#  Present text graphics display of verbose-GC output.
#  Verbosegc is obtained by providing the -verbose:gc
#  to the JVM command line options.  The output is found
#  in the JVM's stderr.
#
#  The verbosegc output differes somewhat from one version
#  of the JVM to the next.  That's why each version of this
#  script is unique to a particular version of a JVM (not
#  just a particular vendor.
#
#  This version works with the IBM JDK 1.3.0 with the following
#  -fullversion output:
#     "J2RE 1.3.0 IBM build cn130-20010925was"
#
#  Paul Glezen <pglezen@us.ibm.com>

my @slices = ();
my $sliceId = "";
my $currentSec = 0;
my $month, $day, $hour, $min, $sec;
my $key;
my $lastAF = 0;

while (<>)
{
   # How long since last GC.
	#
   if (/^<AF\[\d+\]: Allocation .+ bytes, (\d+) ms since last AF/) {
	   $lastAF = $1;
	}


	# If we're starting a new GC record
	#
	if (/^<GC: ... (...) (\d+) (\d+):(\d+):(\d+) /)
	{
		($month, $day, $hour, $min, $sec) = ($1, $2, $3, $4, $5);

		# If another second has passed, we're starting a new slice.
		#
		if ($sliceId ne "$month $day $hour:$min:$sec")
		{
			$sliceId = "$month $day $hour:$min:$sec";
			$slice = {
			   "month"   => $month,
				"day"     => $day,
				"hour"    => $hour,
				"min"     => $min,
				"sec"     => $sec,
				"lastAF"  => $lastAF,
				"gcTime"  => 0
         };
			$lastAF = 0;
			push(@slices, $slice);
	   }
   }

	# If we're adding time from a current GC record
	#
	if (/^<AF\[\d+\]: completed in (\d+) ms>$/)
	{
		$$slice{"gcTime"} += $1;
   }
}

close LOG;

my $rowCount = 0;
my $showHeaderAgain = 40;
print "\n%GC\n";
foreach $slice (@slices)
{
   #  Show the header every so often.
	#
   if ( ! ($rowCount % $showHeaderAgain)) {
		print "                  0%       10%       20%       30%       30%       50%\n";
		print "                  |---------|---------|---------|---------|---------|\n";
	}
	$rowCount++;
	#  The magic number 20 = 1000 msec / 50 tic marks.
	# my $tics = $$slice{"gcTime"} / 20;
	my $tics = 100 * $$slice{gcTime} / ($$slice{gcTime} + $$slice{lastAF});
	my $bar = "*" x $tics;
	print "[$$slice{\"month\"} $$slice{\"day\"} ";
	print "$$slice{\"hour\"}:$$slice{\"min\"}:$$slice{\"sec\"}] $bar\n";
}