NAME

Acme::Selection::RarestFirst - Rarest-First Selection Algorithm

SYNOPSIS

use Acme::Selection::RarestFirst;

my $selector = Acme::Selection::RarestFirst->new( size => 100 );

# Update availability based on what peers have
$selector->update( $peer_bitfield, 1 ); # peer joined
$selector->update( $peer_bitfield, -1); # peer left

# Pick the next best item to request
my $idx = $selector->pick( $my_bitfield );

DESCRIPTION

Acme::Selection::RarestFirst implements the classic "rarest-first" algorithm used in distributed systems to ensure high data availability. It prioritizes items that have the lowest count in the global set (the "swarm").

METHODS

update( $bitfield, $delta )

Increments or decrements the availability count for every item marked in the provided bitfield (which must support a get( $index ) method).

pick( $my_bitfield, [$priorities] )

Finds the rarest item that is not present in $my_bitfield.

$priorities is an optional arrayref of weights. Items with priority less than or equal to 0 are skipped. Higher weights are picked before lower weights, even if they aren't the rarest.

get_availability( $index )

Returns the current availability count for a specific item.

AUTHOR

Sanko Robinson sanko@cpan.org

COPYRIGHT

Copyright (C) 2026 by Sanko Robinson.

This library is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0.