#!/usr/bin/perl -w

# Sun JVM memory statistics.  Parses a verbose log of minor GC and
# tenured GC stats.

# To determine the totalheap value it looks for maxmem stats (from a
# tenured gc) in the last 5 minutes of the log file.  If there are no
# log lines in the last 5 minutes the value will be U(ndefined).

# Since the log lines are timestamped with seconds since the JVM
# started we look at the last line of the log to determine when "now"
# is for the JVM.  In a reasonably active JVM there will be several
# minor GCs a minute so the "now" approximation based on these log
# lines are close enough.

# Configuration (common with the other sun_jvm_* plugins in this family):
# [jvm_sun_*]
#    env.logfile /var/foo/java.log  (default: /var/log/app/jvm/gc.log)
#    env.graphtitle                 (default: "Sun Java")

# You need to configure your Sun JVM with these options:
# -verbose:gc
# -Xloggc:/var/log/app/jvm/gc.log
# -XX:+PrintGCTimeStamps
# -XX:+PrintGCDetails

# History:

# This plugin was developed by various people over some time - no logs
# of this has been found. - In 2006 significant contributions was
# financed by NRK (Norwegian Broadcasting Coproration) and performed
# by Nicolai Langfeldt of Linpro AS in Oslo, Norway.

# $Id: $

use strict;
use warnings;
use Fcntl qw(:seek);

# Full path to jvm log file
my $logfile = $ENV{logfile} || "/var/log/app/jvm/gc.log";
my $grtitle = $ENV{graphtitle} || "Sun Java";

# Title that appears on munin graph
my $title = "$grtitle memory usage";
# Extended information that appears below munin graph
my $info = "Write some info about this graph...";

sub analyze_record {
    # Match all interesting elements of a record and insert them
    # into a hash

    my $record = shift;
    my %elements;

    if ( $record =~
	 m/(\d+\.\d+).+?(\d+\.\d+).+?DefNew: (\d+).+?(\d+).+?(\d+).+?(\d+\.\d+).+?(\d+\.\d+): \[Tenured(\[U.+\])*: (\d+).+?(\d+).+?(\d+).+?(\d+\.\d+).+?(\d+).+?(\d+).+?(\d+).+?(\d+\.\d+).+/
	 ) {
	%elements = (
		     total_timestamp   => $1,
		     defnew_timestamp  => $2,
		     defnew_mem_from   => $3*1024,
		     defnew_mem_to     => $4*1024,
		     defnew_mem_max    => $5*1024,
		     defnew_time_used  => $6,
		     tenured_timestamp => $7,
		     tenured_mem_from  => $9*1024,
		     tenured_mem_to    => $10*1024,
		     tenured_mem_max   => $11*1024,
		     tenured_time_used => $12,
		     total_mem_from    => $13*1024,
		     total_mem_to      => $14*1024,
		     total_mem_max     => $15*1024,
		     total_time_used   => $16 );
    }
    return %elements;
}

my $record='';

# Print config information to munin server
if ( $ARGV[0] and $ARGV[0] eq "config" ) {
  print "graph_title $title\n";
  print "graph_vlabel Bytes Memory\n";
  print "graph_category virtualization\n";
  print "graph_args --lower-limit 0\n";
  print "graph_info Show heap memory usage of JVM\n";
  print "graph_order defnew_max tenured_max tenured_start tenured_end defnew_start defnew_end totalheap totalheapmax\n";
  print "defnew_max.label DefNew max\n";
  print "defnew_max.draw AREA\n";
  print "tenured_max.label Tenured max\n";
  print "tenured_max.draw STACK\n";
  print "tenured_max.info DefNew max and Tenured max are stacked to show the total heap memory usage\n";
  print "tenured_start.label Tenured start\n";
  print "tenured_start.info Tenured (long term) memory used at start of GC\n";
  print "tenured_end.label Tenured end\n";
  print "tenured_end.info Tenured (long term) memory used at end of GC\n";
  print "defnew_start.label DefNew start\n";
  print "defnew_start.info Short term memory used by objects at start of GC\n";
  print "defnew_end.label DefNew end\n";
  print "defnew_end.info Short term memory claimed by objects that survived the GC\n";
  print "totalheapmax.label Maximum total heap\n";
  print "totalheapmax.info Maximum used total heap last 5 minutes\n";
  print "totalheaptomax.label Total heap end\n";
  print "totalheaptomax.info Heapsize at maximum after GC\n";
  exit 0;
}

# Scan through the log file and keep the last instance of a
# Tenured record in $record.

my %last;
# We can't be sure that there is a totalmemto in the log.
my $totalmemto_atmax = 0;
my $totalmemfrom_max = 0;


open( FILE, "< $logfile" ) or die "Can't open $logfile: $!\n";

# We want to collect the highest total_mem_max in the last 5 minute period.
seek(FILE,-4096,SEEK_END);
my $now;
my $lastnow = 0;

while (<FILE>) {
    chomp;
    if (/:/) {
	($now,undef) = split(/:/,$_,2);
	$now = $lastnow unless $now;
    }
}

my $noolderthan = $now - 300;

# print "Latest time is: $now.  5 min ago is $noolderthan\n";

seek(FILE,0,SEEK_SET);

$lastnow = 0;
$now=0;

while (<FILE>) {
    chomp;
    if (/:/) {
	($now,undef) = split(/:/,$_,2);
	$now = $lastnow unless $now;
    }

    if (/.+Tenured.+/) {
	$record = $_;
    } elsif (/^:.+/) {
	$record .= $_;
    }
    if ($record =~ /Tenured.+secs\]$/) {
	%last = analyze_record($record);

#print "($now > $noolderthan and $last{total_mem_from} > $totalmemfrom_max)\n";

	if ($now > $noolderthan and $last{total_mem_from} > $totalmemfrom_max) {
	    $totalmemfrom_max = $last{total_mem_max};
	    $totalmemto_atmax = $last{total_mem_to};
#	    print "New larger at $now: $totalmemto_max\n";
	}
	$record = '';
    }
    $lastnow=$now;
}
close FILE;

$totalmemfrom_max=$totalmemto_atmax='U' if $totalmemfrom_max==0;

# Print the values to be represented in the munin graph
print "tenured_max.value  $last{total_mem_max}\n";
print "tenured_start.value $last{total_mem_from}\n";
print "tenured_end.value $last{total_mem_to}\n";

print "defnew_max.value $last{defnew_mem_max}\n";
print "defnew_start.value $last{defnew_mem_from}\n";
print "defnew_end.value $last{defnew_mem_to}\n";

print "totalheapmax.value $totalmemfrom_max\n";
print "totalheaptomax.value $totalmemto_atmax\n";