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.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
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.IX Title "Mail::Box::Locker::POSIX 3"
.TH Mail::Box::Locker::POSIX 3 2026-04-11 "perl v5.42.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Mail::Box::Locker::POSIX \- lock a folder using kernel file\-locking
.SH INHERITANCE
.IX Header "INHERITANCE"
.Vb 3
\& Mail::Box::Locker::POSIX
\&   is a Mail::Box::Locker
\&   is a Mail::Reporter
.Ve
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  See Mail::Box::Locker
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This locker object is created by the folder to get an exclusive lock on
the file which contains the data using the kernel\*(Aqs POSIX facilities.  This
lock is created on a separate file\-handle to the folder file, so not the
handle which is reading.
.PP
\&\fBWARNING\fR: Not all platforms support POSIX locking (via fcntl) and not
always in the same way.  This implementation does not use XS to access
the structure of \fBfcntl()\fR: it is better to use the ::FcntlLock which does.
No, this implementation "guesses" the location of the bytes.
.PP
Extends "DESCRIPTION" in Mail::Box::Locker.
.SH METHODS
.IX Header "METHODS"
Extends "METHODS" in Mail::Box::Locker.
.SS Constructors
.IX Subsection "Constructors"
Extends "Constructors" in Mail::Box::Locker.
.ie n .IP $class\->\fBnew\fR(%options) 4
.el .IP \f(CW$class\fR\->\fBnew\fR(%options) 4
.IX Item "$class->new(%options)"
Inherited, see "METHODS" in Mail::Box::Locker
.Sp
.Vb 7
\& \-Option    \-\-Defined in       \-\-Default
\&  expires     Mail::Box::Locker  1 hour
\&  file        Mail::Box::Locker  undef
\&  folder      Mail::Box::Locker  <C<undef>>
\&  method      Mail::Box::Locker  POSIX
\&  posix_file                     <C<undef>>
\&  timeout     Mail::Box::Locker  10
.Ve
.RS 4
.ie n .IP "expires => $seconds" 2
.el .IP "expires => \f(CW$seconds\fR" 2
.IX Item "expires => $seconds"
.PD 0
.ie n .IP "file => $file" 2
.el .IP "file => \f(CW$file\fR" 2
.IX Item "file => $file"
.ie n .IP "folder => $folder" 2
.el .IP "folder => \f(CW$folder\fR" 2
.IX Item "folder => $folder"
.ie n .IP "method => $name|CLASS|\e@names" 2
.el .IP "method => \f(CW$name\fR|CLASS|\e@names" 2
.IX Item "method => $name|CLASS|@names"
.IP "posix_file => FILENAME" 2
.IX Item "posix_file => FILENAME"
.PD
Alternative name for \f(CW\*(C`file\*(C'\fR, especially useful to avoid confusion
when the multi\-locker is used.
.ie n .IP "timeout => $seconds|\*(AqNOTIMEOUT\*(Aq" 2
.el .IP "timeout => \f(CW$seconds\fR|\*(AqNOTIMEOUT\*(Aq" 2
.IX Item "timeout => $seconds|'NOTIMEOUT'"
.RE
.RS 4
.RE
.SS Attributes
.IX Subsection "Attributes"
Extends "Attributes" in Mail::Box::Locker.
.ie n .IP "$obj\->\fBexpires\fR( [SECONDS] )" 4
.el .IP "\f(CW$obj\fR\->\fBexpires\fR( [SECONDS] )" 4
.IX Item "$obj->expires( [SECONDS] )"
Inherited, see "Attributes" in Mail::Box::Locker
.ie n .IP "$obj\->\fBfilename\fR( [$filename] )" 4
.el .IP "\f(CW$obj\fR\->\fBfilename\fR( [$filename] )" 4
.IX Item "$obj->filename( [$filename] )"
Inherited, see "Attributes" in Mail::Box::Locker
.ie n .IP "$obj\->\fBfolder\fR( [$folder] )" 4
.el .IP "\f(CW$obj\fR\->\fBfolder\fR( [$folder] )" 4
.IX Item "$obj->folder( [$folder] )"
Inherited, see "Attributes" in Mail::Box::Locker
.ie n .IP $obj\->\fBname\fR() 4
.el .IP \f(CW$obj\fR\->\fBname\fR() 4
.IX Item "$obj->name()"
Inherited, see "Attributes" in Mail::Box::Locker
.ie n .IP "$obj\->\fBtimeout\fR( [SECONDS] )" 4
.el .IP "\f(CW$obj\fR\->\fBtimeout\fR( [SECONDS] )" 4
.IX Item "$obj->timeout( [SECONDS] )"
Inherited, see "Attributes" in Mail::Box::Locker
.SS Locking
.IX Subsection "Locking"
Extends "Locking" in Mail::Box::Locker.
.ie n .IP $obj\->\fBhasLock\fR() 4
.el .IP \f(CW$obj\fR\->\fBhasLock\fR() 4
.IX Item "$obj->hasLock()"
Inherited, see "Locking" in Mail::Box::Locker
.ie n .IP $obj\->\fBisLocked\fR() 4
.el .IP \f(CW$obj\fR\->\fBisLocked\fR() 4
.IX Item "$obj->isLocked()"
Inherited, see "Locking" in Mail::Box::Locker
.ie n .IP $obj\->\fBlock\fR() 4
.el .IP \f(CW$obj\fR\->\fBlock\fR() 4
.IX Item "$obj->lock()"
Inherited, see "Locking" in Mail::Box::Locker
.ie n .IP $obj\->\fBunlock\fR() 4
.el .IP \f(CW$obj\fR\->\fBunlock\fR() 4
.IX Item "$obj->unlock()"
Inherited, see "Locking" in Mail::Box::Locker
.SS "Error handling"
.IX Subsection "Error handling"
Extends "Error handling" in Mail::Box::Locker.
.ie n .IP $obj\->\fBAUTOLOAD\fR() 4
.el .IP \f(CW$obj\fR\->\fBAUTOLOAD\fR() 4
.IX Item "$obj->AUTOLOAD()"
Inherited, see "Error handling" in Mail::Reporter
.ie n .IP $obj\->\fBnotImplemented\fR() 4
.el .IP \f(CW$obj\fR\->\fBnotImplemented\fR() 4
.IX Item "$obj->notImplemented()"
Inherited, see "Error handling" in Mail::Reporter
.SS Cleanup
.IX Subsection "Cleanup"
Extends "Cleanup" in Mail::Box::Locker.
.ie n .IP $obj\->\fBDESTROY\fR() 4
.el .IP \f(CW$obj\fR\->\fBDESTROY\fR() 4
.IX Item "$obj->DESTROY()"
Inherited, see "Cleanup" in Mail::Box::Locker
.SH DIAGNOSTICS
.IX Header "DIAGNOSTICS"
.ie n .IP "Error: class $package does not implement method $method." 4
.el .IP "Error: class \f(CW$package\fR does not implement method \f(CW$method\fR." 4
.IX Item "Error: class $package does not implement method $method."
Fatal error: the specific \f(CW$package\fR (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.
Cast by \f(CWnotImplemented()\fR
.ie n .IP "Warning: folder $name already lockf\*(Aqd." 4
.el .IP "Warning: folder \f(CW$name\fR already lockf\*(Aqd." 4
.IX Item "Warning: folder $name already lockf'd."
Cast by \f(CWlock()\fR
.ie n .IP "Fault: unable to check lock file $file for $folder: $!" 4
.el .IP "Fault: unable to check lock file \f(CW$file\fR for \f(CW$folder:\fR $!" 4
.IX Item "Fault: unable to check lock file $file for $folder: $!"
To check whether the \f(CW$file\fR is used to flock a \f(CW$folder\fR, the file must be
opened.  Apparently this fails, which does not mean that the folder is
locked neither that it is unlocked.
Cast by \f(CWisLocked()\fR
.ie n .IP "Fault: unable to open POSIX lock file $file for $folder: $!" 4
.el .IP "Fault: unable to open POSIX lock file \f(CW$file\fR for \f(CW$folder:\fR $!" 4
.IX Item "Fault: unable to open POSIX lock file $file for $folder: $!"
For POSIX style locking, a \f(CW$folder\fR it must be opened, which does not
succeed for the specified reason.
Cast by \f(CWlock()\fR
.ie n .IP "Fault: will never get a POSIX lock at $file for $folder: $!" 4
.el .IP "Fault: will never get a POSIX lock at \f(CW$file\fR for \f(CW$folder:\fR $!" 4
.IX Item "Fault: will never get a POSIX lock at $file for $folder: $!"
Tried to lock the \f(CW$folder\fR, 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.
Cast by \f(CWlock()\fR
.SH "SEE ALSO"
.IX Header "SEE ALSO"
This module is part of Mail\-Box version 4.02,
built on April 10, 2026. Website: \fIhttp://perl.overmeer.net/CPAN/\fR
.SH LICENSE
.IX Header "LICENSE"
For contributors see file ChangeLog.
.PP
This software is copyright (c) 2001\-2026 by Mark Overmeer.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.