=head1 NAME

Mail::Box::Locker::POSIX - lock a folder using kernel file-locking

=head1 INHERITANCE

 Mail::Box::Locker::POSIX
   is a Mail::Box::Locker
   is a Mail::Reporter

=head1 SYNOPSIS

 See Mail::Box::Locker

=head1 DESCRIPTION

This locker object is created by the folder to get an exclusive lock on
the file which contains the data using the kernel's POSIX facilities.  This
lock is created on a separate file-handle to the folder file, so not the
handle which is reading.  Not all platforms support POSIX locking.

=head1 METHODS

=head2 Constructors

Mail::Box::Locker::POSIX-E<gt>B<new>(OPTIONS)

=over 4

 Option --Defined in     --Default
 expires  Mail::Box::Locker  1 hour
 file     Mail::Box::Locker  undef
 folder   Mail::Box::Locker  <required>
 log      Mail::Reporter   'WARNINGS'
 method   Mail::Box::Locker  POSIX
 timeout  Mail::Box::Locker  10 seconds
 trace    Mail::Reporter   'WARNINGS'

. expires => SECONDS

. file => FILENAME

. folder => FOLDER

. log => LEVEL

. method => STRING|CLASS|ARRAY

. timeout => SECONDS|'NOTIMEOUT'

. trace => LEVEL

=back

=head2 The Locker

$obj-E<gt>B<filename>([FILENAME])

=over 4

See L<Mail::Box::Locker/"The Locker">

=back

$obj-E<gt>B<folder>

=over 4

See L<Mail::Box::Locker/"The Locker">

=back

$obj-E<gt>B<name>

=over 4

See L<Mail::Box::Locker/"The Locker">

=back

=head2 Locking

$obj-E<gt>B<hasLock>

=over 4

See L<Mail::Box::Locker/"Locking">

=back

$obj-E<gt>B<isLocked>

=over 4

=back

$obj-E<gt>B<lock>

=over 4

=back

$obj-E<gt>B<unlock>

=over 4

See L<Mail::Box::Locker/"Locking">

=back

=head2 Error handling

$obj-E<gt>B<AUTOLOAD>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<addReport>(OBJECT)

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<defaultTrace>([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])

Mail::Box::Locker::POSIX-E<gt>B<defaultTrace>([LEVEL]|[LOGLEVEL, TRACELEVEL]|[LEVEL, CALLBACK])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<errors>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<log>([LEVEL [,STRINGS]])

Mail::Box::Locker::POSIX-E<gt>B<log>([LEVEL [,STRINGS]])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<logPriority>(LEVEL)

Mail::Box::Locker::POSIX-E<gt>B<logPriority>(LEVEL)

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<logSettings>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<notImplemented>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<report>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<reportAll>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<trace>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<warnings>

=over 4

See L<Mail::Reporter/"Error handling">

=back

=head2 Cleanup

$obj-E<gt>B<DESTROY>

=over 4

See L<Mail::Box::Locker/"Cleanup">

=back

$obj-E<gt>B<inGlobalDestruction>

=over 4

See L<Mail::Reporter/"Cleanup">

=back

=head1 DIAGNOSTICS

Warning: Folder $folder already lockf'd

=over 4

=back

Error: Package $package does not implement $method.

=over 4

Fatal error: the specific package (or one of its superclasses) does not
implement this method where it should. This message means that some other
related classes do implement this method however the class at hand does
not.  Probably you should investigate this and probably inform the author
of the package.

=back

Error: Unable to check lock file $filename for $folder: $!

=over 4

To check whether the filename is used to flock a folder, the file must be
opened.  Apparently this fails, which does not mean that the folder is
locked neither that it is unlocked.

=back

Error: Unable to open POSIX lock file $filename for $folder: $!

=over 4

For POSIX style locking, a folder it must be opened, which does not
succeed for the specified reason.

=back

Error: Will never get a POSIX lock at $filename for $folder: $!

=over 4

Tried to lock the folder, but it did not succeed.  The error code received
from the OS indicates that it will not succeed ever, so we do not need to
try again.

=back

=head1 SEE ALSO

This module is part of Mail-Box distribution version 2.079,
built on November 28, 2007. Website: F<http://perl.overmeer.net/mailbox/>

=head1 LICENSE

Copyrights 2001-2007 by Mark Overmeer. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://www.perl.com/perl/misc/Artistic.html>