/ 
MyCPAN-Indexer-1.18_01
River stage one • 2 direct dependents • 2 total dependents
/ MyCPAN::Indexer::Tutorial

NAME

MyCPAN::Indexer::Tutorial - How the backpan_indexer.pl pieces fit together

DESCRIPTION

The MyCPAN::Indexer system lets you plug in different engines to control major portions of the process. It's up to each class to obey the interface and do that parts the other portions it expects it to do. The idea is to decouple some of these bits as much as possible.

As backpan_indexer.pl does its work, it stores information about its components in an anonymous hash called $Notes. The different components have access to this hash. (To Do: this is some pretty bad design smell, but that's how it is right now).

Specific implementations will impose other requirements not listed in this tutorial.

The Queue class

The Queue class is responsible for getting the list of distributions to process.

backpan_indexer.pl calls get_queue and passes it a ConfigReader::Simple object. get_queue does whatever it needs to do, then returns an array reference of file paths to process. Each path should represent a single Perl distribution.

Implements:

get_queue( $Notes )

Creates in $Notes:

queue - a reference to the array reference returned by get_queue.

Expects in $Notes:

config - the configuration object

To Do: The Queue class should really be an iterator of some sort. Instead of returning an array (which it can't change), return an iterator.

The Worker class

The Worker class returns the anonymous subroutine that the interface class calls for each of its cycles. Inside that code reference, do the actual indexing work, including saving the results. backpan_indexer.pl calls get_task with a reference to its $Notes hash.

Implements:

get_task( $Notes )

Creates in $Notes

child_task - a reference to the code reference returned by get_task.

Expects in $Notes

config - the configuration object

To Do: There should be a storage class which the worker class hands the results to.

The Reporter class

The Reporter class implements the bits to store the result of the Worker class. backpan_indexer.pl calls get_storer with a reference to its $Notes hash.

Implements:

get_reporter( $Notes, $info )

Creates in $Notes:

reporter - the code ref to handle storing the information

Expects in $Notes:

config

Expects in config:

The Dispatcher class

The Dispatcher class implements the bits to hand out work to the worker class. The Interface class, discussed next, repeatedly calls the interface_callback code ref the Dispatcher class provides.

Implements:

get_dispatcher( $Notes )

Creates in $Notes

dispatcher - the dispatcher object, with start and finish methods
interface_callback - a code ref to call repeatedly in the Interface class

Expects in $Notes

config     - the configuration object
child_task - the code ref that handles indexing a single dist
queue      - the array ref of dist paths

The Interface class

The Interface class really has two jobs. It makes the live reporting interface while backpan_indexer.pl runs, at it repeatedly calls the dispatcher to start new work.

Implements:

do_interface( $Notes )

Creates in $Notes

Expects in $Notes

config             - the configuration object
interface_callback - a code ref to call repeatedly in the Interface class

SEE ALSO

MyCPAN::Indexer

SOURCE AVAILABILITY

This code is in Github:

git://github.com/briandfoy/mycpan-indexer.git

AUTHOR

brian d foy, <bdfoy@cpan.org>

COPYRIGHT AND LICENSE

Copyright (c) 2008, brian d foy, All Rights Reserved.

You may redistribute this under the same terms as Perl itself.