SWE/DB/Lock.pm

package SWE::DB::Lock;
use strict;

my $CurrentlyLocking = {};
my $LockTypes = [qw/
  ID Name Index IDs Names Graph Weight Global
/];
  ## If you are locking for Graph, then you cannot lock for Global, but
  ## still you can lock for ID.

  ## idgen is currently controled by Names lock.

use Fcntl ':flock';

sub new ($) {
  my $self = bless {
    'file_name' => 'lock',
    lock_type => 'Global',
  }, shift;
  return $self;
} # new

sub lock_type ($;$) {
  my $self = shift;
  if (@_) {
    $self->{lock_type} = shift;
  }
  return $self->{lock_type};
} # lock_type

sub check_lockability ($) {
  my $self = shift;
  
  my $self_lt = $self->lock_type;
  for my $lt (@$LockTypes) {
    if ($self_lt eq $lt) {
      last;
    } elsif ($CurrentlyLocking->{$lt}) {
      die qq[$0: It is currently locking for "$lt" so that it cannot be locked for the "$self_lt"];
    }
  }

  return 1;
} # check_lockability
                       
sub lock ($) {
  my $self = shift;

  $self->check_lockability;
  $CurrentlyLocking->{$self->lock_type}++;
warn "@{[$self->lock_type]} $CurrentlyLocking->{$self->lock_type} $self->{file_name}";
  
  open my $file, '>', $self->{file_name} or die "$0: $self->{file_name}: $!";
  flock $file, LOCK_EX;
  $self->{lock} = $file;
} # lock

sub unlock ($) {
  my $self = shift;

  $CurrentlyLocking->{$self->lock_type}--;

  close $self->{lock};
} # unlock

sub DESTROY ($) {
  $_[0]->unlock;
} # DESTROY

1;
1	package SWE::DB::Lock;
2	use strict;
3
4	my $CurrentlyLocking = {};
5	my $LockTypes = [qw/
6	ID Name Index IDs Names Graph Weight Global
7	/];
8	## If you are locking for Graph, then you cannot lock for Global, but
9	## still you can lock for ID.
10
11	## idgen is currently controled by Names lock.
12
13	use Fcntl ':flock';
14
15	sub new ($) {
16	my $self = bless {
17	'file_name' => 'lock',
18	lock_type => 'Global',
19	}, shift;
20	return $self;
21	} # new
22
23	sub lock_type ($;$) {
24	my $self = shift;
25	if (@_) {
26	$self->{lock_type} = shift;
27	}
28	return $self->{lock_type};
29	} # lock_type
30
31	sub check_lockability ($) {
32	my $self = shift;
33
34	my $self_lt = $self->lock_type;
35	for my $lt (@$LockTypes) {
36	if ($self_lt eq $lt) {
37	last;
38	} elsif ($CurrentlyLocking->{$lt}) {
39	die qq[$0: It is currently locking for "$lt" so that it cannot be locked for the "$self_lt"];
40	}
41	}
42
43	return 1;
44	} # check_lockability
45
46	sub lock ($) {
47	my $self = shift;
48
49	$self->check_lockability;
50	$CurrentlyLocking->{$self->lock_type}++;
51	warn "@{[$self->lock_type]} $CurrentlyLocking->{$self->lock_type} $self->{file_name}";
52
53	open my $file, '>', $self->{file_name} or die "$0: $self->{file_name}: $!";
54	flock $file, LOCK_EX;
55	$self->{lock} = $file;
56	} # lock
57
58	sub unlock ($) {
59	my $self = shift;
60
61	$CurrentlyLocking->{$self->lock_type}--;
62
63	close $self->{lock};
64	} # unlock
65
66	sub DESTROY ($) {
67	$_[0]->unlock;
68	} # DESTROY
69
70	1;