#!/usr/bin/perl

use strict;

#use Data::Dumper;
use File::Basename;

# return unknown status to check_mk and exit
sub exit_unknown {
	(my $message) = @_;
	for my $label (values %main::labels) {
		printf("3 %s - %s\n", "$main::name.$label", $message);
	}
	exit 0;
}

# global variables
my $prog = basename($0);
my $config = "/etc/check-mk-agent/$prog.cfg";
my $line;
our %labels;
my %thresholds;
my $pid;

# set defaults
our $name = $prog;
my $pidcmd = "pidof java";
$name =~ s/^check_(.*)/\U\1/i;
%labels = (
	S0  => "SurvivorSpace0",
	S1  => "SurvivorSpace1",
	E   => "EdenSpace",
	O   => "OldGen",
	P   => "PermGen",
	M   => "MetaSpace",
	CCS => "CompressedClassSpace",
);

# read config
# format is like this:
#
#Name: TOMCAT_MEMORY
#PidCommand: pidof java
#PidCommand: cat /var/run/tomcat.pid
#PidCommand: pidof ovirt-engine
#Label S0  : SurvivorSpace0
#Label S1  : SurvivorSpace1
#Label E   : EdenSpace
#Label O   : OldGen
#Label P   : PermGen
#Label M   : MetaSpace
#Label CCS : CompressedClassSpace
#Threshold SurvivorSpace0       :
#Threshold SurvivorSpace1       :
#Threshold EdenSpace            :
#Threshold OldGen               : ;98;99
#Threshold PermGen              :
#Threshold MetaSpace            :
#Threshold CompressedClassSpace :
if ( open(my $fh, '<', $config) ) {
	while ($line = <$fh>) {
		# skip over comments
		if ($line =~ m/^\s*#/ || $line =~ /^\s*$/) {
			next;
		}
	
		# remove trailing comments
		$line =~ s/\s+#.*$//;
	
		# parse line
		if      ($line =~ m/^\s*Name\s*:\s*(.*)\s*/) {
			$name = $1;
		} elsif ($line =~ m/^\s*Label\s+(\S+)\s*:\s*(\S+)\s*/) {
			$labels{$1} = $2;
		} elsif ($line =~ m/^\s*Threshold\s+(\S+)\s*:\s*(\S*)\s*/) {
			$thresholds{$1} = $2;
		} elsif ($line =~ m/^\s*PidCommand\s*:\s*(.*)\s*/) {
			$pidcmd = $1;
		} else {
			exit_unknown "Could not parse configuration directive $line";
		}
	}
	close($fh);
}

# find pid
open (my $fh, '-|', $pidcmd)
	or exit_unknown "Could not read command output: $pidcmd";
# read fiest line
$line = <$fh>;
($pid) = $line =~ /(\d+)/;
# end of $pidcmd output
close ($fh);
if (!$pid =~ /^\d+$/) {
	exit_unknown "Could not find pid in command output: $pidcmd";
}

# read jstat output
open (my $cmd, '-|', "jstat -gc $pid")
	or exit_unknown "Could not read command output: jstat -gc $pid";
# read first line
$line = <$cmd>;
$line =~ s/^\s+|\s+$//;
my @keys = split(/\s+/, $line);
# read second line
$line = <$cmd>;
$line =~ s/^\s+|\s+$//;
my @values = split(/\s+/, $line);
# end of jstat output
close $cmd;

# check that we were able to parse jstat
if (scalar @keys == 0 || scalar @values == 0 || scalar @keys != scalar @values) {
	exit_unknown "Could not parse command output: jstat -gc $pid";
}

# put data in associative array
my %data;
for my $i (0 .. $#keys) {
	$data{$keys[$i]} = $values[$i];
}

# compute data
for my $key (keys %data) {
	if ($key =~ /U$/) {
		my $mem = $key;
		$mem =~ s/U$//;
		my $used  = $data{"${mem}U"};
		my $total = $data{"${mem}C"};
		my $percent = 100 * $used / $total;
		my $label = $labels{$mem} || $mem;
		my $threshold = $thresholds{$label};
		printf("P %s %s=%f%%%s %s %.1f%% (%.2f / %.2f MB)\n",
			"$name.$label",
			$label, $percent, $threshold,
			$label, $percent, $used/1024, $total/1024
		);
	}
}