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}
CODE
	}

	foreach my $method (qw(entry exists load_callback validate_callback)) {
		_eval <<'CODE', method => $method;
sub [% method %] {
	my ( $self, @args ) = @_;

	foreach my $cache ( @{ $self->caches } ) {
		if ( my $res = $cache->[% method %]( @args ) ) {
			return $res;
		}
	}

	return;
}
CODE
	}
}

__PACKAGE__;

__END__

=pod

=encoding UTF-8

=head1 NAME

Cache::Cascade - Get/set values to/from a group of caches, with some advanced semantics.

=head1 VERSION

version 0.07

=head1 SYNOPSIS

	use Cache::Cascade;

	Cache::Cascade->new(
		caches => [
			Cache::Bounded->new(...),
			Cache::FastMmap->new(...),
			Cache::Memcached->new(...),
		],
		float_hits => 1,
		set_deep   => 1,
	);

=head1 DESCRIPTION

=for stopwords tradeoff multiserver MemoryCache FastMmap

In a multiprocess, and especially a multiserver application caching is a very
effective means of improving results.

The tradeoff of increasing the scale of the caching is in added complexity.
For example, caching in a FastMmap based storage is much slower than using a
memory based cache, because pages must be locked to ensure that no corruption
will happen. Likewise Memcached is even more overhead than FastMmap because it
is network bound, and uses blocking IO (on the client side).

This module attempts to make a transparent cascade of caches using several
backends.

The idea is to search from the cheapest backend to the most expensive, and
depending on the options also cache results in the cheaper backends.

The benefits of using a cascade are that if the chance of a hit is much higher
in a slow cache, but checking a cheap cache is negligible in comparison, we
may already have the result we want in the cheap cache. Configure your
expiration policy so that there is approximately an order of magnitude better
probability of cache hits (bigger cache) for each level of the cascade.

=head1 FIELDS

=over 4

=item set_deep

Defaults to true. See C<set>.

=item float_hits

Defaults to false. See C<get>.

=back

=head1 METHODS

=over 4

=item get $key

This method will delegate C<get> to every cache object in order, and return the first match.

Additionally, if C<float_hits> is set to a true value, it will also call C<set>
with the match on every cache object before the one that matched.

=item set $key, $value

If C<set_deep> is set to a true value this method will delegate C<set> to every
cache object in the list.

If C<set_deep> is set to a false value this method will delegate C<set> just to
the first cache object in the list.

=item remove $key

=item clear

These methods will delegate C<remove> on every cache object in the list.

=item entry $key

=item exists $key

Returns the first match.