use Fcntl qw( :DEFAULT :flock :seek );
use Digest::MD5 ();
+use FileHandle::Fmode ();
use Scalar::Util ();
use DBM::Deep::Engine;
die "DBM::Deep: $_[1]\n";
}
-sub _is_writable {
- my $fh = shift;
- (O_WRONLY | O_RDWR) & fcntl( $fh, F_GETFL, my $slush = 0);
-}
-
-#sub _is_readable {
-# my $fh = shift;
-# (O_RDONLY | O_RDWR) & fcntl( $fh, F_GETFL, my $slush = 0);
-#}
-
sub _find_parent {
my $self = shift;
my ($key, $value, $orig_key) = @_;
- if ( $^O ne 'MSWin32' && !_is_writable( $self->_fh ) ) {
+ if ( !FileHandle::Fmode::is_W( $self->_fh ) ) {
$self->_throw_error( 'Cannot write to a readonly filehandle' );
}
my $self = shift->_get_self;
my ($key, $orig_key) = @_;
- if ( $^O ne 'MSWin32' && !_is_writable( $self->_fh ) ) {
+ if ( !FileHandle::Fmode::is_W( $self->_fh ) ) {
$self->_throw_error( 'Cannot write to a readonly filehandle' );
}
##
my $self = shift->_get_self;
- if ( $^O ne 'MSWin32' && !_is_writable( $self->_fh ) ) {
+ if ( !FileHandle::Fmode::is_W( $self->_fh ) ) {
$self->_throw_error( 'Cannot write to a readonly filehandle' );
}
The recommended way to construct a DBM::Deep object is to use the new()
method, which gets you a blessed I<and> tied hash (or array) reference.
- my $db = DBM::Deep->new( "foo.db" );
+ my $db = DBM::Deep->new( "foo.db" );
This opens a new database handle, mapped to the file "foo.db". If this
file does not exist, it will automatically be created. DB files are
You can pass a number of options to the constructor to specify things like
locking, autoflush, etc. This is done by passing an inline hash (or hashref):
- my $db = DBM::Deep->new(
- file => "foo.db",
- locking => 1,
- autoflush => 1
- );
+ my $db = DBM::Deep->new(
+ file => "foo.db",
+ locking => 1,
+ autoflush => 1
+ );
Notice that the filename is now specified I<inside> the hash with
the "file" parameter, as opposed to being the sole argument to the
You can also start with an array instead of a hash. For this, you must
specify the C<type> parameter:
- my $db = DBM::Deep->new(
- file => "foo.db",
- type => DBM::Deep->TYPE_ARRAY
- );
+ my $db = DBM::Deep->new(
+ file => "foo.db",
+ type => DBM::Deep->TYPE_ARRAY
+ );
B<Note:> Specifing the C<type> parameter only takes effect when beginning
a new DB file. If you create a DBM::Deep object with an existing file, the
such as lock() and unlock(). (That object can be retrieved from the tied
variable at any time using tied() - please see L<perltie/> for more info.
- my %hash;
- my $db = tie %hash, "DBM::Deep", "foo.db";
+ my %hash;
+ my $db = tie %hash, "DBM::Deep", "foo.db";
- my @array;
- my $db = tie @array, "DBM::Deep", "bar.db";
+ my @array;
+ my $db = tie @array, "DBM::Deep", "bar.db";
As with the OO constructor, you can replace the DB filename parameter with
a hash containing one or more options (see L<OPTIONS> just below for the
complete list).
- tie %hash, "DBM::Deep", {
- file => "foo.db",
- locking => 1,
- autoflush => 1
- };
+ tie %hash, "DBM::Deep", {
+ file => "foo.db",
+ locking => 1,
+ autoflush => 1
+ };
=head2 OPTIONS
You can treat any DBM::Deep object like a normal Perl hash reference. Add keys,
or even nested hashes (or arrays) using standard Perl syntax:
- my $db = DBM::Deep->new( "foo.db" );
+ my $db = DBM::Deep->new( "foo.db" );
- $db->{mykey} = "myvalue";
- $db->{myhash} = {};
- $db->{myhash}->{subkey} = "subvalue";
+ $db->{mykey} = "myvalue";
+ $db->{myhash} = {};
+ $db->{myhash}->{subkey} = "subvalue";
- print $db->{myhash}->{subkey} . "\n";
+ print $db->{myhash}->{subkey} . "\n";
You can even step through hash keys using the normal Perl C<keys()> function:
- foreach my $key (keys %$db) {
- print "$key: " . $db->{$key} . "\n";
- }
+ foreach my $key (keys %$db) {
+ print "$key: " . $db->{$key} . "\n";
+ }
Remember that Perl's C<keys()> function extracts I<every> key from the hash and
pushes them onto an array, all before the loop even begins. If you have an
Perl's C<each()> function, which pulls keys/values one at a time, using very
little memory:
- while (my ($key, $value) = each %$db) {
- print "$key: $value\n";
- }
+ while (my ($key, $value) = each %$db) {
+ print "$key: $value\n";
+ }
Please note that when using C<each()>, you should always pass a direct
hash reference, not a lookup. Meaning, you should B<never> do this:
- # NEVER DO THIS
- while (my ($key, $value) = each %{$db->{foo}}) { # BAD
+ # NEVER DO THIS
+ while (my ($key, $value) = each %{$db->{foo}}) { # BAD
This causes an infinite loop, because for each iteration, Perl is calling
FETCH() on the $db handle, resulting in a "new" hash for foo every time, so
The object must have first been created using type C<DBM::Deep-E<gt>TYPE_ARRAY>,
or simply be a nested array reference inside a hash. Example:
- my $db = DBM::Deep->new(
- file => "foo-array.db",
- type => DBM::Deep->TYPE_ARRAY
- );
+ my $db = DBM::Deep->new(
+ file => "foo-array.db",
+ type => DBM::Deep->TYPE_ARRAY
+ );
- $db->[0] = "foo";
- push @$db, "bar", "baz";
- unshift @$db, "bah";
+ $db->[0] = "foo";
+ push @$db, "bar", "baz";
+ unshift @$db, "bah";
- my $last_elem = pop @$db; # baz
- my $first_elem = shift @$db; # bah
- my $second_elem = $db->[1]; # bar
+ my $last_elem = pop @$db; # baz
+ my $first_elem = shift @$db; # bah
+ my $second_elem = $db->[1]; # bar
- my $num_elements = scalar @$db;
+ my $num_elements = scalar @$db;
=head1 OO INTERFACE
arguments, the hash key or array index, and the new value. The value can be
a scalar, hash ref or array ref. Returns true on success, false on failure.
- $db->put("foo", "bar"); # for hashes
- $db->put(1, "bar"); # for arrays
+ $db->put("foo", "bar"); # for hashes
+ $db->put(1, "bar"); # for arrays
=item * get() / fetch()
key or array index. Returns a scalar, hash ref or array ref, depending on the
data type stored.
- my $value = $db->get("foo"); # for hashes
- my $value = $db->get(1); # for arrays
+ my $value = $db->get("foo"); # for hashes
+ my $value = $db->get(1); # for arrays
=item * exists()
Checks if a hash key or array index exists. Takes one argument: the hash key
or array index. Returns true if it exists, false if not.
- if ($db->exists("foo")) { print "yay!\n"; } # for hashes
- if ($db->exists(1)) { print "yay!\n"; } # for arrays
+ if ($db->exists("foo")) { print "yay!\n"; } # for hashes
+ if ($db->exists(1)) { print "yay!\n"; } # for arrays
=item * delete()
key/value or element is B<not> reused again -- see L<UNUSED SPACE RECOVERY>
below for details and workarounds.
- $db->delete("foo"); # for hashes
- $db->delete(1); # for arrays
+ $db->delete("foo"); # for hashes
+ $db->delete(1); # for arrays
=item * clear()
elements is B<not> reused again -- see L<UNUSED SPACE RECOVERY> below for
details and workarounds.
- $db->clear(); # hashes or arrays
+ $db->clear(); # hashes or arrays
=item * lock() / unlock()
fetched in an undefined order (which appears random). Takes no arguments,
returns the key as a scalar value.
- my $key = $db->first_key();
+ my $key = $db->first_key();
=item * next_key()
Returns the "next" key in the hash, given the previous one as the sole argument.
Returns undef if there are no more keys to be fetched.
- $key = $db->next_key($key);
+ $key = $db->next_key($key);
=back
Here are some examples of using hashes:
- my $db = DBM::Deep->new( "foo.db" );
+ my $db = DBM::Deep->new( "foo.db" );
- $db->put("foo", "bar");
- print "foo: " . $db->get("foo") . "\n";
+ $db->put("foo", "bar");
+ print "foo: " . $db->get("foo") . "\n";
- $db->put("baz", {}); # new child hash ref
- $db->get("baz")->put("buz", "biz");
- print "buz: " . $db->get("baz")->get("buz") . "\n";
+ $db->put("baz", {}); # new child hash ref
+ $db->get("baz")->put("buz", "biz");
+ print "buz: " . $db->get("baz")->get("buz") . "\n";
- my $key = $db->first_key();
- while ($key) {
- print "$key: " . $db->get($key) . "\n";
- $key = $db->next_key($key);
- }
+ my $key = $db->first_key();
+ while ($key) {
+ print "$key: " . $db->get($key) . "\n";
+ $key = $db->next_key($key);
+ }
- if ($db->exists("foo")) { $db->delete("foo"); }
+ if ($db->exists("foo")) { $db->delete("foo"); }
=head2 ARRAYS
Returns the number of elements in the array. Takes no arguments.
- my $len = $db->length();
+ my $len = $db->length();
=item * push()
Adds one or more elements onto the end of the array. Accepts scalars, hash
refs or array refs. No return value.
- $db->push("foo", "bar", {});
+ $db->push("foo", "bar", {});
=item * pop()
Fetches the last element in the array, and deletes it. Takes no arguments.
Returns undef if array is empty. Returns the element value.
- my $elem = $db->pop();
+ my $elem = $db->pop();
=item * shift()
method is not recommended with large arrays -- see L<LARGE ARRAYS> below for
details.
- my $elem = $db->shift();
+ my $elem = $db->shift();
=item * unshift()
No return value. This method is not recommended with large arrays -- see
<LARGE ARRAYS> below for details.
- $db->unshift("foo", "bar", {});
+ $db->unshift("foo", "bar", {});
=item * splice()
Here are some examples of using arrays:
- my $db = DBM::Deep->new(
- file => "foo.db",
- type => DBM::Deep->TYPE_ARRAY
- );
+ my $db = DBM::Deep->new(
+ file => "foo.db",
+ type => DBM::Deep->TYPE_ARRAY
+ );
- $db->push("bar", "baz");
- $db->unshift("foo");
- $db->put(3, "buz");
+ $db->push("bar", "baz");
+ $db->unshift("foo");
+ $db->put(3, "buz");
- my $len = $db->length();
- print "length: $len\n"; # 4
+ my $len = $db->length();
+ print "length: $len\n"; # 4
- for (my $k=0; $k<$len; $k++) {
- print "$k: " . $db->get($k) . "\n";
- }
+ for (my $k=0; $k<$len; $k++) {
+ print "$k: " . $db->get($k) . "\n";
+ }
- $db->splice(1, 2, "biz", "baf");
+ $db->splice(1, 2, "biz", "baf");
- while (my $elem = shift @$db) {
- print "shifted: $elem\n";
- }
+ while (my $elem = shift @$db) {
+ print "shifted: $elem\n";
+ }
=head1 LOCKING
Enable automatic file locking by passing a true value to the C<locking>
parameter when constructing your DBM::Deep object (see L<SETUP> above).
- my $db = DBM::Deep->new(
- file => "foo.db",
- locking => 1
- );
+ my $db = DBM::Deep->new(
+ file => "foo.db",
+ locking => 1
+ );
This causes DBM::Deep to C<flock()> the underlying filehandle with exclusive
mode for writes, and shared mode for reads. This is required if you have
useful for things like counters, where the current value needs to be fetched,
then incremented, then stored again.
- $db->lock();
- my $counter = $db->get("counter");
- $counter++;
- $db->put("counter", $counter);
- $db->unlock();
+ $db->lock();
+ my $counter = $db->get("counter");
+ $counter++;
+ $db->put("counter", $counter);
+ $db->unlock();
- # or...
+ # or...
- $db->lock();
- $db->{counter}++;
- $db->unlock();
+ $db->lock();
+ $db->{counter}++;
+ $db->unlock();
You can pass C<lock()> an optional argument, which specifies which mode to use
(exclusive or shared). Use one of these two constants:
directly to C<flock()>, and are the same as the constants defined in Perl's
L<Fcntl/> module.
- $db->lock( $db->LOCK_SH );
- # something here
- $db->unlock();
+ $db->lock( $db->LOCK_SH );
+ # something here
+ $db->unlock();
=head1 IMPORTING/EXPORTING
simply pass a reference to the C<import()> method. This recursively adds
everything to an existing DBM::Deep object for you. Here is an example:
- my $struct = {
- key1 => "value1",
- key2 => "value2",
- array1 => [ "elem0", "elem1", "elem2" ],
- hash1 => {
- subkey1 => "subvalue1",
- subkey2 => "subvalue2"
- }
- };
+ my $struct = {
+ key1 => "value1",
+ key2 => "value2",
+ array1 => [ "elem0", "elem1", "elem2" ],
+ hash1 => {
+ subkey1 => "subvalue1",
+ subkey2 => "subvalue2"
+ }
+ };
- my $db = DBM::Deep->new( "foo.db" );
- $db->import( $struct );
+ my $db = DBM::Deep->new( "foo.db" );
+ $db->import( $struct );
- print $db->{key1} . "\n"; # prints "value1"
+ print $db->{key1} . "\n"; # prints "value1"
This recursively imports the entire C<$struct> object into C<$db>, including
all nested hashes and arrays. If the DBM::Deep object contains exsiting data,
recursively, so all nested hashes/arrays are all exported to standard Perl
objects. Here is an example:
- my $db = DBM::Deep->new( "foo.db" );
+ my $db = DBM::Deep->new( "foo.db" );
- $db->{key1} = "value1";
- $db->{key2} = "value2";
- $db->{hash1} = {};
- $db->{hash1}->{subkey1} = "subvalue1";
- $db->{hash1}->{subkey2} = "subvalue2";
+ $db->{key1} = "value1";
+ $db->{key2} = "value2";
+ $db->{hash1} = {};
+ $db->{hash1}->{subkey1} = "subvalue1";
+ $db->{hash1}->{subkey2} = "subvalue2";
- my $struct = $db->export();
+ my $struct = $db->export();
- print $struct->{key1} . "\n"; # prints "value1"
+ print $struct->{key1} . "\n"; # prints "value1"
This makes a complete copy of the database in memory, and returns a reference
to it. The C<export()> method can be called on any database level (not just
Here are the two ways to setup a filter hook:
- my $db = DBM::Deep->new(
- file => "foo.db",
- filter_store_value => \&my_filter_store,
- filter_fetch_value => \&my_filter_fetch
- );
+ my $db = DBM::Deep->new(
+ file => "foo.db",
+ filter_store_value => \&my_filter_store,
+ filter_fetch_value => \&my_filter_fetch
+ );
- # or...
+ # or...
- $db->set_filter( "filter_store_value", \&my_filter_store );
- $db->set_filter( "filter_fetch_value", \&my_filter_fetch );
+ $db->set_filter( "filter_store_value", \&my_filter_store );
+ $db->set_filter( "filter_fetch_value", \&my_filter_fetch );
Your filter function will be called only when dealing with SCALAR keys or
values. When nested hashes and arrays are being stored/fetched, filtering
argument, and expected to return a single SCALAR value. If you want to
remove a filter, set the function reference to C<undef>:
- $db->set_filter( "filter_store_value", undef );
+ $db->set_filter( "filter_store_value", undef );
=head2 REAL-TIME ENCRYPTION EXAMPLE
Please visit L<http://search.cpan.org/search?module=Crypt::Blowfish> for more
on I<Crypt::Blowfish>. You'll also need the I<Crypt::CBC> module.
- use DBM::Deep;
- use Crypt::Blowfish;
- use Crypt::CBC;
-
- my $cipher = Crypt::CBC->new({
- 'key' => 'my secret key',
- 'cipher' => 'Blowfish',
- 'iv' => '$KJh#(}q',
- 'regenerate_key' => 0,
- 'padding' => 'space',
- 'prepend_iv' => 0
- });
-
- my $db = DBM::Deep->new(
- file => "foo-encrypt.db",
- filter_store_key => \&my_encrypt,
- filter_store_value => \&my_encrypt,
- filter_fetch_key => \&my_decrypt,
- filter_fetch_value => \&my_decrypt,
- );
-
- $db->{key1} = "value1";
- $db->{key2} = "value2";
- print "key1: " . $db->{key1} . "\n";
- print "key2: " . $db->{key2} . "\n";
-
- undef $db;
- exit;
-
- sub my_encrypt {
- return $cipher->encrypt( $_[0] );
- }
- sub my_decrypt {
- return $cipher->decrypt( $_[0] );
- }
+ use DBM::Deep;
+ use Crypt::Blowfish;
+ use Crypt::CBC;
+
+ my $cipher = Crypt::CBC->new({
+ 'key' => 'my secret key',
+ 'cipher' => 'Blowfish',
+ 'iv' => '$KJh#(}q',
+ 'regenerate_key' => 0,
+ 'padding' => 'space',
+ 'prepend_iv' => 0
+ });
+
+ my $db = DBM::Deep->new(
+ file => "foo-encrypt.db",
+ filter_store_key => \&my_encrypt,
+ filter_store_value => \&my_encrypt,
+ filter_fetch_key => \&my_decrypt,
+ filter_fetch_value => \&my_decrypt,
+ );
+
+ $db->{key1} = "value1";
+ $db->{key2} = "value2";
+ print "key1: " . $db->{key1} . "\n";
+ print "key2: " . $db->{key2} . "\n";
+
+ undef $db;
+ exit;
+
+ sub my_encrypt {
+ return $cipher->encrypt( $_[0] );
+ }
+ sub my_decrypt {
+ return $cipher->decrypt( $_[0] );
+ }
=head2 REAL-TIME COMPRESSION EXAMPLE
Please visit L<http://search.cpan.org/search?module=Compress::Zlib> for
more on I<Compress::Zlib>.
- use DBM::Deep;
- use Compress::Zlib;
-
- my $db = DBM::Deep->new(
- file => "foo-compress.db",
- filter_store_key => \&my_compress,
- filter_store_value => \&my_compress,
- filter_fetch_key => \&my_decompress,
- filter_fetch_value => \&my_decompress,
- );
-
- $db->{key1} = "value1";
- $db->{key2} = "value2";
- print "key1: " . $db->{key1} . "\n";
- print "key2: " . $db->{key2} . "\n";
-
- undef $db;
- exit;
-
- sub my_compress {
- return Compress::Zlib::memGzip( $_[0] ) ;
- }
- sub my_decompress {
- return Compress::Zlib::memGunzip( $_[0] ) ;
- }
+ use DBM::Deep;
+ use Compress::Zlib;
+
+ my $db = DBM::Deep->new(
+ file => "foo-compress.db",
+ filter_store_key => \&my_compress,
+ filter_store_value => \&my_compress,
+ filter_fetch_key => \&my_decompress,
+ filter_fetch_value => \&my_decompress,
+ );
+
+ $db->{key1} = "value1";
+ $db->{key2} = "value2";
+ print "key1: " . $db->{key1} . "\n";
+ print "key2: " . $db->{key2} . "\n";
+
+ undef $db;
+ exit;
+
+ sub my_compress {
+ return Compress::Zlib::memGzip( $_[0] ) ;
+ }
+ sub my_decompress {
+ return Compress::Zlib::memGunzip( $_[0] ) ;
+ }
B<Note:> Filtering of keys only applies to hashes. Array "keys" are
actually numerical index numbers, and are not filtered.
Most DBM::Deep methods return a true value for success, and call die() on
failure. You can wrap calls in an eval block to catch the die.
- my $db = DBM::Deep->new( "foo.db" ); # create hash
- eval { $db->push("foo"); }; # ILLEGAL -- push is array-only call
+ my $db = DBM::Deep->new( "foo.db" ); # create hash
+ eval { $db->push("foo"); }; # ILLEGAL -- push is array-only call
- print $@; # prints error message
+ print $@; # prints error message
=head1 LARGEFILE SUPPORT
DBM::Deep by default uses 32-bit file offset tags, but these can be changed
by specifying the 'pack_size' parameter when constructing the file.
- DBM::Deep->new(
- filename => $filename,
- pack_size => 'large',
- );
+ DBM::Deep->new(
+ filename => $filename,
+ pack_size => 'large',
+ );
This tells DBM::Deep to pack all file offsets with 8-byte (64-bit) quad words
instead of 32-bit longs. After setting these values your DB files have a
If you require low-level access to the underlying filehandle that DBM::Deep uses,
you can call the C<_fh()> method, which returns the handle:
- my $fh = $db->_fh();
+ my $fh = $db->_fh();
This method can be called on the root level of the datbase, or any child
hashes or arrays. All levels share a I<root> structure, which contains things
when you created the object. You can get access to this file object by
calling the C<_fileobj()> method.
- my $file_obj = $db->_fileobj();
+ my $file_obj = $db->_fileobj();
This is useful for changing options after the object has already been created,
such as enabling/disabling locking. You can also store your own temporary user
I<Digest::SHA256> module. Please see
L<http://search.cpan.org/search?module=Digest::SHA256> for more information.
- use DBM::Deep;
- use Digest::SHA256;
+ use DBM::Deep;
+ use Digest::SHA256;
- my $context = Digest::SHA256::new(256);
+ my $context = Digest::SHA256::new(256);
- my $db = DBM::Deep->new(
- filename => "foo-sha.db",
- digest => \&my_digest,
- hash_size => 32,
- );
+ my $db = DBM::Deep->new(
+ filename => "foo-sha.db",
+ digest => \&my_digest,
+ hash_size => 32,
+ );
- $db->{key1} = "value1";
- $db->{key2} = "value2";
- print "key1: " . $db->{key1} . "\n";
- print "key2: " . $db->{key2} . "\n";
+ $db->{key1} = "value1";
+ $db->{key2} = "value2";
+ print "key1: " . $db->{key1} . "\n";
+ print "key2: " . $db->{key2} . "\n";
- undef $db;
- exit;
+ undef $db;
+ exit;
- sub my_digest {
- return substr( $context->hash($_[0]), 0, 32 );
- }
+ sub my_digest {
+ return substr( $context->hash($_[0]), 0, 32 );
+ }
B<Note:> Your returned digest strings must be B<EXACTLY> the number
of bytes you specify in the hash_size parameter (in this case 32).
This relationship is stored in the DB file, and is preserved between sessions.
Here is an example:
- my $db = DBM::Deep->new( "foo.db" );
+ my $db = DBM::Deep->new( "foo.db" );
- $db->{foo} = "bar";
- $db->{circle} = $db; # ref to self
+ $db->{foo} = "bar";
+ $db->{circle} = $db; # ref to self
- print $db->{foo} . "\n"; # prints "bar"
- print $db->{circle}->{foo} . "\n"; # prints "bar" again
+ print $db->{foo} . "\n"; # prints "bar"
+ print $db->{circle}->{foo} . "\n"; # prints "bar" again
B<Note>: Passing the object to a function that recursively walks the
object tree (such as I<Data::Dumper> or even the built-in C<optimize()> or
but in the meantime you can call the built-in C<optimize()> method from time to
time (perhaps in a crontab or something) to recover all your unused space.
- $db->optimize(); # returns true on success
+ $db->optimize(); # returns true on success
This rebuilds the ENTIRE database into a new file, then moves it on top of
the original. The new file will have no unused space, thus it will take up as
Instead, use DBM::Deep's C<clone()> method which safely copies the object and
returns a new, blessed, tied hash or array to the same level in the DB.
- my $copy = $db->clone();
+ my $copy = $db->clone();
B<Note>: Since clone() here is cloning the object, not the database location, any
modifications to either $db or $copy will be visible to both.
projects / dbsrgits/DBM-Deep.git / commitdiff