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Digital Mages - Paranoid::IO::FileMultiplexer::Block::BATHeader(3)

Paranoid::IO::FileMultiplexer::Block::BATHeader

Section: User Contributed Perl Documentation (3)
Updated: 2021-12-28
Index  

NAME

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

VERSION

$Id: lib/Paranoid/IO/FileMultiplexer/Block/BATHeader.pm, 2.09 2021/12/28 15:46:49 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::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)


 

Index

NAME
VERSION
SYNOPSIS
DESCRIPTION
SUBROUTINES/METHODS
new
maxData
sequence
dataBlocks
full
writeSig
readSig
writeData
readData
addData
DEPENDENCIES
BUGS AND LIMITATIONS
AUTHOR
LICENSE AND COPYRIGHT