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	wakaba	1.1	package SWE::DB::Lock;
2			use strict;
3	wakaba	1.2
4			my $CurrentlyLocking = {};
5			my $LockTypes = [qw/
6			ID Name Index IDs Names Graph Weight Global
7			/];
8	wakaba	1.4	## If you are locking for Graph, then you cannot lock for Global, but
9			## still you can lock for ID.
10
11			## idgen is currently controled by Names lock.
12	wakaba	1.1
13			use Fcntl ':flock';
14
15			sub new ($) {
16			my $self = bless {
17			'file_name' => 'lock',
18	wakaba	1.2	lock_type => 'Global',
19	wakaba	1.1	}, shift;
20			return $self;
21			} # new
22
23	wakaba	1.2	sub lock_type ($;$) {
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 "$self_lt"];
40			}
41			}
42
43			return 1;
44			} # check_lockability
45
46	wakaba	1.1	sub lock ($) {
47			my $self = shift;
48	wakaba	1.2
49			$self->check_lockability;
50			$CurrentlyLocking->{$self->lock_type}++;
51			warn "@{[$self->lock_type]} $CurrentlyLocking->{$self->lock_type} $self->{file_name}";
52	wakaba	1.1
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	wakaba	1.2	my $self = shift;
60
61			$CurrentlyLocking->{$self->lock_type}--;
62
63			close $self->{lock};
64	wakaba	1.1	} # unlock
65
66			sub DESTROY ($) {
67			$_[0]->unlock;
68			} # DESTROY
69
70			1;