Digital Mages - Paranoid::BerkeleyDB(3)

Paranoid::BerkeleyDB

Section: User Contributed Perl Documentation (3)
Updated: 2022-03-08
Index

NAME

Paranoid::BerkeleyDB -- BerkeleyDB Wrapper

VERSION

$Id: lib/Paranoid/BerkeleyDB.pm, 2.06 2022/03/08 22:26:06 acorliss Exp $

SYNOPSIS

  tie %db, 'Paranoid::BerkeleyDB', Filename => './dbdir/data.db';

  # Normal hash activities...

  # Ensure atomic updates
  $dref = tied %db;
  $lock = $dref->cds_lock;
  $db{$key}++;
  $lock->cds_unlock;

  untie %db;

DESCRIPTION

This module provides an OO/tie-based wrapper for BerkeleyDB CDS implementations intended for use in tied hashes.

NOTE: This module breaks significantly with previous incarnations of this module. The primary differences are as follows:

    Pros
    -------------------------------------------------------------
    * Places no limitations on the developer regarding BerekelyDB
      environment and database options
    * Automatically reuses existing environments for multiple 
      tied hashses
    * Uses Btree databases in lieu of hashes, which tended to 
      have issues when the database size grew too large
    * Has a fully implemented tied hash interface incorporating 
      CDS locks
    * Has pervasive debugging built in using L<Paranoid::Debug>

    Cons
    -------------------------------------------------------------
    * Is no longer considered fork-safe, attempted accesses will
      case the child process to B<croak>.
    * Uses Btree databases in lieu of hashes, which does add 
      some additional memory overhead

SUBROUTINES/METHODS

new

  tie %db, 'Paranoid::BerkeleyDB', 
    Filename => './dbdir/data.db';
  tie %db, 'Paranoid::BerkeleyDB', 
    Home     => './dbenv';
    Filename => './dbdir/data.db';

This method is called implicitly when an object is tied. It supports a few differnet invocation styles. The simplest involves simply providing the Home and Filename options. This will set up a CDS environment using the defaults documented in Paranoid::BerkeleyDB::Env(3) and Paranoid::BerkeleyDB::Db(3).

Alternately, you can provide it with Filename and a Paranoid::BerkeleyDB::Env(3) object (or subclassed object) that you instantiated yourself:

  tie %db, 'Paranoid::BerkeleyDB', 
    Env      => $env,
    Filename => 'data.db';

Finally, you can provide it with two hash options to fully control the environment and database instantiation of Paranoid::BerkeleyDB::Env(3) and Paranoid::BerkeleyDB::Db(3):

  tie %db, 'Paranoid::BerkeleyDB', 
    Env      => { %envOpts },
    Db       => { %dbOpts };

dbh

    $dref = tied %db;
    $dbh  = $dref->dbh;

This method provides access to the BerkeleyDB::Btree(3) object reference.

cds_lock

    $dref = tied %db;
    $lock = $dref->cds_lock;

This method provides access to the CDS locks for atomic updates.

DEPENDENCIES

o: BerkeleyDB
o: Carp
o: Class::EHierarchy
o: Fcntl
o: Paranoid
o: Paranoid::BerkeleyDB::Db
o: Paranoid::BerkeleyDB::Env
o: Paranoid::Debug
o: Paranoid::IO
o: Paranoid::IO::Lockfile

BUGS AND LIMITATIONS

-Filename is interpreted differently depending on whether you're using an environment or not. If you're using this module as a standalone DB object any relative paths are interpreted according to your current working directory. If you are using an environment, however, it is interpreted relative to that environment's -Home.

HISTORY

02/12/2016 Complete rewrite

AUTHOR

Arthur Corliss (corliss@digitalmages.com)

LICENSE AND COPYRIGHT

This software is licensed under the same terms as Perl, itself. Please see http://dev.perl.org/licenses/ for more information.

Index

SUBROUTINES/METHODS

new
dbh
cds_lock

DEPENDENCIES

BUGS AND LIMITATIONS

SEE ALSO

HISTORY

AUTHOR