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# -*- cperl -*-
# Copyright (C) 2006 MySQL AB
#
# 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 02110-1301 USA
#
# This file is used from drizzle-test-run.pl when choosing
# port numbers and directories to use for running drizzled.
#
use strict;
use Fcntl ':flock';
#
# Requested IDs are stored in a hash and released upon END.
#
my %dtr_unique_assigned_ids = ();
my $dtr_unique_pid;
BEGIN {
$dtr_unique_pid = $$ unless defined $dtr_unique_pid;
}
END {
if($dtr_unique_pid == $$) {
while(my ($id,$file) = each(%dtr_unique_assigned_ids)) {
print "Autoreleasing $file:$id\n";
dtr_release_unique_id($file, $id);
}
}
}
#
# Require a unique, numerical ID, given a file name (where all
# requested IDs are stored), a minimum and a maximum value.
#
# We use flock to implement locking for the ID file and ignore
# possible problems arising from lack of support for it on
# some platforms (it should work on most, and the possible
# race condition would occur rarely). The proper solution for
# this is a daemon that manages IDs, of course.
#
# If no unique ID within the specified parameters can be
# obtained, return undef.
#
sub dtr_require_unique_id($$$) {
my $file = shift;
my $min = shift;
my $max = shift;
my $ret = undef;
my $changed = 0;
my $can_use_ps = `ps -e | grep '^[ ]*$$ '`;
if(eval("readlink '$file'") || eval("readlink '$file.sem'")) {
die 'lock file is a symbolic link';
}
chmod 0777, "$file.sem";
open SEM, ">", "$file.sem" or die "can't write to $file.sem";
flock SEM, LOCK_EX or die "can't lock $file.sem";
if(! -e $file) {
open FILE, ">", $file or die "can't create $file";
close FILE;
}
if(eval("readlink '$file'") || eval("readlink '$file.sem'")) {
die 'lock file is a symbolic link';
}
chmod 0777, $file;
open FILE, "+<", $file or die "can't open $file";
select undef,undef,undef,0.2;
seek FILE, 0, 0;
my %taken = ();
while(<FILE>) {
chomp;
my ($id, $pid) = split / /;
$taken{$id} = $pid;
if($can_use_ps) {
my $res = `ps -e | grep '^[ ]*$pid '`;
if(!$res) {
print "Ignoring slot $id used by missing process $pid.\n";
delete $taken{$id};
++$changed;
}
}
}
for(my $i=$min; $i<=$max; ++$i) {
if(! exists $taken{$i}) {
$ret = $i;
$taken{$i} = $$;
++$changed;
last;
}
}
if($changed) {
seek FILE, 0, 0;
truncate FILE, 0 or die "can't truncate $file";
for my $k (keys %taken) {
print FILE $k . ' ' . $taken{$k} . "\n";
}
}
close FILE;
flock SEM, LOCK_UN or warn "can't unlock $file.sem";
close SEM;
$dtr_unique_assigned_ids{$ret} = $file if defined $ret;
return $ret;
}
#
# Require a unique ID like above, but sleep if no ID can be
# obtained immediately.
#
sub dtr_require_unique_id_and_wait($$$) {
my $ret = dtr_require_unique_id($_[0],$_[1],$_[2]);
while(! defined $ret) {
sleep 30;
$ret = dtr_require_unique_id($_[0],$_[1],$_[2]);
print "Waiting for unique id to become available...\n" unless $ret;
}
return $ret;
}
#
# Release a unique ID.
#
sub dtr_release_unique_id($$) {
my $file = shift;
my $myid = shift;
if(eval("readlink '$file'") || eval("readlink '$file.sem'")) {
die 'lock file is a symbolic link';
}
open SEM, ">", "$file.sem" or die "can't write to $file.sem";
flock SEM, LOCK_EX or die "can't lock $file.sem";
if(eval("readlink '$file'") || eval("readlink '$file.sem'")) {
die 'lock file is a symbolic link';
}
if(! -e $file) {
open FILE, ">", $file or die "can't create $file";
close FILE;
}
open FILE, "+<", $file or die "can't open $file";
select undef,undef,undef,0.2;
seek FILE, 0, 0;
my %taken = ();
while(<FILE>) {
chomp;
my ($id, $pid) = split / /;
$taken{$id} = $pid;
}
delete $taken{$myid};
seek FILE, 0, 0;
truncate FILE, 0 or die "can't truncate $file";
for my $k (keys %taken) {
print FILE $k . ' ' . $taken{$k} . "\n";
}
close FILE;
flock SEM, LOCK_UN or warn "can't unlock $file.sem";
close SEM;
delete $dtr_unique_assigned_ids{$myid};
}
1;
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