#!/usr/bin/perl -w

# Copyright (C) 2007,2008,2009,2010,2011 Ole Tange and Free Software
# Foundation, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, see <http://www.gnu.org/licenses/>
# or write to the Free Software Foundation, Inc., 51 Franklin St,
# Fifth Floor, Boston, MA 02110-1301 USA
#
# SPDX-FileCopyrightText: 2021 Ole Tange, http://ole.tange.dk and Free Software and Foundation, Inc.
# SPDX-License-Identifier: GPL-3.0-or-later

=head1 NAME

christmastree - use memory similar to a christmas tree profile

=head1 SYNOPSIS

B<christmastree> [-s I<per_second>] [-m I<min>] <max>

=head1 DESCRIPTION

GNU B<christmastree> is a test script that increases and decreases its
memory usage. The increase and descrease will happen at random, but
the memory usage will grow on average.

=over 9

=item I<max>

The maximal amount of memory to use before exitting.


=item B<-s> I<per_second>

The amount of memory it should grow per second on average. Default to max/10.


=item B<-m> I<min>

The minimal amount of memory to use before exitting.

=back


=head1 EXAMPLES



=head1 REPORTING BUGS

B<christmastree> is part of GNU B<parallel>. Report bugs to <bug-parallel@gnu.org>.


=head1 AUTHOR

Copyright (C) 2011 Ole Tange, http://ole.tange.dk and Free
Software Foundation, Inc.

=head1 LICENSE

Copyright (C) 2011 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

=head2 Documentation license I

Permission is granted to copy, distribute and/or modify this documentation
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the file fdl.txt.

=head2 Documentation license II

You are free:

=over 9

=item B<to Share>

to copy, distribute and transmit the work

=item B<to Remix>

to adapt the work

=back

Under the following conditions:

=over 9

=item B<Attribution>

You must attribute the work in the manner specified by the author or
licensor (but not in any way that suggests that they endorse you or
your use of the work).

=item B<Share Alike>

If you alter, transform, or build upon this work, you may distribute
the resulting work only under the same, similar or a compatible
license.

=back

With the understanding that:

=over 9

=item B<Waiver>

Any of the above conditions can be waived if you get permission from
the copyright holder.

=item B<Public Domain>

Where the work or any of its elements is in the public domain under
applicable law, that status is in no way affected by the license.

=item B<Other Rights>

In no way are any of the following rights affected by the license:

=over 9

=item *

Your fair dealing or fair use rights, or other applicable
copyright exceptions and limitations;

=item *

The author's moral rights;

=item *

Rights other persons may have either in the work itself or in
how the work is used, such as publicity or privacy rights.

=back

=item B<Notice>

For any reuse or distribution, you must make clear to others the
license terms of this work.

=back

A copy of the full license is included in the file as cc-by-sa.txt.

=head1 DEPENDENCIES

B<christmastree> uses Perl.


=head1 SEE ALSO

B<parallel>(1)

=cut

use Getopt::Long;

parse_options();
my $start_time = time;
my $max = multiply_binary_prefix(shift);
my $min = (multiply_binary_prefix($::opt_m) or $max);
my $target_max = int(rand($max - $min)) + $min;
my $per_second = (multiply_binary_prefix($::opt_s) or $target_max/10);
my ($memusage,@a,$target,$this_round);

do {
   $memusage = my_memory_usage();
   $target = (time - $start_time)*int($per_second);
   $this_round = $target - my_memory_usage();
   if($this_round > 0) {
       my $this_size = min(rand($this_round*3), $target_max-$memusage);
       my $a = "x"x$this_size;
       push @a,$a;
   } else {
       pop @a;
   }
   debug("$#a memusage $memusage target $target this_round $this_round target_max $target_max\n");
   usleep(500);
} while($memusage < $target_max);


sub min {
    # Returns:
    #   Minimum value of array
    my $min;
    for (@_) {
        # Skip undefs
        defined $_ or next;
        defined $min or do { $min = $_; next; }; # Set $_ to the first non-undef
        $min = ($min < $_) ? $min : $_;
    }
    return $min;
}


sub debug {
    # Returns: N/A
    $Global::debug or return;
    @_ = grep { defined $_ ? $_ : "" } @_;
    if($Global::original_stdout) {
        print $Global::original_stdout @_;
    } else {
        print @_;
    }
}

sub parse_options {
    $Global::version = 20110822;
    $Global::progname = 'christmastree';

    Getopt::Long::Configure ("bundling","require_order");
    GetOptions("s=s" => \$::opt_s,
	       "m=s" => \$::opt_m,
	       "r=s" => \$::opt_r,
	       "debug" => \$::opt_debug,
	       # GNU requirements
	       "help|h" => \$::opt_help,
	       "version|V" => \$::opt_version,
	) || die_usage();

    if(defined $::opt_r) { srand($::opt_r); }
    if(defined $::opt_help) { die_usage(); }
    if(defined $::opt_version) { version(); exit(0); }
    $Global::debug = $::opt_debug;
}

sub usleep {
    # Sleep this many milliseconds.
    my $secs = shift;
    ::debug("Sleeping ",$secs," millisecs\n");
    select(undef, undef, undef, $secs/1000);
    if($::opt_timeout) {
	::debug(my_dump($Global::timeoutq));
	$Global::timeoutq->process_timeouts();
    }
}

sub undef_as_zero {
    my $a = shift;
    return $a ? $a : 0;
}

sub undef_as_empty {
    my $a = shift;
    return $a ? $a : "";
}

sub my_memory_usage {
    # Returns:
    #   memory usage if found
    #   0 otherwise
    use strict;
    use FileHandle;

    my $pid = $$;
    if(-e "/proc/$pid/stat") {
        my $fh = FileHandle->new("</proc/$pid/stat");

        my $data = <$fh>;
        chomp $data;
        $fh->close;

        my @procinfo = split(/\s+/,$data);

        return undef_as_zero($procinfo[22]);
    } else {
        return 0;
    }
}

sub multiply_binary_prefix {
    # Evalualte numbers with binary prefix
    # k=10^3, m=10^6, g=10^9, t=10^12, p=10^15, e=10^18, z=10^21, y=10^24
    # K=2^10, M=2^20, G=2^30, T=2^40, P=2^50, E=2^70, Z=2^80, Y=2^80
    # Ki=2^10, Mi=2^20, Gi=2^30, Ti=2^40, Pi=2^50, Ei=2^70, Zi=2^80, Yi=2^80
    # ki=2^10, mi=2^20, gi=2^30, ti=2^40, pi=2^50, ei=2^70, zi=2^80, yi=2^80
    # 13G = 13*1024*1024*1024 = 13958643712
    my $s = undef_as_empty(shift);
    $s =~ s/k/*1000/g;
    $s =~ s/M/*1000*1000/g;
    $s =~ s/G/*1000*1000*1000/g;
    $s =~ s/T/*1000*1000*1000*1000/g;
    $s =~ s/P/*1000*1000*1000*1000*1000/g;
    $s =~ s/E/*1000*1000*1000*1000*1000*1000/g;
    $s =~ s/Z/*1000*1000*1000*1000*1000*1000*1000/g;
    $s =~ s/Y/*1000*1000*1000*1000*1000*1000*1000*1000/g;
    $s =~ s/X/*1000*1000*1000*1000*1000*1000*1000*1000*1000/g;

    $s =~ s/Ki?/*1024/gi;
    $s =~ s/Mi?/*1024*1024/gi;
    $s =~ s/Gi?/*1024*1024*1024/gi;
    $s =~ s/Ti?/*1024*1024*1024*1024/gi;
    $s =~ s/Pi?/*1024*1024*1024*1024*1024/gi;
    $s =~ s/Ei?/*1024*1024*1024*1024*1024*1024/gi;
    $s =~ s/Zi?/*1024*1024*1024*1024*1024*1024*1024/gi;
    $s =~ s/Yi?/*1024*1024*1024*1024*1024*1024*1024*1024/gi;
    $s =~ s/Xi?/*1024*1024*1024*1024*1024*1024*1024*1024*1024/gi;
    $s = eval $s;
    return $s;
}