use strict;
use warnings FATAL => 'all';
+no warnings 'recursion';
# Never import symbols into our namespace. We are a class, not a library.
# -RobK, 2008-05-27
sub SIG_FREE () { 'F' }
sub SIG_SIZE () { 1 }
+use DBM::Deep::Iterator ();
+use DBM::Deep::Engine::Sector::Data ();
+use DBM::Deep::Engine::Sector::BucketList ();
+use DBM::Deep::Engine::Sector::Index ();
+use DBM::Deep::Engine::Sector::Null ();
+use DBM::Deep::Engine::Sector::Reference ();
+use DBM::Deep::Engine::Sector::Scalar ();
+use DBM::Deep::Null ();
+
my $STALE_SIZE = 2;
# Please refer to the pack() documentation for further information
8 => 'Q', # Usigned quad (no order specified, presumably machine-dependent)
);
-################################################################################
+=head1 NAME
+
+DBM::Deep::Engine
+
+=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.
+
+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
+documentation and what it documents can and will change without notice.
+
+=head1 OVERVIEW
+
+The engine exposes an API to the DBM::Deep objects (DBM::Deep, DBM::Deep::Array,
+and DBM::Deep::Hash) for their use to access the actual stored values. This API
+is the following:
+
+=over 4
+
+=item * new
+
+=item * read_value
+
+=item * get_classname
+
+=item * make_reference
+
+=item * key_exists
+
+=item * delete_key
+
+=item * write_value
+
+=item * get_next_key
+
+=item * clear
+
+=item * setup_fh
+
+=item * begin_work
+
+=item * commit
+
+=item * rollback
+
+=item * lock_exclusive
+
+=item * lock_shared
+
+=item * unlock
+
+=back
+
+They are explained in their own sections below. These methods, in turn, may
+provide some bounds-checking, but primarily act to instantiate objects in the
+Engine::Sector::* hierarchy and dispatch to them.
+
+=head1 TRANSACTIONS
+
+Transactions in DBM::Deep are implemented using a variant of MVCC. This attempts
+to keep the amount of actual work done against the file low while stil providing
+Atomicity, Consistency, and Isolation. Durability, unfortunately, cannot be done
+with only one file.
+
+=head2 STALENESS
+
+If another process uses a transaction slot and writes stuff to it, then terminates,
+the data that process wrote it still within the file. In order to address this,
+there is also a transaction staleness counter associated within every write.
+Each time a transaction is started, that process increments that transaction's
+staleness counter. If, when it reads a value, the staleness counters aren't
+identical, DBM::Deep will consider the value on disk to be stale and discard it.
+
+=head2 DURABILITY
+
+The fourth leg of ACID is Durability, the guarantee that when a commit returns,
+the data will be there the next time you read from it. This should be regardless
+of any crashes or powerdowns in between the commit and subsequent read. DBM::Deep
+does provide that guarantee; once the commit returns, all of the data has been
+transferred from the transaction shadow to the HEAD. The issue arises with partial
+commits - a commit that is interrupted in some fashion. In keeping with DBM::Deep's
+"tradition" of very light error-checking and non-existent error-handling, there is
+no way to recover from a partial commit. (This is probably a failure in Consistency
+as well as Durability.)
+
+Other DBMSes use transaction logs (a separate file, generally) to achieve Durability.
+As DBM::Deep is a single-file, we would have to do something similar to what SQLite
+and BDB do in terms of committing using synchonized writes. To do this, we would have
+to use a much higher RAM footprint and some serious programming that make my head
+hurts just to think about it.
+
+=head1 EXTERNAL METHODS
+
+=head2 new()
+
+This takes a set of args. These args are described in the documentation for
+L<DBM::Deep/new>.
+
+=cut
sub new {
my $class = shift;
return $self;
}
-################################################################################
+=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 {
my $self = shift;
return $value_sector->data;
}
+=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 {
my $self = shift;
my ($obj) = @_;
return $sector->get_classname;
}
+=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 {
my $self = shift;
my ($obj, $old_key, $new_key) = @_;
# This will be a Reference sector
my $sector = $self->_load_sector( $obj->_base_offset )
- or DBM::Deep->_throw_error( "How did get_classname fail (no sector for '$obj')?!" );
+ or DBM::Deep->_throw_error( "How did make_reference fail (no sector for '$obj')?!" );
if ( $sector->staleness != $obj->_staleness ) {
return;
value => $value_sector->clone,
});
}
+
+ return;
}
+=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 {
my $self = shift;
my ($obj, $key) = @_;
return $data ? 1 : '';
}
+=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 {
my $self = shift;
my ($obj, $key) = @_;
});
}
+=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 {
my $self = shift;
my ($obj, $key, $value) = @_;
return 1;
}
+=head2 get_next_key( $obj, $prev_key )
+
+This takes an object that provides _base_offset() and an optional string
+representing the prior key returned via a prior invocation of this method.
+
+This method delegates to C<< DBM::Deep::Iterator->get_next_key() >>.
+
+=cut
+
# XXX Add staleness here
sub get_next_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 ) {
+ unless ( defined $prev_key ) {
$obj->{iterator} = DBM::Deep::Iterator->new({
base_offset => $obj->_base_offset,
engine => $self,
return $obj->{iterator}->get_next_key( $obj );
}
-################################################################################
+=head2 clear( $obj )
+
+This takes an object that provides _base_offset() and deletes all its
+elements, returning nothing.
+
+=cut
+
+sub clear {
+ my $self = shift;
+ my $obj = shift;
+
+ my $sector = $self->_load_sector( $obj->_base_offset )
+ or return;
+
+ if ( $sector->staleness != $obj->_staleness ) {
+ return;
+ }
+
+ $sector->clear;
+ return;
+}
+
+=head2 setup_fh( $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_fh {
my $self = shift;
return 1;
}
+=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 {
my $self = shift;
my ($obj) = @_;
return;
}
+=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 {
my $self = shift;
my ($obj) = @_;
return 1;
}
+=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 {
my $self = shift;
my ($obj) = @_;
return 1;
}
+=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 all locks taken.
+
+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.
+
+=cut
+
+=head2 read_txn_slots()
+
+This takes no arguments.
+
+This will return an array with a 1 or 0 in each slot. Each spot represents one
+available transaction. If the slot is 1, that transaction is taken. If it is 0,
+the transaction is available.
+
+=cut
+
sub read_txn_slots {
my $self = shift;
my $bl = $self->txn_bitfield_len;
);
}
+=head2 write_txn_slots( @slots )
+
+This takes an array of 1's and 0's. This array represents the transaction slots
+returned by L</read_txn_slots()>. In other words, the following is true:
+
+ @x = read_txn_slots( write_txn_slots( @x ) );
+
+(With the obviously missing object referents added back in.)
+
+=cut
+
sub write_txn_slots {
my $self = shift;
my $num_bits = $self->txn_bitfield_len * 8;
);
}
+=head2 get_running_txn_ids()
+
+This takes no arguments.
+
+This will return an array of taken transaction IDs. This wraps L</read_txn_slots()>.
+
+=cut
+
sub get_running_txn_ids {
my $self = shift;
my @transactions = $self->read_txn_slots;
- my @trans_ids = map { $_+1} grep { $transactions[$_] } 0 .. $#transactions;
+ my @trans_ids = map { $_+1 } grep { $transactions[$_] } 0 .. $#transactions;
}
+=head2 get_txn_staleness_counter( $trans_id )
+
+This will return the staleness counter for the given transaction ID. Please see
+L</TRANSACTION STALENESS> for more information.
+
+=cut
+
sub get_txn_staleness_counter {
my $self = shift;
my ($trans_id) = @_;
);
}
+=head2 inc_txn_staleness_counter( $trans_id )
+
+This will increment the staleness counter for the given transaction ID. Please see
+L</TRANSACTION STALENESS> for more information.
+
+=cut
+
sub inc_txn_staleness_counter {
my $self = shift;
my ($trans_id) = @_;
);
}
+=head2 get_entries()
+
+This takes no arguments.
+
+This returns a list of all the sectors that have been modified by this transaction.
+
+=cut
+
sub get_entries {
my $self = shift;
return [ keys %{ $self->{entries}{$self->trans_id} ||= {} } ];
}
+=head2 add_entry( $trans_id, $location )
+
+This takes a transaction ID and a file location and marks the sector at that location
+as having been modified by the transaction identified by $trans_id.
+
+This returns nothing.
+
+B<NOTE>: Unlike all the other _entries() methods, there are several cases where
+C<< $trans_id != $self->trans_id >> for this method.
+
+=cut
+
sub add_entry {
my $self = shift;
my ($trans_id, $loc) = @_;
$self->{entries}{$trans_id}{$loc} = undef;
}
-# If the buckets are being relocated because of a reindexing, the entries
-# mechanism needs to be made aware of it.
+=head2 reindex_entry( $old_loc, $new_loc )
+
+This takes two locations (old and new, respectively). If a location that has been
+modified by this transaction is subsequently reindexed due to a bucketlist
+overflowing, then the entries hash needs to be made aware of this change.
+
+This returns nothing.
+
+=cut
+
sub reindex_entry {
my $self = shift;
my ($old_loc, $new_loc) = @_;
}
}
+=head2 clear_entries()
+
+This takes no arguments. It will clear the entries list for the running transaction.
+
+This returns nothing.
+
+=cut
+
sub clear_entries {
my $self = shift;
delete $self->{entries}{$self->trans_id};
}
-################################################################################
+=head2 _write_file_header()
+
+This writes the file header for a new file. This will write the various settings
+that set how the file is interpreted.
+
+=head2 _read_file_header()
+
+This reads the file header from an existing file. This will read the various
+settings that set how the file is interpreted.
+
+=cut
{
my $header_fixed = length( SIG_FILE ) + 1 + 4 + 4;
}
}
+=head2 _load_sector( $offset )
+
+This will instantiate and return the sector object that represents the data found
+at $offset.
+
+=cut
+
sub _load_sector {
my $self = shift;
my ($offset) = @_;
DBM::Deep->_throw_error( "'$offset': Don't know what to do with type '$type'" );
}
+=head2 _apply_digest( @stuff )
+
+This will apply the digest methd (default to Digest::MD5::md5) to the arguments
+passed in and return the result.
+
+=cut
+
sub _apply_digest {
my $self = shift;
return $self->{digest}->(@_);
}
+=head2 _add_free_blist_sector( $offset, $size )
+
+=head2 _add_free_data_sector( $offset, $size )
+
+=head2 _add_free_index_sector( $offset, $size )
+
+These methods are all wrappers around _add_free_sector(), providing the proper
+chain offset ($multiple) for the sector type.
+
+=cut
+
sub _add_free_blist_sector { shift->_add_free_sector( 0, @_ ) }
sub _add_free_data_sector { shift->_add_free_sector( 1, @_ ) }
sub _add_free_index_sector { shift->_add_free_sector( 2, @_ ) }
+=head2 _add_free_sector( $multiple, $offset, $size )
+
+_add_free_sector() takes the offset into the chains location, the offset of the
+sector, and the size of that sector. It will mark the sector as a free sector
+and put it into the list of sectors that are free of this type for use later.
+
+This returns nothing.
+
+B<NOTE>: $size is unused?
+
+=cut
+
sub _add_free_sector {
my $self = shift;
my ($multiple, $offset, $size) = @_;
$storage->print_at( $offset + SIG_SIZE + $STALE_SIZE, $old_head );
}
+=head2 _request_blist_sector( $size )
+
+=head2 _request_data_sector( $size )
+
+=head2 _request_index_sector( $size )
+
+These methods are all wrappers around _request_sector(), providing the proper
+chain offset ($multiple) for the sector type.
+
+=cut
+
sub _request_blist_sector { shift->_request_sector( 0, @_ ) }
sub _request_data_sector { shift->_request_sector( 1, @_ ) }
sub _request_index_sector { shift->_request_sector( 2, @_ ) }
+=head2 _request_sector( $multiple $size )
+
+This takes the offset into the chains location and the size of that sector.
+
+This returns the object with the sector. If there is an available free sector of
+that type, then it will be reused. If there isn't one, then a new one will be
+allocated.
+
+=cut
+
sub _request_sector {
my $self = shift;
my ($multiple, $size) = @_;
return $loc;
}
-################################################################################
+=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_fh().
+
+This returns nothing.
+
+=cut
sub flush {
my $self = shift;
-# my $sectors = $self->dirty_sectors;
-# for my $offset (sort { $a <=> $b } keys %{ $sectors }) {
-# $self->storage->print_at( $offset, $self->sector_cache->{$offset} );
-# }
-
# Why do we need to have the storage flush? Shouldn't autoflush take care of things?
# -RobK, 2008-06-26
$self->storage->flush;
+}
-# $self->clear_dirty_sectors;
+=head2 ACCESSORS
-# $self->clear_sector_cache;
-}
+The following are readonly attributes.
-sub lock_exclusive {
- my $self = shift;
- my ($obj) = @_;
- return $self->storage->lock_exclusive( $obj );
-}
+=over 4
-sub lock_shared {
- my $self = shift;
- my ($obj) = @_;
- return $self->storage->lock_shared( $obj );
-}
+=item * storage
-sub unlock {
- my $self = shift;
- my ($obj) = @_;
+=item * byte_size
- my $rv = $self->storage->unlock( $obj );
+=item * hash_size
- $self->flush if $rv;
+=item * hash_chars
- return $rv;
-}
+=item * num_txns
+
+=item * max_buckets
+
+=item * blank_md5
+
+=item * data_sector_size
-################################################################################
+=item * txn_bitfield_len
+
+=back
+
+=cut
sub storage { $_[0]{storage} }
sub byte_size { $_[0]{byte_size} }
return $self->{txn_bitfield_len};
}
+=pod
+
+The following are read/write attributes.
+
+=over 4
+
+=item * trans_id / set_trans_id( $new_id )
+
+=item * trans_loc / set_trans_loc( $new_loc )
+
+=item * chains_loc / set_chains_loc( $new_loc )
+
+=back
+
+=cut
+
sub trans_id { $_[0]{trans_id} }
sub set_trans_id { $_[0]{trans_id} = $_[1] }
sub cache { $_[0]{cache} ||= {} }
sub clear_cache { %{$_[0]->cache} = () }
+=head2 _dump_file()
+
+This method takes no arguments. It's used to print out a textual representation of the DBM::Deep
+DB file. It assumes the file is not-corrupted.
+
+=cut
+
sub _dump_file {
my $self = shift;
return $return;
}
-################################################################################
-
-package DBM::Deep::Iterator;
-
-sub new {
- my $class = shift;
- my ($args) = @_;
-
- my $self = bless {
- breadcrumbs => [],
- engine => $args->{engine},
- base_offset => $args->{base_offset},
- }, $class;
-
- Scalar::Util::weaken( $self->{engine} );
-
- return $self;
-}
-
-sub reset { $_[0]{breadcrumbs} = [] }
-
-sub get_sector_iterator {
- my $self = shift;
- my ($loc) = @_;
-
- my $sector = $self->{engine}->_load_sector( $loc )
- or return;
-
- if ( $sector->isa( 'DBM::Deep::Engine::Sector::Index' ) ) {
- return DBM::Deep::Iterator::Index->new({
- iterator => $self,
- sector => $sector,
- });
- }
- elsif ( $sector->isa( 'DBM::Deep::Engine::Sector::BucketList' ) ) {
- return DBM::Deep::Iterator::BucketList->new({
- iterator => $self,
- sector => $sector,
- });
- }
-
- DBM::Deep->_throw_error( "get_sector_iterator(): Why did $loc make a $sector?" );
-}
-
-sub get_next_key {
- my $self = shift;
- my ($obj) = @_;
-
- my $crumbs = $self->{breadcrumbs};
- my $e = $self->{engine};
-
- unless ( @$crumbs ) {
- # This will be a Reference sector
- my $sector = $e->_load_sector( $self->{base_offset} )
- # If no sector is found, thist must have been deleted from under us.
- or return;
-
- if ( $sector->staleness != $obj->_staleness ) {
- return;
- }
-
- my $loc = $sector->get_blist_loc
- or return;
-
- push @$crumbs, $self->get_sector_iterator( $loc );
- }
-
- FIND_NEXT_KEY: {
- # We're at the end.
- unless ( @$crumbs ) {
- $self->reset;
- return;
- }
-
- my $iterator = $crumbs->[-1];
-
- # This level is done.
- if ( $iterator->at_end ) {
- pop @$crumbs;
- redo FIND_NEXT_KEY;
- }
-
- if ( $iterator->isa( 'DBM::Deep::Iterator::Index' ) ) {
- # If we don't have any more, it will be caught at the
- # prior check.
- if ( my $next = $iterator->get_next_iterator ) {
- push @$crumbs, $next;
- }
- redo FIND_NEXT_KEY;
- }
-
- unless ( $iterator->isa( 'DBM::Deep::Iterator::BucketList' ) ) {
- DBM::Deep->_throw_error(
- "Should have a bucketlist iterator here - instead have $iterator"
- );
- }
-
- # At this point, we have a BucketList iterator
- my $key = $iterator->get_next_key;
- if ( defined $key ) {
- return $key;
- }
- #XXX else { $iterator->set_to_end() } ?
-
- # We hit the end of the bucketlist iterator, so redo
- redo FIND_NEXT_KEY;
- }
-
- DBM::Deep->_throw_error( "get_next_key(): How did we get here?" );
-}
-
-package DBM::Deep::Iterator::Index;
-
-sub new {
- my $self = bless $_[1] => $_[0];
- $self->{curr_index} = 0;
- return $self;
-}
-
-sub at_end {
- my $self = shift;
- return $self->{curr_index} >= $self->{iterator}{engine}->hash_chars;
-}
-
-sub get_next_iterator {
- my $self = shift;
-
- my $loc;
- while ( !$loc ) {
- return if $self->at_end;
- $loc = $self->{sector}->get_entry( $self->{curr_index}++ );
- }
-
- return $self->{iterator}->get_sector_iterator( $loc );
-}
-
-package DBM::Deep::Iterator::BucketList;
-
-sub new {
- my $self = bless $_[1] => $_[0];
- $self->{curr_index} = 0;
- return $self;
-}
-
-sub at_end {
- my $self = shift;
- return $self->{curr_index} >= $self->{iterator}{engine}->max_buckets;
-}
-
-sub get_next_key {
- my $self = shift;
-
- return if $self->at_end;
-
- my $idx = $self->{curr_index}++;
-
- my $data_loc = $self->{sector}->get_data_location_for({
- allow_head => 1,
- idx => $idx,
- }) or return;
-
- #XXX Do we want to add corruption checks here?
- return $self->{sector}->get_key_for( $idx )->data;
-}
-
-package DBM::Deep::Engine::Sector;
-
-sub new {
- my $self = bless $_[1], $_[0];
- Scalar::Util::weaken( $self->{engine} );
- $self->_init;
- return $self;
-}
-
-#sub _init {}
-#sub clone { DBM::Deep->_throw_error( "Must be implemented in the child class" ); }
-
-sub engine { $_[0]{engine} }
-sub offset { $_[0]{offset} }
-sub type { $_[0]{type} }
-
-sub base_size {
- my $self = shift;
- return $self->engine->SIG_SIZE + $STALE_SIZE;
-}
-
-sub free {
- my $self = shift;
-
- my $e = $self->engine;
-
- $e->storage->print_at( $self->offset, $e->SIG_FREE );
- # Skip staleness counter
- $e->storage->print_at( $self->offset + $self->base_size,
- chr(0) x ($self->size - $self->base_size),
- );
-
- my $free_meth = $self->free_meth;
- $e->$free_meth( $self->offset, $self->size );
-
- return;
-}
-
-package DBM::Deep::Engine::Sector::Data;
-
-our @ISA = qw( DBM::Deep::Engine::Sector );
-
-# This is in bytes
-sub size { $_[0]{engine}->data_sector_size }
-sub free_meth { return '_add_free_data_sector' }
-
-sub clone {
- my $self = shift;
- return ref($self)->new({
- engine => $self->engine,
- type => $self->type,
- data => $self->data,
- });
-}
-
-package DBM::Deep::Engine::Sector::Scalar;
-
-our @ISA = qw( DBM::Deep::Engine::Sector::Data );
-
-sub free {
- my $self = shift;
-
- my $chain_loc = $self->chain_loc;
-
- $self->SUPER::free();
-
- if ( $chain_loc ) {
- $self->engine->_load_sector( $chain_loc )->free;
- }
-
- return;
-}
-
-sub type { $_[0]{engine}->SIG_DATA }
-sub _init {
- my $self = shift;
-
- my $engine = $self->engine;
-
- unless ( $self->offset ) {
- my $data_section = $self->size - $self->base_size - $engine->byte_size - 1;
-
- $self->{offset} = $engine->_request_data_sector( $self->size );
-
- my $data = delete $self->{data};
- my $dlen = length $data;
- my $continue = 1;
- my $curr_offset = $self->offset;
- while ( $continue ) {
-
- my $next_offset = 0;
-
- my ($leftover, $this_len, $chunk);
- if ( $dlen > $data_section ) {
- $leftover = 0;
- $this_len = $data_section;
- $chunk = substr( $data, 0, $this_len );
-
- $dlen -= $data_section;
- $next_offset = $engine->_request_data_sector( $self->size );
- $data = substr( $data, $this_len );
- }
- else {
- $leftover = $data_section - $dlen;
- $this_len = $dlen;
- $chunk = $data;
-
- $continue = 0;
- }
-
- $engine->storage->print_at( $curr_offset, $self->type ); # Sector type
- # Skip staleness
- $engine->storage->print_at( $curr_offset + $self->base_size,
- pack( $StP{$engine->byte_size}, $next_offset ), # Chain loc
- pack( $StP{1}, $this_len ), # Data length
- $chunk, # Data to be stored in this sector
- chr(0) x $leftover, # Zero-fill the rest
- );
-
- $curr_offset = $next_offset;
- }
-
- return;
- }
-}
-
-sub data_length {
- my $self = shift;
-
- my $buffer = $self->engine->storage->read_at(
- $self->offset + $self->base_size + $self->engine->byte_size, 1
- );
-
- return unpack( $StP{1}, $buffer );
-}
-
-sub chain_loc {
- my $self = shift;
- return unpack(
- $StP{$self->engine->byte_size},
- $self->engine->storage->read_at(
- $self->offset + $self->base_size,
- $self->engine->byte_size,
- ),
- );
-}
-
-sub data {
- my $self = shift;
-# my ($args) = @_;
-# $args ||= {};
-
- my $data;
- while ( 1 ) {
- my $chain_loc = $self->chain_loc;
-
- $data .= $self->engine->storage->read_at(
- $self->offset + $self->base_size + $self->engine->byte_size + 1, $self->data_length,
- );
-
- last unless $chain_loc;
-
- $self = $self->engine->_load_sector( $chain_loc );
- }
-
- return $data;
-}
-
-package DBM::Deep::Engine::Sector::Null;
-
-our @ISA = qw( DBM::Deep::Engine::Sector::Data );
-
-sub type { $_[0]{engine}->SIG_NULL }
-sub data_length { 0 }
-sub data { return }
-
-sub _init {
- my $self = shift;
-
- my $engine = $self->engine;
-
- unless ( $self->offset ) {
- my $leftover = $self->size - $self->base_size - 1 * $engine->byte_size - 1;
-
- $self->{offset} = $engine->_request_data_sector( $self->size );
- $engine->storage->print_at( $self->offset, $self->type ); # Sector type
- # Skip staleness counter
- $engine->storage->print_at( $self->offset + $self->base_size,
- pack( $StP{$engine->byte_size}, 0 ), # Chain loc
- pack( $StP{1}, $self->data_length ), # Data length
- chr(0) x $leftover, # Zero-fill the rest
- );
-
- return;
- }
-}
-
-package DBM::Deep::Engine::Sector::Reference;
-
-our @ISA = qw( DBM::Deep::Engine::Sector::Data );
-
-sub _init {
- my $self = shift;
-
- my $e = $self->engine;
-
- unless ( $self->offset ) {
- my $classname = Scalar::Util::blessed( delete $self->{data} );
- my $leftover = $self->size - $self->base_size - 3 * $e->byte_size;
-
- my $class_offset = 0;
- if ( defined $classname ) {
- my $class_sector = DBM::Deep::Engine::Sector::Scalar->new({
- engine => $e,
- data => $classname,
- });
- $class_offset = $class_sector->offset;
- }
-
- $self->{offset} = $e->_request_data_sector( $self->size );
- $e->storage->print_at( $self->offset, $self->type ); # Sector type
- # Skip staleness counter
- $e->storage->print_at( $self->offset + $self->base_size,
- pack( $StP{$e->byte_size}, 0 ), # Index/BList loc
- pack( $StP{$e->byte_size}, $class_offset ), # Classname loc
- pack( $StP{$e->byte_size}, 1 ), # Initial refcount
- chr(0) x $leftover, # Zero-fill the rest
- );
- }
- else {
- $self->{type} = $e->storage->read_at( $self->offset, 1 );
- }
-
- $self->{staleness} = unpack(
- $StP{$STALE_SIZE},
- $e->storage->read_at( $self->offset + $e->SIG_SIZE, $STALE_SIZE ),
- );
-
- return;
-}
-
-sub staleness { $_[0]{staleness} }
-
-sub get_data_location_for {
- my $self = shift;
- my ($args) = @_;
-
- # Assume that the head is not allowed unless otherwise specified.
- $args->{allow_head} = 0 unless exists $args->{allow_head};
-
- # Assume we don't create a new blist location unless otherwise specified.
- $args->{create} = 0 unless exists $args->{create};
-
- my $blist = $self->get_bucket_list({
- key_md5 => $args->{key_md5},
- key => $args->{key},
- create => $args->{create},
- });
- return unless $blist && $blist->{found};
-
- # At this point, $blist knows where the md5 is. What it -doesn't- know yet
- # is whether or not this transaction has this key. That's part of the next
- # function call.
- my $location = $blist->get_data_location_for({
- allow_head => $args->{allow_head},
- }) or return;
-
- return $location;
-}
-
-sub get_data_for {
- my $self = shift;
- my ($args) = @_;
-
- my $location = $self->get_data_location_for( $args )
- or return;
-
- return $self->engine->_load_sector( $location );
-}
-
-sub write_data {
- my $self = shift;
- my ($args) = @_;
-
- my $blist = $self->get_bucket_list({
- key_md5 => $args->{key_md5},
- key => $args->{key},
- create => 1,
- }) or DBM::Deep->_throw_error( "How did write_data fail (no blist)?!" );
-
- # Handle any transactional bookkeeping.
- if ( $self->engine->trans_id ) {
- if ( ! $blist->has_md5 ) {
- $blist->mark_deleted({
- trans_id => 0,
- });
- }
- }
- else {
- my @trans_ids = $self->engine->get_running_txn_ids;
- if ( $blist->has_md5 ) {
- if ( @trans_ids ) {
- my $old_value = $blist->get_data_for;
- foreach my $other_trans_id ( @trans_ids ) {
- next if $blist->get_data_location_for({
- trans_id => $other_trans_id,
- allow_head => 0,
- });
- $blist->write_md5({
- trans_id => $other_trans_id,
- key => $args->{key},
- key_md5 => $args->{key_md5},
- value => $old_value->clone,
- });
- }
- }
- }
- else {
- if ( @trans_ids ) {
- foreach my $other_trans_id ( @trans_ids ) {
- #XXX This doesn't seem to possible to ever happen . . .
- next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
- $blist->mark_deleted({
- trans_id => $other_trans_id,
- });
- }
- }
- }
- }
-
- #XXX Is this safe to do transactionally?
- # Free the place we're about to write to.
- if ( $blist->get_data_location_for({ allow_head => 0 }) ) {
- $blist->get_data_for({ allow_head => 0 })->free;
- }
-
- $blist->write_md5({
- key => $args->{key},
- key_md5 => $args->{key_md5},
- value => $args->{value},
- });
-}
-
-sub delete_key {
- my $self = shift;
- my ($args) = @_;
-
- # XXX What should happen if this fails?
- my $blist = $self->get_bucket_list({
- key_md5 => $args->{key_md5},
- }) or DBM::Deep->_throw_error( "How did delete_key fail (no blist)?!" );
-
- # Save the location so that we can free the data
- my $location = $blist->get_data_location_for({
- allow_head => 0,
- });
- my $old_value = $location && $self->engine->_load_sector( $location );
-
- my @trans_ids = $self->engine->get_running_txn_ids;
-
- # If we're the HEAD and there are running txns, then we need to clone this value to the other
- # transactions to preserve Isolation.
- if ( $self->engine->trans_id == 0 ) {
- if ( @trans_ids ) {
- foreach my $other_trans_id ( @trans_ids ) {
- next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 });
- $blist->write_md5({
- trans_id => $other_trans_id,
- key => $args->{key},
- key_md5 => $args->{key_md5},
- value => $old_value->clone,
- });
- }
- }
- }
-
- my $data;
- if ( @trans_ids ) {
- $blist->mark_deleted( $args );
-
- if ( $old_value ) {
- $data = $old_value->data({ export => 1 });
- $old_value->free;
- }
- }
- else {
- $data = $blist->delete_md5( $args );
- }
-
- return $data;
-}
-
-sub get_blist_loc {
- my $self = shift;
-
- my $e = $self->engine;
- my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size );
- return unpack( $StP{$e->byte_size}, $blist_loc );
-}
-
-sub get_bucket_list {
- my $self = shift;
- my ($args) = @_;
- $args ||= {};
-
- # XXX Add in check here for recycling?
-
- my $engine = $self->engine;
-
- my $blist_loc = $self->get_blist_loc;
-
- # There's no index or blist yet
- unless ( $blist_loc ) {
- return unless $args->{create};
-
- my $blist = DBM::Deep::Engine::Sector::BucketList->new({
- engine => $engine,
- key_md5 => $args->{key_md5},
- });
-
- $engine->storage->print_at( $self->offset + $self->base_size,
- pack( $StP{$engine->byte_size}, $blist->offset ),
- );
-
- return $blist;
- }
-
- my $sector = $engine->_load_sector( $blist_loc )
- or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
- my $i = 0;
- my $last_sector = undef;
- while ( $sector->isa( 'DBM::Deep::Engine::Sector::Index' ) ) {
- $blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) );
- $last_sector = $sector;
- if ( $blist_loc ) {
- $sector = $engine->_load_sector( $blist_loc )
- or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" );
- }
- else {
- $sector = undef;
- last;
- }
- }
-
- # This means we went through the Index sector(s) and found an empty slot
- unless ( $sector ) {
- return unless $args->{create};
-
- DBM::Deep->_throw_error( "No last_sector when attempting to build a new entry" )
- unless $last_sector;
-
- my $blist = DBM::Deep::Engine::Sector::BucketList->new({
- engine => $engine,
- key_md5 => $args->{key_md5},
- });
-
- $last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset );
-
- return $blist;
- }
-
- $sector->find_md5( $args->{key_md5} );
-
- # See whether or not we need to reindex the bucketlist
- # Yes, the double-braces are there for a reason. if() doesn't create a redo-able block,
- # so we have to create a bare block within the if() for redo-purposes. Patch and idea
- # submitted by sprout@cpan.org. -RobK, 2008-01-09
- if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {{
- my $redo;
-
- my $new_index = DBM::Deep::Engine::Sector::Index->new({
- engine => $engine,
- });
-
- my %blist_cache;
- #XXX q.v. the comments for this function.
- foreach my $entry ( $sector->chopped_up ) {
- my ($spot, $md5) = @{$entry};
- my $idx = ord( substr( $md5, $i, 1 ) );
-
- # XXX This is inefficient
- my $blist = $blist_cache{$idx}
- ||= DBM::Deep::Engine::Sector::BucketList->new({
- engine => $engine,
- });
-
- $new_index->set_entry( $idx => $blist->offset );
-
- my $new_spot = $blist->write_at_next_open( $md5 );
- $engine->reindex_entry( $spot => $new_spot );
- }
-
- # Handle the new item separately.
- {
- my $idx = ord( substr( $args->{key_md5}, $i, 1 ) );
-
- # If all the previous blist's items have been thrown into one
- # blist and the new item belongs in there too, we need
- # another index.
- if ( keys %blist_cache == 1 and each %blist_cache == $idx ) {
- ++$i, ++$redo;
- } else {
- my $blist = $blist_cache{$idx}
- ||= DBM::Deep::Engine::Sector::BucketList->new({
- engine => $engine,
- });
-
- $new_index->set_entry( $idx => $blist->offset );
-
- #XXX THIS IS HACKY!
- $blist->find_md5( $args->{key_md5} );
- $blist->write_md5({
- key => $args->{key},
- key_md5 => $args->{key_md5},
- value => DBM::Deep::Engine::Sector::Null->new({
- engine => $engine,
- data => undef,
- }),
- });
- }
-# my $blist = $blist_cache{$idx}
-# ||= DBM::Deep::Engine::Sector::BucketList->new({
-# engine => $engine,
-# });
-#
-# $new_index->set_entry( $idx => $blist->offset );
-#
-# #XXX THIS IS HACKY!
-# $blist->find_md5( $args->{key_md5} );
-# $blist->write_md5({
-# key => $args->{key},
-# key_md5 => $args->{key_md5},
-# value => DBM::Deep::Engine::Sector::Null->new({
-# engine => $engine,
-# data => undef,
-# }),
-# });
- }
-
- if ( $last_sector ) {
- $last_sector->set_entry(
- ord( substr( $args->{key_md5}, $i - 1, 1 ) ),
- $new_index->offset,
- );
- } else {
- $engine->storage->print_at( $self->offset + $self->base_size,
- pack( $StP{$engine->byte_size}, $new_index->offset ),
- );
- }
-
- $sector->clear;
- $sector->free;
-
- if ( $redo ) {
- (undef, $sector) = %blist_cache;
- $last_sector = $new_index;
- redo;
- }
-
- $sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) };
- $sector->find_md5( $args->{key_md5} );
- }}
-
- return $sector;
-}
-
-sub get_class_offset {
- my $self = shift;
-
- my $e = $self->engine;
- return unpack(
- $StP{$e->byte_size},
- $e->storage->read_at(
- $self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size,
- ),
- );
-}
-
-sub get_classname {
- my $self = shift;
-
- my $class_offset = $self->get_class_offset;
-
- return unless $class_offset;
-
- return $self->engine->_load_sector( $class_offset )->data;
-}
-
-sub data {
- my $self = shift;
- my ($args) = @_;
- $args ||= {};
-
- my $obj;
- unless ( $obj = $self->engine->cache->{ $self->offset } ) {
- $obj = DBM::Deep->new({
- type => $self->type,
- base_offset => $self->offset,
- staleness => $self->staleness,
- storage => $self->engine->storage,
- engine => $self->engine,
- });
-
- if ( $self->engine->storage->{autobless} ) {
- my $classname = $self->get_classname;
- if ( defined $classname ) {
- bless $obj, $classname;
- }
- }
-
- $self->engine->cache->{$self->offset} = $obj;
- }
-
- # We're not exporting, so just return.
- unless ( $args->{export} ) {
- return $obj;
- }
-
- # We shouldn't export if this is still referred to.
- if ( $self->get_refcount > 1 ) {
- return $obj;
- }
-
- return $obj->export;
-}
-
-sub free {
- my $self = shift;
-
- # We're not ready to be removed yet.
- if ( $self->decrement_refcount > 0 ) {
- return;
- }
-
- # Rebless the object into DBM::Deep::Null.
- eval { %{ $self->engine->cache->{ $self->offset } } = (); };
- eval { @{ $self->engine->cache->{ $self->offset } } = (); };
- bless $self->engine->cache->{ $self->offset }, 'DBM::Deep::Null';
- delete $self->engine->cache->{ $self->offset };
-
- my $blist_loc = $self->get_blist_loc;
- $self->engine->_load_sector( $blist_loc )->free if $blist_loc;
-
- my $class_loc = $self->get_class_offset;
- $self->engine->_load_sector( $class_loc )->free if $class_loc;
-
- $self->SUPER::free();
-}
-
-sub increment_refcount {
- my $self = shift;
-
- my $refcount = $self->get_refcount;
-
- $refcount++;
-
- $self->write_refcount( $refcount );
-
- return $refcount;
-}
-
-sub decrement_refcount {
- my $self = shift;
-
- my $refcount = $self->get_refcount;
-
- $refcount--;
-
- $self->write_refcount( $refcount );
-
- return $refcount;
-}
-
-sub get_refcount {
- my $self = shift;
-
- my $e = $self->engine;
- return unpack(
- $StP{$e->byte_size},
- $e->storage->read_at(
- $self->offset + $self->base_size + 2 * $e->byte_size, $e->byte_size,
- ),
- );
-}
-
-sub write_refcount {
- my $self = shift;
- my ($num) = @_;
-
- my $e = $self->engine;
- $e->storage->print_at(
- $self->offset + $self->base_size + 2 * $e->byte_size,
- pack( $StP{$e->byte_size}, $num ),
- );
-}
-
-package DBM::Deep::Engine::Sector::BucketList;
-
-our @ISA = qw( DBM::Deep::Engine::Sector );
-
-sub _init {
- my $self = shift;
-
- my $engine = $self->engine;
-
- unless ( $self->offset ) {
- my $leftover = $self->size - $self->base_size;
-
- $self->{offset} = $engine->_request_blist_sector( $self->size );
- $engine->storage->print_at( $self->offset, $engine->SIG_BLIST ); # Sector type
- # Skip staleness counter
- $engine->storage->print_at( $self->offset + $self->base_size,
- chr(0) x $leftover, # Zero-fill the data
- );
- }
-
- if ( $self->{key_md5} ) {
- $self->find_md5;
- }
-
- return $self;
-}
-
-sub clear {
- my $self = shift;
- $self->engine->storage->print_at( $self->offset + $self->base_size,
- chr(0) x ($self->size - $self->base_size), # Zero-fill the data
- );
-}
-
-sub size {
- my $self = shift;
- unless ( $self->{size} ) {
- my $e = $self->engine;
- # Base + numbuckets * bucketsize
- $self->{size} = $self->base_size + $e->max_buckets * $self->bucket_size;
- }
- return $self->{size};
-}
-
-sub free_meth { return '_add_free_blist_sector' }
-
-sub free {
- my $self = shift;
-
- my $e = $self->engine;
- foreach my $bucket ( $self->chopped_up ) {
- my $rest = $bucket->[-1];
-
- # Delete the keysector
- my $l = unpack( $StP{$e->byte_size}, substr( $rest, $e->hash_size, $e->byte_size ) );
- my $s = $e->_load_sector( $l ); $s->free if $s;
-
- # Delete the HEAD sector
- $l = unpack( $StP{$e->byte_size},
- substr( $rest,
- $e->hash_size + $e->byte_size,
- $e->byte_size,
- ),
- );
- $s = $e->_load_sector( $l ); $s->free if $s;
-
- foreach my $txn ( 0 .. $e->num_txns - 2 ) {
- my $l = unpack( $StP{$e->byte_size},
- substr( $rest,
- $e->hash_size + 2 * $e->byte_size + $txn * ($e->byte_size + $STALE_SIZE),
- $e->byte_size,
- ),
- );
- my $s = $e->_load_sector( $l ); $s->free if $s;
- }
- }
-
- $self->SUPER::free();
-}
-
-sub bucket_size {
- my $self = shift;
- unless ( $self->{bucket_size} ) {
- my $e = $self->engine;
- # Key + head (location) + transactions (location + staleness-counter)
- my $location_size = $e->byte_size + $e->byte_size + ($e->num_txns - 1) * ($e->byte_size + $STALE_SIZE);
- $self->{bucket_size} = $e->hash_size + $location_size;
- }
- return $self->{bucket_size};
-}
-
-# XXX This is such a poor hack. I need to rethink this code.
-sub chopped_up {
- my $self = shift;
-
- my $e = $self->engine;
-
- my @buckets;
- foreach my $idx ( 0 .. $e->max_buckets - 1 ) {
- my $spot = $self->offset + $self->base_size + $idx * $self->bucket_size;
- my $md5 = $e->storage->read_at( $spot, $e->hash_size );
-
- #XXX If we're chopping, why would we ever have the blank_md5?
- last if $md5 eq $e->blank_md5;
-
- my $rest = $e->storage->read_at( undef, $self->bucket_size - $e->hash_size );
- push @buckets, [ $spot, $md5 . $rest ];
- }
-
- return @buckets;
-}
-
-sub write_at_next_open {
- my $self = shift;
- my ($entry) = @_;
-
- #XXX This is such a hack!
- $self->{_next_open} = 0 unless exists $self->{_next_open};
-
- my $spot = $self->offset + $self->base_size + $self->{_next_open}++ * $self->bucket_size;
- $self->engine->storage->print_at( $spot, $entry );
-
- return $spot;
-}
-
-sub has_md5 {
- my $self = shift;
- unless ( exists $self->{found} ) {
- $self->find_md5;
- }
- return $self->{found};
-}
-
-sub find_md5 {
- my $self = shift;
-
- $self->{found} = undef;
- $self->{idx} = -1;
-
- if ( @_ ) {
- $self->{key_md5} = shift;
- }
-
- # If we don't have an MD5, then what are we supposed to do?
- unless ( exists $self->{key_md5} ) {
- DBM::Deep->_throw_error( "Cannot find_md5 without a key_md5 set" );
- }
-
- my $e = $self->engine;
- foreach my $idx ( 0 .. $e->max_buckets - 1 ) {
- my $potential = $e->storage->read_at(
- $self->offset + $self->base_size + $idx * $self->bucket_size, $e->hash_size,
- );
-
- if ( $potential eq $e->blank_md5 ) {
- $self->{idx} = $idx;
- return;
- }
-
- if ( $potential eq $self->{key_md5} ) {
- $self->{found} = 1;
- $self->{idx} = $idx;
- return;
- }
- }
-
- return;
-}
-
-sub write_md5 {
- my $self = shift;
- my ($args) = @_;
-
- DBM::Deep->_throw_error( "write_md5: no key" ) unless exists $args->{key};
- DBM::Deep->_throw_error( "write_md5: no key_md5" ) unless exists $args->{key_md5};
- DBM::Deep->_throw_error( "write_md5: no value" ) unless exists $args->{value};
-
- my $engine = $self->engine;
-
- $args->{trans_id} = $engine->trans_id unless exists $args->{trans_id};
-
- my $spot = $self->offset + $self->base_size + $self->{idx} * $self->bucket_size;
- $engine->add_entry( $args->{trans_id}, $spot );
-
- unless ($self->{found}) {
- my $key_sector = DBM::Deep::Engine::Sector::Scalar->new({
- engine => $engine,
- data => $args->{key},
- });
-
- $engine->storage->print_at( $spot,
- $args->{key_md5},
- pack( $StP{$engine->byte_size}, $key_sector->offset ),
- );
- }
-
- my $loc = $spot
- + $engine->hash_size
- + $engine->byte_size;
-
- if ( $args->{trans_id} ) {
- $loc += $engine->byte_size + ($args->{trans_id} - 1) * ( $engine->byte_size + $STALE_SIZE );
-
- $engine->storage->print_at( $loc,
- pack( $StP{$engine->byte_size}, $args->{value}->offset ),
- pack( $StP{$STALE_SIZE}, $engine->get_txn_staleness_counter( $args->{trans_id} ) ),
- );
- }
- else {
- $engine->storage->print_at( $loc,
- pack( $StP{$engine->byte_size}, $args->{value}->offset ),
- );
- }
-}
-
-sub mark_deleted {
- my $self = shift;
- my ($args) = @_;
- $args ||= {};
-
- my $engine = $self->engine;
-
- $args->{trans_id} = $engine->trans_id unless exists $args->{trans_id};
-
- my $spot = $self->offset + $self->base_size + $self->{idx} * $self->bucket_size;
- $engine->add_entry( $args->{trans_id}, $spot );
-
- my $loc = $spot
- + $engine->hash_size
- + $engine->byte_size;
-
- if ( $args->{trans_id} ) {
- $loc += $engine->byte_size + ($args->{trans_id} - 1) * ( $engine->byte_size + $STALE_SIZE );
-
- $engine->storage->print_at( $loc,
- pack( $StP{$engine->byte_size}, 1 ), # 1 is the marker for deleted
- pack( $StP{$STALE_SIZE}, $engine->get_txn_staleness_counter( $args->{trans_id} ) ),
- );
- }
- else {
- $engine->storage->print_at( $loc,
- pack( $StP{$engine->byte_size}, 1 ), # 1 is the marker for deleted
- );
- }
-
-}
-
-sub delete_md5 {
- my $self = shift;
- my ($args) = @_;
-
- my $engine = $self->engine;
- return undef unless $self->{found};
-
- # Save the location so that we can free the data
- my $location = $self->get_data_location_for({
- allow_head => 0,
- });
- my $key_sector = $self->get_key_for;
-
- my $spot = $self->offset + $self->base_size + $self->{idx} * $self->bucket_size;
- $engine->storage->print_at( $spot,
- $engine->storage->read_at(
- $spot + $self->bucket_size,
- $self->bucket_size * ( $engine->max_buckets - $self->{idx} - 1 ),
- ),
- chr(0) x $self->bucket_size,
- );
-
- $key_sector->free;
-
- my $data_sector = $self->engine->_load_sector( $location );
- my $data = $data_sector->data({ export => 1 });
- $data_sector->free;
-
- return $data;
-}
-
-sub get_data_location_for {
- my $self = shift;
- my ($args) = @_;
- $args ||= {};
-
- $args->{allow_head} = 0 unless exists $args->{allow_head};
- $args->{trans_id} = $self->engine->trans_id unless exists $args->{trans_id};
- $args->{idx} = $self->{idx} unless exists $args->{idx};
-
- my $e = $self->engine;
-
- my $spot = $self->offset + $self->base_size
- + $args->{idx} * $self->bucket_size
- + $e->hash_size
- + $e->byte_size;
-
- if ( $args->{trans_id} ) {
- $spot += $e->byte_size + ($args->{trans_id} - 1) * ( $e->byte_size + $STALE_SIZE );
- }
-
- my $buffer = $e->storage->read_at(
- $spot,
- $e->byte_size + $STALE_SIZE,
- );
- my ($loc, $staleness) = unpack( $StP{$e->byte_size} . ' ' . $StP{$STALE_SIZE}, $buffer );
-
- # XXX Merge the two if-clauses below
- if ( $args->{trans_id} ) {
- # We have found an entry that is old, so get rid of it
- if ( $staleness != (my $s = $e->get_txn_staleness_counter( $args->{trans_id} ) ) ) {
- $e->storage->print_at(
- $spot,
- pack( $StP{$e->byte_size} . ' ' . $StP{$STALE_SIZE}, (0) x 2 ),
- );
- $loc = 0;
- }
- }
-
- # If we're in a transaction and we never wrote to this location, try the
- # HEAD instead.
- if ( $args->{trans_id} && !$loc && $args->{allow_head} ) {
- return $self->get_data_location_for({
- trans_id => 0,
- allow_head => 1,
- idx => $args->{idx},
- });
- }
-
- return $loc <= 1 ? 0 : $loc;
-}
-
-sub get_data_for {
- my $self = shift;
- my ($args) = @_;
- $args ||= {};
-
- return unless $self->{found};
- my $location = $self->get_data_location_for({
- allow_head => $args->{allow_head},
- });
- return $self->engine->_load_sector( $location );
-}
-
-sub get_key_for {
- my $self = shift;
- my ($idx) = @_;
- $idx = $self->{idx} unless defined $idx;
-
- if ( $idx >= $self->engine->max_buckets ) {
- DBM::Deep->_throw_error( "get_key_for(): Attempting to retrieve $idx" );
- }
-
- my $location = $self->engine->storage->read_at(
- $self->offset + $self->base_size + $idx * $self->bucket_size + $self->engine->hash_size,
- $self->engine->byte_size,
- );
- $location = unpack( $StP{$self->engine->byte_size}, $location );
- DBM::Deep->_throw_error( "get_key_for: No location?" ) unless $location;
-
- return $self->engine->_load_sector( $location );
-}
-
-package DBM::Deep::Engine::Sector::Index;
-
-our @ISA = qw( DBM::Deep::Engine::Sector );
-
-sub _init {
- my $self = shift;
-
- my $engine = $self->engine;
-
- unless ( $self->offset ) {
- my $leftover = $self->size - $self->base_size;
-
- $self->{offset} = $engine->_request_index_sector( $self->size );
- $engine->storage->print_at( $self->offset, $engine->SIG_INDEX ); # Sector type
- # Skip staleness counter
- $engine->storage->print_at( $self->offset + $self->base_size,
- chr(0) x $leftover, # Zero-fill the rest
- );
- }
-
- return $self;
-}
-
-#XXX Change here
-sub size {
- my $self = shift;
- unless ( $self->{size} ) {
- my $e = $self->engine;
- $self->{size} = $self->base_size + $e->byte_size * $e->hash_chars;
- }
- return $self->{size};
-}
-
-sub free_meth { return '_add_free_index_sector' }
-
-sub free {
- my $self = shift;
- my $e = $self->engine;
-
- for my $i ( 0 .. $e->hash_chars - 1 ) {
- my $l = $self->get_entry( $i ) or next;
- $e->_load_sector( $l )->free;
- }
-
- $self->SUPER::free();
-}
-
-sub _loc_for {
- my $self = shift;
- my ($idx) = @_;
- return $self->offset + $self->base_size + $idx * $self->engine->byte_size;
-}
-
-sub get_entry {
- my $self = shift;
- my ($idx) = @_;
-
- my $e = $self->engine;
-
- DBM::Deep->_throw_error( "get_entry: Out of range ($idx)" )
- if $idx < 0 || $idx >= $e->hash_chars;
-
- return unpack(
- $StP{$e->byte_size},
- $e->storage->read_at( $self->_loc_for( $idx ), $e->byte_size ),
- );
-}
-
-sub set_entry {
- my $self = shift;
- my ($idx, $loc) = @_;
-
- my $e = $self->engine;
-
- DBM::Deep->_throw_error( "set_entry: Out of range ($idx)" )
- if $idx < 0 || $idx >= $e->hash_chars;
-
- $self->engine->storage->print_at(
- $self->_loc_for( $idx ),
- pack( $StP{$e->byte_size}, $loc ),
- );
-}
-
-# This was copied from MARCEL's Class::Null. However, I couldn't use it because
-# I need an undef value, not an implementation of the Null Class pattern.
-package DBM::Deep::Null;
-
-use overload
- 'bool' => sub { undef },
- '""' => sub { undef },
- '0+' => sub { undef },
- fallback => 1,
- nomethod => 'AUTOLOAD';
-
-sub AUTOLOAD { return; }
-
1;
__END__
projects / dbsrgits/DBM-Deep.git / blobdiff