#!/usr/bin/perl

# Make a log-based histogram of object sizes
#
#	perl object-size-hist.pl < /usr/local/squid/logs/access.log > hist
#	gnuplot
#	> set logscale x
#	> plot 'hist' using 1:4 with lines


$SF = 10;

while (<>) {
	@F = split;
	next unless ($F[3] =~ /^TCP_\S+\/200/);
	$size = $F[4];
	next unless ($size > 0);
	$bin = int( $SF * log($size) + 0.5);
	$H[$bin]++;
}

$sum1 = 0;
$sum2 = 0;

for ($i=0; $i<=$#H; $i++) {
	$sum1 += $H[$i];
}

for ($i=0; $i<=$#H; $i++) {
	$sum2 += $H[$i];
	printf "%14.5f %9d %10.5f %10.5f\n",
		exp($i/$SF),
		$H[$i],
		$H[$i]/$sum1,
		$sum2/$sum1;
}

# print the median
$sum3 = 0;
for ($i=0; $i<=$#H; $i++) {
	$sum3 += $H[$i];
	$S[$i] = $sum3;
	last if ($sum3 / $sum1 >= 0.5);
}

$X = $S[$i-1];
$Z = $S[$i];
$Y = $sum2 / 2;
print "#i=$i\n";
print "#X=$X\n";
print "#Z=$Z\n";
print "#Y=$Y\n";
die if ($Y < $X);
die if ($Y > $Z);
$B = ($i -1)  + ($Y-$X) / ($Z - $X);
print "#B=$B\n";
printf "# median is %f bytes\n", exp($B/$SF);