X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBM%2FDeep%2FEngine.pm;h=73917a4d9bf6614a54a4789bb47eb5670f4e67bd;hb=fb451ba69d35e7acbd996e3de8c073f6ce76d7ea;hp=72d0690ca8babb5ded87667d1d4514d76da557f5;hpb=994ccd8e3cac357677196eb4ad5dad76089626a7;p=dbsrgits%2FDBM-Deep.git diff --git a/lib/DBM/Deep/Engine.pm b/lib/DBM/Deep/Engine.pm index 72d0690..73917a4 100644 --- a/lib/DBM/Deep/Engine.pm +++ b/lib/DBM/Deep/Engine.pm @@ -1,13 +1,31 @@ package DBM::Deep::Engine; +use 5.6.0; + use strict; +use warnings; + +our $VERSION = q(0.99_03); + +use Fcntl qw( :DEFAULT :flock ); +use Scalar::Util (); -use Fcntl qw( :DEFAULT :flock :seek ); +# File-wide notes: +# * To add to bucket_size, make sure you modify the following: +# - calculate_sizes() +# - _get_key_subloc() +# - add_bucket() - where the buckets are printed +# +# * Every method in here assumes that the _storage has been appropriately +# safeguarded. This can be anything from flock() to some sort of manual +# mutex. But, it's the caller's responsability to make sure that this has +# been done. ## # Setup file and tag signatures. These should never change. ## sub SIG_FILE () { 'DPDB' } +sub SIG_HEADER () { 'h' } sub SIG_INTERNAL () { 'i' } sub SIG_HASH () { 'H' } sub SIG_ARRAY () { 'A' } @@ -15,223 +33,322 @@ sub SIG_NULL () { 'N' } sub SIG_DATA () { 'D' } sub SIG_INDEX () { 'I' } sub SIG_BLIST () { 'B' } +sub SIG_FREE () { 'F' } +sub SIG_KEYS () { 'K' } sub SIG_SIZE () { 1 } -sub precalc_sizes { - ## - # Precalculate index, bucket and bucket list sizes - ## - my $self = shift; +# This is the transaction ID for the HEAD +sub HEAD () { 0 } - $self->{index_size} = (2**8) * $self->{long_size}; - $self->{bucket_size} = $self->{hash_size} + $self->{long_size}; - $self->{bucket_list_size} = $self->{max_buckets} * $self->{bucket_size}; +################################################################################ +# +# This is new code. It is a complete rewrite of the engine based on a new API +# +################################################################################ - return 1; +sub read_value { + my $self = shift; + my ($offset, $key, $orig_key) = @_; + + my $dig_key = $self->apply_digest( $key ); + my $tag = $self->find_blist( $offset, $dig_key ) or return; + return $self->get_bucket_value( $tag, $dig_key, $orig_key ); } -sub set_pack { - ## - # Set pack/unpack modes (see file header for more) - ## +sub key_exists { my $self = shift; - my ($long_s, $long_p, $data_s, $data_p) = @_; + my ($offset, $key) = @_; - ## - # Set to 4 and 'N' for 32-bit offset tags (default). Theoretical limit of 4 - # GB per file. - # (Perl must be compiled with largefile support for files > 2 GB) - # - # Set to 8 and 'Q' for 64-bit offsets. Theoretical limit of 16 XB per file. - # (Perl must be compiled with largefile and 64-bit long support) - ## - $self->{long_size} = $long_s ? $long_s : 4; - $self->{long_pack} = $long_p ? $long_p : 'N'; + my $dig_key = $self->apply_digest( $key ); + # exists() returns the empty string, not undef + my $tag = $self->find_blist( $offset, $dig_key ) or return ''; + return $self->bucket_exists( $tag, $dig_key, $key ); +} - ## - # Set to 4 and 'N' for 32-bit data length prefixes. Limit of 4 GB for each - # key/value. Upgrading this is possible (see above) but probably not - # necessary. If you need more than 4 GB for a single key or value, this - # module is really not for you :-) - ## - $self->{data_size} = $data_s ? $data_s : 4; - $self->{data_pack} = $data_p ? $data_p : 'N'; +sub get_next_key { + my $self = shift; + my ($offset) = @_; + + # If the previous key was not specifed, start at the top and + # return the first one found. + my $temp; + if ( @_ > 1 ) { + $temp = { + prev_md5 => $self->apply_digest($_[1]), + return_next => 0, + }; + } + else { + $temp = { + prev_md5 => chr(0) x $self->{hash_size}, + return_next => 1, + }; + } - return $self->precalc_sizes(); + return $self->traverse_index( $temp, $offset, 0 ); } -sub set_digest { - ## - # Set key digest function (default is MD5) - ## +sub delete_key { my $self = shift; - my ($digest_func, $hash_size) = @_; + my ($offset, $key, $orig_key) = @_; - $self->{digest} = $digest_func ? $digest_func : \&Digest::MD5::md5; - $self->{hash_size} = $hash_size ? $hash_size : 16; + my $dig_key = $self->apply_digest( $key ); + my $tag = $self->find_blist( $offset, $dig_key ) or return; + my $value = $self->get_bucket_value( $tag, $dig_key, $orig_key ); + $self->delete_bucket( $tag, $dig_key, $orig_key ); + return $value; +} - return $self->precalc_sizes(); +sub write_value { + my $self = shift; + my ($offset, $key, $value, $orig_key) = @_; + + my $dig_key = $self->apply_digest( $key ); + my $tag = $self->find_blist( $offset, $dig_key, { create => 1 } ); + return $self->add_bucket( $tag, $dig_key, $key, $value, undef, $orig_key ); } +################################################################################ +# +# Below here is the old code. It will be folded into the code above as it can. +# +################################################################################ + sub new { my $class = shift; my ($args) = @_; my $self = bless { - long_size => 4, - long_pack => 'N', - data_size => 4, - data_pack => 'N', + long_size => 4, + long_pack => 'N', + data_size => 4, + data_pack => 'N', - digest => \&Digest::MD5::md5, - hash_size => 16, + digest => \&Digest::MD5::md5, + hash_size => 16, # In bytes ## - # Maximum number of buckets per list before another level of indexing is - # done. - # Increase this value for slightly greater speed, but larger database + # Number of buckets per blist before another level of indexing is + # done. Increase this value for slightly greater speed, but larger database # files. DO NOT decrease this value below 16, due to risk of recursive # reindex overrun. ## max_buckets => 16, + + storage => undef, + obj => undef, }, $class; - $self->precalc_sizes; + if ( defined $args->{pack_size} ) { + if ( lc $args->{pack_size} eq 'small' ) { + $args->{long_size} = 2; + $args->{long_pack} = 'n'; + } + elsif ( lc $args->{pack_size} eq 'medium' ) { + $args->{long_size} = 4; + $args->{long_pack} = 'N'; + } + elsif ( lc $args->{pack_size} eq 'large' ) { + $args->{long_size} = 8; + $args->{long_pack} = 'Q'; + } + else { + die "Unknown pack_size value: '$args->{pack_size}'\n"; + } + } + + # Grab the parameters we want to use + foreach my $param ( keys %$self ) { + next unless exists $args->{$param}; + $self->{$param} = $args->{$param}; + } + Scalar::Util::weaken( $self->{obj} ) if $self->{obj}; + + if ( $self->{max_buckets} < 16 ) { + warn "Floor of max_buckets is 16. Setting it to 16 from '$self->{max_buckets}'\n"; + $self->{max_buckets} = 16; + } return $self; } -sub setup_fh { - my $self = shift; - my ($obj) = @_; - - $self->open( $obj ) if !defined $obj->_fh; +sub _storage { return $_[0]{storage} } - #XXX We have to make sure we don't mess up when autoflush isn't turned on - unless ( $obj->_root->{inode} ) { - my @stats = stat($obj->_fh); - $obj->_root->{inode} = $stats[1]; - $obj->_root->{end} = $stats[7]; - } - - return 1; +sub apply_digest { + my $self = shift; + return $self->{digest}->(@_); } -sub open { - ## - # Open a fh to the database, create if nonexistent. - # Make sure file signature matches DBM::Deep spec. - ## +sub calculate_sizes { my $self = shift; - my ($obj) = @_; - if (defined($obj->_fh)) { $self->close_fh( $obj ); } + # The 2**8 here indicates the number of different characters in the + # current hashing algorithm + #XXX Does this need to be updated with different hashing algorithms? + $self->{hash_chars_used} = (2**8); + $self->{index_size} = $self->{hash_chars_used} * $self->{long_size}; - # Theoretically, adding O_BINARY should remove the need for the binmode - # Of course, testing it is going to be ... interesting. - my $flags = O_RDWR | O_CREAT | O_BINARY; + $self->{bucket_size} = $self->{hash_size} + $self->{long_size} * 2; + $self->{bucket_list_size} = $self->{max_buckets} * $self->{bucket_size}; - my $fh; - my $filename = $obj->_root->{file}; - sysopen( $fh, $filename, $flags ) - or $obj->_throw_error("Cannot sysopen file '$filename': $!"); - $obj->_root->{fh} = $fh; + $self->{key_size} = $self->{long_size} * 2; + $self->{keyloc_size} = $self->{max_buckets} * $self->{key_size}; - #XXX Can we remove this by using the right sysopen() flags? - # Maybe ... q.v. above - binmode $fh; # for win32 + return; +} - if ($obj->_root->{autoflush}) { - my $old = select $fh; - $|=1; - select $old; - } +sub write_file_header { + my $self = shift; - seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET); - my $signature; - my $bytes_read = read( $fh, $signature, length(SIG_FILE)); + my $loc = $self->_storage->request_space( length( SIG_FILE ) + 33 ); + + $self->_storage->print_at( $loc, + SIG_FILE, + SIG_HEADER, + pack('N', 1), # header version + pack('N', 24), # header size + pack('N4', 0, 0, 0, 0), # currently running transaction IDs + pack('n', $self->{long_size}), + pack('A', $self->{long_pack}), + pack('n', $self->{data_size}), + pack('A', $self->{data_pack}), + pack('n', $self->{max_buckets}), + ); - ## - # File is empty -- write signature and master index - ## - if (!$bytes_read) { - seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET); - print( $fh SIG_FILE); + $self->_storage->set_transaction_offset( 13 ); - $obj->_root->{end} = length( SIG_FILE ); + return; +} - $obj->{base_offset} = $self->_request_space($obj, $self->{index_size}); +sub read_file_header { + my $self = shift; - $self->create_tag( - $obj, $obj->_base_offset, $obj->_type, chr(0) x $self->{index_size}, - ); + my $buffer = $self->_storage->read_at( 0, length(SIG_FILE) + 9 ); + return unless length($buffer); - # Flush the filehandle - my $old_fh = select $fh; - my $old_af = $|; $| = 1; $| = $old_af; - select $old_fh; + my ($file_signature, $sig_header, $header_version, $size) = unpack( + 'A4 A N N', $buffer + ); - return 1; + unless ( $file_signature eq SIG_FILE ) { + $self->_storage->close; + $self->_throw_error( "Signature not found -- file is not a Deep DB" ); } - ## - # Check signature was valid - ## - unless ($signature eq SIG_FILE) { - $self->close_fh( $obj ); - $obj->_throw_error("Signature not found -- file is not a Deep DB"); + unless ( $sig_header eq SIG_HEADER ) { + $self->_storage->close; + $self->_throw_error( "Old file version found." ); } - ## - # Get our type from master index signature - ## - my $tag = $self->load_tag($obj, $obj->_base_offset) - or $obj->_throw_error("Corrupted file, no master index record"); + my $buffer2 = $self->_storage->read_at( undef, $size ); + my ($a1, $a2, $a3, $a4, @values) = unpack( 'N4 n A n A n', $buffer2 ); + + $self->_storage->set_transaction_offset( 13 ); - unless ($obj->{type} eq $tag->{signature}) { - $obj->_throw_error("File type mismatch"); + if ( @values < 5 || grep { !defined } @values ) { + $self->_storage->close; + $self->_throw_error("Corrupted file - bad header"); } -#XXX We probably also want to store the hash algorithm name and not assume anything -#XXX The cool thing would be to allow a different hashing algorithm at every level + #XXX Add warnings if values weren't set right + @{$self}{qw(long_size long_pack data_size data_pack max_buckets)} = @values; - return 1; + return length($buffer) + length($buffer2); } -sub close_fh { +sub setup_fh { my $self = shift; my ($obj) = @_; - if ( my $fh = $obj->_root->{fh} ) { - close $fh; + # Need to remove use of $fh here + my $fh = $self->_storage->{fh}; + flock $fh, LOCK_EX; + + #XXX The duplication of calculate_sizes needs to go away + unless ( $obj->{base_offset} ) { + my $bytes_read = $self->read_file_header; + + $self->calculate_sizes; + + ## + # File is empty -- write header and master index + ## + if (!$bytes_read) { + $self->_storage->audit( "# Database created on" ); + + $self->write_file_header; + + $obj->{base_offset} = $self->_storage->request_space( + $self->tag_size( $self->{index_size} ), + ); + + $self->write_tag( + $obj->_base_offset, $obj->_type, + chr(0)x$self->{index_size}, + ); + + # Flush the filehandle + my $old_fh = select $fh; + my $old_af = $|; $| = 1; $| = $old_af; + select $old_fh; + } + else { + $obj->{base_offset} = $bytes_read; + + ## + # Get our type from master index header + ## + my $tag = $self->load_tag($obj->_base_offset); + unless ( $tag ) { + flock $fh, LOCK_UN; + $self->_throw_error("Corrupted file, no master index record"); + } + + unless ($obj->_type eq $tag->{signature}) { + flock $fh, LOCK_UN; + $self->_throw_error("File type mismatch"); + } + } + } + else { + $self->calculate_sizes; } - $obj->_root->{fh} = undef; + + #XXX We have to make sure we don't mess up when autoflush isn't turned on + $self->_storage->set_inode; + + flock $fh, LOCK_UN; return 1; } -sub create_tag { +sub tag_size { + my $self = shift; + my ($size) = @_; + return SIG_SIZE + $self->{data_size} + $size; +} + +sub write_tag { ## # Given offset, signature and content, create tag and write to disk ## my $self = shift; - my ($obj, $offset, $sig, $content) = @_; - my $size = length($content); - - my $fh = $obj->_fh; + my ($offset, $sig, $content) = @_; + my $size = length( $content ); - seek($fh, $offset + $obj->_root->{file_offset}, SEEK_SET); - print( $fh $sig . pack($self->{data_pack}, $size) . $content ); + $self->_storage->print_at( + $offset, + $sig, pack($self->{data_pack}, $size), $content, + ); - if ($offset == $obj->_root->{end}) { - $obj->_root->{end} += SIG_SIZE + $self->{data_size} + $size; - } + return unless defined $offset; return { signature => $sig, - size => $size, - offset => $offset + SIG_SIZE + $self->{data_size}, - content => $content + #XXX Is this even used? + size => $size, + offset => $offset + SIG_SIZE + $self->{data_size}, + content => $content }; } @@ -240,246 +357,235 @@ sub load_tag { # Given offset, load single tag and return signature, size and data ## my $self = shift; - my ($obj, $offset) = @_; - - my $fh = $obj->_fh; - - seek($fh, $offset + $obj->_root->{file_offset}, SEEK_SET); - - #XXX I'm not sure this check will work if autoflush isn't enabled ... - return if eof $fh; + my ($offset) = @_; - my $b; - read( $fh, $b, SIG_SIZE + $self->{data_size} ); - my ($sig, $size) = unpack( "A $self->{data_pack}", $b ); + my $storage = $self->_storage; - my $buffer; - read( $fh, $buffer, $size); + my ($sig, $size) = unpack( + "A $self->{data_pack}", + $storage->read_at( $offset, SIG_SIZE + $self->{data_size} ), + ); return { signature => $sig, - size => $size, - offset => $offset + SIG_SIZE + $self->{data_size}, - content => $buffer + size => $size, #XXX Is this even used? + start => $offset, + offset => $offset + SIG_SIZE + $self->{data_size}, + content => $storage->read_at( undef, $size ), }; } +sub find_keyloc { + my $self = shift; + my ($tag, $transaction_id) = @_; + $transaction_id = $self->_storage->transaction_id + unless defined $transaction_id; + + for ( my $i = 0; $i < $self->{max_buckets}; $i++ ) { + my ($loc, $trans_id, $is_deleted) = unpack( + "$self->{long_pack} C C", + substr( $tag->{content}, $i * $self->{key_size}, $self->{key_size} ), + ); + + next if $loc != HEAD && $transaction_id != $trans_id; + return( $loc, $is_deleted, $i * $self->{key_size} ); + } + + return; +} + sub add_bucket { ## # Adds one key/value pair to bucket list, given offset, MD5 digest of key, # plain (undigested) key and value. ## my $self = shift; - my ($obj, $tag, $md5, $plain_key, $value) = @_; + my ($tag, $md5, $plain_key, $value, $deleted, $orig_key) = @_; # This verifies that only supported values will be stored. { my $r = Scalar::Util::reftype( $value ); - last if !defined $r; + last if !defined $r; last if $r eq 'HASH'; last if $r eq 'ARRAY'; - $obj->_throw_error( - "Storage of variables of type '$r' is not supported." + $self->_throw_error( + "Storage of references of type '$r' is not supported." ); } - my $location = 0; - my $result = 2; + my $storage = $self->_storage; - my $root = $obj->_root; + #ACID - This is a mutation. Must only find the exact transaction + my ($keyloc, $offset) = $self->_find_in_buckets( $tag, $md5, 1 ); - my $is_dbm_deep = eval { - local $SIG{'__DIE__'}; - $value->isa( 'DBM::Deep' ); - }; - - my $internal_ref = $is_dbm_deep && ($value->_root eq $root); + my @transactions; + if ( $storage->transaction_id == 0 ) { + @transactions = $storage->current_transactions; + } - my $fh = $obj->_fh; +# $self->_release_space( $size, $subloc ); +#XXX This needs updating to use _release_space - my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 ); + my $location; + my $size = $self->_length_needed( $value, $plain_key ); # Updating a known md5 - if ( $subloc ) { - $result = 1; - - ## - # If value is a hash, array, or raw value with equal or less size, we - # can reuse the same content area of the database. Otherwise, we have - # to create a new content area at the EOF. - ## - my $actual_length; - if ( $internal_ref ) { - $actual_length = $self->{long_size}; - } - else { - my $r = Scalar::Util::reftype( $value ) || ''; - if ( $r eq 'HASH' || $r eq 'ARRAY' ) { - $actual_length = $self->{index_size}; - - # if autobless is enabled, must also take into consideration - # the class name, as it is stored along with key/value. - if ( $root->{autobless} ) { - my $value_class = Scalar::Util::blessed($value); - if ( defined $value_class && !$value->isa('DBM::Deep') ) { - $actual_length += length($value_class); - } + if ( $keyloc ) { + my $keytag = $self->load_tag( $keyloc ); + my ($subloc, $is_deleted, $offset) = $self->find_keyloc( $keytag ); + + if ( $subloc && !$is_deleted && @transactions ) { + my $old_value = $self->read_from_loc( $subloc, $orig_key ); + my $old_size = $self->_length_needed( $old_value, $plain_key ); + + for my $trans_id ( @transactions ) { + my ($loc, $is_deleted, $offset2) = $self->find_keyloc( $keytag, $trans_id ); + unless ($loc) { + my $location2 = $storage->request_space( $old_size ); + $storage->print_at( $keytag->{offset} + $offset2, + pack($self->{long_pack}, $location2 ), + pack( 'C C', $trans_id, 0 ), + ); + $self->_write_value( $location2, $plain_key, $old_value, $orig_key ); } } - else { $actual_length = length($value); } } - seek($fh, $subloc + SIG_SIZE + $root->{file_offset}, SEEK_SET); - my $size; - read( $fh, $size, $self->{data_size}); - $size = unpack($self->{data_pack}, $size); + $location = $self->_storage->request_space( $size ); + #XXX This needs to be transactionally-aware in terms of which keytag->{offset} to use + $storage->print_at( $keytag->{offset} + $offset, + pack($self->{long_pack}, $location ), + pack( 'C C', $storage->transaction_id, 0 ), + ); + } + # Adding a new md5 + else { + my $keyloc = $storage->request_space( $self->tag_size( $self->{keyloc_size} ) ); - if ($actual_length <= $size) { - $location = $subloc; + # The bucket fit into list + if ( defined $offset ) { + $storage->print_at( $tag->{offset} + $offset, + $md5, pack( $self->{long_pack}, $keyloc ), + ); } + # If bucket didn't fit into list, split into a new index level else { - $location = $root->{end}; - seek( - $fh, - $tag->{offset} + $offset + $self->{hash_size} + $root->{file_offset}, - SEEK_SET, - ); - print( $fh pack($self->{long_pack}, $location) ); + $self->split_index( $tag, $md5, $keyloc ); } - } - # Adding a new md5 - elsif ( defined $offset ) { - $location = $root->{end}; - seek( $fh, $tag->{offset} + $offset + $root->{file_offset}, SEEK_SET ); - print( $fh $md5 . pack($self->{long_pack}, $location) ); - } - # If bucket didn't fit into list, split into a new index level - else { - $self->split_index( $obj, $md5, $tag ); + my $keytag = $self->write_tag( + $keyloc, SIG_KEYS, chr(0)x$self->{keyloc_size}, + ); + + $location = $self->_storage->request_space( $size ); + $storage->print_at( $keytag->{offset}, + pack( $self->{long_pack}, $location ), + pack( 'C C', $storage->transaction_id, 0 ), + ); - $location = $root->{end}; + my $offset = 1; + for my $trans_id ( @transactions ) { + $storage->print_at( $keytag->{offset} + $self->{key_size} * $offset++, + pack( $self->{long_pack}, 0 ), + pack( 'C C', $trans_id, 1 ), + ); + } } - $self->write_value( $obj, $location, $plain_key, $value ); + $self->_write_value( $location, $plain_key, $value, $orig_key ); - return $result; + return 1; } -sub write_value { +sub _write_value { my $self = shift; - my ($obj, $location, $key, $value) = @_; + my ($location, $key, $value, $orig_key) = @_; - my $fh = $obj->_fh; - my $root = $obj->_root; + my $storage = $self->_storage; - my $is_dbm_deep = eval { - local $SIG{'__DIE__'}; - $value->isa( 'DBM::Deep' ); - }; - - my $internal_ref = $is_dbm_deep && ($value->_root eq $root); - - seek($fh, $location + $root->{file_offset}, SEEK_SET); + my $dbm_deep_obj = _get_dbm_object( $value ); + if ( $dbm_deep_obj && $dbm_deep_obj->_storage ne $storage ) { + $self->_throw_error( "Cannot cross-reference. Use export() instead" ); + } ## # Write signature based on content type, set content length and write # actual value. ## - my $r = Scalar::Util::reftype($value) || ''; - my $content_length; - if ( $internal_ref ) { - print( $fh SIG_INTERNAL ); - print( $fh pack($self->{data_pack}, $self->{long_size}) ); - print( $fh pack($self->{long_pack}, $value->_base_offset) ); - $content_length = $self->{long_size}; + my $r = Scalar::Util::reftype( $value ) || ''; + if ( $dbm_deep_obj ) { + $self->write_tag( $location, SIG_INTERNAL,pack($self->{long_pack}, $dbm_deep_obj->_base_offset) ); } - else { - if ($r eq 'HASH') { - print( $fh SIG_HASH ); - print( $fh pack($self->{data_pack}, $self->{index_size}) . chr(0) x $self->{index_size} ); - $content_length = $self->{index_size}; - } - elsif ($r eq 'ARRAY') { - print( $fh SIG_ARRAY ); - print( $fh pack($self->{data_pack}, $self->{index_size}) . chr(0) x $self->{index_size} ); - $content_length = $self->{index_size}; - } - elsif (!defined($value)) { - print( $fh SIG_NULL ); - print( $fh pack($self->{data_pack}, 0) ); - $content_length = 0; + elsif ($r eq 'HASH') { + if ( !$dbm_deep_obj && tied %{$value} ) { + $self->_throw_error( "Cannot store something that is tied" ); } - else { - print( $fh SIG_DATA ); - print( $fh pack($self->{data_pack}, length($value)) . $value ); - $content_length = length($value); + $self->write_tag( $location, SIG_HASH, chr(0)x$self->{index_size} ); + } + elsif ($r eq 'ARRAY') { + if ( !$dbm_deep_obj && tied @{$value} ) { + $self->_throw_error( "Cannot store something that is tied" ); } + $self->write_tag( $location, SIG_ARRAY, chr(0)x$self->{index_size} ); + } + elsif (!defined($value)) { + $self->write_tag( $location, SIG_NULL, '' ); + } + else { + $self->write_tag( $location, SIG_DATA, $value ); } ## # Plain key is stored AFTER value, as keys are typically fetched less often. ## - print( $fh pack($self->{data_pack}, length($key)) . $key ); + $storage->print_at( undef, pack($self->{data_pack}, length($key)) . $key ); + + # Internal references don't care about autobless + return 1 if $dbm_deep_obj; ## # If value is blessed, preserve class name ## - if ( $root->{autobless} ) { - my $value_class = Scalar::Util::blessed($value); - if ( defined $value_class && !$value->isa( 'DBM::Deep' ) ) { - ## - # Blessed ref -- will restore later - ## - print( $fh chr(1) ); - print( $fh pack($self->{data_pack}, length($value_class)) . $value_class ); - $content_length += 1; - $content_length += $self->{data_size} + length($value_class); + if ( $storage->{autobless} ) { + if ( defined( my $c = Scalar::Util::blessed($value) ) ) { + $storage->print_at( undef, chr(1), pack($self->{data_pack}, length($c)) . $c ); } else { - print( $fh chr(0) ); - $content_length += 1; + $storage->print_at( undef, chr(0) ); } } ## - # If this is a new content area, advance EOF counter + # Tie the passed in reference so that changes to it are reflected in the + # datafile. The use of $location as the base_offset will act as the + # the linkage between parent and child. + # + # The overall assignment is a hack around the fact that just tying doesn't + # store the values. This may not be the wrong thing to do. ## - if ($location == $root->{end}) { - $root->{end} += SIG_SIZE; - $root->{end} += $self->{data_size} + $content_length; - $root->{end} += $self->{data_size} + length($key); + if ($r eq 'HASH') { + my %x = %$value; + tie %$value, 'DBM::Deep', { + base_offset => $location, + storage => $storage, + parent => $self->{obj}, + parent_key => $orig_key, + }; + %$value = %x; + bless $value, 'DBM::Deep::Hash' unless Scalar::Util::blessed( $value ); } - - ## - # If content is a hash or array, create new child DBM::Deep object and - # pass each key or element to it. - ## - if ( ! $internal_ref ) { - if ($r eq 'HASH') { - my $branch = DBM::Deep->new( - type => DBM::Deep->TYPE_HASH, - base_offset => $location, - root => $root, - ); - foreach my $key (keys %{$value}) { - $branch->STORE( $key, $value->{$key} ); - } - } - elsif ($r eq 'ARRAY') { - my $branch = DBM::Deep->new( - type => DBM::Deep->TYPE_ARRAY, - base_offset => $location, - root => $root, - ); - my $index = 0; - foreach my $element (@{$value}) { - $branch->STORE( $index, $element ); - $index++; - } - } + elsif ($r eq 'ARRAY') { + my @x = @$value; + tie @$value, 'DBM::Deep', { + base_offset => $location, + storage => $storage, + parent => $self->{obj}, + parent_key => $orig_key, + }; + @$value = @x; + bless $value, 'DBM::Deep::Array' unless Scalar::Util::blessed( $value ); } return 1; @@ -487,125 +593,159 @@ sub write_value { sub split_index { my $self = shift; - my ($obj, $md5, $tag) = @_; - - my $fh = $obj->_fh; - my $root = $obj->_root; - my $keys = $tag->{content}; + my ($tag, $md5, $keyloc) = @_; - seek($fh, $tag->{ref_loc} + $root->{file_offset}, SEEK_SET); - print( $fh pack($self->{long_pack}, $root->{end}) ); + my $storage = $self->_storage; - my $index_tag = $self->create_tag( - $obj, - $root->{end}, - SIG_INDEX, - chr(0) x $self->{index_size}, + my $loc = $storage->request_space( + $self->tag_size( $self->{index_size} ), ); - my @offsets = (); + $storage->print_at( $tag->{ref_loc}, pack($self->{long_pack}, $loc) ); - $keys .= $md5 . pack($self->{long_pack}, 0); + my $index_tag = $self->write_tag( + $loc, SIG_INDEX, + chr(0)x$self->{index_size}, + ); + + my $keys = $tag->{content} + . $md5 . pack($self->{long_pack}, $keyloc); + my @newloc = (); BUCKET: + # The <= here is deliberate - we have max_buckets+1 keys to iterate + # through, unlike every other loop that uses max_buckets as a stop. for (my $i = 0; $i <= $self->{max_buckets}; $i++) { my ($key, $old_subloc) = $self->_get_key_subloc( $keys, $i ); - next BUCKET unless $key; + die "[INTERNAL ERROR]: No key in split_index()\n" unless $key; + die "[INTERNAL ERROR]: No subloc in split_index()\n" unless $old_subloc; my $num = ord(substr($key, $tag->{ch} + 1, 1)); - if ($offsets[$num]) { - my $offset = $offsets[$num] + SIG_SIZE + $self->{data_size}; - seek($fh, $offset + $root->{file_offset}, SEEK_SET); - my $subkeys; - read( $fh, $subkeys, $self->{bucket_list_size}); + if ($newloc[$num]) { + my $subkeys = $storage->read_at( $newloc[$num], $self->{bucket_list_size} ); - for (my $k=0; $k<$self->{max_buckets}; $k++) { - my ($temp, $subloc) = $self->_get_key_subloc( $subkeys, $k ); + # This is looking for the first empty spot + my ($subloc, $offset) = $self->_find_in_buckets( + { content => $subkeys }, '', + ); - if (!$subloc) { - seek($fh, $offset + ($k * $self->{bucket_size}) + $root->{file_offset}, SEEK_SET); - print( $fh $key . pack($self->{long_pack}, $old_subloc || $root->{end}) ); - last; - } - } # k loop + $storage->print_at( + $newloc[$num] + $offset, + $key, pack($self->{long_pack}, $old_subloc), + ); + + next; } - else { - $offsets[$num] = $root->{end}; - seek($fh, $index_tag->{offset} + ($num * $self->{long_size}) + $root->{file_offset}, SEEK_SET); - print( $fh pack($self->{long_pack}, $root->{end}) ); - my $blist_tag = $self->create_tag($obj, $root->{end}, SIG_BLIST, chr(0) x $self->{bucket_list_size}); + my $loc = $storage->request_space( + $self->tag_size( $self->{bucket_list_size} ), + ); - seek($fh, $blist_tag->{offset} + $root->{file_offset}, SEEK_SET); - print( $fh $key . pack($self->{long_pack}, $old_subloc || $root->{end}) ); - } - } # i loop + $storage->print_at( + $index_tag->{offset} + ($num * $self->{long_size}), + pack($self->{long_pack}, $loc), + ); - return; + my $blist_tag = $self->write_tag( + $loc, SIG_BLIST, + chr(0)x$self->{bucket_list_size}, + ); + + $storage->print_at( $blist_tag->{offset}, $key . pack($self->{long_pack}, $old_subloc) ); + + $newloc[$num] = $blist_tag->{offset}; + } + + $self->_release_space( + $self->tag_size( $self->{bucket_list_size} ), + $tag->{start}, + ); + + return 1; } sub read_from_loc { my $self = shift; - my ($obj, $subloc) = @_; + my ($subloc, $orig_key) = @_; - my $fh = $obj->_fh; + my $storage = $self->_storage; - ## - # Found match -- seek to offset and read signature - ## - my $signature; - seek($fh, $subloc + $obj->_root->{file_offset}, SEEK_SET); - read( $fh, $signature, SIG_SIZE); + my $signature = $storage->read_at( $subloc, SIG_SIZE ); ## # If value is a hash or array, return new DBM::Deep object with correct offset ## if (($signature eq SIG_HASH) || ($signature eq SIG_ARRAY)) { - my $obj = DBM::Deep->new( - type => $signature, + #XXX This needs to be a singleton +# my $new_obj; +# my $is_autobless; +# if ( $signature eq SIG_HASH ) { +# $new_obj = {}; +# tie %$new_obj, 'DBM::Deep', { +# base_offset => $subloc, +# storage => $self->_storage, +# parent => $self->{obj}, +# parent_key => $orig_key, +# }; +# $is_autobless = tied(%$new_obj)->_storage->{autobless}; +# } +# else { +# $new_obj = []; +# tie @$new_obj, 'DBM::Deep', { +# base_offset => $subloc, +# storage => $self->_storage, +# parent => $self->{obj}, +# parent_key => $orig_key, +# }; +# $is_autobless = tied(@$new_obj)->_storage->{autobless}; +# } +# +# if ($is_autobless) { + + my $new_obj = DBM::Deep->new({ + type => $signature, base_offset => $subloc, - root => $obj->_root, - ); + storage => $self->_storage, + parent => $self->{obj}, + parent_key => $orig_key, + }); - if ($obj->_root->{autobless}) { + if ($new_obj->_storage->{autobless}) { ## # Skip over value and plain key to see if object needs # to be re-blessed ## - seek($fh, $self->{data_size} + $self->{index_size}, SEEK_CUR); - - my $size; - read( $fh, $size, $self->{data_size}); $size = unpack($self->{data_pack}, $size); - if ($size) { seek($fh, $size, SEEK_CUR); } - - my $bless_bit; - read( $fh, $bless_bit, 1); - if (ord($bless_bit)) { - ## - # Yes, object needs to be re-blessed - ## - my $class_name; - read( $fh, $size, $self->{data_size}); $size = unpack($self->{data_pack}, $size); - if ($size) { read( $fh, $class_name, $size); } - if ($class_name) { $obj = bless( $obj, $class_name ); } + $storage->increment_pointer( $self->{data_size} + $self->{index_size} ); + + my $size = $storage->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + if ($size) { $storage->increment_pointer( $size ); } + + my $bless_bit = $storage->read_at( undef, 1 ); + if ( ord($bless_bit) ) { + my $size = unpack( + $self->{data_pack}, + $storage->read_at( undef, $self->{data_size} ), + ); + + if ( $size ) { + $new_obj = bless $new_obj, $storage->read_at( undef, $size ); + } } } - return $obj; + return $new_obj; } elsif ( $signature eq SIG_INTERNAL ) { - my $size; - read( $fh, $size, $self->{data_size}); + my $size = $storage->read_at( undef, $self->{data_size} ); $size = unpack($self->{data_pack}, $size); if ( $size ) { - my $new_loc; - read( $fh, $new_loc, $size ); - $new_loc = unpack( $self->{long_pack}, $new_loc ); - - return $self->read_from_loc( $obj, $new_loc ); + my $new_loc = $storage->read_at( undef, $size ); + $new_loc = unpack( $self->{long_pack}, $new_loc ); + return $self->read_from_loc( $new_loc, $orig_key ); } else { return; @@ -614,13 +754,11 @@ sub read_from_loc { ## # Otherwise return actual value ## - elsif ($signature eq SIG_DATA) { - my $size; - read( $fh, $size, $self->{data_size}); + elsif ( $signature eq SIG_DATA ) { + my $size = $storage->read_at( undef, $self->{data_size} ); $size = unpack($self->{data_pack}, $size); - my $value = ''; - if ($size) { read( $fh, $value, $size); } + my $value = $size ? $storage->read_at( undef, $size ) : ''; return $value; } @@ -635,12 +773,28 @@ sub get_bucket_value { # Fetch single value given tag and MD5 digested key. ## my $self = shift; - my ($obj, $tag, $md5) = @_; + my ($tag, $md5, $orig_key) = @_; - my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 ); - if ( $subloc ) { - return $self->read_from_loc( $obj, $subloc ); + #ACID - This is a read. Can find exact or HEAD + my ($keyloc, $offset) = $self->_find_in_buckets( $tag, $md5 ); + + if ( !$keyloc ) { + #XXX Need to use real key +# $self->add_bucket( $tag, $md5, $orig_key, undef, $orig_key ); +# return; + } +# elsif ( !$is_deleted ) { + else { + my $keytag = $self->load_tag( $keyloc ); + my ($subloc, $is_deleted) = $self->find_keyloc( $keytag ); + if (!$subloc && !$is_deleted) { + ($subloc, $is_deleted) = $self->find_keyloc( $keytag, 0 ); + } + if ( $subloc && !$is_deleted ) { + return $self->read_from_loc( $subloc, $orig_key ); + } } + return; } @@ -649,18 +803,62 @@ sub delete_bucket { # Delete single key/value pair given tag and MD5 digested key. ## my $self = shift; - my ($obj, $tag, $md5) = @_; + my ($tag, $md5, $orig_key) = @_; + + #ACID - Although this is a mutation, we must find any transaction. + # This is because we need to mark something as deleted that is in the HEAD. + my ($keyloc, $offset) = $self->_find_in_buckets( $tag, $md5 ); + + return if !$keyloc; - my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 ); - if ( $subloc ) { - my $fh = $obj->_fh; - seek($fh, $tag->{offset} + $offset + $obj->_root->{file_offset}, SEEK_SET); - print( $fh substr($tag->{content}, $offset + $self->{bucket_size} ) ); - print( $fh chr(0) x $self->{bucket_size} ); + my $storage = $self->_storage; - return 1; + my @transactions; + if ( $storage->transaction_id == 0 ) { + @transactions = $storage->current_transactions; } - return; + + if ( $storage->transaction_id == 0 ) { + my $keytag = $self->load_tag( $keyloc ); + + my ($subloc, $is_deleted, $offset) = $self->find_keyloc( $keytag ); + return if !$subloc || $is_deleted; + + my $value = $self->read_from_loc( $subloc, $orig_key ); + + my $size = $self->_length_needed( $value, $orig_key ); + + for my $trans_id ( @transactions ) { + my ($loc, $is_deleted, $offset2) = $self->find_keyloc( $keytag, $trans_id ); + unless ($loc) { + my $location2 = $storage->request_space( $size ); + $storage->print_at( $keytag->{offset} + $offset2, + pack($self->{long_pack}, $location2 ), + pack( 'C C', $trans_id, 0 ), + ); + $self->_write_value( $location2, $orig_key, $value, $orig_key ); + } + } + + $keytag = $self->load_tag( $keyloc ); + ($subloc, $is_deleted, $offset) = $self->find_keyloc( $keytag ); + $storage->print_at( $keytag->{offset} + $offset, + substr( $keytag->{content}, $offset + $self->{key_size} ), + chr(0) x $self->{key_size}, + ); + } + else { + my $keytag = $self->load_tag( $keyloc ); + + my ($subloc, $is_deleted, $offset) = $self->find_keyloc( $keytag ); + + $storage->print_at( $keytag->{offset} + $offset, + pack($self->{long_pack}, 0 ), + pack( 'C C', $storage->transaction_id, 1 ), + ); + } + + return 1; } sub bucket_exists { @@ -668,44 +866,51 @@ sub bucket_exists { # Check existence of single key given tag and MD5 digested key. ## my $self = shift; - my ($obj, $tag, $md5) = @_; + my ($tag, $md5) = @_; - my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 ); - return $subloc && 1; + #ACID - This is a read. Can find exact or HEAD + my ($keyloc) = $self->_find_in_buckets( $tag, $md5 ); + my $keytag = $self->load_tag( $keyloc ); + my ($subloc, $is_deleted, $offset) = $self->find_keyloc( $keytag ); + if ( !$subloc && !$is_deleted ) { + ($subloc, $is_deleted, $offset) = $self->find_keyloc( $keytag, 0 ); + } + return ($subloc && !$is_deleted) && 1; } -sub find_bucket_list { +sub find_blist { ## # Locate offset for bucket list, given digested key ## my $self = shift; - my ($obj, $md5, $args) = @_; + my ($offset, $md5, $args) = @_; $args = {} unless $args; ## # Locate offset for bucket list using digest index system ## - my $tag = $self->load_tag($obj, $obj->_base_offset) - or $obj->_throw_error( "INTERNAL ERROR - Cannot find tag" ); + my $tag = $self->load_tag( $offset ) + or $self->_throw_error( "INTERNAL ERROR - Cannot find tag" ); - my $ch = 0; - while ($tag->{signature} ne SIG_BLIST) { + #XXX What happens when $ch >= $self->{hash_size} ?? + for (my $ch = 0; $tag->{signature} ne SIG_BLIST; $ch++) { my $num = ord substr($md5, $ch, 1); my $ref_loc = $tag->{offset} + ($num * $self->{long_size}); - $tag = $self->index_lookup( $obj, $tag, $num ); + $tag = $self->index_lookup( $tag, $num ); if (!$tag) { - return if ! $args->{create}; + return if !$args->{create}; - my $fh = $obj->_fh; - seek($fh, $ref_loc + $obj->_root->{file_offset}, SEEK_SET); - print( $fh pack($self->{long_pack}, $obj->_root->{end}) ); + my $loc = $self->_storage->request_space( + $self->tag_size( $self->{bucket_list_size} ), + ); + + $self->_storage->print_at( $ref_loc, pack($self->{long_pack}, $loc) ); - $tag = $self->create_tag( - $obj, $obj->_root->{end}, - SIG_BLIST, - chr(0) x $self->{bucket_list_size}, + $tag = $self->write_tag( + $loc, SIG_BLIST, + chr(0)x$self->{bucket_list_size}, ); $tag->{ref_loc} = $ref_loc; @@ -716,8 +921,6 @@ sub find_bucket_list { $tag->{ch} = $ch; $tag->{ref_loc} = $ref_loc; - - $ch++; } return $tag; @@ -728,7 +931,7 @@ sub index_lookup { # Given index tag, lookup single entry in index and return . ## my $self = shift; - my ($obj, $tag, $index) = @_; + my ($tag, $index) = @_; my $location = unpack( $self->{long_pack}, @@ -741,7 +944,7 @@ sub index_lookup { if (!$location) { return; } - return $self->load_tag( $obj, $location ); + return $self->load_tag( $location ); } sub traverse_index { @@ -749,103 +952,88 @@ sub traverse_index { # Scan index and recursively step into deeper levels, looking for next key. ## my $self = shift; - my ($obj, $offset, $ch, $force_return_next) = @_; + my ($xxxx, $offset, $ch, $force_return_next) = @_; - my $tag = $self->load_tag($obj, $offset ); - - my $fh = $obj->_fh; + my $tag = $self->load_tag( $offset ); if ($tag->{signature} ne SIG_BLIST) { - my $content = $tag->{content}; - my $start = $obj->{return_next} ? 0 : ord(substr($obj->{prev_md5}, $ch, 1)); + my $start = $xxxx->{return_next} ? 0 : ord(substr($xxxx->{prev_md5}, $ch, 1)); - for (my $idx = $start; $idx < (2**8); $idx++) { + for (my $idx = $start; $idx < $self->{hash_chars_used}; $idx++) { my $subloc = unpack( $self->{long_pack}, - substr($content, $idx * $self->{long_size}, $self->{long_size}), + substr( + $tag->{content}, + $idx * $self->{long_size}, + $self->{long_size}, + ), ); if ($subloc) { my $result = $self->traverse_index( - $obj, $subloc, $ch + 1, $force_return_next, + $xxxx, $subloc, $ch + 1, $force_return_next, ); - if (defined($result)) { return $result; } + if (defined $result) { return $result; } } } # index loop - $obj->{return_next} = 1; - } # tag is an index - + $xxxx->{return_next} = 1; + } + # This is the bucket list else { my $keys = $tag->{content}; - if ($force_return_next) { $obj->{return_next} = 1; } + if ($force_return_next) { $xxxx->{return_next} = 1; } ## # Iterate through buckets, looking for a key match ## + my $transaction_id = $self->_storage->transaction_id; for (my $i = 0; $i < $self->{max_buckets}; $i++) { - my ($key, $subloc) = $self->_get_key_subloc( $keys, $i ); + my ($key, $keyloc) = $self->_get_key_subloc( $keys, $i ); # End of bucket list -- return to outer loop - if (!$subloc) { - $obj->{return_next} = 1; + if (!$keyloc) { + $xxxx->{return_next} = 1; last; } # Located previous key -- return next one found - elsif ($key eq $obj->{prev_md5}) { - $obj->{return_next} = 1; + elsif ($key eq $xxxx->{prev_md5}) { + $xxxx->{return_next} = 1; next; } # Seek to bucket location and skip over signature - elsif ($obj->{return_next}) { - seek($fh, $subloc + $obj->_root->{file_offset}, SEEK_SET); + elsif ($xxxx->{return_next}) { + my $storage = $self->_storage; + + my $keytag = $self->load_tag( $keyloc ); + my ($subloc, $is_deleted) = $self->find_keyloc( $keytag ); + if ( $subloc == 0 && !$is_deleted ) { + ($subloc, $is_deleted) = $self->find_keyloc( $keytag, 0 ); + } + next if $is_deleted; # Skip over value to get to plain key - my $sig; - read( $fh, $sig, SIG_SIZE ); + my $sig = $storage->read_at( $subloc, SIG_SIZE ); - my $size; - read( $fh, $size, $self->{data_size}); + my $size = $storage->read_at( undef, $self->{data_size} ); $size = unpack($self->{data_pack}, $size); - if ($size) { seek($fh, $size, SEEK_CUR); } + if ($size) { $storage->increment_pointer( $size ); } # Read in plain key and return as scalar - my $plain_key; - read( $fh, $size, $self->{data_size}); + $size = $storage->read_at( undef, $self->{data_size} ); $size = unpack($self->{data_pack}, $size); - if ($size) { read( $fh, $plain_key, $size); } + my $plain_key; + if ($size) { $plain_key = $storage->read_at( undef, $size); } return $plain_key; } } - $obj->{return_next} = 1; - } # tag is a bucket list - - return; -} - -sub get_next_key { - ## - # Locate next key, given digested previous one - ## - my $self = shift; - my ($obj) = @_; - - $obj->{prev_md5} = $_[1] ? $_[1] : undef; - $obj->{return_next} = 0; - - ## - # If the previous key was not specifed, start at the top and - # return the first one found. - ## - if (!$obj->{prev_md5}) { - $obj->{prev_md5} = chr(0) x $self->{hash_size}; - $obj->{return_next} = 1; + $xxxx->{return_next} = 1; } - return $self->traverse_index( $obj, $obj->_base_offset, 0 ); + return; } # Utilities @@ -854,7 +1042,9 @@ sub _get_key_subloc { my $self = shift; my ($keys, $idx) = @_; - my ($key, $subloc) = unpack( + return unpack( + # This is 'a', not 'A'. Please read the pack() documentation for the + # difference between the two and why it's important. "a$self->{hash_size} $self->{long_pack}", substr( $keys, @@ -862,8 +1052,6 @@ sub _get_key_subloc { $self->{bucket_size}, ), ); - - return ($key, $subloc); } sub _find_in_buckets { @@ -872,57 +1060,120 @@ sub _find_in_buckets { BUCKET: for ( my $i = 0; $i < $self->{max_buckets}; $i++ ) { - my ($key, $subloc) = $self->_get_key_subloc( $tag->{content}, $i ); - - return ($subloc, $i * $self->{bucket_size}) unless $subloc; - - next BUCKET if $key ne $md5; + my ($key, $subloc) = $self->_get_key_subloc( + $tag->{content}, $i, + ); - return ($subloc, $i * $self->{bucket_size}); + next BUCKET if $subloc && $key ne $md5; + return( $subloc, $i * $self->{bucket_size} ); } return; } -sub _request_space { +sub _release_space { my $self = shift; - my ($obj, $size) = @_; + my ($size, $loc) = @_; + + my $next_loc = 0; + + $self->_storage->print_at( $loc, + SIG_FREE, + pack($self->{long_pack}, $size ), + pack($self->{long_pack}, $next_loc ), + ); - my $loc = $obj->_root->{end}; + return; +} - return $loc; +sub _throw_error { + die "DBM::Deep: $_[1]\n"; } -sub _release_space { - my $self = shift; - my ($obj, $size, $loc) = @_; +sub _get_dbm_object { + my $item = shift; + + my $obj = eval { + local $SIG{__DIE__}; + if ($item->isa( 'DBM::Deep' )) { + return $item; + } + return; + }; + return $obj if $obj; + + my $r = Scalar::Util::reftype( $item ) || ''; + if ( $r eq 'HASH' ) { + my $obj = eval { + local $SIG{__DIE__}; + my $obj = tied(%$item); + if ($obj->isa( 'DBM::Deep' )) { + return $obj; + } + return; + }; + return $obj if $obj; + } + elsif ( $r eq 'ARRAY' ) { + my $obj = eval { + local $SIG{__DIE__}; + my $obj = tied(@$item); + if ($obj->isa( 'DBM::Deep' )) { + return $obj; + } + return; + }; + return $obj if $obj; + } return; } -1; -__END__ - -# This will be added in later, after more refactoring is done. This is an early -# attempt at refactoring on the physical level instead of the virtual level. -sub _read_at { +sub _length_needed { my $self = shift; - my ($obj, $spot, $amount, $unpack) = @_; + my ($value, $key) = @_; - my $fh = $obj->_fh; - seek( $fh, $spot + $obj->_root->{file_offset}, SEEK_SET ); + my $is_dbm_deep = eval { + local $SIG{'__DIE__'}; + $value->isa( 'DBM::Deep' ); + }; - my $buffer; - my $bytes_read = read( $fh, $buffer, $amount ); + my $len = SIG_SIZE + + $self->{data_size} # size for value + + $self->{data_size} # size for key + + length( $key ); # length of key - if ( $unpack ) { - $buffer = unpack( $unpack, $buffer ); + if ( $is_dbm_deep && $value->_storage eq $self->_storage ) { + # long_size is for the internal reference + return $len + $self->{long_size}; } - if ( wantarray ) { - return ($buffer, $bytes_read); + if ( $self->_storage->{autobless} ) { + # This is for the bit saying whether or not this thing is blessed. + $len += 1; } - else { - return $buffer; + + my $r = Scalar::Util::reftype( $value ) || ''; + unless ( $r eq 'HASH' || $r eq 'ARRAY' ) { + if ( defined $value ) { + $len += length( $value ); + } + return $len; + } + + $len += $self->{index_size}; + + # if autobless is enabled, must also take into consideration + # the class name as it is stored after the key. + if ( $self->_storage->{autobless} ) { + my $c = Scalar::Util::blessed($value); + if ( defined $c && !$is_dbm_deep ) { + $len += $self->{data_size} + length($c); + } } + + return $len; } + +1; +__END__