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# -*- cperl -*-
# Copyright (c) 2006, 2008 MySQL AB, 2009 Sun Microsystems, Inc.
# Use is subject to license terms.
#
# 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 of the License.
#
# 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA
package mtr_unique;
use strict;
use Fcntl ':flock';
use base qw(Exporter);
our @EXPORT= qw(mtr_get_unique_id mtr_release_unique_id);
use My::Platform;
sub msg {
# print "### unique($$) - ", join(" ", @_), "\n";
}
my $dir;
if(!IS_WINDOWS)
{
$dir= "/tmp/mysql-unique-ids";
}
else
{
# Try to use machine-wide directory location for unique IDs,
# $ALLUSERSPROFILE . IF it is not available, fallback to $TEMP
# which is typically a per-user temporary directory
if (exists $ENV{'ALLUSERSPROFILE'} && -w $ENV{'ALLUSERSPROFILE'})
{
$dir= $ENV{'ALLUSERSPROFILE'}."/mysql-unique-ids";
}
else
{
$dir= $ENV{'TEMP'}."/mysql-unique-ids";
}
}
my $mtr_unique_fh = undef;
END
{
mtr_release_unique_id();
}
#
# Get a unique, numerical ID in a specified range.
#
# If no unique ID within the specified parameters can be
# obtained, return undef.
#
sub mtr_get_unique_id($$) {
my ($min, $max)= @_;;
msg("get $min-$max, $$");
die "Can only get one unique id per process!" if defined $mtr_unique_fh;
# Make sure our ID directory exists
if (! -d $dir)
{
# If there is a file with the reserved
# directory name, just delete the file.
if (-e $dir)
{
unlink($dir);
}
mkdir $dir;
chmod 0777, $dir;
if(! -d $dir)
{
die "can't make directory $dir";
}
}
my $fh;
for(my $id = $min; $id <= $max; $id++)
{
open( $fh, ">$dir/$id");
chmod 0666, "$dir/$id";
# Try to lock the file exclusively. If lock succeeds, we're done.
if (flock($fh, LOCK_EX|LOCK_NB))
{
# Store file handle - we would need it to release the ID (==unlock the file)
$mtr_unique_fh = $fh;
return $id;
}
else
{
close $fh;
}
}
return undef;
}
#
# Release a unique ID.
#
sub mtr_release_unique_id()
{
msg("release $$");
if (defined $mtr_unique_fh)
{
close $mtr_unique_fh;
$mtr_unique_fh = undef;
}
}
1;
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