NAME

       Paranoid::IO::FileMultiplexer::Block::BATHeader - BAT Header Block

VERSION

       $Id: lib/Paranoid/IO/FileMultiplexer/Block/BATHeader.pm, 2.10 2022/03/08 00:01:04 acorliss
       Exp $

SYNOPSIS

           $obj = Paranoid::IO::FileMultiplexer::Block::BATHeader->new($file,
               $blockNo, $blockSize, $strmName, $sequenceNo);

           $max  = $obj->maxData;
           $seq  = $obj->sequence;
           @data = $obj->dataBlocks;
           $rv   = $obj->full;

           $rv = $obj->writeSig;
           $rv = $obj->readSig;
           $rv = $obj->writeData;
           $rv = $obj->readData;
           $rv = $obj->addData($bn);

DESCRIPTION

       This class is not meant to be used directly, but as part of the
       Paranoid::IO::FileMultiplexer functionality.  This provides functionality necessary for
       manipulation of the stream header block.

       This module does presume that whatever file it is being used on has already been opened in
       the appropriate mode, and that the Paranoid::IO flock stack has been enabled.  For the
       purposes of Paranoid::IO::FileMultiplexer, this is done in that class.

SUBROUTINES/METHODS

   new
           $obj = Paranoid::IO::FileMultiplexer::Block::BATHeader->new($file,
               $blockNo, $blockSize, $strmName, $sequenceNo);

       This creates a new instance of a BAT header block object.  It requires the filename in
       order to retrieve the cached file handle from Paranoid::IO, the block number of the block,
       the size of the block, the name of the stream, and the block sequence number.

       NOTE: creating an object does not automatically create the file and/or write a signature.
       That must be done using the methods below.

   maxData
           $max = $obj->maxData;

       This method returns the maximum number of data blocks that can be tracked in a single BAT
       block.

   sequence
           $seq = $obj->sequence;

       This method returns the sequence number of the BAT.  In essence, this is the ordinal index
       of the BAT in a stream's array of BATs.

   dataBlocks
           @data = $obj->dataBlocks;

       This method returns the list of data blocks being tracked by this BAT.

   full
           $rv   = $obj->full;

       This method returns a boolean value denoting whether this BAT's array of data blocks is at
       maximum capacity or not.

   writeSig
           $rv = $obj->writeSig;

       This method writes the BAT header signature to disk, returning a boolean value denoting
       its success.  Note that the signature contains the file format, stream name, and the BAT
       sequence number.  This does not include the allocated data block numbers.

   readSig
           $rv = $obj->readSig;

       This method reads the BAT header signature from disk and performs basic validation that
       the information in it is acceptable.  It validates that the stream name and sequence
       number matches what is expected and the block format is correct.

       If the method call was successful it will update the cached values in the object.  Note
       that this is only the signature values, not the data block numbers.

   writeData
           $rv = $obj->writeData;

       This method writes the data block numbers to the header block, and returns a boolean
       denoting success.

   readData
           $rv = $obj->readData;

       This method reads the data block numbers from the file, and returns a boolean value
       denoting success.  If the read is successful, this will update the cached data blocks in
       the object.

   addData
           $rv = $obj->addData($bn);

       This method does some basic validation of the requested BAT, and if it passes, updates the
       data block number list on the disk.

DEPENDENCIES

       o   Fcntl

       o   Paranoid

       o   Paranoid::Debug

       o   Paranoid::Data

       o   Paranoid::IO

       o   Paranoid::IOFileMultiplexer::Block

BUGS AND LIMITATIONS

AUTHOR

       Arthur Corliss (corliss@digitalmages.com)

LICENSE AND COPYRIGHT

       This software is free software.  Similar to Perl, you can redistribute it and/or modify it
       under the terms of either:

         a)     the GNU General Public License
                <https://www.gnu.org/licenses/gpl-1.0.html> as published by the
                Free Software Foundation <http://www.fsf.org/>; either version 1
                <https://www.gnu.org/licenses/gpl-1.0.html>, or any later version
                <https://www.gnu.org/licenses/license-list.html#GNUGPL>, or
         b)     the Artistic License 2.0
                <https://opensource.org/licenses/Artistic-2.0>,

       subject to the following additional term:  No trademark rights to "Paranoid" have been or
       are conveyed under any of the above licenses.  However, "Paranoid" may be used fairly to
       describe this unmodified software, in good faith, but not as a trademark.

       (c) 2005 - 2021, Arthur Corliss (corliss@digitalmages.com) (tm) 2008 - 2021, Paranoid Inc.
       (www.paranoid.com)

perl v5.34.0                                2Paranoid::IO::FileMultiplexer::Block::BATHeader(3pm)