1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
package matchers::avgratio;
=head1 NAME
matchers::avgratio - detect changes in average median latency
=head1 OVERVIEW
The avgratio matcher establishes a historic average median latency over
several measurement rounds. It compares this average, against a second
average latency value again build over several rounds of measurment.
=head1 DESCRIPTION
Call the matcher with the following sequence:
type = matcher
pattern = avgratio(historic=>a,current=>b,comparator=>o,percentage=>p)
=over
=item historic
The number of median values to use for building the 'historic' average.
=item current
The number of median values to use for building the 'current' average.
=item comparator
Which comparison operator should be used to compare current/historic with percentage.
=item percentage
Right hand side of the comparison.
=back
old <--- historic ---><--- current ---> now
=head1 EXAMPLE
Take build the average median latency over 10 samples, use this to divid the
current average latency built over 2 samples and check if it is bigger than
150%.
avgratio(historic=>10,current=>2,comparator=>'>',percentage=>150);
avg(current)/avg(historic) > 150/100
This means the matcher will activate when the current latency average if
more than 1.5 times the historic latency average established over the last
10 rounds of measurement.
=head1 COPYRIGHT
Copyright (c) 2004 by OETIKER+PARTNER AG. All rights reserved.
=head1 SPONSORSHIP
The development of this matcher has been sponsored by Virtela Communications www.virtela.net.
=head1 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.
=head1 AUTHOR
Tobias Oetiker <tobi@oetiker.ch>
=cut
use vars qw($VERSION);
$VERSION = 1.0;
use strict;
use base qw(matchers::base);
use Carp;
sub new(@)
{
my $class = shift;
my $rules = {
historic=>'\d+',
current=>'\d+',
comparator=>'(<|>|<=|>=|==)',
percentage=>'\d+(\.\d+)?' };
my $self = $class->SUPER::new($rules,@_);
$self->{param}{sub} = eval "sub {\$_[0] ".$self->{param}{comparator}." \$_[1]}";
croak "compiling comparator $self->{param}{comparator}: $@" if $@;
$self->{param}{value} = $self->{param}{percentage}/100;
return $self;
}
sub Length($)
{
my $self = shift;
return $self->{param}{historic} + $self->{param}{current};
}
sub Desc ($) {
croak "Detect changes in average median latency";
}
sub avg(@){
my $sum=0;
my $cnt=0;
for (@_){
next unless defined $_;
$sum += $_;
$cnt ++;
}
return $sum/$cnt if $cnt;
return undef;
}
sub Test($$)
{ my $self = shift;
my $data = shift; # @{$data->{rtt}} and @{$data->{loss}}
my $len = $self->Length;
my $rlen = scalar @{$data->{rtt}};
return undef
if $rlen < $len
or (defined $data->{rtt}[-$len] and $data->{rtt}[-$len] eq 'S');
my $ac = $self->{param}{historic};
my $bc = $self->{param}{current};
my $cc = $ac +$bc;
my $ha = avg(@{$data->{rtt}}[-$cc..-$bc-1]);
my $ca = avg(@{$data->{rtt}}[-$bc..-1]);
return undef unless $ha and $ca;
return &{$self->{param}{sub}}($ca/$ha,$self->{param}{value});
}
|
