[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 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 write_blist_loc {
    my $self = shift;
    my ($loc) = @_;

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

}

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 clear {
#    my $self = shift;
#    my ($args) = @_;
#    $args ||= {};
#
#    my $engine = $self->engine;
#
#    # If there's nothing pointed to from this reference, there's nothing to do.
#    my $loc = $self->get_blist_loc
#        or return;
#
#    my $sector = $engine->load_sector( $loc )
#        or DBM::Deep->_throw_error( "Cannot read sector at $loc in clear()" );
#
#    $sector->clear;
#
#    $self->write_blist_loc( 0 );
#
#    return;
#}

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},
        });

        $self->write_blist_loc( $blist->offset );
#        $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,
                    }),
                });
            }
        }

        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->wipe;
        $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
f0276afb	60	sub get_data_location_for {
	61	my $self = shift;
	62	my ($args) = @_;
	63
	64	# Assume that the head is not allowed unless otherwise specified.
	65	$args->{allow_head} = 0 unless exists $args->{allow_head};
	66
	67	# Assume we don't create a new blist location unless otherwise specified.
	68	$args->{create} = 0 unless exists $args->{create};
	69
	70	my $blist = $self->get_bucket_list({
	71	key_md5 => $args->{key_md5},
	72	key => $args->{key},
	73	create => $args->{create},
	74	});
	75	return unless $blist && $blist->{found};
	76
	77	# At this point, $blist knows where the md5 is. What it -doesn't- know yet
	78	# is whether or not this transaction has this key. That's part of the next
	79	# function call.
	80	my $location = $blist->get_data_location_for({
	81	allow_head => $args->{allow_head},
	82	}) or return;
	83
	84	return $location;
	85	}
	86
	87	sub get_data_for {
	88	my $self = shift;
	89	my ($args) = @_;
	90
	91	my $location = $self->get_data_location_for( $args )
	92	or return;
	93
d6ecf579	94	return $self->engine->load_sector( $location );
f0276afb	95	}
	96
	97	sub write_data {
	98	my $self = shift;
	99	my ($args) = @_;
	100
	101	my $blist = $self->get_bucket_list({
	102	key_md5 => $args->{key_md5},
	103	key => $args->{key},
	104	create => 1,
	105	}) or DBM::Deep->_throw_error( "How did write_data fail (no blist)?!" );
	106
	107	# Handle any transactional bookkeeping.
	108	if ( $self->engine->trans_id ) {
	109	if ( ! $blist->has_md5 ) {
	110	$blist->mark_deleted({
	111	trans_id => 0,
	112	});
	113	}
	114	}
	115	else {
	116	my @trans_ids = $self->engine->get_running_txn_ids;
	117	if ( $blist->has_md5 ) {
	118	if ( @trans_ids ) {
	119	my $old_value = $blist->get_data_for;
	120	foreach my $other_trans_id ( @trans_ids ) {
	121	next if $blist->get_data_location_for({
	122	trans_id => $other_trans_id,
	123	allow_head => 0,
	124	});
	125	$blist->write_md5({
	126	trans_id => $other_trans_id,
	127	key => $args->{key},
	128	key_md5 => $args->{key_md5},
	129	value => $old_value->clone,
	130	});
	131	}
	132	}
	133	}
	134	else {
	135	if ( @trans_ids ) {
	136	foreach my $other_trans_id ( @trans_ids ) {
	137	#XXX This doesn't seem to possible to ever happen . . .
	138	next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
	139	$blist->mark_deleted({
	140	trans_id => $other_trans_id,
	141	});
	142	}
	143	}
	144	}
	145	}
	146
	147	#XXX Is this safe to do transactionally?
	148	# Free the place we're about to write to.
	149	if ( $blist->get_data_location_for({ allow_head => 0 }) ) {
	150	$blist->get_data_for({ allow_head => 0 })->free;
	151	}
	152
	153	$blist->write_md5({
	154	key => $args->{key},
	155	key_md5 => $args->{key_md5},
	156	value => $args->{value},
	157	});
	158	}
159
160	sub delete_key {
161	my $self = shift;
162	my ($args) = @_;
163
c803879b	164	# This can return nothing if we are deleting an entry in a hashref that was
	165	# auto-vivified as part of the delete process. For example:
	166	# my $x = {};
	167	# delete $x->{foo}{bar};
f0276afb	168	my $blist = $self->get_bucket_list({
f0276afb	169	key_md5 => $args->{key_md5},
c803879b	170	}) or return;
f0276afb	171
	172	# Save the location so that we can free the data
	173	my $location = $blist->get_data_location_for({
	174	allow_head => 0,
	175	});
d6ecf579	176	my $old_value = $location && $self->engine->load_sector( $location );
f0276afb	177
	178	my @trans_ids = $self->engine->get_running_txn_ids;
	179
a4d36ff6	180	# If we're the HEAD and there are running txns, then we need to clone this
a4d36ff6	181	# value to the other transactions to preserve Isolation.
f0276afb	182	if ( $self->engine->trans_id == 0 ) {
	183	if ( @trans_ids ) {
	184	foreach my $other_trans_id ( @trans_ids ) {
	185	next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
	186	$blist->write_md5({
	187	trans_id => $other_trans_id,
	188	key => $args->{key},
	189	key_md5 => $args->{key_md5},
	190	value => $old_value->clone,
	191	});
	192	}
	193	}
	194	}
	195
	196	my $data;
	197	if ( @trans_ids ) {
	198	$blist->mark_deleted( $args );
	199
	200	if ( $old_value ) {
a4d36ff6	201	#XXX Is this export => 1 actually doing anything?
f0276afb	202	$data = $old_value->data({ export => 1 });
	203	$old_value->free;
	204	}
	205	}
	206	else {
	207	$data = $blist->delete_md5( $args );
	208	}
	209
	210	return $data;
	211	}
	212
d3aaaf5e	213	sub write_blist_loc {
	214	my $self = shift;
	215	my ($loc) = @_;
	216
	217	my $engine = $self->engine;
	218	$engine->storage->print_at( $self->offset + $self->base_size,
	219	pack( $StP{$engine->byte_size}, $loc ),
	220	);
	221
	222	}
	223
f0276afb	224	sub get_blist_loc {
	225	my $self = shift;
	226
	227	my $e = $self->engine;
	228	my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size );
	229	return unpack( $StP{$e->byte_size}, $blist_loc );
	230	}
	231
d3aaaf5e	232	#sub clear {
	233	# my $self = shift;
	234	# my ($args) = @_;
	235	# $args \|\|= {};
	236	#
	237	# my $engine = $self->engine;
	238	#
	239	# # If there's nothing pointed to from this reference, there's nothing to do.
	240	# my $loc = $self->get_blist_loc
	241	# or return;
	242	#
	243	# my $sector = $engine->load_sector( $loc )
	244	# or DBM::Deep->_throw_error( "Cannot read sector at $loc in clear()" );
	245	#
	246	# $sector->clear;
	247	#
	248	# $self->write_blist_loc( 0 );
	249	#
	250	# return;
	251	#}
	252
f0276afb	253	sub get_bucket_list {
	254	my $self = shift;
	255	my ($args) = @_;
	256	$args \|\|= {};
	257
	258	# XXX Add in check here for recycling?
	259
	260	my $engine = $self->engine;
	261
	262	my $blist_loc = $self->get_blist_loc;
	263
	264	# There's no index or blist yet
	265	unless ( $blist_loc ) {
	266	return unless $args->{create};
	267
2c70efe1	268	my $blist = DBM::Deep::Sector::File::BucketList->new({
f0276afb	269	engine => $engine,
	270	key_md5 => $args->{key_md5},
	271	});
	272
d3aaaf5e	273	$self->write_blist_loc( $blist->offset );
	274	# $engine->storage->print_at( $self->offset + $self->base_size,
	275	# pack( $StP{$engine->byte_size}, $blist->offset ),
	276	# );
f0276afb	277
	278	return $blist;
	279	}
	280
d6ecf579	281	my $sector = $engine->load_sector( $blist_loc )
f0276afb	282	or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
	283	my $i = 0;
	284	my $last_sector = undef;
2c70efe1	285	while ( $sector->isa( 'DBM::Deep::Sector::File::Index' ) ) {
f0276afb	286	$blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) );
	287	$last_sector = $sector;
	288	if ( $blist_loc ) {
d6ecf579	289	$sector = $engine->load_sector( $blist_loc )
f0276afb	290	or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
	291	}
	292	else {
	293	$sector = undef;
	294	last;
	295	}
	296	}
	297
	298	# This means we went through the Index sector(s) and found an empty slot
	299	unless ( $sector ) {
	300	return unless $args->{create};
	301
	302	DBM::Deep->_throw_error( "No last_sector when attempting to build a new entry" )
	303	unless $last_sector;
	304
2c70efe1	305	my $blist = DBM::Deep::Sector::File::BucketList->new({
f0276afb	306	engine => $engine,
	307	key_md5 => $args->{key_md5},
	308	});
	309
	310	$last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset );
	311
	312	return $blist;
	313	}
	314
	315	$sector->find_md5( $args->{key_md5} );
	316
	317	# See whether or not we need to reindex the bucketlist
cd5303b4	318	# Yes, the double-braces are there for a reason. if() doesn't create a
	319	# redo-able block, so we have to create a bare block within the if() for
	320	# redo-purposes.
	321	# Patch and idea submitted by sprout@cpan.org. -RobK, 2008-01-09
f0276afb	322	if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {{
	323	my $redo;
	324
2c70efe1	325	my $new_index = DBM::Deep::Sector::File::Index->new({
f0276afb	326	engine => $engine,
	327	});
	328
	329	my %blist_cache;
	330	#XXX q.v. the comments for this function.
	331	foreach my $entry ( $sector->chopped_up ) {
	332	my ($spot, $md5) = @{$entry};
	333	my $idx = ord( substr( $md5, $i, 1 ) );
	334
	335	# XXX This is inefficient
	336	my $blist = $blist_cache{$idx}
2c70efe1	337	\|\|= DBM::Deep::Sector::File::BucketList->new({
f0276afb	338	engine => $engine,
	339	});
	340
	341	$new_index->set_entry( $idx => $blist->offset );
	342
	343	my $new_spot = $blist->write_at_next_open( $md5 );
	344	$engine->reindex_entry( $spot => $new_spot );
	345	}
	346
	347	# Handle the new item separately.
	348	{
	349	my $idx = ord( substr( $args->{key_md5}, $i, 1 ) );
	350
	351	# If all the previous blist's items have been thrown into one
	352	# blist and the new item belongs in there too, we need
	353	# another index.
	354	if ( keys %blist_cache == 1 and each %blist_cache == $idx ) {
	355	++$i, ++$redo;
	356	} else {
	357	my $blist = $blist_cache{$idx}
2c70efe1	358	\|\|= DBM::Deep::Sector::File::BucketList->new({
f0276afb	359	engine => $engine,
	360	});
	361
	362	$new_index->set_entry( $idx => $blist->offset );
	363
	364	#XXX THIS IS HACKY!
	365	$blist->find_md5( $args->{key_md5} );
	366	$blist->write_md5({
	367	key => $args->{key},
	368	key_md5 => $args->{key_md5},
2c70efe1	369	value => DBM::Deep::Sector::File::Null->new({
f0276afb	370	engine => $engine,
	371	data => undef,
	372	}),
	373	});
	374	}
f0276afb	375	}
	376
	377	if ( $last_sector ) {
	378	$last_sector->set_entry(
	379	ord( substr( $args->{key_md5}, $i - 1, 1 ) ),
	380	$new_index->offset,
	381	);
	382	} else {
	383	$engine->storage->print_at( $self->offset + $self->base_size,
	384	pack( $StP{$engine->byte_size}, $new_index->offset ),
	385	);
	386	}
	387
d3aaaf5e	388	$sector->wipe;
f0276afb	389	$sector->free;
	390
	391	if ( $redo ) {
	392	(undef, $sector) = %blist_cache;
	393	$last_sector = $new_index;
	394	redo;
	395	}
	396
	397	$sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) };
	398	$sector->find_md5( $args->{key_md5} );
	399	}}
	400
	401	return $sector;
	402	}
	403
	404	sub get_class_offset {
	405	my $self = shift;
	406
	407	my $e = $self->engine;
	408	return unpack(
	409	$StP{$e->byte_size},
	410	$e->storage->read_at(
	411	$self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size,
	412	),
	413	);
	414	}
	415
	416	sub get_classname {
	417	my $self = shift;
	418
	419	my $class_offset = $self->get_class_offset;
	420
	421	return unless $class_offset;
	422
d6ecf579	423	return $self->engine->load_sector( $class_offset )->data;
f0276afb	424	}
f0276afb	425
4f034d8f	426	# Look to hoist this method into a ::Reference trait
f0276afb	427	sub data {
	428	my $self = shift;
	429	my ($args) = @_;
	430	$args \|\|= {};
	431
	432	my $obj;
	433	unless ( $obj = $self->engine->cache->{ $self->offset } ) {
	434	$obj = DBM::Deep->new({
	435	type => $self->type,
	436	base_offset => $self->offset,
	437	staleness => $self->staleness,
	438	storage => $self->engine->storage,
	439	engine => $self->engine,
	440	});
	441
	442	if ( $self->engine->storage->{autobless} ) {
	443	my $classname = $self->get_classname;
	444	if ( defined $classname ) {
	445	bless $obj, $classname;
	446	}
	447	}
	448
	449	$self->engine->cache->{$self->offset} = $obj;
	450	}
	451
	452	# We're not exporting, so just return.
	453	unless ( $args->{export} ) {
	454	return $obj;
	455	}
	456
	457	# We shouldn't export if this is still referred to.
	458	if ( $self->get_refcount > 1 ) {
	459	return $obj;
	460	}
	461
	462	return $obj->export;
	463	}
	464
	465	sub free {
	466	my $self = shift;
	467
	468	# We're not ready to be removed yet.
4f034d8f	469	return if $self->decrement_refcount > 0;
f0276afb	470
	471	# Rebless the object into DBM::Deep::Null.
	472	eval { %{ $self->engine->cache->{ $self->offset } } = (); };
	473	eval { @{ $self->engine->cache->{ $self->offset } } = (); };
	474	bless $self->engine->cache->{ $self->offset }, 'DBM::Deep::Null';
	475	delete $self->engine->cache->{ $self->offset };
	476
	477	my $blist_loc = $self->get_blist_loc;
d6ecf579	478	$self->engine->load_sector( $blist_loc )->free if $blist_loc;
f0276afb	479
f0276afb	480	my $class_loc = $self->get_class_offset;
d6ecf579	481	$self->engine->load_sector( $class_loc )->free if $class_loc;
f0276afb	482
	483	$self->SUPER::free();
	484	}
	485
	486	sub increment_refcount {
	487	my $self = shift;
	488
	489	my $refcount = $self->get_refcount;
	490
	491	$refcount++;
	492
	493	$self->write_refcount( $refcount );
	494
	495	return $refcount;
	496	}
	497
	498	sub decrement_refcount {
	499	my $self = shift;
	500
	501	my $refcount = $self->get_refcount;
	502
	503	$refcount--;
	504
	505	$self->write_refcount( $refcount );
	506
	507	return $refcount;
	508	}
	509
	510	sub get_refcount {
	511	my $self = shift;
	512
	513	my $e = $self->engine;
	514	return unpack(
	515	$StP{$e->byte_size},
	516	$e->storage->read_at(
	517	$self->offset + $self->base_size + 2 * $e->byte_size, $e->byte_size,
	518	),
	519	);
	520	}
	521
	522	sub write_refcount {
	523	my $self = shift;
	524	my ($num) = @_;
	525
	526	my $e = $self->engine;
	527	$e->storage->print_at(
	528	$self->offset + $self->base_size + 2 * $e->byte_size,
	529	pack( $StP{$e->byte_size}, $num ),
	530	);
	531	}
	532
	533	1;
	534	__END__