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130 lines
2.6 KiB
Perl
130 lines
2.6 KiB
Perl
# -*- cperl -*-
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# Copyright (c) 2006, 2008 MySQL AB, 2009 Sun Microsystems, Inc.
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# Use is subject to license terms.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; version 2 of the License.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA
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package mtr_unique;
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use strict;
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use Fcntl ':flock';
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use base qw(Exporter);
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our @EXPORT= qw(mtr_get_unique_id mtr_release_unique_id);
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use My::Platform;
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sub msg {
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# print "### unique($$) - ", join(" ", @_), "\n";
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}
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my $dir;
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if(!IS_WINDOWS)
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{
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$dir= "/tmp/mysql-unique-ids";
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}
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else
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{
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# Try to use machine-wide directory location for unique IDs,
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# $ALLUSERSPROFILE . IF it is not available, fallback to $TEMP
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# which is typically a per-user temporary directory
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if (exists $ENV{'ALLUSERSPROFILE'} && -w $ENV{'ALLUSERSPROFILE'})
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{
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$dir= $ENV{'ALLUSERSPROFILE'}."/mysql-unique-ids";
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}
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else
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{
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$dir= $ENV{'TEMP'}."/mysql-unique-ids";
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}
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}
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my $mtr_unique_fh = undef;
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END
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{
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mtr_release_unique_id();
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}
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#
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# Get a unique, numerical ID in a specified range.
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#
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# If no unique ID within the specified parameters can be
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# obtained, return undef.
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#
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sub mtr_get_unique_id($$) {
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my ($min, $max)= @_;;
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msg("get $min-$max, $$");
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die "Can only get one unique id per process!" if defined $mtr_unique_fh;
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# Make sure our ID directory exists
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if (! -d $dir)
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{
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# If there is a file with the reserved
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# directory name, just delete the file.
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if (-e $dir)
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{
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unlink($dir);
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}
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mkdir $dir;
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chmod 0777, $dir;
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if(! -d $dir)
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{
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die "can't make directory $dir";
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}
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}
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my $fh;
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for(my $id = $min; $id <= $max; $id++)
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{
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open( $fh, ">$dir/$id");
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chmod 0666, "$dir/$id";
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# Try to lock the file exclusively. If lock succeeds, we're done.
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if (flock($fh, LOCK_EX|LOCK_NB))
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{
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# Store file handle - we would need it to release the ID (==unlock the file)
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$mtr_unique_fh = $fh;
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return $id;
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}
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else
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{
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close $fh;
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}
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}
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return undef;
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}
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#
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# Release a unique ID.
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#
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sub mtr_release_unique_id()
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{
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msg("release $$");
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if (defined $mtr_unique_fh)
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{
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close $mtr_unique_fh;
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$mtr_unique_fh = undef;
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}
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}
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1;
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