1 package DBM::Deep::Storage::File;
6 use warnings FATAL => 'all';
8 use Fcntl qw( :DEFAULT :flock :seek );
10 use constant DEBUG => 0;
12 use base 'DBM::Deep::Storage';
16 DBM::Deep::Storage::File
20 This is an internal-use-only object for L<DBM::Deep>. It mediates the low-level
21 interaction with the storage mechanism.
23 Currently, the only storage mechanism supported is the file system.
27 This class provides an abstraction to the storage mechanism so that the Engine
28 (the only class that uses this class) doesn't have to worry about that.
49 #XXX Migrate this to the engine, where it really belongs.
50 filter_store_key => undef,
51 filter_store_value => undef,
52 filter_fetch_key => undef,
53 filter_fetch_value => undef,
56 # Grab the parameters we want to use
57 foreach my $param ( keys %$self ) {
58 next unless exists $args->{$param};
59 $self->{$param} = $args->{$param};
62 if ( $self->{fh} && !$self->{file_offset} ) {
63 $self->{file_offset} = tell( $self->{fh} );
66 $self->open unless $self->{fh};
73 This method opens the filehandle for the filename in C< file >.
75 There is no return value.
79 # TODO: What happens if we ->open when we already have a $fh?
83 # Adding O_BINARY should remove the need for the binmode below. However,
84 # I'm not going to remove it because I don't have the Win32 chops to be
85 # absolutely certain everything will be ok.
86 my $flags = O_CREAT | O_BINARY;
88 if ( !-e $self->{file} || -w _ ) {
96 sysopen( $fh, $self->{file}, $flags )
97 or die "DBM::Deep: Cannot sysopen file '$self->{file}': $!\n";
100 # Even though we use O_BINARY, better be safe than sorry.
103 if ($self->{autoflush}) {
104 my $old = select $fh;
114 If the filehandle is opened, this will close it.
116 There is no return value.
133 This will return the size of the DB. If file_offset is set, this will take that into account.
140 return 0 unless $self->{fh};
141 return( (-s $self->{fh}) - $self->{file_offset} );
146 This will set the inode value of the underlying file object.
148 This is only needed to handle some obscure Win32 bugs. It reqlly shouldn't be
149 needed outside this object.
151 There is no return value.
158 unless ( defined $self->{inode} ) {
159 my @stats = stat($self->{fh});
160 $self->{inode} = $stats[1];
161 $self->{end} = $stats[7];
167 =head2 print_at( $offset, @data )
169 This takes an optional offset and some data to print.
171 C< $offset >, if defined, will be used to seek into the file. If file_offset is
172 set, it will be used as the zero location. If it is undefined, no seeking will
173 occur. Then, C< @data > will be printed to the current location.
175 There is no return value.
185 my $fh = $self->{fh};
186 if ( defined $loc ) {
187 seek( $fh, $loc + $self->{file_offset}, SEEK_SET );
191 my $caller = join ':', (caller)[0,2];
192 my $len = length( join '', @_ );
193 warn "($caller) print_at( " . (defined $loc ? $loc : '<undef>') . ", $len )\n";
196 print( $fh @_ ) or die "Internal Error (print_at($loc)): $!\n";
201 =head2 read_at( $offset, $length )
203 This takes an optional offset and a length.
205 C< $offset >, if defined, will be used to seek into the file. If file_offset is
206 set, it will be used as the zero location. If it is undefined, no seeking will
207 occur. Then, C< $length > bytes will be read from the current location.
209 The data read will be returned.
215 my ($loc, $size) = @_;
217 my $fh = $self->{fh};
218 if ( defined $loc ) {
219 seek( $fh, $loc + $self->{file_offset}, SEEK_SET );
223 my $caller = join ':', (caller)[0,2];
224 warn "($caller) read_at( " . (defined $loc ? $loc : '<undef>') . ", $size )\n";
228 read( $fh, $buffer, $size);
235 When the ::Storage::File object goes out of scope, it will be closed.
248 =head2 request_space( $size )
250 This takes a size and adds that much space to the DBM.
252 This returns the offset for the new location.
260 #XXX Do I need to reset $self->{end} here? I need a testcase
261 my $loc = $self->{end};
262 $self->{end} += $size;
267 =head2 copy_stats( $target_filename )
269 This will take the stats for the current filehandle and apply them to
270 C< $target_filename >. The stats copied are:
274 =item * Onwer UID and GID
284 my ($temp_filename) = @_;
286 my @stats = stat( $self->{fh} );
287 my $perms = $stats[2] & 07777;
290 chown( $uid, $gid, $temp_filename );
291 chmod( $perms, $temp_filename );
297 # Flush the filehandle
298 my $old_fh = select $self->{fh};
299 my $old_af = $|; $| = 1; $| = $old_af;
308 my $fh = $self->{fh};
309 return unless defined $fh;
310 return unless defined fileno $fh;
311 local $\ = ''; # just in case
312 no warnings; # temporarily disable warnings
313 local $^W; # temporarily disable warnings
320 return $self->_lock( $obj, LOCK_EX );
326 return $self->_lock( $obj, LOCK_SH );
331 my ($obj, $type) = @_;
333 $type = LOCK_EX unless defined $type;
335 #XXX This is a temporary fix for Win32 and autovivification. It
336 # needs to improve somehow. -RobK, 2008-03-09
337 if ( $^O eq 'MSWin32' || $^O eq 'cygwin' ) {
341 if (!defined($self->{fh})) { return; }
343 #XXX This either needs to allow for upgrading a shared lock to an
344 # exclusive lock or something else with autovivification.
346 if ($self->{locking}) {
347 if (!$self->{locked}) {
348 flock($self->{fh}, $type);
350 # refresh end counter in case file has changed size
351 my @stats = stat($self->{fh});
352 $self->{end} = $stats[7];
354 # double-check file inode, in case another process
355 # has optimize()d our file while we were waiting.
356 if (defined($self->{inode}) && $stats[1] != $self->{inode}) {
361 $obj->{engine}->setup( $obj );
363 flock($self->{fh}, $type); # re-lock
365 # This may not be necessary after re-opening
366 $self->{end} = (stat($self->{fh}))[7]; # re-end
380 if (!defined($self->{fh})) { return; }
382 if ($self->{locking} && $self->{locked} > 0) {
385 if (!$self->{locked}) {
386 flock($self->{fh}, LOCK_UN);