lib-python.2.5.bsddb.dbshelve.py Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jython Show documentation
Show all versions of jython Show documentation
Jython is an implementation of the high-level, dynamic, object-oriented
language Python written in 100% Pure Java, and seamlessly integrated with
the Java platform. It thus allows you to run Python on any Java platform.
#!/bin/env python
#------------------------------------------------------------------------
# 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 cPickle
try:
from UserDict import DictMixin
except ImportError:
# DictMixin is new in Python 2.3
class DictMixin: pass
import db
#------------------------------------------------------------------------
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(DictMixin):
"""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.binary = 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 = cPickle.dumps(value, self.binary)
self.db[key] = data
def __delitem__(self, key):
del self.db[key]
def keys(self, txn=None):
if txn != None:
return self.db.keys(txn)
else:
return self.db.keys()
def items(self, txn=None):
if txn != 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 != 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 = cPickle.dumps(value, self.binary)
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):
data = cPickle.loads(priData)
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 = apply(self.db.get, args, kw)
try:
return cPickle.loads(data)
except (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 = cPickle.dumps(value, self.binary)
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.binary = self.binary
return c
def put(self, key, value, txn=None, flags=0):
data = cPickle.dumps(value, self.binary)
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):
return DBShelfCursor(self.dbc.dup(flags))
def put(self, key, value, flags=0):
data = cPickle.dumps(value, self.binary)
return self.dbc.put(key, data, flags)
def get(self, *args):
count = len(args) # a method overloading hack
method = getattr(self, 'get_%d' % count)
apply(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 = cPickle.dumps(value, self.binary)
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 = cPickle.dumps(value, self.binary)
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
return key, cPickle.loads(data)
#----------------------------------------------
# Methods allowed to pass-through to self.dbc
#
# close, count, delete, get_recno, join_item
#---------------------------------------------------------------------------