#!/usr/bin/perl -w

# This plugin watches the Linux kernel SMAPS memory usage statistics
# available in kernel revisions later than 2.6.14. It watches only the
# Apache 2 processes, and creates averages, maximums and minimums for
# a given moment in time for the shared size and the virtual size of
# the processes. This is useful for estimating the constraints to give
# to Apache2::SizeLimit.

# Author: Kjetil Kjernsmo <kjetilk@opera.com>, based on work by William Viker
# Copyright (C) 2007 Opera Software ASA
#
# Contibutors: Earle Nietzel <earle.nietzel@gmail.com>
#
# 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

use strict;

my $ret = undef;
if (!eval "require Linux::Smaps;") {
    $ret = "Linux::Smaps not found, fix with cpan -i Linux::Smaps";
}

# allow process name and process user to be specified
my $PNAME = exists $ENV{'pname'} ? $ENV{'pname'} : "httpd";
my $PUSER = exists $ENV{'puser'} ? $ENV{'puser'} : "apache";

if (@ARGV && ($ARGV[0] eq 'config')) {
  print "graph_title Apache Smaps\n";
  print "graph_args --base 1024 -l 0\n";
  print "graph_vlabel Bytes\n";
  print "graph_category webserver\n";
  print "graph_info This graph shows memory usage for each given process.\n";

  print "shr_max.label Shared memory max\n";
  print "shr_max.draw LINE2\n";
  print "shr_max.info Max shared memory.\n";
  print "shr_min.label Shared memory min\n";
  print "shr_min.draw LINE2\n";
  print "shr_min.info Minimum shared memory.\n";
  print "shr_avg.label Shared memory average\n";
  print "shr_avg.draw LINE2\n";
  print "shr_avg.info Average shared memory.\n";

  print "vsz_max.label Virtual memory max\n";
  print "vsz_max.draw LINE2\n";
  print "vsz_max.info Max Virtual memory.\n";
  print "vsz_min.label Virtual memory min\n";
  print "vsz_min.draw LINE2\n";
  print "vsz_min.info Minimum Virtual memory.\n";
  print "vsz_avg.label Virtual memory avg\n";
  print "vsz_avg.draw LINE2\n";
  print "vsz_avg.info Average Virtual memory.\n";
  exit(0);
}

my $i = 0;
my $max_shared = 0;
my $sum_shared = 0;
my $min_shared = 1171541713117116171; # An insanely high number
my $max_virt = 0;
my $sum_virt = 0;
my $min_virt = 1171541713117116171; # An insanely high number
for my $pid (split(/\n/,`pgrep -x $PNAME -u $PUSER`)) {
  my $map = Linux::Smaps->new($pid);
  $i++;
  my $shared = $map->shared_clean + $map->shared_dirty;
  my $size = $map->size;
  $sum_shared += $shared;
  $max_shared = $shared if ($shared > $max_shared);
  $min_shared = $shared if ($shared < $min_shared);
  $sum_virt += $size;
  $max_virt = $size if ($size > $max_virt);
  $min_virt = $size if ($size < $min_virt);
}

# if no processes were found prevents divide by 0
if ($i gt 0) {
  print "shr_max.value $max_shared\n";
  print "shr_min.value $min_shared\n";
  print "shr_avg.value ".$sum_shared/$i."\n";
  print "vsz_max.value $max_virt\n";
  print "vsz_min.value $min_virt\n";
  print "vsz_avg.value ".$sum_virt/$i."\n";
}