phpman > perldoc > Mail::Box::Thread::Manager(3pm)

NAME
    Mail::Box::Thread::Manager - maintain threads within a set of folders

INHERITANCE
     Mail::Box::Thread::Manager
       is a Mail::Reporter

SYNOPSIS
     my $mgr     = Mail::Box::Manager->new;
     my $folder  = $mgr->open(folder => '/tmp/inbox');

     my $threads = $mgr->threads();
     $threads->includeFolder($folder);

     my $threads = $msg->threads(folder => $folder);

     foreach my $thread ($threads->all) {
         $thread->print;
     }

     $threads->removeFolder($folder);

DESCRIPTION
    A (message-)*thread* is a message with links to messages which followed in reply of that
    message. And then the messages with replied to the messages, which replied the original message.
    And so on. Some threads are only one message long (never replied to), some threads are very
    long.

    The "Mail::Box::Thread::Manager" is very powerful. Not only is it able to do a descent job on
    MH-like folders (makes a trade-off between perfection and speed), it also can maintain threads
    from messages residing in different opened folders. Both facilities are rare for mail-agents.
    The manager creates flexible trees with Mail::Box::Thread::Node objects.

    Extends "DESCRIPTION" in Mail::Reporter.

METHODS
    Extends "METHODS" in Mail::Reporter.

  Constructors
    Extends "Constructors" in Mail::Reporter.

    Mail::Box::Thread::Manager->new(%options)
        A "Mail::Box::Thread::Manager" object is usually created by a Mail::Box::Manager. One
        manager can produce more than one of these objects. One thread manager can combine messages
        from a set of folders, which may be partially overlapping with other objects of the same
        type.

         -Option     --Defined in     --Default
          dummy_type                    Mail::Message::Dummy
          folder                        [ ]
          folders                       [ ]
          log          Mail::Reporter   'WARNINGS'
          thread_body                   <false>
          thread_type                   Mail::Box::Thread::Node
          timespan                      '3 days'
          trace        Mail::Reporter   'WARNINGS'
          window                        10

        dummy_type => CLASS
          The type of dummy messages. Dummy messages are used to fill holes in detected threads:
          referred to by messages found in the folder, but itself not in the folder.

        folder => FOLDER | REF-ARRAY-FOLDERS
          Specifies which folders are to be covered by the threads. You can specify one or more open
          folders. When you close a folder, the manager will automatically remove the messages of
          that folder from your threads.

        folders => FOLDER | REF-ARRAY-FOLDERS
          Equivalent to the "folder" option.

        log => LEVEL
        thread_body => BOOLEAN
          May thread-detection be based on the content of a message? This has a serious performance
          implication when there are many messages without "In-Reply-To" and "References" headers in
          the folder, because it will cause many messages to be parsed. NOT IMPLEMENTED YET.

        thread_type => CLASS
          Type of the thread nodes.

        timespan => TIME | 'EVER'
          Specify how fast threads usually work: the amount of time between an answer and a reply.
          This is used in combination with the "window" option to determine when to give-up filling
          the holes in threads.

          See Mail::Box::timespan2seconds() for the possibilities for TIME. With 'EVER', the search
          for messages in a thread will only be limited by the window-size.

        trace => LEVEL
        window => INTEGER|'ALL'
          The thread-window describes how many messages should be checked at maximum to fill `holes'
          in threads for folder which use delay-loading of message headers.

          The constant 'ALL' will cause thread-detection not to stop trying to fill holes, but
          continue looking until the first message of the folder is reached. Gives the best quality
          results, but may perform bad.

        example:

         use Mail::Box::Manager;
         my $mgr     = Mail::Box::Manager->new;
         my $inbox   = $mgr->open(folder => $ENV{MAIL});
         my $read    = $mgr->open(folder => 'Mail/read');
         my $threads = $mgr->threads(folders => [$inbox, $read]);

         # longer alternative for last line:
         my $threads = $mgr->threads;
         $threads->includeFolder($inbox);
         $threads->includeFolder($read);

  Grouping Folders
    $obj->folders()
        Returns the folders as managed by this threader.

    $obj->includeFolder($folders)
        Add one or more folders to the list of folders whose messages are organized in the threads
        maintained by this object. Duplicated inclusions will not cause any problems.

        From the folders, the messages which have their header lines parsed (see Mail::Box about
        lazy extracting) will be immediately scanned. Messages of which the header is known only
        later will have to report this (see toBeThreaded()).

        example:

         $threads->includeFolder($inbox, $draft);

    $obj->removeFolder($folders)
        Remove one or more folders from the list of folders whose messages are organized in the
        threads maintained by this object.

        example:

         $threads->removeFolder($draft);

  The Threads
    $obj->all()
        Returns all messages which start a thread. The list may contain dummy messages and messages
        which are scheduled for deletion.

        To be able to return all threads, thread construction on each message is performed first,
        which may be slow for some folder-types because is will enforce parsing of message-bodies.

    $obj->known()
        Returns the list of all messages which are known to be the start of a thread. Threads
        containing messages which where not read from their folder (like often happens MH-folder
        messages) are not yet known, and hence will not be returned.

        The list may contain dummy messages, and messages which are scheduled for deletion. Threads
        are detected based on explicitly calling inThread() and thread() with a messages from the
        folder.

        Be warned that, each time a message's header is read from the folder, the return of the
        method can change.

    $obj->sortedAll( [$prepare, [$compare]] )
        Returns all() the threads by default, but sorted on timestamp.

    $obj->sortedKnown( [$prepare, [$compare]] )
        Returns all known() threads, in sorted order. By default, the threads will be sorted on
        timestamp, But a different $compare method can be specified.

    $obj->thread($message)
        Returns the thread where this $message is the start of. However, there is a possibility that
        this message is a reply itself.

        Usually, all messages which are in reply of this message are dated later than the specified
        one. All headers of messages later than this one are getting parsed first, for each folder
        in this threads-object.

        example:

         my $threads = $mgr->threads(folder => $inbox);
         my $thread  = $threads->thread($inbox->message(3));
         print $thread->string;

    $obj->threadStart($message)
        Based on a message, and facts from previously detected threads, try to build solid knowledge
        about the thread where this message is in.

  Internals
    $obj->createDummy($message_id)
        Get a replacement message to be used in threads. Be warned that a dummy is not a member of
        any folder, so the program working with threads must test with Mail::Message::isDummy()
        before trying things only available to real messages.

    $obj->inThread($message)
        Collect the thread-information of one message. The `In-Reply-To' and `Reference'
        header-fields are processed. If this method is called on a message whose header was not read
        yet (as usual for MH-folders, for instance) the reading of that header will be triggered
        here.

    $obj->outThread($message)
        Remove the message from the thread-infrastructure. A message is replaced by a dummy.

    $obj->toBeThreaded($folder, @messages)
        Include the specified messages in/from the threads managed by this object, if this folder is
        maintained by this thread-manager.

    $obj->toBeUnthreaded($folder, @messages)
        Remove the specified @messages in/from the threads managed by this object, if this folder is
        maintained by this thread-manager.

  Error handling
    Extends "Error handling" in Mail::Reporter.

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

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

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

    $obj->logPriority($level)
    Mail::Box::Thread::Manager->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::Reporter.

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

DETAILS
    This module implements thread-detection on a folder. Messages created by the better mailers will
    include "In-Reply-To" and "References" lines, which are used to figure out how messages are
    related. If you prefer a better thread detection, they are implementable, but there may be a
    serious performance hit (depends on the type of folder used).

  Maintaining threads
    A "Mail::Box::Thread::Manager" object is created by the Mail::Box::Manager, using
    Mail::Box::Manager::threads(). Each object can monitor the thread-relations between messages in
    one or more folders. When more than one folder is specified, the messages are merged while
    reading the threads, although nothing changes in the folder-structure. Adding and removing
    folders which have to be maintained is permitted at any moment, although may be quite costly in
    performance.

    An example of the maintained structure is shown below. The Mail::Box::Manager has two open
    folders, and a thread-builder which monitors them both. The combined folders have two threads,
    the second is two long (msg3 is a reply on msg2). Msg2 is in two folders at once.

           manager
            |    \
            |     `----------- threads
            |                  |     |
            |                thread thread---thread
            |                  |    /|        /
            |                  |   //        /
            +---- folder1      |  //        /
            |       |         /  //        /
            |       `-----msg1  //        /
            |       `-----msg2-'/        /
            |                  /        /
            `-----folder2     /        /
                    |        /        /
                    `-----msg2       /
                    `-----msg3------'

  Delayed thread detection
    With all() you get the start-messages of each thread of this folder. When that message was not
    found in the folder (not saved or already removed), you get a message of the dummy-type. These
    thread descriptions are in perfect state: all messages of the folder are included somewhere, and
    each missing message of the threads (*holes*) are filled by dummies.

    However, to be able to detect all threads it is required to have the headers of all messages,
    which is very slow for some types of folders, especially MH and IMAP folders.

    For interactive mail-readers, it is preferred to detect threads only on messages which are in
    the viewport of the user. This may be sloppy in some situations, but everything is preferable
    over reading an MH mailbox with 10k e-mails to read only the see most recent messages.

    In this object, we take special care not to cause unnecessary parsing (loading) of messages.
    Threads will only be detected on command, and by default only the message headers are used.

    The following reports the Mail::Box::Thread::Node which is related to a message:

     my $thread = $message->thread;

    When the message was not put in a thread yet, it is done now. But, more work is done to return
    the best thread. Based on various parameters, which where specified when the folder was created,
    the method walks through the folder to fill the holes which are in this thread.

    Walking from back to front (recently arrived messages are usually in the back of the folder),
    message after message are triggered to be included in their thread. At a certain moment, the
    whole thread of the requested method is found, a certain maximum number of messages was tried,
    but that didn't help (search window bound reached), or the messages within the folder are
    getting too old. Then the search to complete the thread will end, although more messages of them
    might have been in the folder: we don't scan the whole folder for performance reasons.

    Finally, for each message where the head is known, for instance for all messages in
    mbox-folders, the correct thread is determined immediately. Also, all messages where the head
    get loaded later, are automatically included.

DIAGNOSTICS
    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.

SEE ALSO
    This module is part of Mail-Box distribution version 3.009, built on August 18, 2020. Website:
    http://perl.overmeer.net/CPAN/

LICENSE
    Copyrights 2001-2020 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/