#!/usr/bin/perl

use strict;
use Devel::Size qw(total_size);

# creating a reference to an anonymous hash
my $coverage = {};
# I'm going to run a loop twice with these values
my @times = qw(once twice);
# some data to use to fill an array in the sub
my %lengths = (
 "id1" => 50000000,
 "id2" => 50000000,
 );

# keeping track of the estimated memory size of the coverage hashref
my $total_size = total_size($coverage);
print "size before the loops = $total_size\n";

# OK run the sub twice with different parameters
foreach my $t (@times){

 if ($t eq "once"){
  # I'm doing stuff here that's conditional on $t
  # then running the sub
  &doWork($t);
  }
 elsif ($t eq "twice"){
  # I'm doing stuff here that's conditional on $t
  # then running the sub
  &doWork($t);
  }

 # keeping track of the estimated memory size of the coverage hashref
 my $total_size = total_size($coverage);
 print "size after $t sub = $total_size\n";

 # reset the hashref so that memory should be small again
 %{ $coverage } = ();

 # keeping track of the estimated memory size of the coverage hashref
 my $total_size = total_size($coverage);
 print "size after resetting the hashref = $total_size\n";
 # while total_size reports that the hashref is small, top shows that the program is still hogging memory
 # what am I doing wrong????
 print "what's the mem doing?\n";
 sleep(10);
 }
sub doWork {
my $time = shift;

# keeping track of the estimated memory size of the coverage hashref
my $total_size = total_size($coverage);
print "size at the start of $time = $total_size\n";

# the main work in the sub is to fill a large reference to an array
foreach my $l (keys %lengths){
 print "creating $l\n";
 push @{ $coverage->{$l} }, 0 for(1 .. $lengths{$l});
 }

# keeping track of the estimated memory size of the coverage hashref
my $total_size = total_size($coverage);
print "size after cov made in $time = $total_size\n";
sleep(5);

# then the sub goes off and does some work that gives back some coordinates to use to increment particular values in the array created above
# get some data to work with
my %increments = {
 "id1" => qw(400-500,6000-6500,100000-100500),
 "id2" => qw(400-500,6000-6500,100000-100500)
 };

# then the values in the array are incremented and passed back to the main program to do something with it
print "incrementing\n";
foreach my $i (keys %increments){
 foreach my $p (@{ $increments{$i} }){
  my ($s,$e) = split("-",$p);
  $coverage->{$i}->[$_]++ for ($s - 1 .. $e - 1);
  }
 }

# keeping track of the estimated memory size of the coverage hashref
my $total_size = total_size($coverage);
print "size after increments made in $time = $total_size\n";
sleep(5);
}