NAME

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

INHERITANCE

        Mail::Box::Locker::Flock
          is a Mail::Box::Locker
          is a Mail::Reporter

SYNOPSIS

        See Mail::Box::Locker

DESCRIPTION

       The "::Flock" object locks the folder by creating an exclusive lock on the file using the
       kernel's "flock" facilities.  This lock is created on a separate file-handle to the folder
       file, so not the handle which is reading.

       File locking does not work in some situations, for instance for operating systems do not
       support "flock".

       Extends "DESCRIPTION" in Mail::Box::Locker.

METHODS

       Extends "METHODS" in Mail::Box::Locker.

   Constructors
       Extends "Constructors" in Mail::Box::Locker.

       Mail::Box::Locker::Flock->new(%options)
            -Option --Defined in       --Default
             expires  Mail::Box::Locker  1 hour
             file     Mail::Box::Locker  undef
             folder   Mail::Box::Locker  <undef>
             log      Mail::Reporter     'WARNINGS'
             method   Mail::Box::Locker  'FLOCK'
             timeout  Mail::Box::Locker  10
             trace    Mail::Reporter     'WARNINGS'

           expires => SECONDS
           file => FILENAME
           folder => FOLDER
           log => LEVEL
           method => STRING|CLASS|ARRAY
           timeout => SECONDS|'NOTIMEOUT'
           trace => LEVEL

   Attributes
       Extends "Attributes" in Mail::Box::Locker.

       $obj->expires( [SECONDS] )
           Inherited, see "Attributes" in Mail::Box::Locker

       $obj->timeout( [SECONDS] )
           Inherited, see "Attributes" in Mail::Box::Locker

   The Locker
       Extends "The Locker" in Mail::Box::Locker.

       $obj->filename( [$filename] )
           Inherited, see "The Locker" in Mail::Box::Locker

       $obj->folder( [$folder] )
           Inherited, see "The Locker" in Mail::Box::Locker

       $obj->name()
           Inherited, see "The Locker" in Mail::Box::Locker

   Locking
       Extends "Locking" in Mail::Box::Locker.

       $obj->hasLock()
           Inherited, see "Locking" in Mail::Box::Locker

       $obj->isLocked()
       $obj->lock()
       $obj->unlock()
           Inherited, see "Locking" in Mail::Box::Locker

   Error handling
       Extends "Error handling" in Mail::Box::Locker.

       $obj->AUTOLOAD()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->addReport($object)
           Inherited, see "Error handling" in Mail::Reporter

       $obj->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level, $callback] )
       Mail::Box::Locker::Flock->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level,
       $callback] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->errors()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->log( [$level, [$strings]] )
       Mail::Box::Locker::Flock->log( [$level, [$strings]] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->logPriority($level)
       Mail::Box::Locker::Flock->logPriority($level)
           Inherited, see "Error handling" in Mail::Reporter

       $obj->logSettings()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->notImplemented()
           Inherited, see "Error handling" in Mail::Reporter

       $obj->report( [$level] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->reportAll( [$level] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->trace( [$level] )
           Inherited, see "Error handling" in Mail::Reporter

       $obj->warnings()
           Inherited, see "Error handling" in Mail::Reporter

   Cleanup
       Extends "Cleanup" in Mail::Box::Locker.

       $obj->DESTROY()
           Inherited, see "Cleanup" in Mail::Box::Locker

DIAGNOSTICS

       Warning: Folder $folder already flocked
           The folder is already locked, but you attempt to lock it again.  The behavior of
           double flock's is platform dependent, and therefore should not be attempted.  The
           second lock is ignored (but the unlock isn't)

       Error: Package $package does not implement $method.
           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.

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

       Error: Unable to open flock file $filename for $folder: $!
           For flock-ing a folder it must be opened, which does not succeed for the specified
           reason.

       Error: Will never get a flock at $filename for $folder: $!
           Tried to flock 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.

SEE ALSO

       This module is part of Mail-Box distribution version 3.004, built on December 22, 2017.

       Do not forget to read Mail::Box-Overview, Mail::Box-Cookbook, and Mail::Box-Index.
       Examples are included in the Mail-Box distribution, directories 'examples' and 'scripts'.

       Browseable manuals, papers, and other released material van be found at  Website:
       http://perl.overmeer.net/mailbox/

       The central modules (in separate distributions) in the MailBox suite are: Mail::Message,
       Mail::Box, Mail::Box::IMAP4, Mail::Box::POP3, Mail::Box::Parser::C, Mail::Box::Dbx
       (unpublished), Mail::Transport, Object::Realize::Later, and User::Identity.

       Please post questions or ideas to the author markov@cpan.org.

LICENSE

       Copyrights 2001-2017 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 http://dev.perl.org/licenses/