#!/usr/bin/perl -w
use strict;
use Data::Dumper;
use Parallel::ForkManager;

my %sess_hist = ();           # Session history hash
my %hash = ();                # session flow information
my $session;                  # ID of current session
my $hist_file = '~/hist.dat'; # Session history file

## Check for sessions that are due/overdue and run them
for (keys %{$hash{Session}})    {
    $session = $_;
    my $pid = $pm->start($session) and next;
    if (&check_overdue) {
        if (open SESSLOCK, '>', "~/$session.l") {
            my $stime = time;
            flock SESSLOCK, 2;
            &parse_hist;
            if ($stime > $sess_hist{$session}{last}) { &run_session; }
            else { logit "Aborting to avoid simultaneous sessions"; }
            close SESSLOCK;
            unlink "~/$session.l";
        }
        else { logit "Can't open session lock file, aborting"; }            
    }
    exit(0);
    $pm->finish($session);
}
$pm->wait_all_children;
unlink "$hist_file.l";


sub parse_hist  {   # Opens hist file and pulls info into %sess_hist
    if (-s $hist_file)  {                   # If the history file has data,
        local $/ = undef;                   # set slurp mode,
        open HFL, '>', "$hist_file.l";      # History File Lock
        flock HFL, 2;                       # establish an exclusive lock,
        %sess_hist = %{do($hist_file)};     # and load hist file as %sess_hist
        close HFL;
    }
}


sub merge_hist_changes  {
    # Create copy of current session data
    my %temp_hash = %{$sess_hist{$session}};

    # Reload hist file after establishing lock on .l file
    open HFL, '>', "$hist_file.l";
    flock HFL, 2;
    local $/ = undef;
    %sess_hist = %{do($hist_file)} if -s $hist_file;

    # Change reference to point to copy made earlier
    $sess_hist{$session} = \%temp_hash;

    # Dump it
    local $Data::Dumper::Indent = 1;
    open  HF, '>', $hist_file;
    print HF Dumper \%sess_hist;
    close HF;
    close HFL;  # Release lock and let next child update $hist_file
}