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.

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 $LockTypes = [qw/
6			ID Name Index IDs Names Graph Weight Global
7			/];
8			# If you are locking for Graph, then you cannot lock for Global, but
9			# still you can lock for ID.
10	wakaba	1.1
11			use Fcntl ':flock';
12
13			sub new ($) {
14			my $self = bless {
15			'file_name' => 'lock',
16	wakaba	1.2	lock_type => 'Global',
17	wakaba	1.1	}, shift;
18			return $self;
19			} # new
20
21	wakaba	1.2	sub lock_type ($;$) {
22			my $self = shift;
23			if (@_) {
24			$self->{lock_type} = shift;
25			}
26			return $self->{lock_type};
27			} # lock_type
28
29			sub check_lockability ($) {
30			my $self = shift;
31
32			my $self_lt = $self->lock_type;
33			for my $lt (@$LockTypes) {
34			if ($self_lt eq $lt) {
35			last;
36			} elsif ($CurrentlyLocking->{$lt}) {
37			die qq[$0: It is currently locking for "$lt" so that it cannot be locked for the "$self_lt"];
38			}
39			}
40
41			return 1;
42			} # check_lockability
43
44	wakaba	1.1	sub lock ($) {
45			my $self = shift;
46	wakaba	1.2
47			$self->check_lockability;
48			$CurrentlyLocking->{$self->lock_type}++;
49			warn "@{[$self->lock_type]} $CurrentlyLocking->{$self->lock_type} $self->{file_name}";
50	wakaba	1.1
51			open my $file, '>', $self->{file_name} or die "$0: $self->{file_name}: $!";
52			flock $file, LOCK_EX;
53			$self->{lock} = $file;
54			} # lock
55
56			sub unlock ($) {
57	wakaba	1.2	my $self = shift;
58
59			$CurrentlyLocking->{$self->lock_type}--;
60
61			close $self->{lock};
62	wakaba	1.1	} # unlock
63
64			sub DESTROY ($) {
65			$_[0]->unlock;
66			} # DESTROY
67
68			1;