package CHI::Driver::FastMmap;
$CHI::Driver::FastMmap::VERSION = '0.61';
use Carp;
use Cache::FastMmap;
use CHI::Util qw(read_dir);
use File::Path qw(mkpath);
use File::Spec::Functions qw(catdir catfile splitdir tmpdir);
use Moo;
use MooX::Types::MooseLike::Base qw(:all);
use strict;
use warnings;

extends 'CHI::Driver::Base::CacheContainer';

has 'dir_create_mode' => ( is => 'ro', isa => Int, default => sub { oct(775) } );
has 'root_dir'        => ( is => 'ro', isa => Str, default => sub { catdir( tmpdir(), "chi-driver-fastmmap" ) } );

sub BUILD {
    my ( $self, $params ) = @_;

    mkpath( $self->root_dir, 0, $self->dir_create_mode )
      if !-d $self->root_dir;
    $self->{fm_params} = {
        raw_values     => 1,
        unlink_on_exit => 0,
        share_file     => catfile(
            $self->root_dir,
            $self->escape_for_filename( $self->namespace ) . ".dat"
        ),
        %{ $self->non_common_constructor_params($params) },
    };
    $self->{_contained_cache} = $self->_build_contained_cache;
}

sub _build_contained_cache {
    my ($self) = @_;

    return Cache::FastMmap->new( %{ $self->{fm_params} } );
}

sub fm_cache {
    my $self = shift;
    return $self->_contained_cache(@_);
}

sub get_keys {
    my ($self) = @_;

    my @keys = $self->_contained_cache->get_keys(0);
    return @keys;
}

sub get_namespaces {
    my ($self) = @_;

    my $root_dir = $self->root_dir;
    my @contents = read_dir($root_dir);
    my @namespaces =
      map { $self->unescape_for_filename( substr( $_, 0, -4 ) ) }
      grep { /\.dat$/ } @contents;
    return @namespaces;
}

# Capture set failures
sub store {
    my $self   = shift;
    my $result = $self->_contained_cache->set(@_);
    if ( !$result ) {
        my ( $key, $value ) = @_;
        croak(
            sprintf( "fastmmap set failed - value too large? (%d bytes)",
                length($value) )
        );
    }
}

1;

__END__

=pod

=head1 NAME

CHI::Driver::FastMmap - Persistent interprocess cache via mmap'ed files

=head1 VERSION

version 0.61

=head1 SYNOPSIS

    use CHI;

    my $cache = CHI->new(
        driver     => 'FastMmap',
        root_dir   => '/path/to/cache/root',
        cache_size => '1m'
    );

=head1 DESCRIPTION

This cache driver uses Cache::FastMmap to store data in an mmap'ed file. It is
very fast, and can be used to share data between processes on a single host,
though not between hosts.

To support namespaces, this driver takes a directory parameter rather than a
file, and creates one Cache::FastMMap file for each namespace.

Because CHI handles serialization automatically, we pass the C<raw_values> flag
as 1; and to conform to the CHI API, we pass C<unlink_on_exit> as 0, so that
all cache files are permanent.

=head1 REQUIREMENTS

You will need to install L<Cache::FastMmap|Cache::FastMmap> from CPAN to use
this driver.

=head1 CONSTRUCTOR OPTIONS

=over

=item root_dir

Path to the directory that will contain the share files, one per namespace.
Defaults to a directory called 'chi-driver-fastmmap' under the OS default temp
directory (e.g. '/tmp' on UNIX).

=item dir_create_mode

Permissions mode to use when creating directories. Defaults to 0775.

=back

Any other constructor options L<not recognized by CHI|CHI/constructor> are
passed along to L<Cache::FastMmap-E<gt>new>.

=head1 METHODS

=over

=item fm_cache

Returns a handle to the underlying Cache::FastMmap object. You can use this to
call FastMmap-specific methods that are not supported by the general API, e.g.

    $self->fm_cache->get_and_set("key", sub { ... });

=back

=head1 SEE ALSO

L<CHI|CHI>

=head1 AUTHOR

Jonathan Swartz <swartz@pobox.com>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2021 by Jonathan Swartz.

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

=cut