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#
# This file is part of Log-Dispatch-FileRotate
#
# This software is copyright (c) 2005 by Mark Pfeiffer.
#
# This is free software; you can redistribute it and/or modify it under
# the same terms as the Perl 5 programming language system itself.
#
package Log::Dispatch::FileRotate::Mutex;
$Log::Dispatch::FileRotate::Mutex::VERSION = '1.38';
# ABSTRACT: Flock Based File Mutex.
use strict;
use warnings;
use Carp 'croak';
use Log::Dispatch::FileRotate::Flock qw(safe_flock flopen);
use Fcntl ':flock';
my $HAS_THREADS = $INC{'threads.pm'} ? 1 : 0;
my $THREAD_ID = $HAS_THREADS ? threads->tid() : 0;
sub CLONE {
$THREAD_ID = threads->tid() if $HAS_THREADS;
}
sub DESTROY {
my $self = shift;
my $pid = $self->pid;
if ($self->{$pid}) {
$self->unlock;
close(delete $self->{_fh});
}
return;
}
sub new {
my ($class, $path, %args) = @_;
$class = ref $class || $class;
my $self = bless {
_path => $path,
%args
}, $class;
return $self;
}
sub lock {
my $self = shift;
my $pid = $self->pid;
unless (exists $self->{$pid}) {
# we have not opened the lockfile in this thread.
my ($fh, $inode) = flopen($self->{_path});
$self->_set_permissions;
unless (defined $fh) {
return 0;
}
$self->{_fh} = $fh;
$self->{_inode} = $inode;
$self->{$pid} = 1;
}
elsif ($self->{$pid} == 0) {
# file is open, but not locked.
if (safe_flock($self->{_fh}, LOCK_EX)) {
my ($inode) = (stat $self->{_path})[1];
if ($inode != $self->{_inode}) {
# file was removed or changed underneath us, reopen instead
delete $self->{$pid};
close(delete $self->{_fh});
delete $self->{$pid};
delete $self->{_inode};
return $self->lock;
}
$self->{$pid} = 1;
}
}
# otherwise this $pid is already holding the lock
return $self->{$pid} || 0;
}
sub _set_permissions {
my $self = shift;
unless (defined $self->{permissions}) {
return;
}
my $file = $self->{_path};
my $current_mode = (stat $self->{_path})[2] & 07777;
if ($current_mode ne $self->{permissions}) {
chmod $self->{permissions}, $self->{_path}
or croak sprintf 'Failed to chmod %s to %04o: %s',
$self->{_path}, $self->{permissions} & 07777, $!;
}
}
sub unlock {
my $self = shift;
my $pid = $self->pid;
if ($self->{$pid}) {
safe_flock($self->{_fh}, LOCK_UN);
$self->{$pid} = 0;
}
}
sub pid {
return $HAS_THREADS
? join('.', $$, $THREAD_ID)
: $$;
}
1;
__END__
=pod
=encoding UTF-8
=head1 NAME
Log::Dispatch::FileRotate::Mutex - Flock Based File Mutex.
=head1 VERSION
version 1.38
=head1 SYNOPSIS
Internal Use Only!
=head1 DESCRIPTION
Internal Use Only!
=head1 METHODS
=head2 new($path)
Create a new mutex for the given file path. Only one mutex per path should be
created. The path will not actually be opened or locked until you call L<lock>.
=head2 lock()
Obtains a lock on the path. If the thread id or pid has changed since the path
was opened, the path will be re-opened automatically in this thread or process.
=head2 unlock()
Releases the lock if the current thread or process is holding it.
=head2 pid(): string
Get the current process or thread id
=head1 SOURCE
The development version is on github at L<https://https://github.com/mschout/perl-log-dispatch-filerotate>
and may be cloned from L<git://https://github.com/mschout/perl-log-dispatch-filerotate.git>
=head1 BUGS
Please report any bugs or feature requests on the bugtracker website
L<https://github.com/mschout/perl-log-dispatch-filerotate/issues>
When submitting a bug or request, please include a test-file or a
patch to an existing test-file that illustrates the bug or desired
feature.
=head1 AUTHOR
Michael Schout <mschout@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2005 by Mark Pfeiffer.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
|
