use strict;
use warnings FATAL => 'all';
+our $VERSION = $DBM::Deep::VERSION;
+
use DBM::Deep::Iterator ();
# File-wide notes:
# mutex. But, it's the caller's responsability to make sure that this has
# been done.
-# Setup file and tag signatures. These should never change.
-sub SIG_FILE () { 'DPDB' }
-sub SIG_HEADER () { 'h' }
-sub SIG_HASH () { 'H' }
-sub SIG_ARRAY () { 'A' }
-sub SIG_NULL () { 'N' }
-sub SIG_DATA () { 'D' }
-sub SIG_INDEX () { 'I' }
-sub SIG_BLIST () { 'B' }
-sub SIG_FREE () { 'F' }
-sub SIG_SIZE () { 1 }
+sub SIG_HASH () { 'H' }
+sub SIG_ARRAY () { 'A' }
=head1 NAME
=head1 PURPOSE
-This is an internal-use-only object for L<DBM::Deep/>. It mediates the low-level
-mapping between the L<DBM::Deep/> objects and the storage medium.
+This is an internal-use-only object for L<DBM::Deep>. It mediates the low-level
+mapping between the L<DBM::Deep> objects and the storage medium.
The purpose of this documentation is to provide low-level documentation for
developers. It is B<not> intended to be used by the general public. This
=item * get_next_key
-=item * setup_fh
+=item * setup
=item * begin_work
=cut
+=head2 read_value( $obj, $key )
+
+This takes an object that provides _base_offset() and a string. It returns the
+value stored in the corresponding Sector::Value's data section.
+
+=cut
+
+sub read_value { die "read_value must be implemented in a child class" }
+
+=head2 get_classname( $obj )
+
+This takes an object that provides _base_offset() and returns the classname (if
+any) associated with it.
+
+It delegates to Sector::Reference::get_classname() for the heavy lifting.
+
+It performs a staleness check.
+
+=cut
+
+sub get_classname { die "get_classname must be implemented in a child class" }
+
+=head2 make_reference( $obj, $old_key, $new_key )
+
+This takes an object that provides _base_offset() and two strings. The
+strings correspond to the old key and new key, respectively. This operation
+is equivalent to (given C<< $db->{foo} = []; >>) C<< $db->{bar} = $db->{foo} >>.
+
+This returns nothing.
+
+=cut
+
+sub make_reference { die "make_reference must be implemented in a child class" }
+
+=head2 key_exists( $obj, $key )
+
+This takes an object that provides _base_offset() and a string for
+the key to be checked. This returns 1 for true and "" for false.
+
+=cut
+
+sub key_exists { die "key_exists must be implemented in a child class" }
+
+=head2 delete_key( $obj, $key )
+
+This takes an object that provides _base_offset() and a string for
+the key to be deleted. This returns the result of the Sector::Reference
+delete_key() method.
+
+=cut
+
+sub delete_key { die "delete_key must be implemented in a child class" }
+
+=head2 write_value( $obj, $key, $value )
+
+This takes an object that provides _base_offset(), a string for the
+key, and a value. This value can be anything storable within L<DBM::Deep>.
+
+This returns 1 upon success.
+
+=cut
+
+sub write_value { die "write_value must be implemented in a child class" }
+
+=head2 setup( $obj )
+
+This takes an object that provides _base_offset(). It will do everything needed
+in order to properly initialize all values for necessary functioning. If this is
+called upon an already initialized object, this will also reset the inode.
+
+This returns 1.
+
+=cut
+
+sub setup { die "setup must be implemented in a child class" }
+
+=head2 begin_work( $obj )
+
+This takes an object that provides _base_offset(). It will set up all necessary
+bookkeeping in order to run all work within a transaction.
+
+If $obj is already within a transaction, an error wiill be thrown. If there are
+no more available transactions, an error will be thrown.
+
+This returns undef.
+
+=cut
+
+sub begin_work { die "begin_work must be implemented in a child class" }
+
+=head2 rollback( $obj )
+
+This takes an object that provides _base_offset(). It will revert all
+actions taken within the running transaction.
+
+If $obj is not within a transaction, an error will be thrown.
+
+This returns 1.
+
+=cut
+sub rollback { die "rollback must be implemented in a child class" }
+
+=head2 commit( $obj )
+
+This takes an object that provides _base_offset(). It will apply all
+actions taken within the transaction to the HEAD.
+
+If $obj is not within a transaction, an error will be thrown.
+
+This returns 1.
+
+=cut
+
+sub commit { die "commit must be implemented in a child class" }
=head2 get_next_key( $obj, $prev_key )
my $self = shift;
my ($obj, $prev_key) = @_;
- # XXX Need to add logic about resetting the iterator if any key in the reference has changed
- unless ( $prev_key ) {
- $obj->{iterator} = DBM::Deep::Iterator->new({
+ # XXX Need to add logic about resetting the iterator if any key in the
+ # reference has changed
+ unless ( defined $prev_key ) {
+ $obj->{iterator} = $self->iterator_class->new({
base_offset => $obj->_base_offset,
engine => $self,
});
return $obj->{iterator}->get_next_key( $obj );
}
+=head2 lock_exclusive()
+
+This takes an object that provides _base_offset(). It will guarantee that
+the storage has taken precautions to be safe for a write.
+
+This returns nothing.
+
+=cut
+
+sub lock_exclusive {
+ my $self = shift;
+ my ($obj) = @_;
+ return $self->storage->lock_exclusive( $obj );
+}
+
+=head2 lock_shared()
+
+This takes an object that provides _base_offset(). It will guarantee that
+the storage has taken precautions to be safe for a read.
+
+This returns nothing.
+
+=cut
+
+sub lock_shared {
+ my $self = shift;
+ my ($obj) = @_;
+ return $self->storage->lock_shared( $obj );
+}
+
+=head2 unlock()
+
+This takes an object that provides _base_offset(). It will guarantee that
+the storage has released the most recently-taken lock.
+
+This returns nothing.
+
+=cut
+
+sub unlock {
+ my $self = shift;
+ my ($obj) = @_;
+
+ my $rv = $self->storage->unlock( $obj );
+
+ $self->flush if $rv;
+
+ return $rv;
+}
+
+=head1 INTERNAL METHODS
+
+The following methods are internal-use-only to DBM::Deep::Engine and its
+child classes.
+
+=cut
+
+=head2 flush()
+
+This takes no arguments. It will do everything necessary to flush all things to
+disk. This is usually called during unlock() and setup().
+
+This returns nothing.
+
+=cut
+
+sub flush {
+ my $self = shift;
+
+ # Why do we need to have the storage flush? Shouldn't autoflush take care of
+ # things? -RobK, 2008-06-26
+ $self->storage->flush;
+
+ return;
+}
+
+=head2 load_sector( $loc )
+
+This takes an id/location/offset and loads the sector based on the engine's
+defined sector type.
+
+=cut
+
+sub load_sector { $_[0]->sector_type->load( @_ ) }
+
+=head2 cache / clear_cache
+
+This is the cache of loaded Reference sectors.
+
+=cut
+
+sub cache { $_[0]{cache} ||= {} }
+sub clear_cache { %{$_[0]->cache} = () }
+
+=head2 supports( $option )
+
+This returns a boolean depending on if this instance of DBM::Dep supports
+that feature. C<$option> can be one of:
+
+=over 4
+
+=item * transactions
+
+=back
+
+=cut
+
+sub supports { die "supports must be implemented in a child class" }
+
+=head2 ACCESSORS
+
+The following are readonly attributes.
+
+=over 4
+
+=item * storage
+
+=item * sector_type
+
+=back
+
+=cut
+
+sub storage { $_[0]{storage} }
+
+sub sector_type { die "sector_type must be implemented in a child class" }
+
+# This code is to make sure we write all the values in the $value to the
+# disk and to make sure all changes to $value after the assignment are
+# reflected on disk. This may be counter-intuitive at first, but it is
+# correct dwimmery.
+# NOTE - simply tying $value won't perform a STORE on each value. Hence,
+# the copy to a temp value.
+sub _descend {
+ my $self = shift;
+ my ($value, $value_sector) = @_;
+ my $r = Scalar::Util::reftype( $value ) || '';
+
+ if ( $r eq 'ARRAY' ) {
+ my @temp = @$value;
+ tie @$value, 'DBM::Deep', {
+ base_offset => $value_sector->offset,
+ staleness => $value_sector->staleness,
+ storage => $self->storage,
+ engine => $self,
+ };
+ @$value = @temp;
+ bless $value, 'DBM::Deep::Array' unless Scalar::Util::blessed( $value );
+ }
+ elsif ( $r eq 'HASH' ) {
+ my %temp = %$value;
+ tie %$value, 'DBM::Deep', {
+ base_offset => $value_sector->offset,
+ staleness => $value_sector->staleness,
+ storage => $self->storage,
+ engine => $self,
+ };
+ %$value = %temp;
+ bless $value, 'DBM::Deep::Hash' unless Scalar::Util::blessed( $value );
+ }
+}
+
1;
__END__
projects / dbsrgits/DBM-Deep.git / blobdiff