munin-node 1.4.6-3ubuntu3 / usr / share / munin / plugins / mysql_

#!/usr/bin/perl
# -*- perl -*-

=encoding utf8

=head1 NAME

mysql_ - Munin plugin to display misc MySQL server status

=head1 APPLICABLE SYSTEMS

Any MySQL platform, tested by the author on MySQL 5.1.29 and 5.0.51

=head1 CONFIGURATION

This script is used to generate data for several graphs. To generate
data for one specific graph, you need to create a symbolic link with a
name like mysql_<GRAPH> to this script.

To get a list of symlinks that can be created, run:

  ./mysql_ suggest

In addition you might need to specify connection parameters in the
plugin configuration to override the defaults. These are the defaults:

  [mysql_*]
    env.mysqlconnection DBI:mysql:mysql
    env.mysqluser root

Non-default example:

  [mysql_*]
    env.mysqlconnection DBI:mysql:mysql;host=127.0.0.1;port=3306
    env.mysqluser root
    env.mysqlpassword geheim

Warning and critical values can be set via the environment in the usual way.
For example:

  [mysql_replication]
    env.slave_io_running_warning 0.5
    env.slave_sql_running_warning 0.5
    env.seconds_behind_master_warning 300
    env.seconds_behind_master_critical 600


=head1 DEPENDENCIES

=over

=item Cache::Cache

The plugin uses shared memory to cache the statistics gathered from
MySQL. This ensures minimal inpact on the MySQL server.

=item DBD::mysql

=back

=head1 INTERPRETATION

=head2 InnoDB

The statistics from innodb are mainly collected from the command

  SHOW ENGINE INNODB STATUS

A nice walk through is found at
L<http://www.mysqlperformanceblog.com/2006/07/17/show-innodb-status-walk-through/>

=head2 The graphs

FIX point to relevant sections in the MySQL manual and other www
resources for each graph

=over

=item mysql_replication

slave_io_running and slave_sql_running both translate the "Yes" values to 0 and
anything else to 1 for their respective fields in the "SHOW SLAVE STATUS" output.
This can be used to warn on slave failure if the warning and critical values
are set as seen in a previous section.

=back

=head1 LICENSE

Copyright (C) 2008,2009 Kjell-Magne Øierud

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; version 2 dated June, 1991.

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, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

=head1 VERSION

git-master + a few munin modifications

This plugin was downloaded from L<http://github.com/kjellm/munin-mysql/>

=head1 MAGICK MARKERS

  #%# family=auto
  #%# capabilities=suggest autoconf

=cut

use warnings;
use strict;
use utf8;

use DBI;
use File::Basename;
use Math::BigInt; # Used to append "=> lib 'GMP'" here, but GMP caused
		  # segfault on some occasions. Removed as I don't
		  # think the tiny performance boost is worth the
		  # debugging effort.

use Munin::Plugin;

my $has_cache;

BEGIN {
    eval 'require Cache::SharedMemoryCache';
    $has_cache = $@ ? 0 : 1;
}


#---------------------------------------------------------------------
#  C O N F I G
#---------------------------------------------------------------------

my %config = (
    'dsn'        => $ENV{'mysqlconnection'} || 'DBI:mysql:mysql',
    'user'       => $ENV{'mysqluser'}       || 'root',
    'password'   => $ENV{'mysqlpassword'}   || '',
);


#---------------------------------------------------------------------
#  C A C H E
#---------------------------------------------------------------------

my %cache_options = (
    'namespace'          => 'munin_mysql',
    'default_expires_in' => 60,
);

my $shared_memory_cache ;
if ($has_cache)
{
  $shared_memory_cache = Cache::SharedMemoryCache->new(\%cache_options)
    or die("Couldn't instantiate SharedMemoryCache");
}

#---------------------------------------------------------------------
#  G R A P H   D E F I N I T I O N S
#---------------------------------------------------------------------

# These are defaults to save typing in the graph definitions
my %defaults = (
    global_attrs => {
	args   => '--base 1000',
    },
    data_source_attrs => {
	min   => '0',
	type  => 'DERIVE',
	draw  => 'AREASTACK',
    },
);

# %graphs contains the graph definitions, it is indexed on the graph
# name. The information stored for each graph is used for both showing
# data source values and for printing the graph configuration. Each
# graph follows the followingformat:
#
# $graph{NAME} => {
#     config => {
#         # The global attributes for this graph
#         global_attrs => {}
#         # Attributes common to all data sources in this graph
#         data_source_attrs => {}
#     },
#     data_sources => [
#         # NAME - The name of the data source (e.g. variable names
#         #        from SHOW STATUS)
#         # DATA_SOURCE_ATTRS - key-value pairs with data source
#         #                     attributes
#         {name => 'NAME', (DATA_SOURCE_ATTRS)},
#         {...},
#     ],
my %graphs = ();

#---------------------------------------------------------------------

$graphs{bin_relay_log} = {
    config => {
	global_attrs => {
	    title  => 'Binary/Relay Logs',
	    vlabel => 'Log activity',
	},
	data_source_attrs => {
	    draw  => 'LINE1',
	},
    },
    data_sources => [
	{name => 'Binlog_cache_disk_use', label => 'Binlog Cache Disk Use'},
	{name => 'Binlog_cache_use',      label => 'Binlog Cache Use'},
	{name => 'ma_binlog_size',        label => 'Binary Log Space'},
	{name => 'relay_log_space',       label => 'Relay Log Space'},
    ],
};

#---------------------------------------------------------------------

$graphs{commands} = {
    config => {
	global_attrs => {
	    title  => 'Command Counters',
	    vlabel => 'Commands per ${graph_period}',
	    total  => 'Questions',
	},
	data_source_attrs => {},
    },
    data_sources => [
	{name => 'Com_delete',         label => 'Delete'},
	{name => 'Com_insert',         label => 'Insert'},
	{name => 'Com_insert_select',  label => 'Insert select'},
	{name => 'Com_load',           label => 'Load Data'},
	{name => 'Com_replace',        label => 'Replace'},
	{name => 'Com_replace_select', label => 'Replace select'},
	{name => 'Com_select',         label => 'Select'},
	{name => 'Com_update',         label => 'Update'},
	{name => 'Com_update_multi',   label => 'Update multi'},
    ],
};

#---------------------------------------------------------------------

$graphs{connections} = {
    config => {
	global_attrs => {
	    title  => 'Connections',
	    vlabel => 'Connections per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE1',
	},
    },
    data_sources => [
	{name => 'max_connections',      label  => 'Max connections',
					 type   => 'GAUGE',
					 draw   => 'AREA',
					 colour => 'cdcfc4'},
	{name => 'Max_used_connections', label  => 'Max used',
					 type   => 'GAUGE',
					 draw   => 'AREA',
					 colour => 'ffd660'},
	{name => 'Aborted_clients',      label => 'Aborted clients'},
	{name => 'Aborted_connects',     label => 'Aborted connects'},
	{name => 'Threads_connected',    label => 'Threads connected',
					 type  => 'GAUGE'},
	{name => 'Connections',          label => 'New connections'},
    ],
};

#---------------------------------------------------------------------

$graphs{files_tables} = {
    config => {
	global_attrs => {
	    title  => 'Files and tables',
	    vlabel => 'Tables',
	},
	data_source_attrs => {
	    type  => 'GAUGE',
	    draw  => 'LINE1',
	},
    },
    data_sources => [
	{name => 'table_open_cache', label  => 'Table cache',
				     draw   => 'AREA',
				     colour => 'cdcfc4'},
	{name => 'Open_files',       label => 'Open files'},
	{name => 'Open_tables',      label => 'Open tables'},
	{name => 'Opened_tables',    label => 'Opened tables',
				     type  => 'DERIVE',
	                             min   => 0},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_bpool} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Buffer Pool',
	    vlabel => 'Pages',
	    args   => '--base 1024',
	},
	data_source_attrs => {
	    draw => 'LINE2',
	    type => 'GAUGE',
	},
    },
    data_sources => [
	{name => 'ib_bpool_size',     label  => 'Buffer pool size',
				      draw   => 'AREA',
				      colour => 'ffd660'},
	{name => 'ib_bpool_dbpages',  label  => 'Database pages',
				      draw   => 'AREA',
				      colour => 'cdcfc4'},
	{name => 'ib_bpool_free',     label => 'Free pages'},
	{name => 'ib_bpool_modpages', label => 'Modified pages'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_bpool_act} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Buffer Pool Activity',
	    vlabel => 'Activity per ${graph_period}',
	    total  => 'Total',
	},
	data_source_attrs => {
	    draw => 'LINE2',
	},
    },
    data_sources => [
	{name => 'ib_bpool_read',    label => 'Pages read'},
	{name => 'ib_bpool_created', label => 'Pages created'},
	{name => 'ib_bpool_written', label => 'Pages written'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_insert_buf} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Insert Buffer',
	    vlabel => 'Activity per ${graph_period}',
	},
	data_source_attrs => {
	    draw => 'LINE1',
	},
    },
    data_sources => [
	{name => 'ib_ibuf_inserts',    label => 'Inserts'},
	{name => 'ib_ibuf_merged_rec', label => 'Merged Records'},
	{name => 'ib_ibuf_merges',     label => 'Merges'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_io} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB IO',
	    vlabel => 'IO operations per ${graph_period}',
	},
	data_source_attrs => {
	    draw => 'LINE1',
	},
    },
    data_sources => [
	{name => 'ib_io_read',  label => 'File reads'},
	{name => 'ib_io_write', label => 'File writes'},
	{name => 'ib_io_log',   label => 'Log writes'},
	{name => 'ib_io_fsync', label => 'File syncs'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_io_pend} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB IO Pending',
	    vlabel => 'Pending operations',
	},
	data_source_attrs => {
	    draw => 'LINE1',
	},
    },
    data_sources => [
	{name => 'ib_iop_log',         label => 'AIO Log'},
	{name => 'ib_iop_sync',        label => 'AIO Sync'},
	{name => 'ib_iop_flush_bpool', label => 'Buf Pool Flush'},
	{name => 'ib_iop_flush_log',   label => 'Log Flushes'},
	{name => 'ib_iop_ibuf_aio',    label => 'Insert Buf AIO Read'},
	{name => 'ib_iop_aioread',     label => 'Normal AIO Reads'},
	{name => 'ib_iop_aiowrite',    label => 'Normal AIO Writes'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_log} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Log',
	    vlabel => 'Log activity per ${graph_period}',
	},
	data_source_attrs => {
	    draw => 'LINE1',
	},
    },
    data_sources => [
	{name => 'innodb_log_buffer_size', label  => 'Buffer Size',
					   type   => 'GAUGE',
					   draw   => 'AREA',
					   colour => 'fafd9e'},
	{name => 'ib_log_flush',           label => 'KB Flushed'},
	{name => 'ib_log_written',         label => 'KB Written'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_rows} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Row Operations',
	    vlabel => 'Operations per ${graph_period}',
	    total  => 'Total',
	},
	data_source_attrs => {},
    },
    data_sources => [
	{name => 'Innodb_rows_deleted',  label => 'Deletes'},
	{name => 'Innodb_rows_inserted', label => 'Inserts'},
	{name => 'Innodb_rows_read',     label => 'Reads'},
	{name => 'Innodb_rows_updated',  label => 'Updates'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_semaphores} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Semaphores',
	    vlabel => 'Semaphores per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE1',
	},
    },
    data_sources => [
	{name => 'ib_spin_rounds', label => 'Spin Rounds'},
	{name => 'ib_spin_waits',  label => 'Spin Waits'},
	{name => 'ib_os_waits',    label => 'OS Waits'},
    ],
};

#---------------------------------------------------------------------

$graphs{innodb_tnx} = {
    config => {
	global_attrs => {
	    title  => 'InnoDB Transactions',
	    vlabel => 'Transactions per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE1',
	},
    },
    data_sources => [
	{name => 'ib_tnx', label => 'Transactions created'},
    ],
};

#---------------------------------------------------------------------

$graphs{myisam_indexes} = {
    config => {
	global_attrs => {
	    title  => 'MyISAM Indexes',
	    vlabel => 'Requests per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE2',
	},
    },
    data_sources => [
	{name => 'Key_read_requests',  label => 'Key read requests'},
	{name => 'Key_reads',          label => 'Key reads'},
	{name => 'Key_write_requests', label => 'Key write requests'},
	{name => 'Key_writes',         label => 'Key writes'},
   ],
};

#---------------------------------------------------------------------

$graphs{network_traffic} = {
    config => {
	global_attrs => {
	    title  => 'Network Traffic',
	    args   => '--base 1024',
	    vlabel => 'Bytes received (-) / sent (+) per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE2',
	},
    },
    data_sources => [
	{name => 'Bytes_received', label => 'Bytes transfered',
				   graph => 'no'},
	{name => 'Bytes_sent',     label    => 'Bytes transfered',
				   negative => 'Bytes_received'},
    ],
};

#---------------------------------------------------------------------

$graphs{qcache} = {
    config => {
	global_attrs => {
	    title  => 'Query Cache',
	    vlabel => 'Commands per ${graph_period}',
	},
	data_source_attrs => {
	     draw => 'LINE1',
	},
    },
    data_sources => [
	{name => 'Qcache_queries_in_cache', label => 'Queries in cache'},
	{name => 'Qcache_hits',             label => 'Cache hits'},
	{name => 'Qcache_inserts',          label => 'Inserts'},
	{name => 'Qcache_not_cached',       label => 'Not cached'},
	{name => 'Qcache_lowmem_prunes',    label => 'Low-memory prunes'},
    ],
};

#---------------------------------------------------------------------

$graphs{qcache_mem} = {
    config => {
	global_attrs => {
	    title  => 'Query Cache Memory',
	    vlabel => 'Bytes',
	    args   => '--base 1024 --lower-limit 0',
	},
	data_source_attrs => {
	    draw => 'AREA',
	    type => 'GAUGE',
	},
    },
    data_sources => [
	{name => 'query_cache_size',    label => 'Cache size'},
	{name => 'Qcache_free_memory',  label => 'Free mem'},
    ],
};

#---------------------------------------------------------------------

$graphs{replication} = {
    config => {
	global_attrs => {
	    title  => 'Replication',
	    vlabel => 'Activity',
	},
	data_source_attrs => {
	    draw => 'LINE1',
	},
    },
    data_sources => [
	{name => 'slave_io_running',           label => 'Slave IO Running',
					       type  => 'GAUGE',
					       draw  => 'AREA'},
	{name => 'slave_sql_running',          label => 'Slave SQL Running',
					       type  => 'GAUGE',
					       draw  => 'AREA'},
	{name => 'Slave_retried_transactions', label => 'Retried Transactions'},
	{name => 'Slave_open_temp_tables',     label => 'Open Temp Tables'},
	{name => 'seconds_behind_master',      label => 'Secs Behind Master',
					       type  => 'GAUGE'},
    ],
};

#---------------------------------------------------------------------

$graphs{select_types} = {
    config => {
	global_attrs => {
	    title  => 'Select types',
	    vlabel => 'Commands per ${graph_period}',
	    total  => 'Total',
	},
	data_source_attrs => {},
    },
    data_sources => [
	{name => 'Select_full_join',       label => 'Full join'},
	{name => 'Select_full_range_join', label => 'Full range'},
	{name => 'Select_range',           label => 'Range'},
	{name => 'Select_range_check',     label => 'Range check'},
	{name => 'Select_scan',            label => 'Scan'},
    ],
};

#---------------------------------------------------------------------

$graphs{slow} = {
    config => {
	global_attrs => {
	    title  => 'Slow Queries',
	    vlabel => 'Slow queries per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE2',
	},
    },
    data_sources => [
	{name => 'Slow_queries', label => 'Slow queries'},
    ],
};

#---------------------------------------------------------------------

$graphs{sorts} = {
    config => {
	global_attrs => {
	    title  => 'Sorts',
	    vlabel => 'Sorts / ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE2',
	},
    },
    data_sources => [
	{name => 'Sort_rows',         label => 'Rows sorted'},
	{name => 'Sort_range',        label => 'Range'},
	{name => 'Sort_merge_passes', label => 'Merge passes'},
	{name => 'Sort_scan',         label => 'Scan'},
    ],
};

#---------------------------------------------------------------------

$graphs{table_locks} = {
    config => {
	global_attrs => {
	    title  => 'Table locks',
	    vlabel => 'locks per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE2',
	},
    },
    data_sources => [
	{name => 'Table_locks_immediate', label => 'Table locks immed'},
	{name => 'Table_locks_waited',    label => 'Table locks waited'},
    ],
};

#---------------------------------------------------------------------

$graphs{tmp_tables} = {
    config => {
	global_attrs => {
	    title  => 'Temporary objects',
	    vlabel => 'Objects per ${graph_period}',
	},
	data_source_attrs => {
	    draw  => 'LINE2',
	},
    },
    data_sources => [
	{name => 'Created_tmp_disk_tables', label => 'Temp disk tables'},
	{name => 'Created_tmp_tables',      label => 'Temp tables'},
	{name => 'Created_tmp_files',       label => 'Temp files'},
    ],
};


#---------------------------------------------------------------------
#  M A I N
#---------------------------------------------------------------------


#
# Global hash holding the data collected from mysql.
#
our $data; # Was 'my'. Changed to 'our' to facilitate testing.


sub main {
    my $graph = substr(basename($0), length('mysql_'));
    my $command = $ARGV[0] || 'show';

    my %command_map = (
	'autoconf' => \&autoconf,
	'config'   => \&config,
	'show'     => \&show,
	'suggest'  => \&suggest,
    );

    die "Unknown command: $command"
	unless exists $command_map{$command};

    die "Missing dependency Cache::Cache"
	unless $has_cache || $command eq 'autoconf';

    return $command_map{$command}->($graph);
}


#---------------------------------------------------------------------
#  C O M M A N D   H A N D L E R S
#---------------------------------------------------------------------

# Each command handler should return an appropriate exit code


# http://munin.projects.linpro.no/wiki/ConcisePlugins#autoconf
sub autoconf {
    unless ($has_cache) {
	print "no (Missing dependency Cache::Cache)\n";
	return 0;
    }

    eval {
	db_connect();
    };
    if ($@) {
	my $err = $@;
	$err =~ s{\s at \s \S+ \s line .*}{}xms;
	print "no ($err)\n";
	return 0;
    }
    print "yes\n";
    return 0;
}


# http://munin.projects.linpro.no/wiki/ConcisePlugins#suggest
sub suggest {

    # What is the best way to decide which graphs is applicable to a
    # given system?
    #
    # Does the database use InnoDB? A zero count from:
    #
    #   SELECT COUNT(*)
    #     FROM tables
    #    WHERE table_type = 'base table'
    #      AND engine     = 'innodb'
    #
    # Does the database use binary logs? 'OFF' as the result from:
    #
    #   SHOW GLOBAL variables LIKE 'log_bin'
    #
    # Is the database setup as a slave? Empty result from:
    #
    #   SHOW SLAVE STATUS

    foreach my $graph (sort keys(%graphs)) {
        print "$graph\n";
    }

    return 0;
}


sub config {
    my $graph_name = shift;

    # In MySQL 5.1 (and probably erlier versions as well) status
    # variables are unique when looking at the last 19 characters.
    #
    #   SELECT RIGHT(variable_name, 19), COUNT(*)
    #     FROM information_schema.global_status
    #    GROUP BY RIGHT(variable_name, 19)
    #   HAVING COUNT(*) > 1;
    #
    #   Empty set (0.06 sec)
    #
    # There is one duplicate when looking at server variables
    #
    #   SELECT RIGHT(variable_name, 19), COUNT(*)
    #     FROM information_schema.global_variables
    #    GROUP BY RIGHT(variable_name, 19)
    #   HAVING COUNT(*) > 1;
    #
    #   +--------------------------+----------+
    #   | RIGHT(variable_name, 19) | COUNT(*) |
    #   +--------------------------+----------+
    #   | OW_PRIORITY_UPDATES      |        2 |
    #   +--------------------------+----------+
    #   1 row in set (0.05 sec)
    #
    #   show global variables like '%OW_PRIORITY_UPDATES';
    #
    #   +--------------------------+-------+
    #   | Variable_name            | Value |
    #   +--------------------------+-------+
    #   | low_priority_updates     | OFF   |
    #   | sql_low_priority_updates | OFF   |
    #   +--------------------------+-------+
    #   2 rows in set (0.00 sec)
    #
    # Not a problem since we don't graph these

    die 'Unknown graph ' . ($graph_name ? $graph_name : '')
	unless $graphs{$graph_name};

    my $graph = $graphs{$graph_name};

    my %conf = (%{$defaults{global_attrs}}, %{$graph->{config}{global_attrs}});
    while (my ($k, $v) = each %conf) {
	print "graph_$k $v\n";
    }
    print "graph_category mysql2\n";

    my $i = 0;
    for my $ds (@{$graph->{data_sources}}) {
	my %ds_spec = (
	    %{$defaults{data_source_attrs}},
	    %{$graph->{config}{data_source_attrs}},
	    %$ds,
	);
	while (my ($k, $v) = each %ds_spec) {
	    # 'name' is only used internally in this script, not
	    # understood by munin.
	    next if ($k eq 'name');

	    # AREASTACK is part of munin as of version 1.3.3 (not
	    # released yet). Until then ...
	    if ($k eq 'draw' && $v eq 'AREASTACK') {
		printf("%s.%s %s\n",
		       clean_fieldname($ds->{name}), $k, ($i ? 'STACK' : 'AREA'));
	    }
	    else {
		printf("%s.%s %s\n", clean_fieldname($ds->{name}), $k, $v);
	    }
	    $i++;
	}
	print_thresholds(clean_fieldname($ds->{name}));
    }

    return 0;
}

sub show {
    my $graph_name = shift;

    die 'Unknown graph ' . ($graph_name ? $graph_name : '')
	unless $graphs{$graph_name};

    my $graph = $graphs{$graph_name};

    update_data();

    die "Can't show data for '$graph_name' because InnoDB is disabled."
	if $graph_name =~ /innodb_/ && $data->{_innodb_disabled};

    for my $ds (@{$graph->{data_sources}}) {
	printf "%s.value %s\n",
	    clean_fieldname($ds->{name}), $data->{$ds->{name}};
    }

    return 0;
}



#---------------------------------------------------------------------
#  U T I L I T Y   S U B S
#---------------------------------------------------------------------


sub db_connect {
    my $dsn = "$config{dsn};mysql_connect_timeout=5";

    return DBI->connect($dsn, $config{user}, $config{password}, {
	RaiseError       => 1,
	PrintError       => 0,
	FetchHashKeyName => 'NAME_lc',
    });
}


sub update_data {
    $data = $shared_memory_cache->get('data');
    return if $data;

    #warn "Need to update cache";

    $data = {};

    my $dbh = db_connect();

    # Set up defaults in case the server is not a slave
    $data->{relay_log_space} = 0;
    $data->{slave_running}   = 0;
    $data->{slave_stopped}   = 0;

    # Set up defaults in case binlog is not enabled
    $data->{ma_binlog_size} = 0;

    update_variables($dbh);
    update_innodb($dbh);
    update_master($dbh);
    update_slave($dbh);

    $shared_memory_cache->set('data', $data);
}


sub update_variables {
    my ($dbh) = @_;
    my @queries = (
	'SHOW GLOBAL STATUS',
	'SHOW GLOBAL VARIABLES',
    );

    my %variable_name_map = (
	table_cache => 'table_open_cache', # table_open_cache was
					   # previously known as
					   # table_cache in MySQL
					   # 5.1.2 and earlier.
    );

    for my $query (@queries) {
	$data->{$query} = {};

	my $sth = $dbh->prepare($query);
	$sth->execute();
	while (my $row = $sth->fetch) {
	    my $var = $variable_name_map{$row->[0]} || $row->[0];
	    $data->{$var} = $row->[1];
	}
	$sth->finish();
    }
}


sub update_innodb {
    my ($dbh) = @_;

    my $sth = $dbh->prepare('SHOW /*!50000 ENGINE*/ INNODB STATUS');
    eval {
	$sth->execute();
    };
    if ($@) {
	if ($@ =~ /Unknown table engine 'INNODB'|Cannot call SHOW INNODB STATUS because skip-innodb is defined/i) {
	    $data->{_innodb_disabled} = 1;
	    return;
	}
	die $@;
    }
    my $row = $sth->fetchrow_hashref();
    my $status = $row->{'status'};
    $sth->finish();

    parse_innodb_status($status);
}


sub update_master {
    my ($dbh) = @_;

    my $sth = $dbh->prepare('SHOW MASTER LOGS');
    eval {
	$sth->execute();
    };
    if ($@) {
	# SHOW MASTER LOGS failed becuase binlog is not enabled
	return if $@ =~ /You are not using binary logging/;
	die $@;
    }

    while (my $row = $sth->fetch) {
	$data->{ma_binlog_size} += $row->[1];
    }

    $sth->finish();
}


sub update_slave {
    my ($dbh) = @_;

    my $sth = $dbh->prepare('SHOW SLAVE STATUS');
    $sth->execute();
    my $row = $sth->fetchrow_hashref();
    return unless $row;
    while (my ($k, $v) = each %$row) {
	$data->{$k} = $v;
    }
    $sth->finish();

    # undef when slave is stopped, or when MySQL fails to calculate
    # the lag (which happens depresingly often). (mk-heartbeat fixes
    # this problem.)
    $data->{seconds_behind_master} ||= 0;

    # Track these two fields so we can trigger warnings if the slave stops
    # running
    $data->{slave_sql_running} = ($data->{slave_sql_running} eq 'Yes')
	    ? 0 : 1;
    $data->{slave_io_running} = ($data->{slave_io_running} eq 'Yes')
	    ? 0 : 1;

}


#
# In 'SHOW ENGINE INNODB STATUS' 64 bit integers are not formated as
# plain integers. They are either:
#
#   - split in two and needs to be shifted together,
#   - or hexadecimal
#
sub innodb_bigint {
    my ($x, $y) = @_;

    return defined $y
	? Math::BigInt->new($x)->blsft(32) + $y
	: Math::BigInt->new("0x$x");
}

#---------------------------------------------------------------------
#  P A R S E   'SHOW ENGINE INNODB STATUS'   O U T P U T
#---------------------------------------------------------------------


# A nice walk through
# http://www.mysqlperformanceblog.com/2006/07/17/show-innodb-status-walk-through/

# The parsing is split in one subrutine per section. Each subroutine
# should parse a block with the following structure
#
# block body ...
# more lines ....
# ----------

sub parse_innodb_status {
    local $_ = shift;

    # Add a dummy section to the end in case the innodb status output
    # has been truncated (Happens for status > 64K characters)
    $_ .= "\n----------\nDUMMY\n";

    my %section_map = (

	'BUFFER POOL AND MEMORY'   => \&parse_buffer_pool_and_memory,
	'FILE I/O'                 => \&parse_file_io,
	'INSERT BUFFER AND ADAPTIVE HASH INDEX'
	    => \&parse_insert_buffer_and_adaptive_hash_index,
	'LATEST DETECTED DEADLOCK' => \&skip,
	'LATEST FOREIGN KEY ERROR' => \&skip,
	'LOG'                      => \&parse_log,
	'ROW OPERATIONS'           => \&skip,
	'SEMAPHORES'               => \&parse_semaphores,
	'TRANSACTIONS'             => \&parse_transactions,
	'BACKGROUND THREAD'        => \&skip,
    );

    skip_heading();
    for (;;) {
	m/\G(.*)\n/gc;
	my $sec = $1;

	last if $sec eq 'END OF INNODB MONITOR OUTPUT';
	if ($sec eq 'DUMMY') {
	    handle_incomplete_innodb_status();
	    last;
	}

	die "Unknown section: $1" unless exists $section_map{$sec};
	die "Parse error. Expected a section separator" unless m/\G-+\n/gc;

	$section_map{$sec}->();
    }
}


# This regular expression handles the different formating of 64-bit
# integers in different versions of the innodb engine. Either two
# decimal 32-bit integers seperated by a space, or a single
# hexadecimal 64-bit integer.
my $innodb_bigint_rx = qr{([[a-fA-F\d]+)(?: (\d+))?};


sub match_dashes { return m/\G-+\n(?!-)/gc;}


sub skip_line    { return m/\G.*\n/gc; }


sub skip_heading {
    # Heading is 6 lines
    for my $foo (1...6) {
	skip_line or die('Parse error');
    }
}


sub parse_section {
    my ($parser) = @_;

    #warn substr($_, pos(), 10);
    for (;;) {
	return if match_dashes();
	next if $parser->();
	skip_line();
    }
}


sub skip { parse_section(sub {}); }


sub parse_semaphores {
    parse_section(
	sub {
	    m/\GMutex spin waits (\d+), rounds (\d+), OS waits (\d+)\n/gc && do {
		$data->{ib_spin_waits}  = $1;
		$data->{ib_spin_rounds} = $2;
		$data->{ib_os_waits}    = $3;
		return 1;
	    };
	}
    );
}


sub parse_transactions {
    parse_section(
	sub {
	    m/\GTrx id counter $innodb_bigint_rx\n/gc && do {
		$data->{ib_tnx} = innodb_bigint($1, $2);
		return 1;
	    };
	    m/\GPurge done for trx's n:o < $innodb_bigint_rx undo n:o < $innodb_bigint_rx\n/gc && do {
		if (defined $3) {
		    # old format
		    $data->{ib_tnx_prg} = innodb_bigint($1, $2);
		    # FIX add to data? innodb_bigint($3, $4);
		}
		else {
		    # new format
		    $data->{ib_tnx_prg} = innodb_bigint($1);
		    # FIX add to data? innodb_bigint($2);
		}
		return 1;
	    };
	    m/\GHistory list length (\d+)\n/gc && do {
		$data->{ib_tnx_hist} = $1;
		return 1;
	    };
	}
    );

}


sub parse_file_io {
    parse_section(
	sub {
	    m/\GPending normal aio reads: (\d+), aio writes: (\d+),\n\s*ibuf aio reads: (\d+), log i\/o's: (\d+), sync i\/o's: (\d+)\n/gc && do {
		$data->{ib_iop_aioread}  = $1;
		$data->{ib_iop_aiowrite} = $2;
		$data->{ib_iop_ibuf_aio} = $3;
		$data->{ib_iop_log}      = $4;
		$data->{ib_iop_sync}     = $5;
		return 1;
	    };
	    m/\GPending flushes \(fsync\) log: (\d+); buffer pool: (\d+)\n/gc && do {
		$data->{ib_iop_flush_log}   = $1;
		$data->{ib_iop_flush_bpool} = $2;
		return 1;
	    };
	    m/\G(\d+) OS file reads, (\d+) OS file writes, (\d+) OS fsyncs\n/gc && do {
		$data->{ib_io_read}  = $1;
		$data->{ib_io_write} = $2;
		$data->{ib_io_fsync} = $3;
		return 1;
	    };
	}
    );
}


sub parse_insert_buffer_and_adaptive_hash_index {
    parse_section(
	sub {
	    m/\G(\d+) inserts, (\d+) merged recs, (\d+) merges\n/gc && do {
		$data->{ib_ibuf_inserts}    = $1;
		$data->{ib_ibuf_merged_rec} = $2;
		$data->{ib_ibuf_merges}     = $3;
		return 1;
	    };
	}
    );
}


sub parse_log {
    parse_section(
	sub {
	    m/\GLog sequence number $innodb_bigint_rx\n/gc && do {
		$data->{ib_log_written} = innodb_bigint($1, $2);
		return 1;
	    };
	    m/\GLog flushed up to\s+$innodb_bigint_rx\n/gc && do {
		$data->{ib_log_flush} = innodb_bigint($1, $2);
		return 1;
	    };
	    m/\G(\d+) log i\/o's done.*\n/gc && do {
		$data->{ib_io_log} = $1;
		return 1;
	    };
	}
    );
}


sub parse_buffer_pool_and_memory {
    parse_section(
	sub {
	    m/\GBuffer pool size\s+(\d+)\n/gc && do {
		$data->{ib_bpool_size} = $1;
		return 1;
	    };
	    m/\GFree buffers\s+(\d+)\n/gc && do {
		$data->{ib_bpool_free} = $1;
		return 1;
	    };
	    m/\GDatabase pages\s+(\d+)\n/gc && do {
		$data->{ib_bpool_dbpages} = $1;
		return 1;
	    };
	    m/\GModified db pages\s+(\d+)\n/gc && do {
		$data->{ib_bpool_modpages} = $1;
		return 1;
	    };
	    m/\GPages read (\d+), created (\d+), written (\d+)\n/gc && do {
		$data->{ib_bpool_read}    = $1;
		$data->{ib_bpool_created} = $2;
		$data->{ib_bpool_written} = $3;
		return 1;
	    };
	}
    );
}


sub handle_incomplete_innodb_status {

    warn "Output from SHOW ENGINE INNDOB STATUS was truncated. "
	. "This happens if the output of SEIS exceeds 64KB. "
	. "Several of the InnoDB graphs might be affected by this.";

    # FIX Is it possible to find some of the missing values from SHOW
    # STATUS?
}


exit main() unless caller;


1;