#!/usr/bin/env perl

use strict;
use warnings;

my @GLOBAL_BUFFERS = qw(
    key_buffer_size
    innodb_buffer_pool_size
    innodb_log_buffer_size
    innodb_additional_mem_pool_size
    net_buffer_length
);

my @THREAD_BUFFERS = qw(
    sort_buffer_size
    myisam_sort_buffer_size
    read_buffer_size
    join_buffer_size
    read_rnd_buffer_size
);

my @HEAP_LIMIT = qw(
    innodb_buffer_pool_size
    key_buffer_size
    sort_buffer_size
    read_buffer_size
    read_rnd_buffer_size
);

my @INNODB_LOG_FILE = qw(innodb_buffer_pool_size innodb_log_files_in_group);
my @OTHER_VARIABLES = qw(max_connections);

my %DEFAULT_VALUES = (
    'key_buffer_size'                 => 8388600,
    'innodb_buffer_pool_size'         => 8388608,
    'innodb_log_buffer_size'          => 1048576,
    'innodb_additional_mem_pool_size' => 1048576,
    'net_buffer_length'               => 16384,
    'sort_buffer_size'                => 8388608,
    'myisam_sort_buffer_size'         => 8388608,
    'read_buffer_size'                => 131072,
    'join_buffer_size'                => 131072,
    'read_rnd_buffer_size'            => 262144,
    'innodb_log_files_in_group'       => 2,
    'max_connections'                 => 100,
);

my $TEMPLATE = get_data_section();

MAIN: {
    my $variables = read_variables();
    report_minimal_memory($variables);
    report_heap_limit($variables) if ~0 == 2**32-1;
    report_innodb_log_file($variables);
    exit 0;
}

sub read_cnf {
    my $filename = shift;

    open my $fh, '<', $filename or die qq{open: $! "$filename"};

    my @content;
    while (<$fh>) {
        if ( my ($dir) = /!includedir\s+(\S+)/ ) {
            opendir my $fh, $dir or die qq{opendir: $! "$dir"};
            my @cnf = map "$dir/$_", sort grep /\.cnf$/, readdir $fh;
            push @content, read_cnf($_) for @cnf;
        }
        elsif ( /!include\s+(\S+)/ ) {
            push @content, read_cnf($1);
        }
        else {
            push @content, $_;
        }
    }

    return @content;
}

sub read_variables {
    my $var;

    my @content;
    if ( defined $ARGV[0] && -r $ARGV[0] ) {
        @content = read_cnf($ARGV[0]);
    }
    else {
        @content = <STDIN>;
    }

    for ( @content ) {
        next if /^#/;
        chomp;
        s/^\|\s+//;

        if ( my ($name, $value) = split /[\s=|]+/ ) {
            next unless defined $value;
            $value =~ s/\s*\|\s*$//;
            $value = to_byte($value) if $value =~ /[KMG]$/;
            $name .= '_size' if $name =~ /buffer$/;

            $var->{ $name } = $value;
        }
    }

    for my $name ( keys %DEFAULT_VALUES ) {
        unless ( exists $var->{ $name } ) {
            $var->{ $name } = $DEFAULT_VALUES{ $name };
        }
    }

    return $var;
}

sub report_minimal_memory {
    my $var = shift;

    my $global_buffer_size;
    for my $key ( @GLOBAL_BUFFERS ) {
        $global_buffer_size += $var->{ $key };
    }

    my $thread_buffer_size;
    for my $key ( @THREAD_BUFFERS ) {
        $thread_buffer_size += $var->{ $key };
    }

    my $minimal_memory = $global_buffer_size
                       + $thread_buffer_size * $var->{'max_connections'};

    my $global_buffers = '';
    for my $key ( @GLOBAL_BUFFERS ) {
        $global_buffers .= sprintf "  %-32s %12d  %12s\n",
            $key, $var->{ $key }, add_unit($var->{ $key });
    }

    my $thread_buffers = '';
    for my $key ( @THREAD_BUFFERS ) {
        $thread_buffers .= sprintf "  %-32s %12d  %12s\n",
            $key, $var->{ $key }, add_unit($var->{ $key });
    }

    my $max_connections = $var->{'max_connections'};

    printf $TEMPLATE->{'minimal_memory'},
        $global_buffers, add_unit($global_buffer_size),
        $thread_buffers, add_unit($thread_buffer_size), $max_connections,
        add_unit($global_buffer_size), add_unit($thread_buffer_size * $max_connections),
        $minimal_memory, add_unit($minimal_memory);

}

sub report_heap_limit {
    my $var = shift;

    my $stack_size = 2 * 1024 ** 2;

    my $heap_limit_size =
          $var->{'innodb_buffer_pool_size'}
        + $var->{'key_buffer_size'}
        + $var->{'max_connections'} * ( $var->{'sort_buffer_size'}
                                      + $var->{'read_buffer_size'}
                                      + $var->{'binlog_cache_size'}
                                      + $stack_size );

    my $result = ( 2147483648 <= $heap_limit_size ) ? 'LIMIT OVER!!' : 'safe';

    printf $TEMPLATE->{'heap_limit'},
        @$var{qw(innodb_buffer_pool_size key_buffer_size max_connections)},
        @$var{qw(sort_buffer_size read_buffer_size read_rnd_buffer_size max_connections)},
        $stack_size, $heap_limit_size, add_unit($heap_limit_size), add_unit($heap_limit_size),
        $result;
}

sub report_innodb_log_file {
    my $var = shift;

    my $max_innodb_log_file_size =
        int($var->{'innodb_buffer_pool_size'} / $var->{'innodb_log_files_in_group'});
    my $result = $var->{'innodb_log_file_size'} > $max_innodb_log_file_size
                    ? 'LIMIT OVER!!' : 'safe';

    printf $TEMPLATE->{'innodb_log_file'},
        $var->{'innodb_buffer_pool_size'}, $var->{'innodb_log_files_in_group'},
        $max_innodb_log_file_size, add_unit($max_innodb_log_file_size),
        $var->{'innodb_log_file_size'}, $max_innodb_log_file_size,
        add_unit($var->{'innodb_log_file_size'}),
        add_unit($max_innodb_log_file_size),
        $result;
}

sub to_byte {
    my $str = shift;

    my ($number, $unit) = $str =~ /^(\d+)([KMG])$/ or return;

    my $power = ( $unit eq 'G' ) ? 3 : ( $unit eq 'M' ) ? 2 : ( $unit eq 'K' ) ? 1 : 0;

    return $number * (1024 ** $power);
}

sub add_unit {
    my $number = shift;

    my $base = 0;
    my $unit = '';

    if ( $number > 1073741824 ) {
        $base = 1073741824;
        $unit = 'G';
    }
    elsif ( $number > 1048576 ) {
        $base = 1048576;
        $unit = 'M';
    }
    elsif ( $number > 1024 ) {
        $base = 1024;
        $unit = 'K';
    }
    else {
        $base = 1;
        $unit = '';
    }

    return sprintf '%.3f%s', $number / $base, $unit;
}

sub get_data_section {
    my $content = join '', <DATA>;
    my @data = split /^@@\s+(.+?)\s*\r?\n/m, $content;
    shift @data; # trailing whitespaces

    my $all = {};
    while ( @data ) {
        my ($name, $content) = splice @data, 0, 2;
        $all->{ $name } = $content;
    }

    return $all;
}

=head1 NAME

mymemcheck - check configuration parameter of MySQL

=head1 SYNOPSIS

  mymemcheck /etc/mysql/my.cnf
  mymemcheck ~/my.cnf
  mysql -e 'SHOW VARIABLES' | mymemcheck

=head1 SEE ALSO

L<http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html>
L<http://dev.mysql.com/doc/refman/5.1/en/innodb-tuning.html>
L<http://dev.mysql.com/doc/refman/5.1/en/innodb-configuration.html>

=head1 AUTHOR

HIROSE, Masaaki E<lt>hirose at klab dot orgE<gt>

Craftworks E<lt>craftwork at cpan dot orgE<gt>

=cut

__DATA__
@@ minimal_memory
[ minimal memory ]============================================================
ref
  * ¡ØHigh Performance MySQL¡Ù, Solving Memory Bottlenecks, p125

global_buffers
%s  -----------------------------------------------------------
                                          total  %12s

thread_buffers
%s  -----------------------------------------------------------
                                          total  %12s

max_connections                    %12d

min_memory_needed = global_buffers + (thread_buffers * max_connections)
                  = %s + %s
                  = %lu (%s)

@@ heap_limit
[ 32bit Linux x86 limitation ]================================================
ref
  * http://dev.mysql.com/doc/mysql/en/innodb-configuration.html
  * need to include read_rnd_buffer.
  * no need myisam_sort_buffer because allocate when repair, check alter.

          2G > process heap
process heap = innodb_buffer_pool + key_buffer
               + max_connections * (sort_buffer + read_buffer + read_rnd_buffer)
               + max_connections * stack_size
             = %d + %d
               + %d * (%d + %d + %d)
               + %d * %d
             = %lu (%s)

          2G > %s ... %s

@@ innodb_log_file
[ maximum size of innodb_log_file_size ]======================================
ref
  * http://dev.mysql.com/doc/mysql/en/innodb-start.html

  1MB < innodb_log_file_size < MAX_innodb_log_file_size < 4GB

MAX_innodb_log_file_size = innodb_buffer_pool_size * 1/innodb_log_files_in_group
                         = %d * 1 / %d
                         = %lu (%s)

    innodb_log_file_size < MAX_innodb_log_file_size
%24d < %lu
%24s < %s ... %s