Data::Stream::Bulk(3pm) 				User Contributed Perl Documentation				   Data::Stream::Bulk(3pm)

NAME

       Data::Stream::Bulk - N at a time iteration API

VERSION

       version 0.11

SYNOPSIS

	       # get a bulk stream from somewere
	       my $s = Data::Stream::Bulk::Foo->new( ... );

	       # can be used like this:
	       until ( $s->is_done ) {
		       foreach my $item ( $s->items ) {
			       process($item);
		       }
	       }

	       # or like this:
	       while( my $block = $s->next ) {
		       foreach my $item ( @$block ) {
			       process($item);
		       }
	       }

DESCRIPTION

       This module tries to find middle ground between one at a time and all at once processing of data sets.

       The purpose of this module is to avoid the overhead of implementing an iterative api when this isn't necessary, without breaking forward
       compatibility in case that becomes necessary later on.

       The API optimizes for when a data set typically fits in memory and is returned as an array, but the consumer cannot assume that the data
       set is bounded.

       The API is destructive in order to minimize the chance that resultsets are leaked due to improper usage.

API

   Required Methods
       The API requires two methods to be implemented:

       is_done
	   Should return true if the stream is exhausted.

	   As long as this method returns a false value (not done) "next" could potentially return another block.

       next
	   Returns the next block.

	   Note that "next" is not guaranteed to return an array reference, even if "is_done" returned false prior to calling it.

   Convenience Methods
       items
	   This method calls "next" and dereferences the result if there are pending items.

       all Force evaluation of the entire resultset.

	   Note that for large data sets this might cause swap thrashing of various other undesired effects. Use with caution.

       cat @streams
	   Concatenates this stream with @streams, returning a single stream.

       list_cat @tail
	   Returns a possibly cleaned up list of streams.

	   Used by "cat".

	   Overridden by Data::Stream::Bulk::Array, Data::Stream::Bulk::Cat and Data::Stream::Bulk::Nil to implement some simple short circuiting.

       filter $filter
	   Applies a per-block block filter to the stream.

	   Returns a possibly new stream with the filtering layered.

	   $filter is invoked once per block and should return an array reference to the filtered block.

       chunk $chunk_size
	   Chunks the input stream so that each block returned by "next" will have at least $chunk_size items.

       loaded
	   Should be overridden to return true if all the items are already realized (e.g.  in the case of Data::Stream::Bulk::Array).

	   Returns false by default.

	   When true calling "all" is supposed to be safe (memory usage should be in the same order of magnitude as stream's own usage).

	   This is typically useful when tranforming an array is easier than transorming a stream (e.g. optional duplicate filtering).

CLASSES

       Data::Stream::Bulk::Array
	   This class is not a stream at all, but just one block. When the data set easily fits in memory this class can be used, while retaining
	   forward compatibility with larger data sets.

       Data::Stream::Bulk::Callback
	   Callback driven iteration.

       Data::Stream::Bulk::Chunked
	   Wrapper to return larger blocks from an existing stream.

       Data::Stream::Bulk::DBI
	   Bulk fetching of data from DBI statement handles.

       Data::Stream::Bulk::DBIC
	   DBIx::Class::ResultSet iteration.

       Data::Stream::Bulk::FileHandle
	   Iterates over lines in a text file.

       Data::Stream::Bulk::Nil
	   An empty result set.

       Data::Stream::Bulk::Cat
	   A concatenation of several streams.

       Data::Stream::Bulk::Filter
	   A filter wrapping a stream.

SEE ALSO

       HOP::Stream, Iterator, Class::Iterator etc for one by one iteration

       DBI, DBIx::Class::ResultSet

       POE::Filter

       Data::Page

       Parallel::Iterator

       <http://en.wikipedia.org/wiki/MapReduce>, LISP, and all that other kool aid

TODO

       Sorted streams
	   Add a hint for sorted streams (like "loaded" but as an attribute in the base role).

	   Introduce a "merge" operation for merging of sorted streams.

	   Optimize "unique" to make use of sorting hints for constant space uniquing.

       More utility functions
	   To assist in proccessing and creating streams.

       Coercion tables
	   Moose::Util::TypeConstraints

VERSION CONTROL

       This module is maintained using git. You can get the latest version from http://github.com/nothingmuch/data-stream-bulk/
       <http://github.com/nothingmuch/data-stream-bulk/>.

AUTHOR

       Yuval Kogman <nothingmuch@woobling.org>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2012 by Yuval Kogman.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.14.2							    2012-02-14						   Data::Stream::Bulk(3pm)