1 package DBM::Deep::Engine::Sector::FileHeader;
6 use warnings FATAL => 'all';
8 use DBM::Deep::Engine::Sector;
9 our @ISA = qw( DBM::Deep::Engine::Sector );
11 my $header_fixed = length( &DBM::Deep::Engine::SIG_FILE ) + 1 + 4 + 4;
12 my $this_file_version = 3;
17 my $e = $self->engine;
19 # This means the file is being created.
20 # Use defined() here because the offset should always be 0. -RobK. 2008-06-20
21 unless ( $e->storage->size ) {
22 my $nt = $e->num_txns;
23 my $bl = $e->txn_bitfield_len;
25 my $header_var = $self->header_var_size;
27 $self->{offset} = $e->storage->request_space( $header_fixed + $header_var );
28 DBM::Deep::_throw_error( "Offset wasn't 0, it's '$self->{offset}'" ) unless $self->offset == 0;
30 $self->write( $self->offset,
33 . pack('N', $this_file_version) # At this point, we're at 9 bytes
34 . pack('N', $header_var) # header size
35 # --- Above is $header_fixed. Below is $header_var
36 . pack('C', $e->byte_size)
38 # These shenanigans are to allow a 256 within a C
39 . pack('C', $e->max_buckets - 1)
40 . pack('C', $e->data_sector_size - 1)
43 . pack('C' . $bl, 0 ) # Transaction activeness bitfield
44 . pack($e->StP($DBM::Deep::Engine::STALE_SIZE).($nt-1), 0 x ($nt-1) ) # Transaction staleness counters
45 . pack($e->StP($e->byte_size), 0) # Start of free chain (blist size)
46 . pack($e->StP($e->byte_size), 0) # Start of free chain (data size)
47 . pack($e->StP($e->byte_size), 0) # Start of free chain (index size)
50 $e->set_trans_loc( $header_fixed + 4 );
51 $e->set_chains_loc( $header_fixed + 4 + $bl + $DBM::Deep::Engine::STALE_SIZE * ($nt-1) );
60 my $buffer = $s->read_at( $self->offset, $header_fixed );
61 return unless length($buffer);
63 my ($file_signature, $sig_header, $file_version, $size) = unpack(
67 unless ( $file_signature eq $e->SIG_FILE ) {
69 DBM::Deep->_throw_error( "Signature not found -- file is not a Deep DB" );
72 unless ( $sig_header eq $e->SIG_HEADER ) {
74 DBM::Deep->_throw_error( "Pre-1.00 file version found" );
77 unless ( $file_version == $this_file_version ) {
79 DBM::Deep->_throw_error(
80 "Wrong file version found - " . $file_version .
81 " - expected " . $this_file_version
85 my $buffer2 = $s->read_at( undef, $size );
86 my @values = unpack( 'C C C C', $buffer2 );
88 if ( @values != 4 || grep { !defined } @values ) {
90 DBM::Deep->_throw_error("Corrupted file - bad header");
93 #XXX Add warnings if values weren't set right
94 @{$e}{qw(byte_size max_buckets data_sector_size num_txns)} = @values;
96 # These shenangians are to allow a 256 within a C
97 $e->{max_buckets} += 1;
98 $e->{data_sector_size} += 1;
100 my $header_var = $self->header_var_size;
101 unless ( $size == $header_var ) {
103 DBM::Deep->_throw_error( "Unexpected size found ($size <-> $header_var)." );
106 $e->set_trans_loc( $header_fixed + scalar(@values) );
108 my $bl = $e->txn_bitfield_len;
109 $e->set_chains_loc( $header_fixed + scalar(@values) + $bl + $DBM::Deep::Engine::STALE_SIZE * ($e->num_txns - 1) );
115 sub header_var_size {
117 my $e = $self->engine;
118 return 1 + 1 + 1 + 1 + $e->txn_bitfield_len + $DBM::Deep::Engine::STALE_SIZE * ($e->num_txns - 1) + 3 * $e->byte_size;
123 $self->{size} ||= $header_fixed + $self->header_var_size;
125 sub is_new { $_[0]{is_new} }