class KDB: def __init__(self, path, truncate=False): """ Open a new connection to a database using the Kyoto Cabinet engine. Args: * path (str): Path to database. Kwargs: * truncate (bool, False): If database should be truncated before opening. """ self.db = DB() self.batchsize = 1000 self.batch = {} dbparams = '.kct#apow=0#bnum=10000000#msiz=' + str(2 << 30) if truncate: result = self.db.open(path + dbparams, DB.OWRITER | DB.OCREATE | DB.OTRUNCATE) else: result = self.db.open(path + dbparams, DB.OWRITER) if not result: raise PathError('DNA outdb open error: %s ' % self.db.error()) exit(1) def get(self, key): """ Retrieve the item with the given `key`. """ return self.db.get(key) def put(self, key, val): """ Put `val` at `key`. Note that disk writing is done in batches, so be sure to call `close` or `flush` to make sure that values are put into the store. """ self.batch[key] = val if len(self.batch) >= self.batchsize: self.flush() def flush(self): """ Write `put` calls to database. """ self.db.set_bulk(self.batch) self.batch = {} def close(self): """ Flush the database and delete the connection to it. """ self.flush() del self.db
class KyotoCabinetGraph(BaseGraph): def __init__(self, path): # create the database object self._path = path self._db = DB() # open the database if not self._db.open(path, DB.OREADER | DB.OWRITER | DB.OCREATE): raise GrapheekDataKyotoCabinetInitFailureException( str(self._db.error())) super(KyotoCabinetGraph, self).__init__() self._ensure_prepared() self._closed = False # Start method overriding : def _db_close(self): if not self._closed: self._db.close() def _transaction_begin(self): self._db.begin_transaction() return True def _transaction_commit(self, txn): self._db.end_transaction(True) def _transaction_rollback(self, txn): self._db.end_transaction(False) def _has_key(self, key): return self._db.check(key) >= 0 def _get(self, txn, key): raw_data = self._db.get(key) if raw_data is None: return UNDEFINED # Not returning None, as None is a valid value return msgpack.loads(raw_data, encoding='utf8') def _bulk_get(self, txn, keys): result = {} key_raw_datas = self._db.get_bulk(keys) for key, raw_data in list(key_raw_datas.items()): if PYTHON2: # pragma : no cover k = key else: # pragma : no cover k = str(key, encoding='utf8') result[k] = msgpack.loads(raw_data, encoding='utf8') return result def _set(self, txn, key, value): res = self._db.set(key, msgpack.dumps(value, encoding='utf8')) if not (res): # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res def _bulk_set(self, txn, updates): dic = {} for key, value in list(updates.items()): dic[key] = msgpack.dumps(value, encoding='utf8') res = self._db.set_bulk(dic) if res == -1: # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res def _remove(self, txn, key): # Contrary to LocalMemoryGraph implementation, it is not needed to wrap # key removal in try.. except because KyotoCabinet only send "False" # when key does not exist # Thus ... _removemethod is idempotent (cf LocalMemoryGraph _remove method comment) self._db.remove(key) def _bulk_remove(self, txn, keys): res = self._db.remove_bulk(list(keys)) if res == -1: # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res def _remove_prefix(self, txn, prefix): keys = self._db.match_prefix(prefix) self._db.remove_bulk(keys) # overriding list methods # looks like a bucket of hacks, and yes indeed it is :) # btw, it REALLY improves performance if we compare to default implementation which, # in the case of KyotoCabinet would involve msgpack deserialization followed by a serialization def _init_lst(self, txn, key): res = self._db.set(key, '') if not (res): # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res def _get_lst(self, txn, key): value = self._db.get(key) if value is None: return UNDEFINED # look _append_to_lst code below to understand why a split is done # And why resulting list is sliced from 1 if PYTHON2: # pragma : no cover return list(map(int, value.split('|')[1:])) return list(map( int, str(value, encoding='utf8').split('|')[1:])) # pragma : no cover def _set_lst(self, txn, key, values): newval = '|'.join([str(value) for value in values]) res = self._db.set(key, '|' + newval) if not (res): # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res def _bulk_get_lst(self, txn, keys): dic_values = self._db.get_bulk(keys) results = [] for key in keys: if PYTHON2: # pragma : no cover values = dic_values.get(key, UNDEFINED) else: # pragma : no cover values = dic_values.get(bytes(key, encoding='utf8'), UNDEFINED) if values == UNDEFINED: results.append([]) else: if PYTHON2: # pragma : no cover results.append(list(map(int, values.split('|')[1:]))) else: # pragma : no cover results.append( list( map(int, str(values, encoding='utf8').split('|')[1:]))) return results def _append_to_lst(self, txn, key, value): self._db.append(key, '|' + str(value)) def _bulk_append_to_lst(self, txn, key, values): newval = '|'.join([str(value) for value in values]) self._db.append(key, '|' + newval) def _remove_from_lst(self, txn, key, value): old = self._db.get(key) if not PYTHON2: # pragma : no cover old = str(old, encoding='utf8') # Caution : we are only removing ONE occurence # This is voluntary # For instance, it lst contains neighbour node, we need to remove only one occurence # cause current entity and neighbour node can be linked multiple time new = old.replace('|%s' % value, '', 1) if new == old: raise ValueError("list.remove(x): x not in list") res = self._db.set(key, new) if not (res): # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res def _bulk_remove_from_lst(self, txn, key, values): assert (len(values)) old = self._db.get(key) if PYTHON2: # pragma : no cover new = old else: # pragma : no cover new = str(old, encoding='utf8') for value in values: new = new.replace('|%s' % value, '', 1) if new == old: # pragma : no cover raise ValueError("list.remove(x): x not in list") res = self._db.set(key, new) if not (res): # pragma : no cover raise GrapheekDataKyotoCabinetException( 'KyotoCabinet : error while saving') return res