JezK
Edit File: dbshelve.py
#------------------------------------------------------------------------ # Copyright (c) 1997-2001 by Total Control Software # All Rights Reserved #------------------------------------------------------------------------ # # Module Name: dbShelve.py # # Description: A reimplementation of the standard shelve.py that # forces the use of cPickle, and DB. # # Creation Date: 11/3/97 3:39:04PM # # License: This is free software. You may use this software for any # purpose including modification/redistribution, so long as # this header remains intact and that you do not claim any # rights of ownership or authorship of this software. This # software has been tested, but no warranty is expressed or # implied. # # 13-Dec-2000: Updated to be used with the new bsddb3 package. # Added DBShelfCursor class. # #------------------------------------------------------------------------ """Manage shelves of pickled objects using bsddb database files for the storage. """ #------------------------------------------------------------------------ import sys absolute_import = (sys.version_info[0] >= 3) if absolute_import : # Because this syntaxis is not valid before Python 2.5 exec("from . import db") else : import db if sys.version_info[0] >= 3 : import cPickle # Will be converted to "pickle" by "2to3" else : if sys.version_info < (2, 6) : import cPickle else : # When we drop support for python 2.4 # we could use: (in 2.5 we need a __future__ statement) # # with warnings.catch_warnings(): # warnings.filterwarnings(...) # ... # # We can not use "with" as is, because it would be invalid syntax # in python 2.4 and (with no __future__) 2.5. # Here we simulate "with" following PEP 343 : import warnings w = warnings.catch_warnings() w.__enter__() try : warnings.filterwarnings('ignore', message='the cPickle module has been removed in Python 3.0', category=DeprecationWarning) import cPickle finally : w.__exit__() del w HIGHEST_PROTOCOL = cPickle.HIGHEST_PROTOCOL def _dumps(object, protocol): return cPickle.dumps(object, protocol=protocol) if sys.version_info < (2, 6) : from UserDict import DictMixin as MutableMapping else : import collections MutableMapping = collections.MutableMapping #------------------------------------------------------------------------ def open(filename, flags=db.DB_CREATE, mode=0660, filetype=db.DB_HASH, dbenv=None, dbname=None): """ A simple factory function for compatibility with the standard shleve.py module. It can be used like this, where key is a string and data is a pickleable object: from bsddb import dbshelve db = dbshelve.open(filename) db[key] = data db.close() """ if type(flags) == type(''): sflag = flags if sflag == 'r': flags = db.DB_RDONLY elif sflag == 'rw': flags = 0 elif sflag == 'w': flags = db.DB_CREATE elif sflag == 'c': flags = db.DB_CREATE elif sflag == 'n': flags = db.DB_TRUNCATE | db.DB_CREATE else: raise db.DBError, "flags should be one of 'r', 'w', 'c' or 'n' or use the bsddb.db.DB_* flags" d = DBShelf(dbenv) d.open(filename, dbname, filetype, flags, mode) return d #--------------------------------------------------------------------------- class DBShelveError(db.DBError): pass class DBShelf(MutableMapping): """A shelf to hold pickled objects, built upon a bsddb DB object. It automatically pickles/unpickles data objects going to/from the DB. """ def __init__(self, dbenv=None): self.db = db.DB(dbenv) self._closed = True if HIGHEST_PROTOCOL: self.protocol = HIGHEST_PROTOCOL else: self.protocol = 1 def __del__(self): self.close() def __getattr__(self, name): """Many methods we can just pass through to the DB object. (See below) """ return getattr(self.db, name) #----------------------------------- # Dictionary access methods def __len__(self): return len(self.db) def __getitem__(self, key): data = self.db[key] return cPickle.loads(data) def __setitem__(self, key, value): data = _dumps(value, self.protocol) self.db[key] = data def __delitem__(self, key): del self.db[key] def keys(self, txn=None): if txn is not None: return self.db.keys(txn) else: return self.db.keys() if sys.version_info >= (2, 6) : def __iter__(self) : # XXX: Load all keys in memory :-( for k in self.db.keys() : yield k # Do this when "DB" support iteration # Or is it enough to pass thru "getattr"? # # def __iter__(self) : # return self.db.__iter__() def open(self, *args, **kwargs): self.db.open(*args, **kwargs) self._closed = False def close(self, *args, **kwargs): self.db.close(*args, **kwargs) self._closed = True def __repr__(self): if self._closed: return '<DBShelf @ 0x%x - closed>' % (id(self)) else: return repr(dict(self.iteritems())) def items(self, txn=None): if txn is not None: items = self.db.items(txn) else: items = self.db.items() newitems = [] for k, v in items: newitems.append( (k, cPickle.loads(v)) ) return newitems def values(self, txn=None): if txn is not None: values = self.db.values(txn) else: values = self.db.values() return map(cPickle.loads, values) #----------------------------------- # Other methods def __append(self, value, txn=None): data = _dumps(value, self.protocol) return self.db.append(data, txn) def append(self, value, txn=None): if self.get_type() == db.DB_RECNO: return self.__append(value, txn=txn) raise DBShelveError, "append() only supported when dbshelve opened with filetype=dbshelve.db.DB_RECNO" def associate(self, secondaryDB, callback, flags=0): def _shelf_callback(priKey, priData, realCallback=callback): # Safe in Python 2.x because expresion short circuit if sys.version_info[0] < 3 or isinstance(priData, bytes) : data = cPickle.loads(priData) else : data = cPickle.loads(bytes(priData, "iso8859-1")) # 8 bits return realCallback(priKey, data) return self.db.associate(secondaryDB, _shelf_callback, flags) #def get(self, key, default=None, txn=None, flags=0): def get(self, *args, **kw): # We do it with *args and **kw so if the default value wasn't # given nothing is passed to the extension module. That way # an exception can be raised if set_get_returns_none is turned # off. data = self.db.get(*args, **kw) try: return cPickle.loads(data) except (EOFError, TypeError, cPickle.UnpicklingError): return data # we may be getting the default value, or None, # so it doesn't need unpickled. def get_both(self, key, value, txn=None, flags=0): data = _dumps(value, self.protocol) data = self.db.get(key, data, txn, flags) return cPickle.loads(data) def cursor(self, txn=None, flags=0): c = DBShelfCursor(self.db.cursor(txn, flags)) c.protocol = self.protocol return c def put(self, key, value, txn=None, flags=0): data = _dumps(value, self.protocol) return self.db.put(key, data, txn, flags) def join(self, cursorList, flags=0): raise NotImplementedError #---------------------------------------------- # Methods allowed to pass-through to self.db # # close, delete, fd, get_byteswapped, get_type, has_key, # key_range, open, remove, rename, stat, sync, # upgrade, verify, and all set_* methods. #--------------------------------------------------------------------------- class DBShelfCursor: """ """ def __init__(self, cursor): self.dbc = cursor def __del__(self): self.close() def __getattr__(self, name): """Some methods we can just pass through to the cursor object. (See below)""" return getattr(self.dbc, name) #---------------------------------------------- def dup(self, flags=0): c = DBShelfCursor(self.dbc.dup(flags)) c.protocol = self.protocol return c def put(self, key, value, flags=0): data = _dumps(value, self.protocol) return self.dbc.put(key, data, flags) def get(self, *args): count = len(args) # a method overloading hack method = getattr(self, 'get_%d' % count) method(*args) def get_1(self, flags): rec = self.dbc.get(flags) return self._extract(rec) def get_2(self, key, flags): rec = self.dbc.get(key, flags) return self._extract(rec) def get_3(self, key, value, flags): data = _dumps(value, self.protocol) rec = self.dbc.get(key, flags) return self._extract(rec) def current(self, flags=0): return self.get_1(flags|db.DB_CURRENT) def first(self, flags=0): return self.get_1(flags|db.DB_FIRST) def last(self, flags=0): return self.get_1(flags|db.DB_LAST) def next(self, flags=0): return self.get_1(flags|db.DB_NEXT) def prev(self, flags=0): return self.get_1(flags|db.DB_PREV) def consume(self, flags=0): return self.get_1(flags|db.DB_CONSUME) def next_dup(self, flags=0): return self.get_1(flags|db.DB_NEXT_DUP) def next_nodup(self, flags=0): return self.get_1(flags|db.DB_NEXT_NODUP) def prev_nodup(self, flags=0): return self.get_1(flags|db.DB_PREV_NODUP) def get_both(self, key, value, flags=0): data = _dumps(value, self.protocol) rec = self.dbc.get_both(key, flags) return self._extract(rec) def set(self, key, flags=0): rec = self.dbc.set(key, flags) return self._extract(rec) def set_range(self, key, flags=0): rec = self.dbc.set_range(key, flags) return self._extract(rec) def set_recno(self, recno, flags=0): rec = self.dbc.set_recno(recno, flags) return self._extract(rec) set_both = get_both def _extract(self, rec): if rec is None: return None else: key, data = rec # Safe in Python 2.x because expresion short circuit if sys.version_info[0] < 3 or isinstance(data, bytes) : return key, cPickle.loads(data) else : return key, cPickle.loads(bytes(data, "iso8859-1")) # 8 bits #---------------------------------------------- # Methods allowed to pass-through to self.dbc # # close, count, delete, get_recno, join_item #---------------------------------------------------------------------------