source: python/trunk/Lib/bsddb/dbshelve.py@ 388

Last change on this file since 388 was 10, checked in by Yuri Dario, 15 years ago

python: merged offline changes.
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1#!/usr/bin/env python
2#------------------------------------------------------------------------
3# Copyright (c) 1997-2001 by Total Control Software
4# All Rights Reserved
5#------------------------------------------------------------------------
6#
7# Module Name: dbShelve.py
8#
9# Description: A reimplementation of the standard shelve.py that
10# forces the use of cPickle, and DB.
11#
12# Creation Date: 11/3/97 3:39:04PM
13#
14# License: This is free software. You may use this software for any
15# purpose including modification/redistribution, so long as
16# this header remains intact and that you do not claim any
17# rights of ownership or authorship of this software. This
18# software has been tested, but no warranty is expressed or
19# implied.
20#
21# 13-Dec-2000: Updated to be used with the new bsddb3 package.
22# Added DBShelfCursor class.
23#
24#------------------------------------------------------------------------
25
26"""Manage shelves of pickled objects using bsddb database files for the
27storage.
28"""
29
30#------------------------------------------------------------------------
31
32import cPickle
33import sys
34
35import sys
36absolute_import = (sys.version_info[0] >= 3)
37if absolute_import :
38 # Because this syntaxis is not valid before Python 2.5
39 exec("from . import db")
40else :
41 import db
42
43#At version 2.3 cPickle switched to using protocol instead of bin
44if sys.version_info[:3] >= (2, 3, 0):
45 HIGHEST_PROTOCOL = cPickle.HIGHEST_PROTOCOL
46# In python 2.3.*, "cPickle.dumps" accepts no
47# named parameters. "pickle.dumps" accepts them,
48# so this seems a bug.
49 if sys.version_info[:3] < (2, 4, 0):
50 def _dumps(object, protocol):
51 return cPickle.dumps(object, protocol)
52 else :
53 def _dumps(object, protocol):
54 return cPickle.dumps(object, protocol=protocol)
55
56else:
57 HIGHEST_PROTOCOL = None
58 def _dumps(object, protocol):
59 return cPickle.dumps(object, bin=protocol)
60
61
62try:
63 from UserDict import DictMixin
64except ImportError:
65 # DictMixin is new in Python 2.3
66 class DictMixin: pass
67
68#------------------------------------------------------------------------
69
70
71def open(filename, flags=db.DB_CREATE, mode=0660, filetype=db.DB_HASH,
72 dbenv=None, dbname=None):
73 """
74 A simple factory function for compatibility with the standard
75 shleve.py module. It can be used like this, where key is a string
76 and data is a pickleable object:
77
78 from bsddb import dbshelve
79 db = dbshelve.open(filename)
80
81 db[key] = data
82
83 db.close()
84 """
85 if type(flags) == type(''):
86 sflag = flags
87 if sflag == 'r':
88 flags = db.DB_RDONLY
89 elif sflag == 'rw':
90 flags = 0
91 elif sflag == 'w':
92 flags = db.DB_CREATE
93 elif sflag == 'c':
94 flags = db.DB_CREATE
95 elif sflag == 'n':
96 flags = db.DB_TRUNCATE | db.DB_CREATE
97 else:
98 raise db.DBError, "flags should be one of 'r', 'w', 'c' or 'n' or use the bsddb.db.DB_* flags"
99
100 d = DBShelf(dbenv)
101 d.open(filename, dbname, filetype, flags, mode)
102 return d
103
104#---------------------------------------------------------------------------
105
106class DBShelveError(db.DBError): pass
107
108
109class DBShelf(DictMixin):
110 """A shelf to hold pickled objects, built upon a bsddb DB object. It
111 automatically pickles/unpickles data objects going to/from the DB.
112 """
113 def __init__(self, dbenv=None):
114 self.db = db.DB(dbenv)
115 self._closed = True
116 if HIGHEST_PROTOCOL:
117 self.protocol = HIGHEST_PROTOCOL
118 else:
119 self.protocol = 1
120
121
122 def __del__(self):
123 self.close()
124
125
126 def __getattr__(self, name):
127 """Many methods we can just pass through to the DB object.
128 (See below)
129 """
130 return getattr(self.db, name)
131
132
133 #-----------------------------------
134 # Dictionary access methods
135
136 def __len__(self):
137 return len(self.db)
138
139
140 def __getitem__(self, key):
141 data = self.db[key]
142 return cPickle.loads(data)
143
144
145 def __setitem__(self, key, value):
146 data = _dumps(value, self.protocol)
147 self.db[key] = data
148
149
150 def __delitem__(self, key):
151 del self.db[key]
152
153
154 def keys(self, txn=None):
155 if txn != None:
156 return self.db.keys(txn)
157 else:
158 return self.db.keys()
159
160
161 def open(self, *args, **kwargs):
162 self.db.open(*args, **kwargs)
163 self._closed = False
164
165
166 def close(self, *args, **kwargs):
167 self.db.close(*args, **kwargs)
168 self._closed = True
169
170
171 def __repr__(self):
172 if self._closed:
173 return '<DBShelf @ 0x%x - closed>' % (id(self))
174 else:
175 return repr(dict(self.iteritems()))
176
177
178 def items(self, txn=None):
179 if txn != None:
180 items = self.db.items(txn)
181 else:
182 items = self.db.items()
183 newitems = []
184
185 for k, v in items:
186 newitems.append( (k, cPickle.loads(v)) )
187 return newitems
188
189 def values(self, txn=None):
190 if txn != None:
191 values = self.db.values(txn)
192 else:
193 values = self.db.values()
194
195 return map(cPickle.loads, values)
196
197 #-----------------------------------
198 # Other methods
199
200 def __append(self, value, txn=None):
201 data = _dumps(value, self.protocol)
202 return self.db.append(data, txn)
203
204 def append(self, value, txn=None):
205 if self.get_type() == db.DB_RECNO:
206 return self.__append(value, txn=txn)
207 raise DBShelveError, "append() only supported when dbshelve opened with filetype=dbshelve.db.DB_RECNO"
208
209
210 def associate(self, secondaryDB, callback, flags=0):
211 def _shelf_callback(priKey, priData, realCallback=callback):
212 # Safe in Python 2.x because expresion short circuit
213 if sys.version_info[0] < 3 or isinstance(priData, bytes) :
214 data = cPickle.loads(priData)
215 else :
216 data = cPickle.loads(bytes(priData, "iso8859-1")) # 8 bits
217 return realCallback(priKey, data)
218
219 return self.db.associate(secondaryDB, _shelf_callback, flags)
220
221
222 #def get(self, key, default=None, txn=None, flags=0):
223 def get(self, *args, **kw):
224 # We do it with *args and **kw so if the default value wasn't
225 # given nothing is passed to the extension module. That way
226 # an exception can be raised if set_get_returns_none is turned
227 # off.
228 data = apply(self.db.get, args, kw)
229 try:
230 return cPickle.loads(data)
231 except (EOFError, TypeError, cPickle.UnpicklingError):
232 return data # we may be getting the default value, or None,
233 # so it doesn't need unpickled.
234
235 def get_both(self, key, value, txn=None, flags=0):
236 data = _dumps(value, self.protocol)
237 data = self.db.get(key, data, txn, flags)
238 return cPickle.loads(data)
239
240
241 def cursor(self, txn=None, flags=0):
242 c = DBShelfCursor(self.db.cursor(txn, flags))
243 c.protocol = self.protocol
244 return c
245
246
247 def put(self, key, value, txn=None, flags=0):
248 data = _dumps(value, self.protocol)
249 return self.db.put(key, data, txn, flags)
250
251
252 def join(self, cursorList, flags=0):
253 raise NotImplementedError
254
255
256 #----------------------------------------------
257 # Methods allowed to pass-through to self.db
258 #
259 # close, delete, fd, get_byteswapped, get_type, has_key,
260 # key_range, open, remove, rename, stat, sync,
261 # upgrade, verify, and all set_* methods.
262
263
264#---------------------------------------------------------------------------
265
266class DBShelfCursor:
267 """
268 """
269 def __init__(self, cursor):
270 self.dbc = cursor
271
272 def __del__(self):
273 self.close()
274
275
276 def __getattr__(self, name):
277 """Some methods we can just pass through to the cursor object. (See below)"""
278 return getattr(self.dbc, name)
279
280
281 #----------------------------------------------
282
283 def dup(self, flags=0):
284 c = DBShelfCursor(self.dbc.dup(flags))
285 c.protocol = self.protocol
286 return c
287
288
289 def put(self, key, value, flags=0):
290 data = _dumps(value, self.protocol)
291 return self.dbc.put(key, data, flags)
292
293
294 def get(self, *args):
295 count = len(args) # a method overloading hack
296 method = getattr(self, 'get_%d' % count)
297 apply(method, args)
298
299 def get_1(self, flags):
300 rec = self.dbc.get(flags)
301 return self._extract(rec)
302
303 def get_2(self, key, flags):
304 rec = self.dbc.get(key, flags)
305 return self._extract(rec)
306
307 def get_3(self, key, value, flags):
308 data = _dumps(value, self.protocol)
309 rec = self.dbc.get(key, flags)
310 return self._extract(rec)
311
312
313 def current(self, flags=0): return self.get_1(flags|db.DB_CURRENT)
314 def first(self, flags=0): return self.get_1(flags|db.DB_FIRST)
315 def last(self, flags=0): return self.get_1(flags|db.DB_LAST)
316 def next(self, flags=0): return self.get_1(flags|db.DB_NEXT)
317 def prev(self, flags=0): return self.get_1(flags|db.DB_PREV)
318 def consume(self, flags=0): return self.get_1(flags|db.DB_CONSUME)
319 def next_dup(self, flags=0): return self.get_1(flags|db.DB_NEXT_DUP)
320 def next_nodup(self, flags=0): return self.get_1(flags|db.DB_NEXT_NODUP)
321 def prev_nodup(self, flags=0): return self.get_1(flags|db.DB_PREV_NODUP)
322
323
324 def get_both(self, key, value, flags=0):
325 data = _dumps(value, self.protocol)
326 rec = self.dbc.get_both(key, flags)
327 return self._extract(rec)
328
329
330 def set(self, key, flags=0):
331 rec = self.dbc.set(key, flags)
332 return self._extract(rec)
333
334 def set_range(self, key, flags=0):
335 rec = self.dbc.set_range(key, flags)
336 return self._extract(rec)
337
338 def set_recno(self, recno, flags=0):
339 rec = self.dbc.set_recno(recno, flags)
340 return self._extract(rec)
341
342 set_both = get_both
343
344 def _extract(self, rec):
345 if rec is None:
346 return None
347 else:
348 key, data = rec
349 # Safe in Python 2.x because expresion short circuit
350 if sys.version_info[0] < 3 or isinstance(data, bytes) :
351 return key, cPickle.loads(data)
352 else :
353 return key, cPickle.loads(bytes(data, "iso8859-1")) # 8 bits
354
355 #----------------------------------------------
356 # Methods allowed to pass-through to self.dbc
357 #
358 # close, count, delete, get_recno, join_item
359
360
361#---------------------------------------------------------------------------
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