NAME

File::Find::Parallel - Traverse a number of similar directories in parallel

VERSION

This document describes File::Find::Parallel version 0.0.1

SYNOPSIS

    use File::Find::Parallel;

    my $ffp = File::Find::Parallel->new( qw( /foo /bar ) );

    print "Union:\n";
    my $union = $ffp->any_iterator
    print "  $_\n" while $_ = $union->();

    print "Intersection:\n";
    my $inter = $ffp->all_iterator
    print "  $_\n" while $_ = $inter->();

DESCRIPTION

File::Find is the ideal tool for quickly scanning a single directory. But sometimes it's nice to be able to perform operations on multiple similar directories in parallel. Perhaps you need to compare the contents of two directories or convert files that are shared in more than one directory into hard links.

This module manufactures iterators that visit each file and directory in either the union or the intersection of a number of directories. Hmm. What does that mean?

Given two directory trees like this

    foo
    foo/a
    foo/b/c
    foo/d

    bar
    bar/a
    bar/b
    bar/e

you can choose to work with the intersection of the two directory structures:

    .
    ./a
    ./b

That is the subdirectories and files that the foo and bar share.

Alternately you can work with the union of the two directory structures:

    .
    ./a
    ./b
    ./b/c
    ./d
    ./e

Still not clear? Well, if you wanted to do a recursive diff on the two directories you'd iterate their union so you could report files that were present in foo but missing from bar and vice-versa.

If, on the other hand you wanted to scan the directories and make any files shared in both into hard links you'd iterate their intersection: there's no potential for hard linking items that exist in only one directory.

File::Find::Parallel can scan any number of directories at the same time. Here's an example (on Unix systems) that returns the list of all files and directories that are contained in all home directories.

    use File::Glob ':glob';
    use File::Find::Parallel;

    my $find = File::Find::Parallel->new( bsd_glob( '/home/*' ) );

    my @common = ( );
    my $iter = $find->all_iterator;
    while ( defined my $obj = $iter->() ) {
        push @common, $obj;
    }

    print "The following files are common to ",
          "all directories below /home :\n";

    print "    $_\n" for @common;

INTERFACE

new

Create a new File::Find::Parallel. You may optionally pass a list of directories to scan.

set_dirs( @dirs )

Set the list of directories to be scanned. Any number of directories may be scanned. If you are scanning just a single directory consider using File::Find instead.

get_dirs

Get the list of directories to be scanned.

    my @dirs_to_scan = $ffp->get_dirs;

add_dirs

Add to the list of directories to be scanned.

    $ffp->add_dirs( 'a' );
    $ffp->add_dirs( 'b', 'c' );

any_iterator

Get an iterator that will return the names of all the files and directories that are in the union of the directories to be scanned.

The returned iterator is a code reference that returns a new name each time it is called. It returns undef when all names have been returned.

The returned names are relative to the base directories. Given directories like this

    foo             bar
    foo/a           bar/a
    foo/b/c         bar/d/e

the iterator would return

    .
    a
    b
    d
    b/c
    d/e

That is it returns the list of names that would result if foo was copied over bar and then bar scanned.

Directories are searched in breadth first order.

all_iterator

Get an iterator that will return the names of all the files and directories that are in the intersection of the directories to be scanned.

Given directories like this

    foo             bar
    foo/a           bar/a
    foo/b/c         bar/d/e

the iterator would return

    .
    a

That is it returns the names of those files and directories that can be found in both foo and bar.

Create a new File::Find::Parallel.

DEPENDENCIES

The tests require File::Tempdir.

BUGS AND LIMITATIONS

I haven't checked but it must be slower than File::Find. Use that instead if you only want to scan a single directory at a time.

Please report any bugs or feature requests to bug-file-find-parallel@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR

Andy Armstrong <andy@hexten.net>

LICENCE AND COPYRIGHT

Copyright (c) 2007, Andy Armstrong <andy@hexten.net>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.