1 package DBM::Deep::Engine;
5 use Fcntl qw( :DEFAULT :flock :seek );
8 # Setup file and tag signatures. These should never change.
10 sub SIG_FILE () { 'DPDB' }
11 sub SIG_INTERNAL () { 'i' }
12 sub SIG_HASH () { 'H' }
13 sub SIG_ARRAY () { 'A' }
14 sub SIG_NULL () { 'N' }
15 sub SIG_DATA () { 'D' }
16 sub SIG_INDEX () { 'I' }
17 sub SIG_BLIST () { 'B' }
22 # Precalculate index, bucket and bucket list sizes
26 $self->{index_size} = (2**8) * $self->{long_size};
27 $self->{bucket_size} = $self->{hash_size} + $self->{long_size};
28 $self->{bucket_list_size} = $self->{max_buckets} * $self->{bucket_size};
35 # Set pack/unpack modes (see file header for more)
38 my ($long_s, $long_p, $data_s, $data_p) = @_;
41 # Set to 4 and 'N' for 32-bit offset tags (default). Theoretical limit of 4
43 # (Perl must be compiled with largefile support for files > 2 GB)
45 # Set to 8 and 'Q' for 64-bit offsets. Theoretical limit of 16 XB per file.
46 # (Perl must be compiled with largefile and 64-bit long support)
48 $self->{long_size} = $long_s ? $long_s : 4;
49 $self->{long_pack} = $long_p ? $long_p : 'N';
52 # Set to 4 and 'N' for 32-bit data length prefixes. Limit of 4 GB for each
53 # key/value. Upgrading this is possible (see above) but probably not
54 # necessary. If you need more than 4 GB for a single key or value, this
55 # module is really not for you :-)
57 $self->{data_size} = $data_s ? $data_s : 4;
58 $self->{data_pack} = $data_p ? $data_p : 'N';
60 return $self->precalc_sizes();
65 # Set key digest function (default is MD5)
68 my ($digest_func, $hash_size) = @_;
70 $self->{digest} = $digest_func ? $digest_func : \&Digest::MD5::md5;
71 $self->{hash_size} = $hash_size ? $hash_size : 16;
73 return $self->precalc_sizes();
86 digest => \&Digest::MD5::md5,
90 # Maximum number of buckets per list before another level of indexing is
92 # Increase this value for slightly greater speed, but larger database
93 # files. DO NOT decrease this value below 16, due to risk of recursive
108 $self->open( $obj ) if !defined $obj->_fh;
110 #XXX We have to make sure we don't mess up when autoflush isn't turned on
111 unless ( $obj->_root->{inode} ) {
112 my @stats = stat($obj->_fh);
113 $obj->_root->{inode} = $stats[1];
114 $obj->_root->{end} = $stats[7];
122 # Open a fh to the database, create if nonexistent.
123 # Make sure file signature matches DBM::Deep spec.
128 if (defined($obj->_fh)) { $self->close_fh( $obj ); }
130 # Theoretically, adding O_BINARY should remove the need for the binmode
131 # Of course, testing it is going to be ... interesting.
132 my $flags = O_RDWR | O_CREAT | O_BINARY;
135 my $filename = $obj->_root->{file};
136 sysopen( $fh, $filename, $flags )
137 or $obj->_throw_error("Cannot sysopen file '$filename': $!");
138 $obj->_root->{fh} = $fh;
140 #XXX Can we remove this by using the right sysopen() flags?
141 # Maybe ... q.v. above
142 binmode $fh; # for win32
144 if ($obj->_root->{autoflush}) {
145 my $old = select $fh;
150 seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET);
152 my $bytes_read = read( $fh, $signature, length(SIG_FILE));
155 # File is empty -- write signature and master index
158 seek($fh, 0 + $obj->_root->{file_offset}, SEEK_SET);
159 print( $fh SIG_FILE);
162 $obj, $obj->_base_offset, $obj->_type,
163 chr(0) x $self->{index_size},
166 # Flush the filehandle
167 my $old_fh = select $fh;
168 my $old_af = $|; $| = 1; $| = $old_af;
175 # Check signature was valid
177 unless ($signature eq SIG_FILE) {
178 $self->close_fh( $obj );
179 $obj->_throw_error("Signature not found -- file is not a Deep DB");
183 # Get our type from master index signature
185 my $tag = $self->load_tag($obj, $obj->_base_offset)
186 or $obj->_throw_error("Corrupted file, no master index record");
188 unless ($obj->{type} eq $tag->{signature}) {
189 $obj->_throw_error("File type mismatch");
192 #XXX We probably also want to store the hash algorithm name and not assume anything
193 #XXX The cool thing would be to allow a different hashing algorithm at every level
202 if ( my $fh = $obj->_root->{fh} ) {
205 $obj->_root->{fh} = undef;
212 # Given offset, signature and content, create tag and write to disk
215 my ($obj, $offset, $sig, $content) = @_;
216 my $size = length($content);
220 seek($fh, $offset + $obj->_root->{file_offset}, SEEK_SET);
221 print( $fh $sig . pack($self->{data_pack}, $size) . $content );
223 if ($offset == $obj->_root->{end}) {
224 $obj->_root->{end} += SIG_SIZE + $self->{data_size} + $size;
230 offset => $offset + SIG_SIZE + $self->{data_size},
237 # Given offset, load single tag and return signature, size and data
240 my ($obj, $offset) = @_;
244 seek($fh, $offset + $obj->_root->{file_offset}, SEEK_SET);
246 #XXX I'm not sure this check will work if autoflush isn't enabled ...
250 read( $fh, $b, SIG_SIZE + $self->{data_size} );
251 my ($sig, $size) = unpack( "A $self->{data_pack}", $b );
254 read( $fh, $buffer, $size);
259 offset => $offset + SIG_SIZE + $self->{data_size},
266 # Adds one key/value pair to bucket list, given offset, MD5 digest of key,
267 # plain (undigested) key and value.
270 my ($obj, $tag, $md5, $plain_key, $value) = @_;
272 # This verifies that only supported values will be stored.
274 my $r = Scalar::Util::reftype( $value );
277 last if $r eq 'HASH';
278 last if $r eq 'ARRAY';
281 "Storage of variables of type '$r' is not supported."
288 my $root = $obj->_root;
290 my $is_dbm_deep = eval {
291 local $SIG{'__DIE__'};
292 $value->isa( 'DBM::Deep' );
295 my $internal_ref = $is_dbm_deep && ($value->_root eq $root);
299 my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 );
301 # Updating a known md5
306 # If value is a hash, array, or raw value with equal or less size, we
307 # can reuse the same content area of the database. Otherwise, we have
308 # to create a new content area at the EOF.
311 if ( $internal_ref ) {
312 $actual_length = $self->{long_size};
315 my $r = Scalar::Util::reftype( $value ) || '';
316 if ( $r eq 'HASH' || $r eq 'ARRAY' ) {
317 $actual_length = $self->{index_size};
319 # if autobless is enabled, must also take into consideration
320 # the class name, as it is stored along with key/value.
321 if ( $root->{autobless} ) {
322 my $value_class = Scalar::Util::blessed($value);
323 if ( defined $value_class && !$value->isa('DBM::Deep') ) {
324 $actual_length += length($value_class);
328 else { $actual_length = length($value); }
331 seek($fh, $subloc + SIG_SIZE + $root->{file_offset}, SEEK_SET);
333 read( $fh, $size, $self->{data_size});
334 $size = unpack($self->{data_pack}, $size);
336 if ($actual_length <= $size) {
340 $location = $root->{end};
343 $tag->{offset} + $offset + $self->{hash_size} + $root->{file_offset},
346 print( $fh pack($self->{long_pack}, $location) );
350 elsif ( defined $offset ) {
351 $location = $root->{end};
353 seek( $fh, $tag->{offset} + $offset + $root->{file_offset}, SEEK_SET );
354 print( $fh $md5 . pack($self->{long_pack}, $location) );
356 # If bucket didn't fit into list, split into a new index level
358 $self->split_index( $obj, $md5, $tag );
360 $location = $root->{end};
363 $self->write_value( $obj, $location, $plain_key, $value );
370 my ($obj, $location, $key, $value) = @_;
373 my $root = $obj->_root;
375 my $is_dbm_deep = eval {
376 local $SIG{'__DIE__'};
377 $value->isa( 'DBM::Deep' );
380 my $internal_ref = $is_dbm_deep && ($value->_root eq $root);
382 seek($fh, $location + $root->{file_offset}, SEEK_SET);
385 # Write signature based on content type, set content length and write
388 my $r = Scalar::Util::reftype($value) || '';
390 if ( $internal_ref ) {
391 print( $fh SIG_INTERNAL );
392 print( $fh pack($self->{data_pack}, $self->{long_size}) );
393 print( $fh pack($self->{long_pack}, $value->_base_offset) );
394 $content_length = $self->{long_size};
398 print( $fh SIG_HASH );
399 print( $fh pack($self->{data_pack}, $self->{index_size}) . chr(0) x $self->{index_size} );
400 $content_length = $self->{index_size};
402 elsif ($r eq 'ARRAY') {
403 print( $fh SIG_ARRAY );
404 print( $fh pack($self->{data_pack}, $self->{index_size}) . chr(0) x $self->{index_size} );
405 $content_length = $self->{index_size};
407 elsif (!defined($value)) {
408 print( $fh SIG_NULL );
409 print( $fh pack($self->{data_pack}, 0) );
413 print( $fh SIG_DATA );
414 print( $fh pack($self->{data_pack}, length($value)) . $value );
415 $content_length = length($value);
420 # Plain key is stored AFTER value, as keys are typically fetched less often.
422 print( $fh pack($self->{data_pack}, length($key)) . $key );
425 # If value is blessed, preserve class name
427 if ( $root->{autobless} ) {
428 my $value_class = Scalar::Util::blessed($value);
429 if ( defined $value_class && !$value->isa( 'DBM::Deep' ) ) {
431 # Blessed ref -- will restore later
434 print( $fh pack($self->{data_pack}, length($value_class)) . $value_class );
435 $content_length += 1;
436 $content_length += $self->{data_size} + length($value_class);
440 $content_length += 1;
445 # If this is a new content area, advance EOF counter
447 if ($location == $root->{end}) {
448 $root->{end} += SIG_SIZE;
449 $root->{end} += $self->{data_size} + $content_length;
450 $root->{end} += $self->{data_size} + length($key);
454 # If content is a hash or array, create new child DBM::Deep object and
455 # pass each key or element to it.
457 if ( ! $internal_ref ) {
459 my $branch = DBM::Deep->new(
460 type => DBM::Deep->TYPE_HASH,
461 base_offset => $location,
464 foreach my $key (keys %{$value}) {
465 $branch->STORE( $key, $value->{$key} );
468 elsif ($r eq 'ARRAY') {
469 my $branch = DBM::Deep->new(
470 type => DBM::Deep->TYPE_ARRAY,
471 base_offset => $location,
475 foreach my $element (@{$value}) {
476 $branch->STORE( $index, $element );
487 my ($obj, $md5, $tag) = @_;
490 my $root = $obj->_root;
491 my $keys = $tag->{content};
493 seek($fh, $tag->{ref_loc} + $root->{file_offset}, SEEK_SET);
494 print( $fh pack($self->{long_pack}, $root->{end}) );
496 my $index_tag = $self->create_tag(
500 chr(0) x $self->{index_size},
505 $keys .= $md5 . pack($self->{long_pack}, 0);
508 for (my $i = 0; $i <= $self->{max_buckets}; $i++) {
509 my ($key, $old_subloc) = $self->_get_key_subloc( $keys, $i );
511 next BUCKET unless $key;
513 my $num = ord(substr($key, $tag->{ch} + 1, 1));
515 if ($offsets[$num]) {
516 my $offset = $offsets[$num] + SIG_SIZE + $self->{data_size};
517 seek($fh, $offset + $root->{file_offset}, SEEK_SET);
519 read( $fh, $subkeys, $self->{bucket_list_size});
521 for (my $k=0; $k<$self->{max_buckets}; $k++) {
522 my ($temp, $subloc) = $self->_get_key_subloc( $subkeys, $k );
525 seek($fh, $offset + ($k * $self->{bucket_size}) + $root->{file_offset}, SEEK_SET);
526 print( $fh $key . pack($self->{long_pack}, $old_subloc || $root->{end}) );
532 $offsets[$num] = $root->{end};
533 seek($fh, $index_tag->{offset} + ($num * $self->{long_size}) + $root->{file_offset}, SEEK_SET);
534 print( $fh pack($self->{long_pack}, $root->{end}) );
536 my $blist_tag = $self->create_tag($obj, $root->{end}, SIG_BLIST, chr(0) x $self->{bucket_list_size});
538 seek($fh, $blist_tag->{offset} + $root->{file_offset}, SEEK_SET);
539 print( $fh $key . pack($self->{long_pack}, $old_subloc || $root->{end}) );
548 my ($obj, $subloc) = @_;
553 # Found match -- seek to offset and read signature
556 seek($fh, $subloc + $obj->_root->{file_offset}, SEEK_SET);
557 read( $fh, $signature, SIG_SIZE);
560 # If value is a hash or array, return new DBM::Deep object with correct offset
562 if (($signature eq SIG_HASH) || ($signature eq SIG_ARRAY)) {
563 my $obj = DBM::Deep->new(
565 base_offset => $subloc,
569 if ($obj->_root->{autobless}) {
571 # Skip over value and plain key to see if object needs
574 seek($fh, $self->{data_size} + $self->{index_size}, SEEK_CUR);
577 read( $fh, $size, $self->{data_size}); $size = unpack($self->{data_pack}, $size);
578 if ($size) { seek($fh, $size, SEEK_CUR); }
581 read( $fh, $bless_bit, 1);
582 if (ord($bless_bit)) {
584 # Yes, object needs to be re-blessed
587 read( $fh, $size, $self->{data_size}); $size = unpack($self->{data_pack}, $size);
588 if ($size) { read( $fh, $class_name, $size); }
589 if ($class_name) { $obj = bless( $obj, $class_name ); }
595 elsif ( $signature eq SIG_INTERNAL ) {
597 read( $fh, $size, $self->{data_size});
598 $size = unpack($self->{data_pack}, $size);
602 read( $fh, $new_loc, $size );
603 $new_loc = unpack( $self->{long_pack}, $new_loc );
605 return $self->read_from_loc( $obj, $new_loc );
612 # Otherwise return actual value
614 elsif ($signature eq SIG_DATA) {
616 read( $fh, $size, $self->{data_size});
617 $size = unpack($self->{data_pack}, $size);
620 if ($size) { read( $fh, $value, $size); }
625 # Key exists, but content is null
630 sub get_bucket_value {
632 # Fetch single value given tag and MD5 digested key.
635 my ($obj, $tag, $md5) = @_;
637 my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 );
639 return $self->read_from_loc( $obj, $subloc );
646 # Delete single key/value pair given tag and MD5 digested key.
649 my ($obj, $tag, $md5) = @_;
651 my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 );
654 seek($fh, $tag->{offset} + $offset + $obj->_root->{file_offset}, SEEK_SET);
655 print( $fh substr($tag->{content}, $offset + $self->{bucket_size} ) );
656 print( $fh chr(0) x $self->{bucket_size} );
665 # Check existence of single key given tag and MD5 digested key.
668 my ($obj, $tag, $md5) = @_;
670 my ($subloc, $offset) = $self->_find_in_buckets( $tag, $md5 );
674 sub find_bucket_list {
676 # Locate offset for bucket list, given digested key
679 my ($obj, $md5, $args) = @_;
680 $args = {} unless $args;
683 # Locate offset for bucket list using digest index system
685 my $tag = $self->load_tag($obj, $obj->_base_offset)
686 or $obj->_throw_error( "INTERNAL ERROR - Cannot find tag" );
689 while ($tag->{signature} ne SIG_BLIST) {
690 my $num = ord substr($md5, $ch, 1);
692 my $ref_loc = $tag->{offset} + ($num * $self->{long_size});
693 $tag = $self->index_lookup( $obj, $tag, $num );
696 return if ! $args->{create};
699 seek($fh, $ref_loc + $obj->_root->{file_offset}, SEEK_SET);
700 print( $fh pack($self->{long_pack}, $obj->_root->{end}) );
702 $tag = $self->create_tag(
703 $obj, $obj->_root->{end},
705 chr(0) x $self->{bucket_list_size},
708 $tag->{ref_loc} = $ref_loc;
715 $tag->{ref_loc} = $ref_loc;
725 # Given index tag, lookup single entry in index and return .
728 my ($obj, $tag, $index) = @_;
730 my $location = unpack(
734 $index * $self->{long_size},
739 if (!$location) { return; }
741 return $self->load_tag( $obj, $location );
746 # Scan index and recursively step into deeper levels, looking for next key.
749 my ($obj, $offset, $ch, $force_return_next) = @_;
751 my $tag = $self->load_tag($obj, $offset );
755 if ($tag->{signature} ne SIG_BLIST) {
756 my $content = $tag->{content};
757 my $start = $obj->{return_next} ? 0 : ord(substr($obj->{prev_md5}, $ch, 1));
759 for (my $idx = $start; $idx < (2**8); $idx++) {
762 substr($content, $idx * $self->{long_size}, $self->{long_size}),
766 my $result = $self->traverse_index(
767 $obj, $subloc, $ch + 1, $force_return_next,
770 if (defined($result)) { return $result; }
774 $obj->{return_next} = 1;
778 my $keys = $tag->{content};
779 if ($force_return_next) { $obj->{return_next} = 1; }
782 # Iterate through buckets, looking for a key match
784 for (my $i = 0; $i < $self->{max_buckets}; $i++) {
785 my ($key, $subloc) = $self->_get_key_subloc( $keys, $i );
787 # End of bucket list -- return to outer loop
789 $obj->{return_next} = 1;
792 # Located previous key -- return next one found
793 elsif ($key eq $obj->{prev_md5}) {
794 $obj->{return_next} = 1;
797 # Seek to bucket location and skip over signature
798 elsif ($obj->{return_next}) {
799 seek($fh, $subloc + $obj->_root->{file_offset}, SEEK_SET);
801 # Skip over value to get to plain key
803 read( $fh, $sig, SIG_SIZE );
806 read( $fh, $size, $self->{data_size});
807 $size = unpack($self->{data_pack}, $size);
808 if ($size) { seek($fh, $size, SEEK_CUR); }
810 # Read in plain key and return as scalar
812 read( $fh, $size, $self->{data_size});
813 $size = unpack($self->{data_pack}, $size);
814 if ($size) { read( $fh, $plain_key, $size); }
820 $obj->{return_next} = 1;
821 } # tag is a bucket list
828 # Locate next key, given digested previous one
833 $obj->{prev_md5} = $_[1] ? $_[1] : undef;
834 $obj->{return_next} = 0;
837 # If the previous key was not specifed, start at the top and
838 # return the first one found.
840 if (!$obj->{prev_md5}) {
841 $obj->{prev_md5} = chr(0) x $self->{hash_size};
842 $obj->{return_next} = 1;
845 return $self->traverse_index( $obj, $obj->_base_offset, 0 );
850 sub _get_key_subloc {
852 my ($keys, $idx) = @_;
854 my ($key, $subloc) = unpack(
855 "a$self->{hash_size} $self->{long_pack}",
858 ($idx * $self->{bucket_size}),
859 $self->{bucket_size},
863 return ($key, $subloc);
866 sub _find_in_buckets {
868 my ($tag, $md5) = @_;
871 for ( my $i = 0; $i < $self->{max_buckets}; $i++ ) {
872 my ($key, $subloc) = $self->_get_key_subloc( $tag->{content}, $i );
874 return ($subloc, $i * $self->{bucket_size}) unless $subloc;
876 next BUCKET if $key ne $md5;
878 return ($subloc, $i * $self->{bucket_size});
887 # This will be added in later, after more refactoring is done. This is an early
888 # attempt at refactoring on the physical level instead of the virtual level.
891 my ($obj, $spot, $amount, $unpack) = @_;
894 seek( $fh, $spot + $obj->_root->{file_offset}, SEEK_SET );
897 my $bytes_read = read( $fh, $buffer, $amount );
900 $buffer = unpack( $unpack, $buffer );
904 return ($buffer, $bytes_read);