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#! /usr/bin/env python2.4
#------------------------------------------------------------------------
# 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 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:
self.append = self.__append
return self.append(value, txn=txn)
raise db.DBError, "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
#---------------------------------------------------------------------------
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