NAME

       Smokeping::matchers::ExpLoss - exponential weighting matcher for packet loss with
       RMON-like thresholds

DESCRIPTION

       Match against exponential weighted average of last samples, thus new values are more
       valuable as old ones. Two thresholds - rising and falling - produce hysteresis loop like
       in RMON alert subsystem. If the average reaches the "rising" threshold, matcher go to the
       "match" state and hold It until the average drops under the "falling" threshold.

       Call the matcher with the following sequence:

        type = matcher
        pattern =  CheckLoss(hist => <hist>, rising=><rising> \
                            [,falling => <falling>] [,skip=><stat>] [,fast=><fast>])

       Arguments:
        hist    - number of samples to weight against; weight will be disposed with
                  exponetial decreasing manner from newest to oldest, so that the
                  oldest sample would have 1% significance;
        rising  - rising threshold for packet loss, 0-100%
        falling - falling threshold for packet loss, default is <rising>
        skip    - skip <skip> number of samples after startup before "fire" alerts.
        fast    - use <fast> samples for fast transition: if the values of last <fast>
                  samples more then <rising> - take "match" state, if less then
                  <falling> - take "no match" state.

       Note:
        If the actual history is less then <hist> value then this value is taken
        as the actual history.

COPYRIGHT

       Copyright (c) 2008 Veniamin Konoplev

       Developed in cooperation with EU EGEE project

LICENSE

       This program 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 of the License, or (at your option) any later version.

       This program 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.

AUTHOR

       Veniamin Konoplev <vkonoplev@acm.org>