin should implement:
        - the __init__ constructor: define the self.display_curse
        - the reset method: to set your self.stats variable to {} or []
        - the update method: where your self.stats variable is set
        and optionnaly:
        - the get_key method: set the key of the dict (only for list of dict)
        - the update_view method: only if you need to trick your output
        - the msg_curse: define the curse (UI) message (if display_curse is True)

        :args: args parameters
        :items_history_list: list of items to store in the history
        :stats_init_value: Default value for a stats item
        """
        # Plugin name (= module name without glances_)
        pos = self.__class__.__module__.find('glances_') + len('glances') + 1
        self.plugin_name = self.__class__.__module__[pos:]
        # logger.debug("Init plugin %s" % self.plugin_name)

        # Init the args
        self.args = args

        # Init the default alignement (for curses)
        self._align = 'left'

        # Init the input method
        self._input_method = 'local'
        self._short_system_name = None

        # Init the history list
        self.items_history_list = items_history_list
        self.stats_history = self.init_stats_history()

        # Init the limits (configuration keys) dictionnary
        self._limits = dict()
        if not self.load_limits(config=config):
            logger.debug('Can not load section {} in {}'.format(self.plugin_name,
                                                                config))

        # Init the actions
        self.actions = GlancesActions(args=args)

        # Init the views
        self.views = dict()

        # Init the stats
        self.stats_init_value = stats_init_value
        self.stats = None
        self.reset()

    def __repr__(self):
        """Return the raw stats."""
        return self.stats

    def __str__(self):
        """Return the human-readable stats."""
        return str(self.stats)

    def get_init_value(self):
        """Return a copy of the init value."""
        return copy.copy(self.stats_init_value)

    def reset(self):
        """Reset the stats.

        This method should be overwrited by childs' classes.
        """
        self.stats = self.get_init_value()

    def exit(self):
        """Just log an event when Glances exit."""
        logger.debug("Stop the {} plugin".format(self.plugin_name))

    def get_key(self):
        """Return the key of the list."""
        return None

    def is_enable(self, plugin_name=None):
        """Return true if plugin is enabled."""
        if not plugin_name:
            plugin_name = self.plugin_name
        try:
            d = getattr(self.args, 'disable_' + plugin_name)
        except AttributeError:
            return True
        else:
            return d is False

    def is_disable(self, plugin_name=None):
        """Return true if plugin is disabled."""
        return not self.is_enable(plugin_name=plugin_name)

    def _json_dumps(self, d):
        """Return the object 'd' in a JSON format.

        Manage the issue #815 for Windows OS
        """
        try:
            return json.dumps(d)
        except UnicodeDecodeError:
            return json.dumps(d, ensure_ascii=False)

    def history_enable(self):
        return self.args is not None and not self.args.disable_history and self.get_items_history_list() is not None

    def init_stats_history(self):
        """Init the stats history (dict of GlancesAttribute)."""
        if self.history_enable():
            init_list = [a['name'] for a in self.get_items_history_list()]
            logger.debug("Stats history activated for plugin {} (items: {})".format(self.plugin_name, init_list))
        return GlancesHistory()

    def reset_stats_history(self):
        """Reset the stats history (dict of GlancesAttribute)."""
        if self.history_enable():
            reset_list = [a['name'] for a in self.get_items_history_list()]
            logger.debug("Reset history for plugin {} (items: {})".format(self.plugin_name, reset_list))
            self.stats_history.reset()

    def update_stats_history(self):
        """Update stats history."""
        # If the plugin data is a dict, the dict's key should be used
        if self.get_key() is None:
            item_name = ''
        else:
            item_name = self.get_key()
        # Build the history
        if self.get_export() and self.history_enable():
            for i in self.get_items_history_list():
                if isinstance(self.get_export(), list):
                    # Stats is a list of data
                    # Iter throught it (for exemple, iter throught network
                    # interface)
                    for l in self.get_export():
                        self.stats_history.add(
                            nativestr(l[item_name]) + '_' + nativestr(i['name']),
                            l[i['name']],
                            description=i['description'],
                            history_max_size=self._limits['history_size'])
                else:
                    # Stats is not a list
                    # Add the item to the history directly
                    self.stats_history.add(nativestr(i['name']),
                                           self.get_export()[i['name']],
                                           description=i['description'],
                                           history_max_size=self._limits['history_size'])

    def get_items_history_list(self):
        """Return the items history list."""
        return self.items_history_list

    def get_raw_history(self, item=None, nb=0):
        """Return the history (RAW format).

        - the stats history (dict of list) if item is None
        - the stats history for the given item (list) instead
        - None if item did not exist in the history
        """
        s = self.stats_history.get(nb=nb)
        if item is None:
            return s
        else:
            if item in s:
                return s[item]
            else:
                return None

    def get_json_history(self, item=None, nb=0):
        """Return the history (JSON format).

        - the stats history (dict of list) if item is None
        - the stats history for the given item (list) instead
        - None if item did not exist in the history
        Limit to lasts nb items (all if nb=0)
        """
        s = self.stats_history.get_json(nb=nb)
        if item is None:
            return s
        else:
            if item in s:
                return s[item]
            else:
                return None

    def get_export_history(self, item=None):
        """Return the stats history object to export."""
        return self.get_raw_history(item=item)

    def get_stats_history(self, item=None, nb=0):
        """Return the stats history (JSON format)."""
        s = self.get_json_history(nb=nb)

        if item is None:
            return self._json_dumps(s)

        if isinstance(s, dict):

This code seems to be duplicated in your project.

            try:
                return self._json_dumps({item: s[item]})
            except KeyError as e:
                logger.error("Cannot get item history {} ({})".format(item, e))
                return None
        elif isinstance(s, list):
            try:
                # Source:
                # http://stackoverflow.com/questions/4573875/python-get-index-of-dictionary-item-in-list
                return self._json_dumps({item: map(itemgetter(item), s)})
            except (KeyError, ValueError) as e:
                logger.error("Cannot get item history {} ({})".format(item, e))
                return None
        else:
            return None

    def get_trend(self, item, nb=6):
        """Get the trend regarding to the last nb values.

        The trend is the diff between the mean of the last nb values
        and the current one.
        """
        raw_history = self.get_raw_history(item=item, nb=nb)
        if raw_history is None or len(raw_history) < nb:
            return None
        last_nb = [v[1] for v in raw_history]
        return last_nb[-1] - mean(last_nb[:-1])

    @property
    def input_method(self):
        """Get the input method."""
        return self._input_method

    @input_method.setter
    def input_method(self, input_method):
        """Set the input method.

        * local: system local grab (psutil or direct access)
        * snmp: Client server mode via SNMP
        * glances: Client server mode via Glances API
        """
        self._input_method = input_method

    @property
    def short_system_name(self):
        """Get the short detected OS name (SNMP)."""
        return self._short_system_name

    def sorted_stats(self):
        """Get the stats sorted by an alias (if present) or key."""
        key = self.get_key()
        return sorted(self.stats, key=lambda stat: tuple(map(
            lambda part: int(part) if part.isdigit() else part.lower(),
            re.split(r"(\d+|\D+)", self.has_alias(stat[key]) or stat[key])
        )))

    @short_system_name.setter
    def short_system_name(self, short_name):
        """Set the short detected OS name (SNMP)."""
        self._short_system_name = short_name

    def set_stats(self, input_stats):
        """Set the stats to input_stats."""
        self.stats = input_stats

    def get_stats_snmp(self, bulk=False, snmp_oid=None):
        """Update stats using SNMP.

        If bulk=True, use a bulk request instead of a get request.
        """
        snmp_oid = snmp_oid or {}

        from glances.snmp import GlancesSNMPClient

        # Init the SNMP request
        clientsnmp = GlancesSNMPClient(host=self.args.client,
                                       port=self.args.snmp_port,
                                       version=self.args.snmp_version,
                                       community=self.args.snmp_community)

        # Process the SNMP request
        ret = {}
        if bulk:
            # Bulk request
            snmpresult = clientsnmp.getbulk_by_oid(0, 10, itervalues(*snmp_oid))

            if len(snmp_oid) == 1:
                # Bulk command for only one OID
                # Note: key is the item indexed but the OID result
                for item in snmpresult:
                    if iterkeys(item)[0].startswith(itervalues(snmp_oid)[0]):
                        ret[iterkeys(snmp_oid)[0] + iterkeys(item)
                            [0].split(itervalues(snmp_oid)[0])[1]] = itervalues(item)[0]
            else:
                # Build the internal dict with the SNMP result
                # Note: key is the first item in the snmp_oid
                index = 1
                for item in snmpresult:
                    item_stats = {}
                    item_key = None
                    for key in iterkeys(snmp_oid):
                        oid = snmp_oid[key] + '.' + str(index)
                        if oid in item:
                            if item_key is None:
                                item_key = item[oid]
                            else:
                                item_stats[key] = item[oid]
                    if item_stats:
                        ret[item_key] = item_stats
                    index += 1
        else:
            # Simple get request
            snmpresult = clientsnmp.get_by_oid(itervalues(*snmp_oid))

            # Build the internal dict with the SNMP result
            for key in iterkeys(snmp_oid):
                ret[key] = snmpresult[snmp_oid[key]]

        return ret

    def get_raw(self):
        """Return the stats object."""
        return self.stats

    def get_export(self):
        """Return the stats object to export."""
        return self.get_raw()

    def get_stats(self):
        """Return the stats object in JSON format."""
        return self._json_dumps(self.stats)

    def get_stats_item(self, item):
        """Return the stats object for a specific item in JSON format.

        Stats should be a list of dict (processlist, network...)
        """
        if isinstance(self.stats, dict):
            try:
                return self._json_dumps({item: self.stats[item]})
            except KeyError as e:
                logger.error("Cannot get item {} ({})".format(item, e))
                return None
        elif isinstance(self.stats, list):
            try:
                # Source:
                # http://stackoverflow.com/questions/4573875/python-get-index-of-dictionary-item-in-list
                # But https://github.com/nicolargo/glances/issues/1401
                return self._json_dumps({item: list(map(itemgetter(item), self.stats))})
            except (KeyError, ValueError) as e:
                logger.error("Cannot get item {} ({})".format(item, e))
                return None
        else:
            return None

    def get_stats_value(self, item, value):
        """Return the stats object for a specific item=value in JSON format.

        Stats should be a list of dict (processlist, network...)
        """
        if not isinstance(self.stats, list):
            return None
        else:
            if value.isdigit():
                value = int(value)
            try:
                return self._json_dumps({value: [i for i in self.stats if i[item] == value]})
            except (KeyError, ValueError) as e:
                logger.error(
                    "Cannot get item({})=value({}) ({})".format(item, value, e))
                return None

    def update_views(self):
        """Update the stats views.

        The V of MVC
        A dict of dict with the needed information to display the stats.
        Example for the stat xxx:
        'xxx': {'decoration': 'DEFAULT',
                'optional': False,
                'additional': False,
                'splittable': False}
        """
        ret = {}

        if (isinstance(self.get_raw(), list) and
                self.get_raw() is not None and
                self.get_key() is not None):
            # Stats are stored in a list of dict (ex: NETWORK, FS...)
            for i in self.get_raw():
                ret[i[self.get_key()]] = {}
                for key in listkeys(i):
                    value = {'decoration': 'DEFAULT',
                             'optional': False,
                             'additional': False,
                             'splittable': False}
                    ret[i[self.get_key()]][key] = value
        elif isinstance(self.get_raw(), dict) and self.get_raw() is not None:
            # Stats are stored in a dict (ex: CPU, LOAD...)
            for key in listkeys(self.get_raw()):
                value = {'decoration': 'DEFAULT',
                         'optional': False,
                         'additional': False,
                         'splittable': False}
                ret[key] = value

        self.views = ret

        return self.views

    def set_views(self, input_views):
        """Set the views to input_views."""
        self.views = input_views

    def get_views(self, item=None, key=None, option=None):
        """Return the views object.

        If key is None, return all the view for the current plugin
        else if option is None return the view for the specific key (all option)
        else return the view fo the specific key/option

        Specify item if the stats are stored in a dict of dict (ex: NETWORK, FS...)
        """
        if item is None:
            item_views = self.views
        else:
            item_views = self.views[item]

        if key is None:
            return item_views
        else:
            if option is None:
                return item_views[key]
            else:
                if option in item_views[key]:
                    return item_views[key][option]
                else:
                    return 'DEFAULT'

    def get_json_views(self, item=None, key=None, option=None):
        """Return the views (in JSON)."""
        return self._json_dumps(self.get_views(item, key, option))

    def load_limits(self, config):
        """Load limits from the configuration file, if it exists."""
        # By default set the history length to 3 points per second during one day
        self._limits['history_size'] = 28800

        if not hasattr(config, 'has_section'):
            return False

        # Read the global section
        if config.has_section('global'):
            self._limits['history_size'] = config.get_float_value('global', 'history_size', default=28800)
            logger.debug("Load configuration key: {} = {}".format('history_size', self._limits['history_size']))

        # Read the plugin specific section
        if config.has_section(self.plugin_name):
            for level, _ in config.items(self.plugin_name):
                # Read limits
                limit = '_'.join([self.plugin_name, level])
                try:
                    self._limits[limit] = config.get_float_value(self.plugin_name, level)
                except ValueError:
                    self._limits[limit] = config.get_value(self.plugin_name, level).split(",")
                logger.debug("Load limit: {} = {}".format(limit, self._limits[limit]))

        return True

    @property
    def limits(self):
        """Return the limits object."""
        return self._limits

    @limits.setter
    def limits(self, input_limits):
        """Set the limits to input_limits."""
        self._limits = input_limits

    def get_stats_action(self):
        """Return stats for the action.

        By default return all the stats.
        Can be overwrite by plugins implementation.
        For example, Docker will return self.stats['containers']
        """
        return self.stats

    def get_stat_name(self, header=""):
        """"Return the stat name with an optional header"""
        ret = self.plugin_name
        if header != "":
            ret += '_' + header
        return ret

    def get_alert(self,
                  current=0,
                  minimum=0,
                  maximum=100,
                  highlight_zero=True,
                  is_max=False,
                  header="",
                  action_key=None,
                  log=False):
        """Return the alert status relative to a current value.

        Use this function for minor stats.

        If current < CAREFUL of max then alert = OK
        If current > CAREFUL of max then alert = CAREFUL
        If current > WARNING of max then alert = WARNING
        If current > CRITICAL of max then alert = CRITICAL

        If highlight=True than 0.0 is highlighted

        If defined 'header' is added between the plugin name and the status.
        Only useful for stats with several alert status.

        If defined, 'action_key' define the key for the actions.
        By default, the action_key is equal to the header.

        If log=True than add log if necessary
        elif log=False than do not log
        elif log=None than apply the config given in the conf file
        """
        # Manage 0 (0.0) value if highlight_zero is not True
        if not highlight_zero and current == 0:
            return 'DEFAULT'

        # Compute the %
        try:
            value = (current * 100) / maximum
        except ZeroDivisionError:
            return 'DEFAULT'
        except TypeError:
            return 'DEFAULT'

        # Build the stat_name
        stat_name = self.get_stat_name(header=header)

        # Manage limits
        # If is_max is set then display the value in MAX
        ret = 'MAX' if is_max else 'OK'
        try:
            if value >= self.get_limit('critical', stat_name=stat_name):
                ret = 'CRITICAL'
            elif value >= self.get_limit('warning', stat_name=stat_name):
                ret = 'WARNING'
            elif value >= self.get_limit('careful', stat_name=stat_name):
                ret = 'CAREFUL'
            elif current < minimum:
                ret = 'CAREFUL'
        except KeyError:
            return 'DEFAULT'

        # Manage log
        log_str = ""
        if self.get_limit_log(stat_name=stat_name, default_action=log):
            # Add _LOG to the return string
            # So stats will be highlited with a specific color
            log_str = "_LOG"
            # Add the log to the list
            glances_events.add(ret, stat_name.upper(), value)

        # Manage threshold
        self.manage_threshold(stat_name, ret)

        # Manage action
        self.manage_action(stat_name, ret.lower(), header, action_key)

        # Default is 'OK'
        return ret + log_str

    def manage_threshold(self,
                         stat_name,
                         trigger):
        """Manage the threshold for the current stat."""
        glances_thresholds.add(stat_name, trigger)

    def manage_action(self,
                      stat_name,
                      trigger,
                      header,
                      action_key):
        """Manage the action for the current stat."""
        # Here is a command line for the current trigger ?
        try:
            command, repeat = self.get_limit_action(trigger, stat_name=stat_name)
        except KeyError:
            # Reset the trigger
            self.actions.set(stat_name, trigger)
        else:
            # Define the action key for the stats dict
            # If not define, then it sets to header
            if action_key is None:
                action_key = header

            # A command line is available for the current alert
            # 1) Build the {{mustache}} dictionnary
            if isinstance(self.get_stats_action(), list):
                # If the stats are stored in a list of dict (fs plugin for exemple)
                # Return the dict for the current header
                mustache_dict = {}
                for item in self.get_stats_action():
                    if item[self.get_key()] == action_key:
                        mustache_dict = item
                        break
            else:
                # Use the stats dict
                mustache_dict = self.get_stats_action()
            # 2) Run the action
            self.actions.run(
                stat_name, trigger,
                command, repeat, mustache_dict=mustache_dict)

    def get_alert_log(self,
                      current=0,
                      minimum=0,
                      maximum=100,
                      header="",
                      action_key=None):
        """Get the alert log."""
        return self.get_alert(current=current,
                              minimum=minimum,
                              maximum=maximum,
                              header=header,
                              action_key=action_key,
                              log=True)

    def get_limit(self, criticity, stat_name=""):
        """Return the limit value for the alert."""
        # Get the limit for stat + header
        # Exemple: network_wlan0_rx_careful
        try:
            limit = self._limits[stat_name + '_' + criticity]
        except KeyError:
            # Try fallback to plugin default limit
            # Exemple: network_careful
            limit = self._limits[self.plugin_name + '_' + criticity]

        # logger.debug("{} {} value is {}".format(stat_name, criticity, limit))

        # Return the limiter
        return limit

    def get_limit_action(self, criticity, stat_name=""):
        """Return the tuple (action, repeat) for the alert.

        - action is a command line
        - repeat is a bool
        """
        # Get the action for stat + header
        # Exemple: network_wlan0_rx_careful_action
        # Action key available ?
        ret = [(stat_name + '_' + criticity + '_action', False),
               (stat_name + '_' + criticity + '_action_repeat', True),
               (self.plugin_name + '_' + criticity + '_action', False),
               (self.plugin_name + '_' + criticity + '_action_repeat', True)]
        for r in ret:
            if r[0] in self._limits:
                return self._limits[r[0]], r[1]

        # No key found, the raise an error
        raise KeyError

    def get_limit_log(self, stat_name, default_action=False):
        """Return the log tag for the alert."""
        # Get the log tag for stat + header
        # Exemple: network_wlan0_rx_log
        try:
            log_tag = self._limits[stat_name + '_log']
        except KeyError:
            # Try fallback to plugin default log
            # Exemple: network_log
            try:
                log_tag = self._limits[self.plugin_name + '_log']
            except KeyError:
                # By defaukt, log are disabled
                return default_action

        # Return the action list
        return log_tag[0].lower() == 'true'

    def get_conf_value(self, value, header="", plugin_name=None, default=[]):
        """Return the configuration (header_) value for the current plugin.

        ...or the one given by the plugin_name var.
        """
        if plugin_name is None:
            # If not default use the current plugin name
            plugin_name = self.plugin_name

        if header != "":
            # Add the header
            plugin_name = plugin_name + '_' + header

        try:
            return self._limits[plugin_name + '_' + value]
        except KeyError:
            return default

    def is_hide(self, value, header=""):
        """Return True if the value is in the hide configuration list.

        The hide configuration list is defined in the glances.conf file.
        It is a comma separed list of regexp.
        Example for diskio:
        hide=sda2,sda5,loop.*
        """
        # TODO: possible optimisation: create a re.compile list
        return not all(j is None for j in [re.match(i, value.lower()) for i in self.get_conf_value('hide', header=header)])

    def has_alias(self, header):
        """Return the alias name for the relative header or None if nonexist."""
        try:
            # Force to lower case (issue #1126)
            return self._limits[self.plugin_name + '_' + header.lower() + '_' + 'alias'][0]
        except (KeyError, IndexError):
            # logger.debug("No alias found for {}".format(header))
            return None

    def msg_curse(self, args=None, max_width=None):
        """Return default string to display in the curse interface."""
        return [self.curse_add_line(str(self.stats))]

    def get_stats_display(self, args=None, max_width=None):
        """Return a dict with all the information needed to display the stat.

        key     | description
        ----------------------------
        display | Display the stat (True or False)
        msgdict | Message to display (list of dict [{ 'msg': msg, 'decoration': decoration } ... ])
        align   | Message position
        """
        display_curse = False

        if hasattr(self, 'display_curse'):
            display_curse = self.display_curse
        if hasattr(self, 'align'):
            align_curse = self._align

        if max_width is not None:
            ret = {'display': display_curse,
                   'msgdict': self.msg_curse(args, max_width=max_width),
                   'align': align_curse}
        else:
            ret = {'display': display_curse,
                   'msgdict': self.msg_curse(args),
                   'align': align_curse}

        return ret

    def curse_add_line(self, msg, decoration="DEFAULT",
                       optional=False, additional=False,
                       splittable=False):
        """Return a dict with.

        Where:
            msg: string
            decoration:
                DEFAULT: no decoration
                UNDERLINE: underline
                BOLD: bold
                TITLE: for stat title
                PROCESS: for process name
                STATUS: for process status
                NICE: for process niceness
                CPU_TIME: for process cpu time
                OK: Value is OK and non logged
                OK_LOG: Value is OK and logged
                CAREFUL: Value is CAREFUL and non logged
                CAREFUL_LOG: Value is CAREFUL and logged
                WARNING: Value is WARINING and non logged
                WARNING_LOG: Value is WARINING and logged
                CRITICAL: Value is CRITICAL and non logged
                CRITICAL_LOG: Value is CRITICAL and logged
            optional: True if the stat is optional (display only if space is available)
            additional: True if the stat is additional (display only if space is available after optional)
            spittable: Line can be splitted to fit on the screen (default is not)
        """
        return {'msg': msg, 'decoration': decoration, 'optional': optional, 'additional': additional, 'splittable': splittable}

    def curse_new_line(self):
        """Go to a new line."""
        return self.curse_add_line('\n')

    @property
    def align(self):
        """Get the curse align."""
        return self._align

    @align.setter
    def align(self, value):
        """Set the curse align.

        value: left, right, bottom.
        """
        self._align = value

    def auto_unit(self, number,
                  low_precision=False,
                  min_symbol='K'
                  ):
        """Make a nice human-readable string out of number.

        Number of decimal places increases as quantity approaches 1.
        CASE: 613421788        RESULT:       585M low_precision:       585M
        CASE: 5307033647       RESULT:      4.94G low_precision:       4.9G
        CASE: 44968414685      RESULT:      41.9G low_precision:      41.9G
        CASE: 838471403472     RESULT:       781G low_precision:       781G
        CASE: 9683209690677    RESULT:      8.81T low_precision:       8.8T
        CASE: 1073741824       RESULT:      1024M low_precision:      1024M
        CASE: 1181116006       RESULT:      1.10G low_precision:       1.1G

        :low_precision: returns less decimal places potentially (default is False)
                        sacrificing precision for more readability.
        :min_symbol: Do not approache if number < min_symbol (default is K)
        """
        symbols = ('K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y')
        if min_symbol in symbols:
            symbols = symbols[symbols.index(min_symbol):]
        prefix = {
            'Y': 1208925819614629174706176,
            'Z': 1180591620717411303424,
            'E': 1152921504606846976,
            'P': 1125899906842624,
            'T': 1099511627776,
            'G': 1073741824,
            'M': 1048576,
            'K': 1024
        }

        for symbol in reversed(symbols):
            value = float(number) / prefix[symbol]
            if value > 1:
                decimal_precision = 0
                if value < 10:
                    decimal_precision = 2
                elif value < 100:
                    decimal_precision = 1
                if low_precision:
                    if symbol in 'MK':
                        decimal_precision = 0
                    else:
                        decimal_precision = min(1, decimal_precision)
                elif symbol in 'K':
                    decimal_precision = 0
                return '{:.{decimal}f}{symbol}'.format(
                    value, decimal=decimal_precision, symbol=symbol)
        return '{!s}'.format(number)

    def trend_msg(self, trend, significant=1):
        """Return the trend message.

        Do not take into account if trend < significant
        """
        ret = '-'
        if trend is None:
            ret = ' '
        elif trend > significant:
            ret = '/'
        elif trend < -significant:
            ret = '\\'
        return ret

    def _check_decorator(fct):
        """Check if the plugin is enabled."""
        def wrapper(self, *args, **kw):
            if self.is_enable():
                ret = fct(self, *args, **kw)
            else:
                ret = self.stats
            return ret
        return wrapper

    def _log_result_decorator(fct):
        """Log (DEBUG) the result of the function fct."""
        def wrapper(*args, **kw):
            ret = fct(*args, **kw)
            logger.debug("%s %s %s return %s" % (
                args[0].__class__.__name__,
                args[0].__class__.__module__[len('glances_'):],
                fct.__name__, ret))
            return ret
        return wrapper

    # Mandatory to call the decorator in childs' classes
    _check_decorator = staticmethod(_check_decorator)
    _log_result_decorator = staticmethod(_log_result_decorator)