[dbsrgits/DBM-Deep.git] / lib / DBM / Deep / Sector / File / Reference.pm

package DBM::Deep::Sector::File::Reference;

use 5.006_000;

use strict;
use warnings FATAL => 'all';

use base qw( DBM::Deep::Sector::File::Data );

my $STALE_SIZE = 2;

# Please refer to the pack() documentation for further information
my %StP = (
    1 => 'C', # Unsigned char value (no order needed as it's just one byte)
    2 => 'n', # Unsigned short in "network" (big-endian) order
    4 => 'N', # Unsigned long in "network" (big-endian) order
    8 => 'Q', # Usigned quad (no order specified, presumably machine-dependent)
);

sub _init {
    my $self = shift;

    my $e = $self->engine;

    unless ( $self->offset ) {
        my $classname = Scalar::Util::blessed( delete $self->{data} );
        my $leftover = $self->size - $self->base_size - 3 * $e->byte_size;

        my $class_offset = 0;
        if ( defined $classname ) {
            my $class_sector = DBM::Deep::Sector::File::Scalar->new({
                engine => $e,
                data   => $classname,
            });
            $class_offset = $class_sector->offset;
        }

        $self->{offset} = $e->_request_data_sector( $self->size );
        $e->storage->print_at( $self->offset, $self->type ); # Sector type
        # Skip staleness counter
        $e->storage->print_at( $self->offset + $self->base_size,
            pack( $StP{$e->byte_size}, 0 ),             # Index/BList loc
            pack( $StP{$e->byte_size}, $class_offset ), # Classname loc
            pack( $StP{$e->byte_size}, 1 ),             # Initial refcount
            chr(0) x $leftover,                         # Zero-fill the rest
        );
    }
    else {
        $self->{type} = $e->storage->read_at( $self->offset, 1 );
    }

    $self->{staleness} = unpack(
        $StP{$STALE_SIZE},
        $e->storage->read_at( $self->offset + $e->SIG_SIZE, $STALE_SIZE ),
    );

    return;
}

sub staleness { $_[0]{staleness} }

sub get_data_location_for {
    my $self = shift;
    my ($args) = @_;

    # Assume that the head is not allowed unless otherwise specified.
    $args->{allow_head} = 0 unless exists $args->{allow_head};

    # Assume we don't create a new blist location unless otherwise specified.
    $args->{create} = 0 unless exists $args->{create};

    my $blist = $self->get_bucket_list({
        key_md5 => $args->{key_md5},
        key => $args->{key},
        create  => $args->{create},
    });
    return unless $blist && $blist->{found};

    # At this point, $blist knows where the md5 is. What it -doesn't- know yet
    # is whether or not this transaction has this key. That's part of the next
    # function call.
    my $location = $blist->get_data_location_for({
        allow_head => $args->{allow_head},
    }) or return;

    return $location;
}

sub get_data_for {
    my $self = shift;
    my ($args) = @_;

    my $location = $self->get_data_location_for( $args )
        or return;

    return $self->engine->load_sector( $location );
}

sub write_data {
    my $self = shift;
    my ($args) = @_;

    my $blist = $self->get_bucket_list({
        key_md5 => $args->{key_md5},
        key => $args->{key},
        create  => 1,
    }) or DBM::Deep->_throw_error( "How did write_data fail (no blist)?!" );

    # Handle any transactional bookkeeping.
    if ( $self->engine->trans_id ) {
        if ( ! $blist->has_md5 ) {
            $blist->mark_deleted({
                trans_id => 0,
            });
        }
    }
    else {
        my @trans_ids = $self->engine->get_running_txn_ids;
        if ( $blist->has_md5 ) {
            if ( @trans_ids ) {
                my $old_value = $blist->get_data_for;
                foreach my $other_trans_id ( @trans_ids ) {
                    next if $blist->get_data_location_for({
                        trans_id   => $other_trans_id,
                        allow_head => 0,
                    });
                    $blist->write_md5({
                        trans_id => $other_trans_id,
                        key      => $args->{key},
                        key_md5  => $args->{key_md5},
                        value    => $old_value->clone,
                    });
                }
            }
        }
        else {
            if ( @trans_ids ) {
                foreach my $other_trans_id ( @trans_ids ) {
                    #XXX This doesn't seem to possible to ever happen . . .
                    next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
                    $blist->mark_deleted({
                        trans_id => $other_trans_id,
                    });
                }
            }
        }
    }

    #XXX Is this safe to do transactionally?
    # Free the place we're about to write to.
    if ( $blist->get_data_location_for({ allow_head => 0 }) ) {
        $blist->get_data_for({ allow_head => 0 })->free;
    }

    $blist->write_md5({
        key      => $args->{key},
        key_md5  => $args->{key_md5},
        value    => $args->{value},
    });
}

sub delete_key {
    my $self = shift;
    my ($args) = @_;

    # This can return nothing if we are deleting an entry in a hashref that was
    # auto-vivified as part of the delete process. For example:
    #     my $x = {};
    #     delete $x->{foo}{bar};
    my $blist = $self->get_bucket_list({
        key_md5 => $args->{key_md5},
    }) or return;

    # Save the location so that we can free the data
    my $location = $blist->get_data_location_for({
        allow_head => 0,
    });
    my $old_value = $location && $self->engine->load_sector( $location );

    my @trans_ids = $self->engine->get_running_txn_ids;

    # If we're the HEAD and there are running txns, then we need to clone this
    # value to the other transactions to preserve Isolation.
    if ( $self->engine->trans_id == 0 ) {
        if ( @trans_ids ) {
            foreach my $other_trans_id ( @trans_ids ) {
                next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
                $blist->write_md5({
                    trans_id => $other_trans_id,
                    key      => $args->{key},
                    key_md5  => $args->{key_md5},
                    value    => $old_value->clone,
                });
            }
        }
    }

    my $data;
    if ( @trans_ids ) {
        $blist->mark_deleted( $args );

        if ( $old_value ) {
            #XXX Is this export => 1 actually doing anything?
            $data = $old_value->data({ export => 1 });
            $old_value->free;
        }
    }
    else {
        $data = $blist->delete_md5( $args );
    }

    return $data;
}

sub get_blist_loc {
    my $self = shift;

    my $e = $self->engine;
    my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size );
    return unpack( $StP{$e->byte_size}, $blist_loc );
}

sub get_bucket_list {
    my $self = shift;
    my ($args) = @_;
    $args ||= {};

    # XXX Add in check here for recycling?

    my $engine = $self->engine;

    my $blist_loc = $self->get_blist_loc;

    # There's no index or blist yet
    unless ( $blist_loc ) {
        return unless $args->{create};

        my $blist = DBM::Deep::Sector::File::BucketList->new({
            engine  => $engine,
            key_md5 => $args->{key_md5},
        });

        $engine->storage->print_at( $self->offset + $self->base_size,
            pack( $StP{$engine->byte_size}, $blist->offset ),
        );

        return $blist;
    }

    my $sector = $engine->load_sector( $blist_loc )
        or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
    my $i = 0;
    my $last_sector = undef;
    while ( $sector->isa( 'DBM::Deep::Sector::File::Index' ) ) {
        $blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) );
        $last_sector = $sector;
        if ( $blist_loc ) {
            $sector = $engine->load_sector( $blist_loc )
                or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
        }
        else {
            $sector = undef;
            last;
        }
    }

    # This means we went through the Index sector(s) and found an empty slot
    unless ( $sector ) {
        return unless $args->{create};

        DBM::Deep->_throw_error( "No last_sector when attempting to build a new entry" )
            unless $last_sector;

        my $blist = DBM::Deep::Sector::File::BucketList->new({
            engine  => $engine,
            key_md5 => $args->{key_md5},
        });

        $last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset );

        return $blist;
    }

    $sector->find_md5( $args->{key_md5} );

    # See whether or not we need to reindex the bucketlist
    # Yes, the double-braces are there for a reason. if() doesn't create a
    # redo-able block, so we have to create a bare block within the if() for
    # redo-purposes.
    # Patch and idea submitted by sprout@cpan.org. -RobK, 2008-01-09
    if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {{
        my $redo;

        my $new_index = DBM::Deep::Sector::File::Index->new({
            engine => $engine,
        });

        my %blist_cache;
        #XXX q.v. the comments for this function.
        foreach my $entry ( $sector->chopped_up ) {
            my ($spot, $md5) = @{$entry};
            my $idx = ord( substr( $md5, $i, 1 ) );

            # XXX This is inefficient
            my $blist = $blist_cache{$idx}
                ||= DBM::Deep::Sector::File::BucketList->new({
                    engine => $engine,
                });

            $new_index->set_entry( $idx => $blist->offset );

            my $new_spot = $blist->write_at_next_open( $md5 );
            $engine->reindex_entry( $spot => $new_spot );
        }

        # Handle the new item separately.
        {
            my $idx = ord( substr( $args->{key_md5}, $i, 1 ) );

            # If all the previous blist's items have been thrown into one
            # blist and the new item belongs in there too, we need
            # another index.
            if ( keys %blist_cache == 1 and each %blist_cache == $idx ) {
                ++$i, ++$redo;
            } else {
                my $blist = $blist_cache{$idx}
                    ||= DBM::Deep::Sector::File::BucketList->new({
                        engine => $engine,
                    });
    
                $new_index->set_entry( $idx => $blist->offset );
    
                #XXX THIS IS HACKY!
                $blist->find_md5( $args->{key_md5} );
                $blist->write_md5({
                    key     => $args->{key},
                    key_md5 => $args->{key_md5},
                    value   => DBM::Deep::Sector::File::Null->new({
                        engine => $engine,
                        data   => undef,
                    }),
                });
            }
#            my $blist = $blist_cache{$idx}
#                ||= DBM::Deep::Sector::File::BucketList->new({
#                    engine => $engine,
#                });
#
#            $new_index->set_entry( $idx => $blist->offset );
#
#            #XXX THIS IS HACKY!
#            $blist->find_md5( $args->{key_md5} );
#            $blist->write_md5({
#                key     => $args->{key},
#                key_md5 => $args->{key_md5},
#                value   => DBM::Deep::Sector::File::Null->new({
#                    engine => $engine,
#                    data   => undef,
#                }),
#            });
        }

        if ( $last_sector ) {
            $last_sector->set_entry(
                ord( substr( $args->{key_md5}, $i - 1, 1 ) ),
                $new_index->offset,
            );
        } else {
            $engine->storage->print_at( $self->offset + $self->base_size,
                pack( $StP{$engine->byte_size}, $new_index->offset ),
            );
        }

        $sector->clear;
        $sector->free;

        if ( $redo ) {
            (undef, $sector) = %blist_cache;
            $last_sector = $new_index;
            redo;
        }

        $sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) };
        $sector->find_md5( $args->{key_md5} );
    }}

    return $sector;
}

sub get_class_offset {
    my $self = shift;

    my $e = $self->engine;
    return unpack(
        $StP{$e->byte_size},
        $e->storage->read_at(
            $self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size,
        ),
    );
}

sub get_classname {
    my $self = shift;

    my $class_offset = $self->get_class_offset;

    return unless $class_offset;

    return $self->engine->load_sector( $class_offset )->data;
}

# Look to hoist this method into a ::Reference trait
sub data {
    my $self = shift;
    my ($args) = @_;
    $args ||= {};

    my $obj;
    unless ( $obj = $self->engine->cache->{ $self->offset } ) {
        $obj = DBM::Deep->new({
            type        => $self->type,
            base_offset => $self->offset,
            staleness   => $self->staleness,
            storage     => $self->engine->storage,
            engine      => $self->engine,
        });

        if ( $self->engine->storage->{autobless} ) {
            my $classname = $self->get_classname;
            if ( defined $classname ) {
                bless $obj, $classname;
            }
        }

        $self->engine->cache->{$self->offset} = $obj;
    }

    # We're not exporting, so just return.
    unless ( $args->{export} ) {
        return $obj;
    }

    # We shouldn't export if this is still referred to.
    if ( $self->get_refcount > 1 ) {
        return $obj;
    }

    return $obj->export;
}

sub free {
    my $self = shift;

    # We're not ready to be removed yet.
    return if $self->decrement_refcount > 0;

    # Rebless the object into DBM::Deep::Null.
    eval { %{ $self->engine->cache->{ $self->offset } } = (); };
    eval { @{ $self->engine->cache->{ $self->offset } } = (); };
    bless $self->engine->cache->{ $self->offset }, 'DBM::Deep::Null';
    delete $self->engine->cache->{ $self->offset };

    my $blist_loc = $self->get_blist_loc;
    $self->engine->load_sector( $blist_loc )->free if $blist_loc;

    my $class_loc = $self->get_class_offset;
    $self->engine->load_sector( $class_loc )->free if $class_loc;

    $self->SUPER::free();
}

sub increment_refcount {
    my $self = shift;

    my $refcount = $self->get_refcount;

    $refcount++;

    $self->write_refcount( $refcount );

    return $refcount;
}

sub decrement_refcount {
    my $self = shift;

    my $refcount = $self->get_refcount;

    $refcount--;

    $self->write_refcount( $refcount );

    return $refcount;
}

sub get_refcount {
    my $self = shift;

    my $e = $self->engine;
    return unpack(
        $StP{$e->byte_size},
        $e->storage->read_at(
            $self->offset + $self->base_size + 2 * $e->byte_size, $e->byte_size,
        ),
    );
}

sub write_refcount {
    my $self = shift;
    my ($num) = @_;

    my $e = $self->engine;
    $e->storage->print_at(
        $self->offset + $self->base_size + 2 * $e->byte_size,
        pack( $StP{$e->byte_size}, $num ),
    );
}

1;
__END__
Commit	Line	Data
2c70efe1	1	package DBM::Deep::Sector::File::Reference;
f0276afb	2
	3	use 5.006_000;
	4
	5	use strict;
	6	use warnings FATAL => 'all';
	7
2c70efe1	8	use base qw( DBM::Deep::Sector::File::Data );
f0276afb	9
5ae752e2	10	my $STALE_SIZE = 2;
	11
	12	# Please refer to the pack() documentation for further information
	13	my %StP = (
	14	1 => 'C', # Unsigned char value (no order needed as it's just one byte)
	15	2 => 'n', # Unsigned short in "network" (big-endian) order
	16	4 => 'N', # Unsigned long in "network" (big-endian) order
	17	8 => 'Q', # Usigned quad (no order specified, presumably machine-dependent)
	18	);
	19
f0276afb	20	sub _init {
	21	my $self = shift;
	22
	23	my $e = $self->engine;
	24
	25	unless ( $self->offset ) {
	26	my $classname = Scalar::Util::blessed( delete $self->{data} );
	27	my $leftover = $self->size - $self->base_size - 3 * $e->byte_size;
	28
	29	my $class_offset = 0;
	30	if ( defined $classname ) {
2c70efe1	31	my $class_sector = DBM::Deep::Sector::File::Scalar->new({
f0276afb	32	engine => $e,
	33	data => $classname,
	34	});
	35	$class_offset = $class_sector->offset;
	36	}
	37
	38	$self->{offset} = $e->_request_data_sector( $self->size );
	39	$e->storage->print_at( $self->offset, $self->type ); # Sector type
	40	# Skip staleness counter
	41	$e->storage->print_at( $self->offset + $self->base_size,
	42	pack( $StP{$e->byte_size}, 0 ), # Index/BList loc
	43	pack( $StP{$e->byte_size}, $class_offset ), # Classname loc
	44	pack( $StP{$e->byte_size}, 1 ), # Initial refcount
	45	chr(0) x $leftover, # Zero-fill the rest
	46	);
	47	}
	48	else {
	49	$self->{type} = $e->storage->read_at( $self->offset, 1 );
	50	}
	51
	52	$self->{staleness} = unpack(
	53	$StP{$STALE_SIZE},
	54	$e->storage->read_at( $self->offset + $e->SIG_SIZE, $STALE_SIZE ),
	55	);
	56
	57	return;
	58	}
	59
	60	sub staleness { $_[0]{staleness} }
	61
	62	sub get_data_location_for {
	63	my $self = shift;
	64	my ($args) = @_;
	65
	66	# Assume that the head is not allowed unless otherwise specified.
	67	$args->{allow_head} = 0 unless exists $args->{allow_head};
	68
	69	# Assume we don't create a new blist location unless otherwise specified.
	70	$args->{create} = 0 unless exists $args->{create};
	71
	72	my $blist = $self->get_bucket_list({
	73	key_md5 => $args->{key_md5},
	74	key => $args->{key},
	75	create => $args->{create},
	76	});
	77	return unless $blist && $blist->{found};
	78
	79	# At this point, $blist knows where the md5 is. What it -doesn't- know yet
	80	# is whether or not this transaction has this key. That's part of the next
	81	# function call.
	82	my $location = $blist->get_data_location_for({
	83	allow_head => $args->{allow_head},
	84	}) or return;
	85
	86	return $location;
	87	}
	88
	89	sub get_data_for {
	90	my $self = shift;
	91	my ($args) = @_;
	92
	93	my $location = $self->get_data_location_for( $args )
	94	or return;
	95
d6ecf579	96	return $self->engine->load_sector( $location );
f0276afb	97	}
	98
	99	sub write_data {
	100	my $self = shift;
	101	my ($args) = @_;
	102
	103	my $blist = $self->get_bucket_list({
	104	key_md5 => $args->{key_md5},
	105	key => $args->{key},
	106	create => 1,
	107	}) or DBM::Deep->_throw_error( "How did write_data fail (no blist)?!" );
	108
	109	# Handle any transactional bookkeeping.
	110	if ( $self->engine->trans_id ) {
	111	if ( ! $blist->has_md5 ) {
	112	$blist->mark_deleted({
	113	trans_id => 0,
	114	});
	115	}
	116	}
	117	else {
	118	my @trans_ids = $self->engine->get_running_txn_ids;
	119	if ( $blist->has_md5 ) {
	120	if ( @trans_ids ) {
	121	my $old_value = $blist->get_data_for;
	122	foreach my $other_trans_id ( @trans_ids ) {
	123	next if $blist->get_data_location_for({
	124	trans_id => $other_trans_id,
	125	allow_head => 0,
	126	});
	127	$blist->write_md5({
	128	trans_id => $other_trans_id,
	129	key => $args->{key},
	130	key_md5 => $args->{key_md5},
	131	value => $old_value->clone,
	132	});
	133	}
	134	}
	135	}
	136	else {
	137	if ( @trans_ids ) {
	138	foreach my $other_trans_id ( @trans_ids ) {
	139	#XXX This doesn't seem to possible to ever happen . . .
	140	next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
	141	$blist->mark_deleted({
	142	trans_id => $other_trans_id,
	143	});
	144	}
	145	}
	146	}
	147	}
	148
	149	#XXX Is this safe to do transactionally?
	150	# Free the place we're about to write to.
	151	if ( $blist->get_data_location_for({ allow_head => 0 }) ) {
	152	$blist->get_data_for({ allow_head => 0 })->free;
	153	}
	154
	155	$blist->write_md5({
	156	key => $args->{key},
	157	key_md5 => $args->{key_md5},
	158	value => $args->{value},
	159	});
	160	}
161
162	sub delete_key {
163	my $self = shift;
164	my ($args) = @_;
165
c803879b	166	# This can return nothing if we are deleting an entry in a hashref that was
	167	# auto-vivified as part of the delete process. For example:
	168	# my $x = {};
	169	# delete $x->{foo}{bar};
f0276afb	170	my $blist = $self->get_bucket_list({
f0276afb	171	key_md5 => $args->{key_md5},
c803879b	172	}) or return;
f0276afb	173
	174	# Save the location so that we can free the data
	175	my $location = $blist->get_data_location_for({
	176	allow_head => 0,
	177	});
d6ecf579	178	my $old_value = $location && $self->engine->load_sector( $location );
f0276afb	179
	180	my @trans_ids = $self->engine->get_running_txn_ids;
	181
a4d36ff6	182	# If we're the HEAD and there are running txns, then we need to clone this
a4d36ff6	183	# value to the other transactions to preserve Isolation.
f0276afb	184	if ( $self->engine->trans_id == 0 ) {
	185	if ( @trans_ids ) {
	186	foreach my $other_trans_id ( @trans_ids ) {
	187	next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
	188	$blist->write_md5({
	189	trans_id => $other_trans_id,
	190	key => $args->{key},
	191	key_md5 => $args->{key_md5},
	192	value => $old_value->clone,
	193	});
	194	}
	195	}
	196	}
	197
	198	my $data;
	199	if ( @trans_ids ) {
	200	$blist->mark_deleted( $args );
	201
	202	if ( $old_value ) {
a4d36ff6	203	#XXX Is this export => 1 actually doing anything?
f0276afb	204	$data = $old_value->data({ export => 1 });
	205	$old_value->free;
	206	}
	207	}
	208	else {
	209	$data = $blist->delete_md5( $args );
	210	}
	211
	212	return $data;
	213	}
	214
	215	sub get_blist_loc {
	216	my $self = shift;
	217
	218	my $e = $self->engine;
	219	my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size );
	220	return unpack( $StP{$e->byte_size}, $blist_loc );
	221	}
	222
	223	sub get_bucket_list {
	224	my $self = shift;
	225	my ($args) = @_;
	226	$args \|\|= {};
	227
	228	# XXX Add in check here for recycling?
	229
	230	my $engine = $self->engine;
	231
	232	my $blist_loc = $self->get_blist_loc;
	233
	234	# There's no index or blist yet
	235	unless ( $blist_loc ) {
	236	return unless $args->{create};
	237
2c70efe1	238	my $blist = DBM::Deep::Sector::File::BucketList->new({
f0276afb	239	engine => $engine,
	240	key_md5 => $args->{key_md5},
	241	});
	242
	243	$engine->storage->print_at( $self->offset + $self->base_size,
	244	pack( $StP{$engine->byte_size}, $blist->offset ),
	245	);
	246
	247	return $blist;
	248	}
	249
d6ecf579	250	my $sector = $engine->load_sector( $blist_loc )
f0276afb	251	or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
	252	my $i = 0;
	253	my $last_sector = undef;
2c70efe1	254	while ( $sector->isa( 'DBM::Deep::Sector::File::Index' ) ) {
f0276afb	255	$blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) );
	256	$last_sector = $sector;
	257	if ( $blist_loc ) {
d6ecf579	258	$sector = $engine->load_sector( $blist_loc )
f0276afb	259	or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
	260	}
	261	else {
	262	$sector = undef;
	263	last;
	264	}
	265	}
	266
	267	# This means we went through the Index sector(s) and found an empty slot
	268	unless ( $sector ) {
	269	return unless $args->{create};
	270
	271	DBM::Deep->_throw_error( "No last_sector when attempting to build a new entry" )
	272	unless $last_sector;
	273
2c70efe1	274	my $blist = DBM::Deep::Sector::File::BucketList->new({
f0276afb	275	engine => $engine,
	276	key_md5 => $args->{key_md5},
	277	});
	278
	279	$last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset );
	280
	281	return $blist;
	282	}
	283
	284	$sector->find_md5( $args->{key_md5} );
	285
	286	# See whether or not we need to reindex the bucketlist
cd5303b4	287	# Yes, the double-braces are there for a reason. if() doesn't create a
	288	# redo-able block, so we have to create a bare block within the if() for
	289	# redo-purposes.
	290	# Patch and idea submitted by sprout@cpan.org. -RobK, 2008-01-09
f0276afb	291	if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {{
	292	my $redo;
	293
2c70efe1	294	my $new_index = DBM::Deep::Sector::File::Index->new({
f0276afb	295	engine => $engine,
	296	});
	297
	298	my %blist_cache;
	299	#XXX q.v. the comments for this function.
	300	foreach my $entry ( $sector->chopped_up ) {
	301	my ($spot, $md5) = @{$entry};
	302	my $idx = ord( substr( $md5, $i, 1 ) );
	303
	304	# XXX This is inefficient
	305	my $blist = $blist_cache{$idx}
2c70efe1	306	\|\|= DBM::Deep::Sector::File::BucketList->new({
f0276afb	307	engine => $engine,
	308	});
	309
	310	$new_index->set_entry( $idx => $blist->offset );
	311
	312	my $new_spot = $blist->write_at_next_open( $md5 );
	313	$engine->reindex_entry( $spot => $new_spot );
	314	}
	315
	316	# Handle the new item separately.
	317	{
	318	my $idx = ord( substr( $args->{key_md5}, $i, 1 ) );
	319
	320	# If all the previous blist's items have been thrown into one
	321	# blist and the new item belongs in there too, we need
	322	# another index.
	323	if ( keys %blist_cache == 1 and each %blist_cache == $idx ) {
	324	++$i, ++$redo;
	325	} else {
	326	my $blist = $blist_cache{$idx}
2c70efe1	327	\|\|= DBM::Deep::Sector::File::BucketList->new({
f0276afb	328	engine => $engine,
	329	});
	330
	331	$new_index->set_entry( $idx => $blist->offset );
	332
	333	#XXX THIS IS HACKY!
	334	$blist->find_md5( $args->{key_md5} );
	335	$blist->write_md5({
	336	key => $args->{key},
	337	key_md5 => $args->{key_md5},
2c70efe1	338	value => DBM::Deep::Sector::File::Null->new({
f0276afb	339	engine => $engine,
	340	data => undef,
	341	}),
	342	});
	343	}
	344	# my $blist = $blist_cache{$idx}
2c70efe1	345	# \|\|= DBM::Deep::Sector::File::BucketList->new({
f0276afb	346	# engine => $engine,
	347	# });
	348	#
	349	# $new_index->set_entry( $idx => $blist->offset );
	350	#
	351	# #XXX THIS IS HACKY!
	352	# $blist->find_md5( $args->{key_md5} );
	353	# $blist->write_md5({
	354	# key => $args->{key},
	355	# key_md5 => $args->{key_md5},
2c70efe1	356	# value => DBM::Deep::Sector::File::Null->new({
f0276afb	357	# engine => $engine,
	358	# data => undef,
	359	# }),
	360	# });
	361	}
	362
	363	if ( $last_sector ) {
	364	$last_sector->set_entry(
	365	ord( substr( $args->{key_md5}, $i - 1, 1 ) ),
	366	$new_index->offset,
	367	);
	368	} else {
	369	$engine->storage->print_at( $self->offset + $self->base_size,
	370	pack( $StP{$engine->byte_size}, $new_index->offset ),
	371	);
	372	}
	373
	374	$sector->clear;
	375	$sector->free;
	376
	377	if ( $redo ) {
	378	(undef, $sector) = %blist_cache;
	379	$last_sector = $new_index;
	380	redo;
	381	}
	382
	383	$sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) };
	384	$sector->find_md5( $args->{key_md5} );
	385	}}
	386
	387	return $sector;
	388	}
	389
	390	sub get_class_offset {
	391	my $self = shift;
	392
	393	my $e = $self->engine;
	394	return unpack(
	395	$StP{$e->byte_size},
	396	$e->storage->read_at(
	397	$self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size,
	398	),
	399	);
	400	}
	401
	402	sub get_classname {
	403	my $self = shift;
	404
	405	my $class_offset = $self->get_class_offset;
	406
	407	return unless $class_offset;
	408
d6ecf579	409	return $self->engine->load_sector( $class_offset )->data;
f0276afb	410	}
f0276afb	411
4f034d8f	412	# Look to hoist this method into a ::Reference trait
f0276afb	413	sub data {
	414	my $self = shift;
	415	my ($args) = @_;
	416	$args \|\|= {};
	417
	418	my $obj;
	419	unless ( $obj = $self->engine->cache->{ $self->offset } ) {
	420	$obj = DBM::Deep->new({
	421	type => $self->type,
	422	base_offset => $self->offset,
	423	staleness => $self->staleness,
	424	storage => $self->engine->storage,
	425	engine => $self->engine,
	426	});
	427
	428	if ( $self->engine->storage->{autobless} ) {
	429	my $classname = $self->get_classname;
	430	if ( defined $classname ) {
	431	bless $obj, $classname;
	432	}
	433	}
	434
	435	$self->engine->cache->{$self->offset} = $obj;
	436	}
	437
	438	# We're not exporting, so just return.
	439	unless ( $args->{export} ) {
	440	return $obj;
	441	}
	442
	443	# We shouldn't export if this is still referred to.
	444	if ( $self->get_refcount > 1 ) {
	445	return $obj;
	446	}
	447
	448	return $obj->export;
	449	}
	450
	451	sub free {
	452	my $self = shift;
	453
	454	# We're not ready to be removed yet.
4f034d8f	455	return if $self->decrement_refcount > 0;
f0276afb	456
	457	# Rebless the object into DBM::Deep::Null.
	458	eval { %{ $self->engine->cache->{ $self->offset } } = (); };
	459	eval { @{ $self->engine->cache->{ $self->offset } } = (); };
	460	bless $self->engine->cache->{ $self->offset }, 'DBM::Deep::Null';
	461	delete $self->engine->cache->{ $self->offset };
	462
	463	my $blist_loc = $self->get_blist_loc;
d6ecf579	464	$self->engine->load_sector( $blist_loc )->free if $blist_loc;
f0276afb	465
f0276afb	466	my $class_loc = $self->get_class_offset;
d6ecf579	467	$self->engine->load_sector( $class_loc )->free if $class_loc;
f0276afb	468
	469	$self->SUPER::free();
	470	}
	471
	472	sub increment_refcount {
	473	my $self = shift;
	474
	475	my $refcount = $self->get_refcount;
	476
	477	$refcount++;
	478
	479	$self->write_refcount( $refcount );
	480
	481	return $refcount;
	482	}
	483
	484	sub decrement_refcount {
	485	my $self = shift;
	486
	487	my $refcount = $self->get_refcount;
	488
	489	$refcount--;
	490
	491	$self->write_refcount( $refcount );
	492
	493	return $refcount;
	494	}
	495
	496	sub get_refcount {
	497	my $self = shift;
	498
	499	my $e = $self->engine;
	500	return unpack(
	501	$StP{$e->byte_size},
	502	$e->storage->read_at(
	503	$self->offset + $self->base_size + 2 * $e->byte_size, $e->byte_size,
	504	),
	505	);
	506	}
	507
	508	sub write_refcount {
	509	my $self = shift;
	510	my ($num) = @_;
	511
	512	my $e = $self->engine;
	513	$e->storage->print_at(
	514	$self->offset + $self->base_size + 2 * $e->byte_size,
	515	pack( $StP{$e->byte_size}, $num ),
	516	);
	517	}
	518
	519	1;
	520	__END__