X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBM%2FDeep%2FEngine.pm;h=e9d0711e164412d0c627c7da56e61ffbd1772b15;hb=42717e465f8d960a2a416cd681e1247f35f5e6f3;hp=1dd7dd69aa64897de7a1a63d313099126cddf5b9;hpb=cd59cad8dbdb2a674496ec03a4e75a154aacd7d5;p=dbsrgits%2FDBM-Deep.git diff --git a/lib/DBM/Deep/Engine.pm b/lib/DBM/Deep/Engine.pm index 1dd7dd6..e9d0711 100644 --- a/lib/DBM/Deep/Engine.pm +++ b/lib/DBM/Deep/Engine.pm @@ -1,115 +1,1041 @@ package DBM::Deep::Engine; +use 5.6.0; + use strict; +use warnings; + +use Fcntl qw( :DEFAULT :flock ); +use Scalar::Util (); + +# 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 + +## +# 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' } +sub SIG_NULL () { 'N' } +sub SIG_DATA () { 'D' } +sub SIG_INDEX () { 'I' } +sub SIG_BLIST () { 'B' } +sub SIG_FREE () { 'F' } +sub SIG_SIZE () { 1 } + +sub new { + my $class = shift; + my ($args) = @_; + + my $self = bless { + long_size => 4, + long_pack => 'N', + data_size => 4, + data_pack => 'N', + + digest => \&Digest::MD5::md5, + hash_size => 16, + + ## + # Maximum number of buckets per list 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, + + fileobj => undef, + obj => undef, + }, $class; + + 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 _fileobj { return $_[0]{fileobj} } + +sub calculate_sizes { + my $self = shift; + + # 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->{index_size} = (2**8) * $self->{long_size}; + $self->{bucket_size} = $self->{hash_size} + $self->{long_size} * 3; + $self->{bucket_list_size} = $self->{max_buckets} * $self->{bucket_size}; + + return; +} + +sub write_file_header { + my $self = shift; + + my $loc = $self->_fileobj->request_space( length( SIG_FILE ) + 21 ); + + $self->_fileobj->print_at( $loc, + SIG_FILE, + SIG_HEADER, + pack('N', 1), # header version + pack('N', 12), # header size + pack('N', 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}), + ); + + $self->_fileobj->set_transaction_offset( 13 ); + + return; +} + +sub read_file_header { + my $self = shift; + + my $buffer = $self->_fileobj->read_at( 0, length(SIG_FILE) + 9 ); + return unless length($buffer); + + my ($file_signature, $sig_header, $header_version, $size) = unpack( + 'A4 A N N', $buffer + ); + + unless ( $file_signature eq SIG_FILE ) { + $self->_fileobj->close; + $self->_throw_error( "Signature not found -- file is not a Deep DB" ); + } + + unless ( $sig_header eq SIG_HEADER ) { + $self->_fileobj->close; + $self->_throw_error( "Old file version found." ); + } + + my $buffer2 = $self->_fileobj->read_at( undef, $size ); + my ($running_transactions, @values) = unpack( 'N n A n A n', $buffer2 ); + + $self->_fileobj->set_transaction_offset( 13 ); + + if ( @values < 5 || grep { !defined } @values ) { + $self->_fileobj->close; + $self->_throw_error("Corrupted file - bad header"); + } -use Fcntl qw( :DEFAULT :flock :seek ); + #XXX Add warnings if values weren't set right + @{$self}{qw(long_size long_pack data_size data_pack max_buckets)} = @values; -sub open { - ## - # Open a fh to the database, create if nonexistent. - # Make sure file signature matches DBM::Deep spec. - ## + return length($buffer) + length($buffer2); +} + +sub setup_fh { my $self = shift; - my $obj = shift; + my ($obj) = @_; + + # Need to remove use of $fh here + my $fh = $self->_fileobj->{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->_fileobj->audit( "# Database created on" ); + + $self->write_file_header; + + $obj->{base_offset} = $self->_fileobj->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 { + $self->calculate_sizes; + } - if (defined($obj->_fh)) { $self->close( $obj ); } - - eval { + #XXX We have to make sure we don't mess up when autoflush isn't turned on + $self->_fileobj->set_inode; + + flock $fh, LOCK_UN; + + return 1; +} + +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 $self = shift; + my ($offset, $sig, $content) = @_; + my $size = length( $content ); + + $self->_fileobj->print_at( + $offset, + $sig, pack($self->{data_pack}, $size), $content, + ); + + return unless defined $offset; + + return { + signature => $sig, + size => $size, + offset => $offset + SIG_SIZE + $self->{data_size}, + content => $content + }; +} + +sub load_tag { + ## + # Given offset, load single tag and return signature, size and data + ## + my $self = shift; + my ($offset) = @_; + + my $fileobj = $self->_fileobj; + + my $s = SIG_SIZE + $self->{data_size}; + my $b = $fileobj->read_at( $offset, $s ); + my ($sig, $size) = unpack( "A $self->{data_pack}", $b ); + + my $buffer = $fileobj->read_at( undef, $size ); + + return { + signature => $sig, + size => $size, + offset => $offset + SIG_SIZE + $self->{data_size}, + content => $buffer + }; +} + +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; +} + +sub _length_needed { + my $self = shift; + my ($value, $key) = @_; + + my $is_dbm_deep = eval { local $SIG{'__DIE__'}; - # 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; + $value->isa( 'DBM::Deep' ); + }; - my $fh; - sysopen( $fh, $obj->_root->{file}, $flags ) - or $fh = undef; - $obj->_root->{fh} = $fh; - }; if ($@ ) { $obj->_throw_error( "Received error: $@\n" ); } - if (! defined($obj->_fh)) { - return $obj->_throw_error("Cannot sysopen file: " . $obj->_root->{file} . ": $!"); - } + my $len = SIG_SIZE + + $self->{data_size} # size for value + + $self->{data_size} # size for key + + length( $key ); # length of key - my $fh = $obj->_fh; + if ( $is_dbm_deep && $value->_fileobj eq $self->_fileobj ) { + # long_size is for the internal reference + return $len + $self->{long_size}; + } - #XXX Can we remove this by using the right sysopen() flags? - # Maybe ... q.v. above - binmode $fh; # for win32 + if ( $self->_fileobj->{autobless} ) { + # This is for the bit saying whether or not this thing is blessed. + $len += 1; + } - if ($obj->_root->{autoflush}) { - my $old = select $fh; - $|=1; - select $old; + my $r = Scalar::Util::reftype( $value ) || ''; + unless ( $r eq 'HASH' || $r eq 'ARRAY' ) { + if ( defined $value ) { + $len += length( $value ); + } + return $len; } - - seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET); - my $signature; - my $bytes_read = read( $fh, $signature, length(DBM::Deep->SIG_FILE)); - + $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->_fileobj->{autobless} ) { + my $c = Scalar::Util::blessed($value); + if ( defined $c && !$is_dbm_deep ) { + $len += $self->{data_size} + length($c); + } + } + + return $len; +} + +sub add_bucket { ## - # File is empty -- write signature and master index + # Adds one key/value pair to bucket list, given offset, MD5 digest of key, + # plain (undigested) key and value. ## - if (!$bytes_read) { - seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET); - print( $fh DBM::Deep->SIG_FILE); - $obj->_create_tag($obj->_base_offset, $obj->_type, chr(0) x $DBM::Deep::INDEX_SIZE); + my $self = shift; + my ($tag, $md5, $plain_key, $value, $deleted, $orig_key) = @_; + $deleted ||= 0; + + local($/,$\); + + # This verifies that only supported values will be stored. + { + my $r = Scalar::Util::reftype( $value ); + last if !defined $r; + + last if $r eq 'HASH'; + last if $r eq 'ARRAY'; + + $self->_throw_error( + "Storage of variables of type '$r' is not supported." + ); + } + + my $location = 0; + my $result = 2; + + my $fileobj = $self->_fileobj; - my $plain_key = "[base]"; - print( $fh pack($DBM::Deep::DATA_LENGTH_PACK, length($plain_key)) . $plain_key ); + my $actual_length = $self->_length_needed( $value, $plain_key ); - # Flush the filehandle - my $old_fh = select $fh; - my $old_af = $|; $| = 1; $| = $old_af; - select $old_fh; + #ACID - This is a mutation. Must only find the exact transaction + my ($subloc, $offset, $size,$is_deleted) = $self->_find_in_buckets( $tag, $md5, 1 ); + + my @transactions; + if ( $fileobj->transaction_id == 0 ) { + @transactions = $fileobj->current_transactions; + } + +# $self->_release_space( $size, $subloc ); + # Updating a known md5 +#XXX This needs updating to use _release_space + if ( $subloc ) { + $result = 1; + + if ($actual_length <= $size) { + $location = $subloc; + } + else { + $location = $fileobj->request_space( $actual_length ); + + $fileobj->print_at( $tag->{offset} + $offset + $self->{hash_size}, + pack($self->{long_pack}, $location ), + pack($self->{long_pack}, $actual_length ), + pack('n n', $fileobj->transaction_id, $deleted ), + ); + } + } + # Adding a new md5 + elsif ( defined $offset ) { + $location = $fileobj->request_space( $actual_length ); - my @stats = stat($fh); - $obj->_root->{inode} = $stats[1]; - $obj->_root->{end} = $stats[7]; + $fileobj->print_at( $tag->{offset} + $offset, + $md5, + pack($self->{long_pack}, $location ), + pack($self->{long_pack}, $actual_length ), + pack('n n', $fileobj->transaction_id, $deleted ), + ); - return 1; + for ( @transactions ) { + my $tag2 = $self->load_tag( $tag->{offset} - SIG_SIZE - $self->{data_size} ); + $fileobj->{transaction_id} = $_; + $self->add_bucket( $tag2, $md5, '', '', 1, $orig_key ); + $fileobj->{transaction_id} = 0; + } + $tag = $self->load_tag( $tag->{offset} - SIG_SIZE - $self->{data_size} ); } - + # If bucket didn't fit into list, split into a new index level + # split_index() will do the _fileobj->request_space() call + else { + $location = $self->split_index( $md5, $tag ); + } + + $self->write_value( $location, $plain_key, $value, $orig_key ); + + return $result; +} + +sub write_value { + my $self = shift; + my ($location, $key, $value, $orig_key) = @_; + + my $fileobj = $self->_fileobj; + + my $dbm_deep_obj = _get_dbm_object( $value ); + if ( $dbm_deep_obj && $dbm_deep_obj->_fileobj ne $fileobj ) { + $self->_throw_error( "Cannot cross-reference. Use export() instead" ); + } + ## - # Check signature was valid + # Write signature based on content type, set content length and write + # actual value. ## - unless ($signature eq DBM::Deep->SIG_FILE) { - $self->close( $obj ); - return $obj->_throw_error("Signature not found -- file is not a Deep DB"); + my $r = Scalar::Util::reftype( $value ) || ''; + if ( $dbm_deep_obj ) { + $self->write_tag( $location, SIG_INTERNAL,pack($self->{long_pack}, $dbm_deep_obj->_base_offset) ); + } + elsif ($r eq 'HASH') { + if ( !$dbm_deep_obj && tied %{$value} ) { + $self->_throw_error( "Cannot store something that is tied" ); + } + $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, $value ); } - my @stats = stat($fh); - $obj->_root->{inode} = $stats[1]; - $obj->_root->{end} = $stats[7]; - ## - # Get our type from master index signature + # Plain key is stored AFTER value, as keys are typically fetched less often. ## - my $tag = $obj->_load_tag($obj->_base_offset); + $fileobj->print_at( undef, pack($self->{data_pack}, length($key)) . $key ); -#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 + # Internal references don't care about autobless + return 1 if $dbm_deep_obj; + + ## + # If value is blessed, preserve class name + ## + if ( $fileobj->{autobless} ) { + if ( defined( my $c = Scalar::Util::blessed($value) ) ) { + $fileobj->print_at( undef, chr(1), pack($self->{data_pack}, length($c)) . $c ); + } + else { + $fileobj->print_at( undef, chr(0) ); + } + } - if (!$tag) { - return $obj->_throw_error("Corrupted file, no master index record"); + ## + # Tie the passed in reference so that changes to it are reflected in the + # datafile. The use of $location as the base_offset will act as the + # the linkage between parent and child. + # + # The overall assignment is a hack around the fact that just tying doesn't + # store the values. This may not be the wrong thing to do. + ## + if ($r eq 'HASH') { + my %x = %$value; + tie %$value, 'DBM::Deep', { + base_offset => $location, + fileobj => $fileobj, + parent => $self->{obj}, + parent_key => $orig_key, + }; + %$value = %x; } - if ($obj->{type} ne $tag->{signature}) { - return $obj->_throw_error("File type mismatch"); + elsif ($r eq 'ARRAY') { + my @x = @$value; + tie @$value, 'DBM::Deep', { + base_offset => $location, + fileobj => $fileobj, + parent => $self->{obj}, + parent_key => $orig_key, + }; + @$value = @x; } - + return 1; } -sub close { +sub split_index { + my $self = shift; + my ($md5, $tag) = @_; + + my $fileobj = $self->_fileobj; + + my $loc = $fileobj->request_space( + $self->tag_size( $self->{index_size} ), + ); + + $fileobj->print_at( $tag->{ref_loc}, pack($self->{long_pack}, $loc) ); + + my $index_tag = $self->write_tag( + $loc, SIG_INDEX, + chr(0)x$self->{index_size}, + ); + + my $newtag_loc = $fileobj->request_space( + $self->tag_size( $self->{bucket_list_size} ), + ); + + my $keys = $tag->{content} + . $md5 . pack($self->{long_pack}, $newtag_loc) + . pack($self->{long_pack}, 0) # size + . pack($self->{long_pack}, 0); # transaction ID + + 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, $size) = $self->_get_key_subloc( $keys, $i ); + + 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, $tag->{ch} + 1, 1)); + + if ($newloc[$num]) { + my $subkeys = $fileobj->read_at( $newloc[$num], $self->{bucket_list_size} ); + + # This is looking for the first empty spot + my ($subloc, $offset, $size) = $self->_find_in_buckets( + { content => $subkeys }, '', + ); + + $fileobj->print_at( + $newloc[$num] + $offset, + $key, pack($self->{long_pack}, $old_subloc), + ); + + next; + } + + my $loc = $fileobj->request_space( + $self->tag_size( $self->{bucket_list_size} ), + ); + + $fileobj->print_at( + $index_tag->{offset} + ($num * $self->{long_size}), + pack($self->{long_pack}, $loc), + ); + + my $blist_tag = $self->write_tag( + $loc, SIG_BLIST, + chr(0)x$self->{bucket_list_size}, + ); + + $fileobj->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->{offset} - SIG_SIZE - $self->{data_size}, + ); + + return $newtag_loc; +} + +sub read_from_loc { + my $self = shift; + my ($subloc, $orig_key) = @_; + + my $fileobj = $self->_fileobj; + + my $signature = $fileobj->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 $new_obj = DBM::Deep->new({ + type => $signature, + base_offset => $subloc, + fileobj => $self->_fileobj, + parent => $self->{obj}, + parent_key => $orig_key, + }); + + if ($new_obj->_fileobj->{autobless}) { + ## + # Skip over value and plain key to see if object needs + # to be re-blessed + ## + $fileobj->increment_pointer( $self->{data_size} + $self->{index_size} ); + + my $size = $fileobj->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + if ($size) { $fileobj->increment_pointer( $size ); } + + my $bless_bit = $fileobj->read_at( undef, 1 ); + if (ord($bless_bit)) { + ## + # Yes, object needs to be re-blessed + ## + my $size = $fileobj->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + + my $class_name; + if ($size) { $class_name = $fileobj->read_at( undef, $size ); } + if (defined $class_name) { $new_obj = bless( $new_obj, $class_name ); } + } + } + + return $new_obj; + } + elsif ( $signature eq SIG_INTERNAL ) { + my $size = $fileobj->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + + if ( $size ) { + my $new_loc = $fileobj->read_at( undef, $size ); + $new_loc = unpack( $self->{long_pack}, $new_loc ); + return $self->read_from_loc( $new_loc, $orig_key ); + } + else { + return; + } + } + ## + # Otherwise return actual value + ## + elsif ( $signature eq SIG_DATA ) { + my $size = $fileobj->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + + my $value = ''; + if ($size) { $value = $fileobj->read_at( undef, $size ); } + return $value; + } + + ## + # Key exists, but content is null + ## + return; +} + +sub get_bucket_value { + ## + # Fetch single value given tag and MD5 digested key. + ## + my $self = shift; + my ($tag, $md5, $orig_key) = @_; + + #ACID - This is a read. Can find exact or HEAD + my ($subloc, $offset, $size, $is_deleted) = $self->_find_in_buckets( $tag, $md5 ); + + if ( !$subloc ) { + #XXX Need to use real key +# $self->add_bucket( $tag, $md5, $orig_key, undef, undef, $orig_key ); +# return; + } + elsif ( !$is_deleted ) { + return $self->read_from_loc( $subloc, $orig_key ); + } + + return; +} + +sub delete_bucket { + ## + # Delete single key/value pair given tag and MD5 digested key. + ## my $self = shift; - my $obj = shift; + my ($tag, $md5, $orig_key) = @_; + + #ACID - Although this is a mutation, we must find any transaction. + # This is because we need to mark something as deleted that is in the HEAD. + my ($subloc, $offset, $size,$is_deleted) = $self->_find_in_buckets( $tag, $md5 ); + + return if !$subloc; + + my $fileobj = $self->_fileobj; - if ( my $fh = $obj->_root->{fh} ) { - close $fh; + my @transactions; + if ( $fileobj->transaction_id == 0 ) { + @transactions = $fileobj->current_transactions; + } + + if ( $fileobj->transaction_id == 0 ) { + my $value = $self->read_from_loc( $subloc, $orig_key ); + + for (@transactions) { + $fileobj->{transaction_id} = $_; + #XXX Need to use real key + $self->add_bucket( $tag, $md5, $orig_key, $value, undef, $orig_key ); + $fileobj->{transaction_id} = 0; + } + $tag = $self->load_tag( $tag->{offset} - SIG_SIZE - $self->{data_size} ); + + #XXX This needs _release_space() for the value and anything below + $fileobj->print_at( + $tag->{offset} + $offset, + substr( $tag->{content}, $offset + $self->{bucket_size} ), + chr(0) x $self->{bucket_size}, + ); + } + else { + $self->add_bucket( $tag, $md5, '', '', 1, $orig_key ); } - $obj->_root->{fh} = undef; return 1; } +sub bucket_exists { + ## + # Check existence of single key given tag and MD5 digested key. + ## + my $self = shift; + my ($tag, $md5) = @_; + + #ACID - This is a read. Can find exact or HEAD + my ($subloc, $offset, $size, $is_deleted) = $self->_find_in_buckets( $tag, $md5 ); + return ($subloc && !$is_deleted) && 1; +} + +sub find_bucket_list { + ## + # Locate offset for bucket list, given digested key + ## + my $self = shift; + my ($offset, $md5, $args) = @_; + $args = {} unless $args; + + local($/,$\); + + ## + # Locate offset for bucket list using digest index system + ## + my $tag = $self->load_tag( $offset ) + or $self->_throw_error( "INTERNAL ERROR - Cannot find tag" ); + + my $ch = 0; + while ($tag->{signature} ne SIG_BLIST) { + my $num = ord substr($md5, $ch, 1); + + my $ref_loc = $tag->{offset} + ($num * $self->{long_size}); + $tag = $self->index_lookup( $tag, $num ); + + if (!$tag) { + return if !$args->{create}; + + my $loc = $self->_fileobj->request_space( + $self->tag_size( $self->{bucket_list_size} ), + ); + + $self->_fileobj->print_at( $ref_loc, pack($self->{long_pack}, $loc) ); + + $tag = $self->write_tag( + $loc, SIG_BLIST, + chr(0)x$self->{bucket_list_size}, + ); + + $tag->{ref_loc} = $ref_loc; + $tag->{ch} = $ch; + + last; + } + + $tag->{ch} = $ch++; + $tag->{ref_loc} = $ref_loc; + } + + return $tag; +} + +sub index_lookup { + ## + # Given index tag, lookup single entry in index and return . + ## + my $self = shift; + my ($tag, $index) = @_; + + my $location = unpack( + $self->{long_pack}, + substr( + $tag->{content}, + $index * $self->{long_size}, + $self->{long_size}, + ), + ); + + if (!$location) { return; } + + return $self->load_tag( $location ); +} + +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 $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)); + + for (my $idx = $start; $idx < (2**8); $idx++) { + my $subloc = unpack( + $self->{long_pack}, + substr( + $content, + $idx * $self->{long_size}, + $self->{long_size}, + ), + ); + + if ($subloc) { + my $result = $self->traverse_index( + $obj, $subloc, $ch + 1, $force_return_next, + ); + + if (defined($result)) { return $result; } + } + } # index loop + + $obj->{return_next} = 1; + } + # This is the bucket list + else { + my $keys = $tag->{content}; + if ($force_return_next) { $obj->{return_next} = 1; } + + ## + # Iterate through buckets, looking for a key match + ## + my $transaction_id = $self->_fileobj->transaction_id; + for (my $i = 0; $i < $self->{max_buckets}; $i++) { + my ($key, $subloc, $size, $trans_id, $is_deleted) = $self->_get_key_subloc( $keys, $i ); + + next if $is_deleted; +#XXX Need to find all the copies of this key to find out if $transaction_id has it +#XXX marked as deleted, in use, or what. + next if $trans_id && $trans_id != $transaction_id; + + # End of bucket list -- return to outer loop + if (!$subloc) { + $obj->{return_next} = 1; + last; + } + # Located previous key -- return next one found + elsif ($key eq $obj->{prev_md5}) { + $obj->{return_next} = 1; + next; + } + # Seek to bucket location and skip over signature + elsif ($obj->{return_next}) { + my $fileobj = $self->_fileobj; + + # Skip over value to get to plain key + my $sig = $fileobj->read_at( $subloc, SIG_SIZE ); + + my $size = $fileobj->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + if ($size) { $fileobj->increment_pointer( $size ); } + + # Read in plain key and return as scalar + $size = $fileobj->read_at( undef, $self->{data_size} ); + $size = unpack($self->{data_pack}, $size); + my $plain_key; + if ($size) { $plain_key = $fileobj->read_at( undef, $size); } + + return $plain_key; + } + } + + $obj->{return_next} = 1; + } + + 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; + } + + return $self->traverse_index( $obj, $obj->_base_offset, 0 ); +} + +# Utilities + +sub _get_key_subloc { + my $self = shift; + my ($keys, $idx) = @_; + + my ($key, $subloc, $size, $transaction_id, $is_deleted) = unpack( + # This is 'a', not 'A'. Please read the pack() documentation for the + # difference between the two and why it's important. + "a$self->{hash_size} $self->{long_pack}2 n2", + substr( + $keys, + ($idx * $self->{bucket_size}), + $self->{bucket_size}, + ), + ); + + return ($key, $subloc, $size, $transaction_id, $is_deleted); +} + +sub _find_in_buckets { + my $self = shift; + my ($tag, $md5, $exact) = @_; + $exact ||= 0; + + my $trans_id = $self->_fileobj->transaction_id; + + my @zero; + + BUCKET: + for ( my $i = 0; $i < $self->{max_buckets}; $i++ ) { + my ($key, $subloc, $size, $transaction_id, $is_deleted) = $self->_get_key_subloc( + $tag->{content}, $i, + ); + + my @rv = ($subloc, $i * $self->{bucket_size}, $size, $is_deleted); + + unless ( $subloc ) { + if ( !$exact && @zero && $trans_id ) { + @rv = ($zero[2], $zero[0] * $self->{bucket_size},$zero[3],$is_deleted); + } + return @rv; + } + + next BUCKET if $key ne $md5; + + # Save off the HEAD in case we need it. + @zero = ($i,$key,$subloc,$size,$transaction_id,$is_deleted) if $transaction_id == 0; + + next BUCKET if $transaction_id != $trans_id; + + return @rv; + } + + return; +} + +sub _release_space { + my $self = shift; + my ($size, $loc) = @_; + + my $next_loc = 0; + + $self->_fileobj->print_at( $loc, + SIG_FREE, + pack($self->{long_pack}, $size ), + pack($self->{long_pack}, $next_loc ), + ); + + return; +} + +sub _throw_error { + die "DBM::Deep: $_[1]\n"; +} + 1; __END__