1 package DBM::Deep::Engine;
7 our $VERSION = q(0.99_03);
12 # * Every method in here assumes that the storage has been appropriately
13 # safeguarded. This can be anything from flock() to some sort of manual
14 # mutex. But, it's the caller's responsability to make sure that this has
17 # Setup file and tag signatures. These should never change.
18 sub SIG_FILE () { 'DPDB' }
19 sub SIG_HEADER () { 'h' }
20 sub SIG_INTERNAL () { 'i' }
21 sub SIG_HASH () { 'H' }
22 sub SIG_ARRAY () { 'A' }
23 sub SIG_NULL () { 'N' }
24 sub SIG_DATA () { 'D' }
25 sub SIG_INDEX () { 'I' }
26 sub SIG_BLIST () { 'B' }
27 sub SIG_FREE () { 'F' }
28 sub SIG_KEYS () { 'K' }
30 sub STALE_SIZE () { 1 }
32 ################################################################################
34 # Please refer to the pack() documentation for further information
36 1 => 'C', # Unsigned char value (no order specified, presumably ASCII)
37 2 => 'n', # Unsigned short in "network" (big-endian) order
38 4 => 'N', # Unsigned long in "network" (big-endian) order
39 8 => 'Q', # Usigned quad (no order specified, presumably machine-dependent)
50 hash_size => 16, # In bytes
51 hash_chars => 256, # Number of chars the algorithm uses per byte
53 num_txns => 16, # HEAD plus 15 running txns
54 trans_id => 0, # Default to the HEAD
56 entries => {}, # This is the list of entries for transactions
60 if ( defined $args->{pack_size} ) {
61 if ( lc $args->{pack_size} eq 'small' ) {
62 $args->{byte_size} = 2;
64 elsif ( lc $args->{pack_size} eq 'medium' ) {
65 $args->{byte_size} = 4;
67 elsif ( lc $args->{pack_size} eq 'large' ) {
68 $args->{byte_size} = 8;
71 die "Unknown pack_size value: '$args->{pack_size}'\n";
75 # Grab the parameters we want to use
76 foreach my $param ( keys %$self ) {
77 next unless exists $args->{$param};
78 $self->{$param} = $args->{$param};
81 $self->{byte_pack} = $StP{ $self->byte_size };
84 # Number of buckets per blist before another level of indexing is
85 # done. Increase this value for slightly greater speed, but larger database
86 # files. DO NOT decrease this value below 16, due to risk of recursive
89 if ( $self->{max_buckets} < 16 ) {
90 warn "Floor of max_buckets is 16. Setting it to 16 from '$self->{max_buckets}'\n";
91 $self->{max_buckets} = 16;
94 if ( !$self->{digest} ) {
96 $self->{digest} = \&Digest::MD5::md5;
102 ################################################################################
106 my ($obj, $key) = @_;
108 # This will be a Reference sector
109 my $sector = $self->_load_sector( $obj->_base_offset )
112 if ( $sector->staleness != $obj->_staleness ) {
116 my $key_md5 = $self->_apply_digest( $key );
118 my $value_sector = $sector->get_data_for({
123 unless ( $value_sector ) {
124 $value_sector = DBM::Deep::Engine::Sector::Null->new({
129 $sector->write_data({
132 value => $value_sector,
136 return $value_sector->data;
143 # This will be a Reference sector
144 my $sector = $self->_load_sector( $obj->_base_offset )
145 or die "How did get_classname fail (no sector for '$obj')?!\n";
147 if ( $sector->staleness != $obj->_staleness ) {
151 return $sector->get_classname;
156 my ($obj, $key) = @_;
158 # This will be a Reference sector
159 my $sector = $self->_load_sector( $obj->_base_offset )
162 if ( $sector->staleness != $obj->_staleness ) {
166 my $data = $sector->get_data_for({
167 key_md5 => $self->_apply_digest( $key ),
171 # exists() returns 1 or '' for true/false.
172 return $data ? 1 : '';
177 my ($obj, $key) = @_;
179 my $sector = $self->_load_sector( $obj->_base_offset )
182 if ( $sector->staleness != $obj->_staleness ) {
186 return $sector->delete_key({
187 key_md5 => $self->_apply_digest( $key ),
194 my ($obj, $key, $value) = @_;
196 my $r = Scalar::Util::reftype( $value ) || '';
199 last if $r eq 'HASH';
200 last if $r eq 'ARRAY';
202 DBM::Deep->_throw_error(
203 "Storage of references of type '$r' is not supported."
208 if ( !defined $value ) {
209 $class = 'DBM::Deep::Engine::Sector::Null';
211 elsif ( $r eq 'ARRAY' || $r eq 'HASH' ) {
212 if ( $r eq 'ARRAY' && tied(@$value) ) {
213 DBM::Deep->_throw_error( "Cannot store something that is tied." );
215 if ( $r eq 'HASH' && tied(%$value) ) {
216 DBM::Deep->_throw_error( "Cannot store something that is tied." );
218 $class = 'DBM::Deep::Engine::Sector::Reference';
219 $type = substr( $r, 0, 1 );
222 $class = 'DBM::Deep::Engine::Sector::Scalar';
225 # This will be a Reference sector
226 my $sector = $self->_load_sector( $obj->_base_offset )
227 or die "Cannot write to a deleted spot in DBM::Deep.\n";
229 if ( $sector->staleness != $obj->_staleness ) {
230 die "Cannot write to a deleted spot in DBM::Deep.\n";
233 # Create this after loading the reference sector in case something bad happens.
234 # This way, we won't allocate value sector(s) needlessly.
235 my $value_sector = $class->new({
241 $sector->write_data({
243 key_md5 => $self->_apply_digest( $key ),
244 value => $value_sector,
247 # This code is to make sure we write all the values in the $value to the disk
248 # and to make sure all changes to $value after the assignment are reflected
249 # on disk. This may be counter-intuitive at first, but it is correct dwimmery.
250 # NOTE - simply tying $value won't perform a STORE on each value. Hence, the
251 # copy to a temp value.
252 if ( $r eq 'ARRAY' ) {
254 tie @$value, 'DBM::Deep', {
255 base_offset => $value_sector->offset,
256 staleness => $value_sector->staleness,
257 storage => $self->storage,
261 bless $value, 'DBM::Deep::Array' unless Scalar::Util::blessed( $value );
263 elsif ( $r eq 'HASH' ) {
265 tie %$value, 'DBM::Deep', {
266 base_offset => $value_sector->offset,
267 staleness => $value_sector->staleness,
268 storage => $self->storage,
273 bless $value, 'DBM::Deep::Hash' unless Scalar::Util::blessed( $value );
279 # XXX Add staleness here
282 my ($obj, $prev_key) = @_;
284 # XXX Need to add logic about resetting the iterator if any key in the reference has changed
285 unless ( $prev_key ) {
286 $obj->{iterator} = DBM::Deep::Iterator->new({
287 base_offset => $obj->_base_offset,
292 return $obj->{iterator}->get_next_key( $obj );
295 ################################################################################
301 # We're opening the file.
302 unless ( $obj->_base_offset ) {
303 my $bytes_read = $self->_read_file_header;
305 # Creating a new file
306 unless ( $bytes_read ) {
307 $self->_write_file_header;
309 # 1) Create Array/Hash entry
310 my $initial_reference = DBM::Deep::Engine::Sector::Reference->new({
314 $obj->{base_offset} = $initial_reference->offset;
315 $obj->{staleness} = $initial_reference->staleness;
317 $self->storage->flush;
319 # Reading from an existing file
321 $obj->{base_offset} = $bytes_read;
322 my $initial_reference = DBM::Deep::Engine::Sector::Reference->new({
324 offset => $obj->_base_offset,
326 unless ( $initial_reference ) {
327 DBM::Deep->_throw_error("Corrupted file, no master index record");
330 unless ($obj->_type eq $initial_reference->type) {
331 DBM::Deep->_throw_error("File type mismatch");
334 $obj->{staleness} = $initial_reference->staleness;
345 if ( $self->trans_id ) {
346 DBM::Deep->_throw_error( "Cannot begin_work within a transaction" );
349 my @slots = $self->read_txn_slots;
350 for my $i ( 1 .. @slots ) {
353 $self->set_trans_id( $i );
356 $self->write_txn_slots( @slots );
358 if ( !$self->trans_id ) {
359 DBM::Deep->_throw_error( "Cannot begin_work - no available transactions" );
369 if ( !$self->trans_id ) {
370 DBM::Deep->_throw_error( "Cannot rollback without a transaction" );
373 # Each entry is the file location for a bucket that has a modification for
374 # this transaction. The entries need to be expunged.
375 foreach my $entry (@{ $self->get_entries } ) {
376 # Remove the entry here
377 my $read_loc = $entry
380 + $self->trans_id * ( $self->byte_size + 4 );
382 my $data_loc = $self->storage->read_at( $read_loc, $self->byte_size );
383 $data_loc = unpack( $StP{$self->byte_size}, $data_loc );
384 $self->storage->print_at( $read_loc, pack( $StP{$self->byte_size}, 0 ) );
386 if ( $data_loc > 1 ) {
387 $self->_load_sector( $data_loc )->free;
391 $self->clear_entries;
393 my @slots = $self->read_txn_slots;
394 $slots[$self->trans_id] = 0;
395 $self->write_txn_slots( @slots );
396 $self->inc_txn_staleness_counter( $self->trans_id );
397 $self->set_trans_id( 0 );
406 if ( !$self->trans_id ) {
407 DBM::Deep->_throw_error( "Cannot commit without a transaction" );
410 foreach my $entry (@{ $self->get_entries } ) {
411 # Overwrite the entry in head with the entry in trans_id
416 my $head_loc = $self->storage->read_at( $base, $self->byte_size );
417 $head_loc = unpack( $StP{$self->byte_size}, $head_loc );
418 my $trans_loc = $self->storage->read_at(
419 $base + $self->trans_id * ( $self->byte_size + 4 ), $self->byte_size,
422 $self->storage->print_at( $base, $trans_loc );
423 $self->storage->print_at(
424 $base + $self->trans_id * ( $self->byte_size + 4 ),
425 pack( $StP{$self->byte_size} . ' N', (0) x 2 ),
428 if ( $head_loc > 1 ) {
429 $self->_load_sector( $head_loc )->free;
433 $self->clear_entries;
435 my @slots = $self->read_txn_slots;
436 $slots[$self->trans_id] = 0;
437 $self->write_txn_slots( @slots );
438 $self->inc_txn_staleness_counter( $self->trans_id );
439 $self->set_trans_id( 0 );
446 return split '', unpack( 'b32',
447 $self->storage->read_at(
453 sub write_txn_slots {
455 $self->storage->print_at( $self->trans_loc,
456 pack( 'b32', join('', @_) ),
460 sub get_running_txn_ids {
462 my @transactions = $self->read_txn_slots;
463 my @trans_ids = grep { $transactions[$_] } 0 .. $#transactions;
466 sub get_txn_staleness_counter {
470 # Hardcode staleness of 0 for the HEAD
471 return 0 unless $trans_id;
474 $self->storage->read_at(
475 $self->trans_loc + 4 * $trans_id,
482 sub inc_txn_staleness_counter {
486 # Hardcode staleness of 0 for the HEAD
487 return unless $trans_id;
489 $self->storage->print_at(
490 $self->trans_loc + 4 * $trans_id,
491 pack( 'N', $self->get_txn_staleness_counter( $trans_id ) + 1 ),
497 return [ keys %{ $self->{entries}{$self->trans_id} ||= {} } ];
502 my ($trans_id, $loc) = @_;
504 $self->{entries}{$trans_id} ||= {};
505 $self->{entries}{$trans_id}{$loc} = undef;
508 # If the buckets are being relocated because of a reindexing, the entries
509 # mechanism needs to be made aware of it.
512 my ($old_loc, $new_loc) = @_;
515 while ( my ($trans_id, $locs) = each %{ $self->{entries} } ) {
516 foreach my $orig_loc ( keys %{ $locs } ) {
517 if ( $orig_loc == $old_loc ) {
518 delete $locs->{orig_loc};
519 $locs->{$new_loc} = undef;
528 delete $self->{entries}{$self->trans_id};
531 ################################################################################
534 my $header_fixed = length( SIG_FILE ) + 1 + 4 + 4;
536 sub _write_file_header {
539 my $header_var = 1 + 1 + 4 + 4 * $self->num_txns + 3 * $self->byte_size;
541 my $loc = $self->storage->request_space( $header_fixed + $header_var );
543 $self->storage->print_at( $loc,
546 pack('N', 1), # header version - at this point, we're at 9 bytes
547 pack('N', $header_var), # header size
548 # --- Above is $header_fixed. Below is $header_var
549 pack('C', $self->byte_size),
550 pack('C', $self->max_buckets),
551 pack('N', 0 ), # Transaction activeness bitfield
552 pack('N' . $self->num_txns, 0 x $self->num_txns ), # Transaction staleness counters
553 pack($StP{$self->byte_size}, 0), # Start of free chain (blist size)
554 pack($StP{$self->byte_size}, 0), # Start of free chain (data size)
555 pack($StP{$self->byte_size}, 0), # Start of free chain (index size)
558 $self->set_trans_loc( $header_fixed + 2 );
559 $self->set_chains_loc( $header_fixed + 2 + 4 + 4 * $self->num_txns );
564 sub _read_file_header {
567 my $buffer = $self->storage->read_at( 0, $header_fixed );
568 return unless length($buffer);
570 my ($file_signature, $sig_header, $header_version, $size) = unpack(
574 unless ( $file_signature eq SIG_FILE ) {
575 $self->storage->close;
576 DBM::Deep->_throw_error( "Signature not found -- file is not a Deep DB" );
579 unless ( $sig_header eq SIG_HEADER ) {
580 $self->storage->close;
581 DBM::Deep->_throw_error( "Old file version found." );
584 my $buffer2 = $self->storage->read_at( undef, $size );
585 my @values = unpack( 'C C', $buffer2 );
587 $self->set_trans_loc( $header_fixed + 2 );
588 $self->set_chains_loc( $header_fixed + 2 + 4 + 4 * $self->num_txns );
590 if ( @values < 2 || grep { !defined } @values ) {
591 $self->storage->close;
592 DBM::Deep->_throw_error("Corrupted file - bad header");
595 #XXX Add warnings if values weren't set right
596 @{$self}{qw(byte_size max_buckets)} = @values;
598 my $header_var = 1 + 1 + 4 + 4 * $self->num_txns + 3 * $self->byte_size;
599 unless ( $size eq $header_var ) {
600 $self->storage->close;
601 DBM::Deep->_throw_error( "Unexpected size found ($size <-> $header_var)." );
604 return length($buffer) + length($buffer2);
612 # Add a catch for offset of 0 or 1
613 return if $offset <= 1;
615 my $type = $self->storage->read_at( $offset, 1 );
616 return if $type eq chr(0);
618 if ( $type eq $self->SIG_ARRAY || $type eq $self->SIG_HASH ) {
619 return DBM::Deep::Engine::Sector::Reference->new({
625 # XXX Don't we need key_md5 here?
626 elsif ( $type eq $self->SIG_BLIST ) {
627 return DBM::Deep::Engine::Sector::BucketList->new({
633 elsif ( $type eq $self->SIG_INDEX ) {
634 return DBM::Deep::Engine::Sector::Index->new({
640 elsif ( $type eq $self->SIG_NULL ) {
641 return DBM::Deep::Engine::Sector::Null->new({
647 elsif ( $type eq $self->SIG_DATA ) {
648 return DBM::Deep::Engine::Sector::Scalar->new({
654 # This was deleted from under us, so just return and let the caller figure it out.
655 elsif ( $type eq $self->SIG_FREE ) {
659 die "'$offset': Don't know what to do with type '$type'\n";
664 return $self->{digest}->(@_);
667 sub _add_free_blist_sector { shift->_add_free_sector( 0, @_ ) }
668 sub _add_free_data_sector { shift->_add_free_sector( 1, @_ ) }
669 sub _add_free_index_sector { shift->_add_free_sector( 2, @_ ) }
671 sub _add_free_sector {
673 my ($multiple, $offset, $size) = @_;
675 my $chains_offset = $multiple * $self->byte_size;
677 my $storage = $self->storage;
679 # Increment staleness.
680 # XXX Can this increment+modulo be done by "&= 0x1" ?
681 my $staleness = unpack( $StP{STALE_SIZE()}, $storage->read_at( $offset + SIG_SIZE, STALE_SIZE ) );
682 $staleness = ($staleness + 1 ) % ( 2 ** ( 8 * STALE_SIZE ) );
683 $storage->print_at( $offset + SIG_SIZE, pack( $StP{STALE_SIZE()}, $staleness ) );
685 my $old_head = $storage->read_at( $self->chains_loc + $chains_offset, $self->byte_size );
687 $storage->print_at( $self->chains_loc + $chains_offset,
688 pack( $StP{$self->byte_size}, $offset ),
691 # Record the old head in the new sector after the signature and staleness counter
692 $storage->print_at( $offset + SIG_SIZE + STALE_SIZE, $old_head );
695 sub _request_blist_sector { shift->_request_sector( 0, @_ ) }
696 sub _request_data_sector { shift->_request_sector( 1, @_ ) }
697 sub _request_index_sector { shift->_request_sector( 2, @_ ) }
699 sub _request_sector {
701 my ($multiple, $size) = @_;
703 my $chains_offset = $multiple * $self->byte_size;
705 my $old_head = $self->storage->read_at( $self->chains_loc + $chains_offset, $self->byte_size );
706 my $loc = unpack( $StP{$self->byte_size}, $old_head );
708 # We don't have any free sectors of the right size, so allocate a new one.
710 my $offset = $self->storage->request_space( $size );
712 # Zero out the new sector. This also guarantees correct increases
714 $self->storage->print_at( $offset, chr(0) x $size );
719 # Read the new head after the signature and the staleness counter
720 my $new_head = $self->storage->read_at( $loc + SIG_SIZE + STALE_SIZE, $self->byte_size );
721 $self->storage->print_at( $self->chains_loc + $chains_offset, $new_head );
726 ################################################################################
728 sub storage { $_[0]{storage} }
729 sub byte_size { $_[0]{byte_size} }
730 sub hash_size { $_[0]{hash_size} }
731 sub hash_chars { $_[0]{hash_chars} }
732 sub num_txns { $_[0]{num_txns} }
733 sub max_buckets { $_[0]{max_buckets} }
734 sub blank_md5 { chr(0) x $_[0]->hash_size }
736 sub trans_id { $_[0]{trans_id} }
737 sub set_trans_id { $_[0]{trans_id} = $_[1] }
739 sub trans_loc { $_[0]{trans_loc} }
740 sub set_trans_loc { $_[0]{trans_loc} = $_[1] }
742 sub chains_loc { $_[0]{chains_loc} }
743 sub set_chains_loc { $_[0]{chains_loc} = $_[1] }
745 ################################################################################
747 package DBM::Deep::Iterator;
755 engine => $args->{engine},
756 base_offset => $args->{base_offset},
759 Scalar::Util::weaken( $self->{engine} );
764 sub reset { $_[0]{breadcrumbs} = [] }
766 sub get_sector_iterator {
770 my $sector = $self->{engine}->_load_sector( $loc )
773 if ( $sector->isa( 'DBM::Deep::Engine::Sector::Index' ) ) {
774 return DBM::Deep::Iterator::Index->new({
779 elsif ( $sector->isa( 'DBM::Deep::Engine::Sector::BucketList' ) ) {
780 return DBM::Deep::Iterator::BucketList->new({
786 die "Why did $loc make a $sector?";
794 my $crumbs = $self->{breadcrumbs};
795 my $e = $self->{engine};
797 unless ( @$crumbs ) {
798 # This will be a Reference sector
799 my $sector = $e->_load_sector( $self->{base_offset} )
800 # If no sector is found, thist must have been deleted from under us.
803 if ( $sector->staleness != $obj->_staleness ) {
807 my $loc = $sector->get_blist_loc
810 push @$crumbs, $self->get_sector_iterator( $loc );
815 unless ( @$crumbs ) {
820 my $iterator = $crumbs->[-1];
822 # This level is done.
823 if ( $iterator->at_end ) {
828 if ( $iterator->isa( 'DBM::Deep::Iterator::Index' ) ) {
829 # If we don't have any more, it will be caught at the
831 if ( my $next = $iterator->get_next_iterator ) {
832 push @$crumbs, $next;
837 unless ( $iterator->isa( 'DBM::Deep::Iterator::BucketList' ) ) {
838 DBM::Deep->_throw_error(
839 "Should have a bucketlist iterator here - instead have $iterator"
843 # At this point, we have a BucketList iterator
844 my $key = $iterator->get_next_key;
845 if ( defined $key ) {
849 # We hit the end of the bucketlist iterator, so redo
853 DBM::Deep->_throw_error( "get_next_key(): How did we get here?" );
856 package DBM::Deep::Iterator::Index;
859 my $self = bless $_[1] => $_[0];
860 $self->{curr_index} = 0;
866 return $self->{curr_index} >= $self->{iterator}{engine}->hash_chars;
869 sub get_next_iterator {
874 return if $self->at_end;
875 $loc = $self->{sector}->get_entry( $self->{curr_index}++ );
878 return $self->{iterator}->get_sector_iterator( $loc );
881 package DBM::Deep::Iterator::BucketList;
884 my $self = bless $_[1] => $_[0];
885 $self->{curr_index} = 0;
891 return $self->{curr_index} >= $self->{iterator}{engine}->max_buckets;
897 return if $self->at_end;
899 my $data_loc = $self->{sector}->get_data_location_for({
901 idx => $self->{curr_index}++,
904 my $key_sector = $self->{sector}->get_key_for( $self->{curr_index} - 1 );
906 #XXX Is this check necessary now?
907 return unless $key_sector;
909 return $key_sector->data;
912 package DBM::Deep::Engine::Sector;
915 my $self = bless $_[1], $_[0];
916 Scalar::Util::weaken( $self->{engine} );
921 sub clone { die "Must be implemented in the child class" }
923 sub engine { $_[0]{engine} }
924 sub offset { $_[0]{offset} }
925 sub type { $_[0]{type} }
929 return $self->engine->SIG_SIZE + $self->engine->STALE_SIZE;
935 my $e = $self->engine;
937 $e->storage->print_at( $self->offset, $e->SIG_FREE );
938 # Skip staleness counter
939 $e->storage->print_at( $self->offset + $self->base_size,
940 chr(0) x ($self->size - $self->base_size),
943 my $free_meth = $self->free_meth;
944 $e->$free_meth( $self->offset, $self->size );
949 package DBM::Deep::Engine::Sector::Data;
951 our @ISA = qw( DBM::Deep::Engine::Sector );
954 sub size { return 256 }
955 sub free_meth { return '_add_free_data_sector' }
959 return ref($self)->new({
960 engine => $self->engine,
966 package DBM::Deep::Engine::Sector::Scalar;
968 our @ISA = qw( DBM::Deep::Engine::Sector::Data );
973 my $chain_loc = $self->chain_loc;
975 $self->SUPER::free();
978 $self->engine->_load_sector( $chain_loc )->free;
984 sub type { $_[0]{engine}->SIG_DATA }
988 my $engine = $self->engine;
990 unless ( $self->offset ) {
991 my $data_section = $self->size - $self->base_size - 1 * $engine->byte_size - 1;
993 $self->{offset} = $engine->_request_data_sector( $self->size );
995 my $data = delete $self->{data};
996 my $dlen = length $data;
998 my $curr_offset = $self->offset;
999 while ( $continue ) {
1001 my $next_offset = 0;
1003 my ($leftover, $this_len, $chunk);
1004 if ( $dlen > $data_section ) {
1006 $this_len = $data_section;
1007 $chunk = substr( $data, 0, $this_len );
1009 $dlen -= $data_section;
1010 $next_offset = $engine->_request_data_sector( $self->size );
1011 $data = substr( $data, $this_len );
1014 $leftover = $data_section - $dlen;
1021 $engine->storage->print_at( $curr_offset, $self->type ); # Sector type
1023 $engine->storage->print_at( $curr_offset + $self->base_size,
1024 pack( $StP{$engine->byte_size}, $next_offset ), # Chain loc
1025 pack( $StP{1}, $this_len ), # Data length
1026 $chunk, # Data to be stored in this sector
1027 chr(0) x $leftover, # Zero-fill the rest
1030 $curr_offset = $next_offset;
1040 my $buffer = $self->engine->storage->read_at(
1041 $self->offset + $self->base_size + $self->engine->byte_size, 1
1044 return unpack( $StP{1}, $buffer );
1049 my $chain_loc = $self->engine->storage->read_at(
1050 $self->offset + $self->base_size, $self->engine->byte_size,
1052 return unpack( $StP{$self->engine->byte_size}, $chain_loc );
1060 my $chain_loc = $self->chain_loc;
1062 $data .= $self->engine->storage->read_at(
1063 $self->offset + $self->base_size + $self->engine->byte_size + 1, $self->data_length,
1066 last unless $chain_loc;
1068 $self = $self->engine->_load_sector( $chain_loc );
1074 package DBM::Deep::Engine::Sector::Null;
1076 our @ISA = qw( DBM::Deep::Engine::Sector::Data );
1078 sub type { $_[0]{engine}->SIG_NULL }
1079 sub data_length { 0 }
1085 my $engine = $self->engine;
1087 unless ( $self->offset ) {
1088 my $leftover = $self->size - $self->base_size - 1 * $engine->byte_size - 1;
1090 $self->{offset} = $engine->_request_data_sector( $self->size );
1091 $engine->storage->print_at( $self->offset, $self->type ); # Sector type
1092 # Skip staleness counter
1093 $engine->storage->print_at( $self->offset + $self->base_size,
1094 pack( $StP{$engine->byte_size}, 0 ), # Chain loc
1095 pack( $StP{1}, $self->data_length ), # Data length
1096 chr(0) x $leftover, # Zero-fill the rest
1103 package DBM::Deep::Engine::Sector::Reference;
1105 our @ISA = qw( DBM::Deep::Engine::Sector::Data );
1110 my $e = $self->engine;
1112 unless ( $self->offset ) {
1113 my $classname = Scalar::Util::blessed( delete $self->{data} );
1114 my $leftover = $self->size - $self->base_size - 2 * $e->byte_size;
1116 my $class_offset = 0;
1117 if ( defined $classname ) {
1118 my $class_sector = DBM::Deep::Engine::Sector::Scalar->new({
1122 $class_offset = $class_sector->offset;
1125 $self->{offset} = $e->_request_data_sector( $self->size );
1126 $e->storage->print_at( $self->offset, $self->type ); # Sector type
1127 # Skip staleness counter
1128 $e->storage->print_at( $self->offset + $self->base_size,
1129 pack( $StP{$e->byte_size}, 0 ), # Index/BList loc
1130 pack( $StP{$e->byte_size}, $class_offset ), # Classname loc
1131 chr(0) x $leftover, # Zero-fill the rest
1135 $self->{type} = $e->storage->read_at( $self->offset, 1 );
1138 $self->{staleness} = unpack(
1139 $StP{$e->STALE_SIZE},
1140 $e->storage->read_at( $self->offset + $e->SIG_SIZE, $e->STALE_SIZE ),
1149 my $blist_loc = $self->get_blist_loc;
1150 $self->engine->_load_sector( $blist_loc )->free if $blist_loc;
1152 my $class_loc = $self->get_class_offset;
1153 $self->engine->_load_sector( $class_loc )->free if $class_loc;
1155 $self->SUPER::free();
1158 sub staleness { $_[0]{staleness} }
1164 # Assume that the head is not allowed unless otherwise specified.
1165 $args->{allow_head} = 0 unless exists $args->{allow_head};
1167 # Assume we don't create a new blist location unless otherwise specified.
1168 $args->{create} = 0 unless exists $args->{create};
1170 my $blist = $self->get_bucket_list({
1171 key_md5 => $args->{key_md5},
1172 key => $args->{key},
1173 create => $args->{create},
1175 return unless $blist && $blist->{found};
1177 # At this point, $blist knows where the md5 is. What it -doesn't- know yet
1178 # is whether or not this transaction has this key. That's part of the next
1180 my $location = $blist->get_data_location_for({
1181 allow_head => $args->{allow_head},
1184 return $self->engine->_load_sector( $location );
1191 my $blist = $self->get_bucket_list({
1192 key_md5 => $args->{key_md5},
1193 key => $args->{key},
1195 }) or die "How did write_data fail (no blist)?!\n";
1197 # Handle any transactional bookkeeping.
1198 if ( $self->engine->trans_id ) {
1199 if ( ! $blist->has_md5 ) {
1200 $blist->mark_deleted({
1206 my @trans_ids = $self->engine->get_running_txn_ids;
1207 if ( $blist->has_md5 ) {
1209 my $old_value = $blist->get_data_for;
1210 foreach my $other_trans_id ( @trans_ids ) {
1211 next if $blist->get_data_location_for({
1212 trans_id => $other_trans_id,
1216 trans_id => $other_trans_id,
1217 key => $args->{key},
1218 key_md5 => $args->{key_md5},
1219 value => $old_value->clone,
1226 foreach my $other_trans_id ( @trans_ids ) {
1227 next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
1228 $blist->mark_deleted({
1229 trans_id => $other_trans_id,
1236 #XXX Is this safe to do transactionally?
1237 # Free the place we're about to write to.
1238 if ( $blist->get_data_location_for({ allow_head => 0 }) ) {
1239 $blist->get_data_for({ allow_head => 0 })->free;
1243 key => $args->{key},
1244 key_md5 => $args->{key_md5},
1245 value => $args->{value},
1253 # XXX What should happen if this fails?
1254 my $blist = $self->get_bucket_list({
1255 key_md5 => $args->{key_md5},
1256 }) or die "How did delete_key fail (no blist)?!\n";
1258 # Save the location so that we can free the data
1259 my $location = $blist->get_data_location_for({
1262 my $old_value = $location && $self->engine->_load_sector( $location );
1264 if ( $self->engine->trans_id == 0 ) {
1265 my @trans_ids = $self->engine->get_running_txn_ids;
1267 foreach my $other_trans_id ( @trans_ids ) {
1268 next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
1270 trans_id => $other_trans_id,
1271 key => $args->{key},
1272 key_md5 => $args->{key_md5},
1273 value => $old_value->clone,
1279 $blist->mark_deleted( $args );
1283 $data = $old_value->data;
1293 my $e = $self->engine;
1294 my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size );
1295 return unpack( $StP{$e->byte_size}, $blist_loc );
1298 sub get_bucket_list {
1303 # XXX Add in check here for recycling?
1305 my $engine = $self->engine;
1307 my $blist_loc = $self->get_blist_loc;
1309 # There's no index or blist yet
1310 unless ( $blist_loc ) {
1311 return unless $args->{create};
1313 my $blist = DBM::Deep::Engine::Sector::BucketList->new({
1315 key_md5 => $args->{key_md5},
1318 $engine->storage->print_at( $self->offset + $self->base_size,
1319 pack( $StP{$engine->byte_size}, $blist->offset ),
1325 # Add searching here through the index layers, if any
1326 my $sector = $engine->_load_sector( $blist_loc )
1327 or die "Cannot read sector at $blist_loc in get_bucket_list()";
1329 my $last_sector = undef;
1330 while ( $sector->isa( 'DBM::Deep::Engine::Sector::Index' ) ) {
1331 $blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) );
1332 $last_sector = $sector;
1334 $sector = $engine->_load_sector( $blist_loc )
1335 or die "Cannot read sector at $blist_loc in get_bucket_list()";
1343 # This means we went through the Index sector(s) and found an empty slot
1344 unless ( $sector ) {
1345 return unless $args->{create};
1347 die "No last_sector when attempting to build a new entry"
1348 unless $last_sector;
1350 my $blist = DBM::Deep::Engine::Sector::BucketList->new({
1352 key_md5 => $args->{key_md5},
1355 $last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset );
1360 $sector->find_md5( $args->{key_md5} );
1362 # See whether or not we need to reindex the bucketlist
1363 if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {
1364 my $new_index = DBM::Deep::Engine::Sector::Index->new({
1369 #XXX q.v. the comments for this function.
1370 foreach my $entry ( $sector->chopped_up ) {
1371 my ($spot, $md5) = @{$entry};
1372 my $idx = ord( substr( $md5, $i, 1 ) );
1374 # XXX This is inefficient
1375 my $blist = $blist_cache{$idx}
1376 ||= DBM::Deep::Engine::Sector::BucketList->new({
1380 $new_index->set_entry( $idx => $blist->offset );
1382 my $new_spot = $blist->write_at_next_open( $md5 );
1383 $engine->reindex_entry( $spot => $new_spot );
1386 # Handle the new item separately.
1388 my $idx = ord( substr( $args->{key_md5}, $i, 1 ) );
1389 my $blist = $blist_cache{$idx}
1390 ||= DBM::Deep::Engine::Sector::BucketList->new({
1394 $new_index->set_entry( $idx => $blist->offset );
1397 $blist->find_md5( $args->{key_md5} );
1399 key => $args->{key},
1400 key_md5 => $args->{key_md5},
1401 value => DBM::Deep::Engine::Sector::Null->new({
1408 if ( $last_sector ) {
1409 $last_sector->set_entry(
1410 ord( substr( $args->{key_md5}, $i - 1, 1 ) ),
1414 $engine->storage->print_at( $self->offset + $self->base_size,
1415 pack( $StP{$engine->byte_size}, $new_index->offset ),
1421 $sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) };
1422 $sector->find_md5( $args->{key_md5} );
1428 sub get_class_offset {
1431 my $e = $self->engine;
1433 $StP{$e->byte_size},
1434 $e->storage->read_at(
1435 $self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size,
1443 my $class_offset = $self->get_class_offset;
1445 return unless $class_offset;
1447 return $self->engine->_load_sector( $class_offset )->data;
1453 my $new_obj = DBM::Deep->new({
1454 type => $self->type,
1455 base_offset => $self->offset,
1456 staleness => $self->staleness,
1457 storage => $self->engine->storage,
1458 engine => $self->engine,
1461 if ( $self->engine->storage->{autobless} ) {
1462 my $classname = $self->get_classname;
1463 if ( defined $classname ) {
1464 bless $new_obj, $classname;
1471 package DBM::Deep::Engine::Sector::BucketList;
1473 our @ISA = qw( DBM::Deep::Engine::Sector );
1478 my $engine = $self->engine;
1480 unless ( $self->offset ) {
1481 my $leftover = $self->size - $self->base_size;
1483 $self->{offset} = $engine->_request_blist_sector( $self->size );
1484 $engine->storage->print_at( $self->offset, $engine->SIG_BLIST ); # Sector type
1485 # Skip staleness counter
1486 $engine->storage->print_at( $self->offset + $self->base_size,
1487 chr(0) x $leftover, # Zero-fill the data
1491 if ( $self->{key_md5} ) {
1500 unless ( $self->{size} ) {
1501 my $e = $self->engine;
1502 # Base + numbuckets * bucketsize
1503 $self->{size} = $self->base_size + $e->max_buckets * $self->bucket_size;
1505 return $self->{size};
1508 sub free_meth { return '_add_free_blist_sector' }
1512 unless ( $self->{bucket_size} ) {
1513 my $e = $self->engine;
1514 # Key + head (location) + transactions (location + staleness-counter)
1515 my $location_size = $e->byte_size + $e->num_txns * ( $e->byte_size + 4 );
1516 $self->{bucket_size} = $e->hash_size + $location_size;
1518 return $self->{bucket_size};
1521 # XXX This is such a poor hack. I need to rethink this code.
1525 my $e = $self->engine;
1528 foreach my $idx ( 0 .. $e->max_buckets - 1 ) {
1529 my $spot = $self->offset + $self->base_size + $idx * $self->bucket_size;
1530 my $md5 = $e->storage->read_at( $spot, $e->hash_size );
1532 last if $md5 eq $e->blank_md5;
1534 my $rest = $e->storage->read_at( undef, $self->bucket_size - $e->hash_size );
1535 push @buckets, [ $spot, $md5 . $rest ];
1541 sub write_at_next_open {
1545 #XXX This is such a hack!
1546 $self->{_next_open} = 0 unless exists $self->{_next_open};
1548 my $spot = $self->offset + $self->base_size + $self->{_next_open}++ * $self->bucket_size;
1549 $self->engine->storage->print_at( $spot, $entry );
1556 unless ( exists $self->{found} ) {
1559 return $self->{found};
1565 $self->{found} = undef;
1569 $self->{key_md5} = shift;
1572 # If we don't have an MD5, then what are we supposed to do?
1573 unless ( exists $self->{key_md5} ) {
1574 DBM::Deep->_throw_error( "Cannot find_md5 without a key_md5 set" );
1577 my $e = $self->engine;
1578 foreach my $idx ( 0 .. $e->max_buckets - 1 ) {
1579 my $potential = $e->storage->read_at(
1580 $self->offset + $self->base_size + $idx * $self->bucket_size, $e->hash_size,
1583 if ( $potential eq $e->blank_md5 ) {
1584 $self->{idx} = $idx;
1588 if ( $potential eq $self->{key_md5} ) {
1590 $self->{idx} = $idx;
1602 DBM::Deep->_throw_error( "write_md5: no key" ) unless exists $args->{key};
1603 DBM::Deep->_throw_error( "write_md5: no key_md5" ) unless exists $args->{key_md5};
1604 DBM::Deep->_throw_error( "write_md5: no value" ) unless exists $args->{value};
1606 my $engine = $self->engine;
1608 $args->{trans_id} = $engine->trans_id unless exists $args->{trans_id};
1610 my $spot = $self->offset + $self->base_size + $self->{idx} * $self->bucket_size;
1611 $engine->add_entry( $args->{trans_id}, $spot );
1613 unless ($self->{found}) {
1614 my $key_sector = DBM::Deep::Engine::Sector::Scalar->new({
1616 data => $args->{key},
1619 $engine->storage->print_at( $spot,
1621 pack( $StP{$engine->byte_size}, $key_sector->offset ),
1626 + $engine->hash_size
1627 + $engine->byte_size
1628 + $args->{trans_id} * ( $engine->byte_size + 4 );
1630 $engine->storage->print_at( $loc,
1631 pack( $StP{$engine->byte_size}, $args->{value}->offset ),
1632 pack( 'N', $engine->get_txn_staleness_counter( $args->{trans_id} ) ),
1641 my $engine = $self->engine;
1643 $args->{trans_id} = $engine->trans_id unless exists $args->{trans_id};
1645 my $spot = $self->offset + $self->base_size + $self->{idx} * $self->bucket_size;
1646 $engine->add_entry( $args->{trans_id}, $spot );
1649 + $engine->hash_size
1650 + $engine->byte_size
1651 + $args->{trans_id} * ( $engine->byte_size + 4 );
1653 $engine->storage->print_at( $loc,
1654 pack( $StP{$engine->byte_size}, 1 ), # 1 is the marker for deleted
1655 pack( 'N', $engine->get_txn_staleness_counter( $args->{trans_id} ) ),
1663 my $engine = $self->engine;
1664 return undef unless $self->{found};
1666 # Save the location so that we can free the data
1667 my $location = $self->get_data_location_for({
1670 my $key_sector = $self->get_key_for;
1672 #XXX This isn't going to work right and you know it! This eradicates data
1673 # that we're not ready to eradicate just yet.
1674 my $spot = $self->offset + $self->base_size + $self->{idx} * $self->bucket_size;
1675 $engine->storage->print_at( $spot,
1676 $engine->storage->read_at(
1677 $spot + $self->bucket_size,
1678 $self->bucket_size * ( $engine->num_txns - $self->{idx} - 1 ),
1680 chr(0) x $self->bucket_size,
1685 my $data_sector = $self->engine->_load_sector( $location );
1686 my $data = $data_sector->data;
1692 sub get_data_location_for {
1697 $args->{allow_head} = 0 unless exists $args->{allow_head};
1698 $args->{trans_id} = $self->engine->trans_id unless exists $args->{trans_id};
1699 $args->{idx} = $self->{idx} unless exists $args->{idx};
1701 my $e = $self->engine;
1703 my $spot = $self->offset + $self->base_size
1704 + $args->{idx} * $self->bucket_size
1707 + $args->{trans_id} * ( $e->byte_size + 4 );
1709 my $buffer = $e->storage->read_at(
1713 my ($loc, $staleness) = unpack( $StP{$e->byte_size} . ' N', $buffer );
1715 # We have found an entry that is old, so get rid of it
1716 if ( $staleness != (my $s = $e->get_txn_staleness_counter( $args->{trans_id} ) ) ) {
1717 $e->storage->print_at(
1719 pack( $StP{$e->byte_size} . ' N', (0) x 2 ),
1724 # If we're in a transaction and we never wrote to this location, try the
1726 if ( $args->{trans_id} && !$loc && $args->{allow_head} ) {
1727 return $self->get_data_location_for({
1730 idx => $args->{idx},
1733 return $loc <= 1 ? 0 : $loc;
1741 return unless $self->{found};
1742 my $location = $self->get_data_location_for({
1743 allow_head => $args->{allow_head},
1745 return $self->engine->_load_sector( $location );
1751 $idx = $self->{idx} unless defined $idx;
1753 if ( $idx >= $self->engine->max_buckets ) {
1754 DBM::Deep->_throw_error( "get_key_for(): Attempting to retrieve $idx" );
1757 my $location = $self->engine->storage->read_at(
1758 $self->offset + $self->base_size + $idx * $self->bucket_size + $self->engine->hash_size,
1759 $self->engine->byte_size,
1761 $location = unpack( $StP{$self->engine->byte_size}, $location );
1762 return unless $location;
1763 return $self->engine->_load_sector( $location );
1766 package DBM::Deep::Engine::Sector::Index;
1768 our @ISA = qw( DBM::Deep::Engine::Sector );
1773 my $engine = $self->engine;
1775 unless ( $self->offset ) {
1776 my $leftover = $self->size - $self->base_size;
1778 $self->{offset} = $engine->_request_index_sector( $self->size );
1779 $engine->storage->print_at( $self->offset, $engine->SIG_INDEX ); # Sector type
1780 # Skip staleness counter
1781 $engine->storage->print_at( $self->offset + $self->base_size,
1782 chr(0) x $leftover, # Zero-fill the rest
1791 unless ( $self->{size} ) {
1792 my $e = $self->engine;
1793 $self->{size} = $self->base_size + $e->byte_size * $e->hash_chars;
1795 return $self->{size};
1798 sub free_meth { return '_add_free_index_sector' }
1802 my $e = $self->engine;
1804 for my $i ( 0 .. $e->hash_chars - 1 ) {
1805 my $l = $self->location_for( $i ) or next;
1806 $e->_load_sector( $l )->free;
1809 $self->SUPER::free();
1815 return $self->offset + $self->base_size + $idx * $self->engine->byte_size;
1822 my $e = $self->engine;
1824 die "get_entry: Out of range ($idx)"
1825 if $idx < 0 || $idx >= $e->hash_chars;
1828 $StP{$e->byte_size},
1829 $e->storage->read_at( $self->_loc_for( $idx ), $e->byte_size ),
1835 my ($idx, $loc) = @_;
1837 my $e = $self->engine;
1839 die "set_entry: Out of range ($idx)"
1840 if $idx < 0 || $idx >= $e->hash_chars;
1842 $self->engine->storage->print_at(
1843 $self->_loc_for( $idx ),
1844 pack( $StP{$e->byte_size}, $loc ),