#!/usr/bin/perl -w
# -*- perl -*-
#
# Show postgres lock statistics
#
# Parameters:
#
#       config   (required)
#
# Config variables:
#
#       dbhost     - Which database server to use. Defaults to
#                    'localhost'. 
#       dbport     - Which port on the database server to connect to.
#                    Defaults to '5432'.
#       dbuser     - A Postgresql user account with read permission to
#                    the given database. Defaults to
#                    'postgres'. Anyway, Munin must be told which user
#                    this plugin should be run as. 
#       dbpass     - The corresponding password, if
#                    applicable. Default to undef. Remember that
#                    pg_hba.conf must be configured accordingly.
#
# Magic markers
#%# family=auto
#%# capabilities=suggest

use strict;
use DBI;

# See postgress_block_read_ for docs

my $dbhost = $ENV{'dbhost'} || '';
my $dbport = $ENV{'dbport'} || '';
my $dbname = $ENV{'dbname'} || 'template1';
my $dbuser = $ENV{'dbuser'} || 'postgres';

if ($ARGV[0] && $ARGV[0] eq "config") {
    print <<EOF;
graph_title Postgres locks
graph_args --base 1000
graph_vlabel Locks
graph_category Postgresql
graph_info Shows Postgresql locks
locks.label Locks
locks.info Locks (more info here, please... :)
locks.type GAUGE
locks.warning 5
locks.critical 10
exlocks.label Exclusive locks
exlocks.info Exclusive locks (here too, please... :)
exlocks.type GAUGE
exlocks.warning 5
exlocks.critical 10
EOF
} else {
    my $Con = "DBI:Pg:dbname=$dbname";
    $Con .= ";host=$dbhost" if $dbhost;
    $Con .= ";port=$dbport" if $dbport;
    my $Dbh = DBI->connect ($Con, $dbuser,
			    '',
			    {RaiseError =>1}) || die "Unable to access Database $dbname on host $dbhost as user $dbuser.\nError returned was: ". $DBI::errstr;

    my $sql="SELECT mode,COUNT(mode) FROM pg_locks GROUP BY mode ORDER BY mode;";
    my $sth = $Dbh->prepare ($sql);
    $sth->execute ();
    my $locks = 0;
    my $exlocks = 0;
    while (my ($mode, $count) = $sth->fetchrow ()) {
	if ($mode =~ /exclusive/i) {
	    $exlocks = $exlocks + $count;
	}
	$locks = $locks+$count;
    }
    print "locks.value $locks\n";
    print "exlocks.value $exlocks\n";
}