1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
# -*- coding: utf-8 -*-
# dbwrapper.py
# Copyright (C) 2013 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Thread-safe wrapper for sqlite/pysqlcipher.
*TODO*
At some point we surely will want to switch to a twisted way of dealing
with this, using defers and proper callbacks. But I had this tested for
some time so postponing that refactor.
"""
import logging
import threading
import Queue
import time
import exceptions
from functools import partial
from leap.soledad import sqlcipher
logger = logging.getLogger(__name__)
class SQLCipherWrapper(threading.Thread):
def __init__(self, *args, **kwargs):
"""
Initializes a wrapper that proxies method and attribute
access to an underlying SQLCipher instance. We instantiate sqlcipher
in a thread, and all method accesses communicate with it using a
Queue.
:param *args: position arguments to pass to pysqlcipher initialization
:type args: tuple
:param **kwargs: keyword arguments to pass to pysqlcipher
initialization
:type kwargs: dict
"""
threading.Thread.__init__(self)
self._db = None
self._wrargs = args, kwargs
self._queue = Queue.Queue()
self._stopped = threading.Event()
self.start()
def _init_db(self):
"""
Initializes sqlcipher database.
This is called on a separate thread.
"""
# instantiate u1db
args, kwargs = self._wrargs
try:
self._db = sqlcipher.open(*args, **kwargs)
except Exception as exc:
logger.debug("Error in init_db: %r" % (exc,))
self._stopped.set()
raise exc
def run(self):
"""
Main loop for the sqlcipher thread.
"""
logger.debug("SQLCipherWrapper thread started.")
logger.debug("Initializing sqlcipher")
end_mths = ("__end_thread", "_SQLCipherWrapper__end_thread")
failed = False
try:
self._init_db()
except:
failed = True
self._lock = threading.Lock()
ct = 0
started = False
while not failed:
if self._db is None:
if started:
break
if ct > 10:
break # XXX DEBUG
logger.debug('db not ready yet, waiting...')
time.sleep(1)
ct += 1
started = True
with self._lock:
try:
mth, q, wrargs = self._queue.get()
except:
logger.error("exception getting args from queue")
res = None
attr = getattr(self._db, mth, None)
if not attr:
if mth not in end_mths:
logger.error('method %s does not exist' % (mth,))
res = AttributeError(
"_db instance has no attribute %s" % mth)
elif callable(attr):
# invoke the method with the passed args
args = wrargs.get('args', [])
kwargs = wrargs.get('kwargs', {})
try:
res = attr(*args, **kwargs)
except Exception as e:
logger.error(
"Error on proxied method %s: '%r'." % (
attr, e))
res = e
else:
# non-callable attribute
res = attr
logger.debug('returning proxied db call...')
q.put(res)
if mth in end_mths:
logger.debug('ending thread')
break
logger.debug("SQLCipherWrapper thread terminated.")
self._stopped.set()
def close(self):
"""
Closes the sqlcipher database and finishes the thread. This method
should always be called explicitely.
"""
self.__getattr__('close')()
self.__end_thread()
def __getattr__(self, attr):
"""
Returns _db proxied attributes.
"""
def __proxied_mth(method, *args, **kwargs):
if not self._stopped.isSet():
wrargs = {'args': args, 'kwargs': kwargs}
q = Queue.Queue()
self._queue.put((method, q, wrargs))
res = q.get()
q.task_done()
if isinstance(res, exceptions.BaseException):
# XXX should get the original bt
raise res
return res
else:
logger.warning("tried to call proxied meth "
"but stopped is set: %s" %
(method,))
rgetattr = object.__getattribute__
if attr != "_db":
proxied = partial(__proxied_mth, attr)
return proxied
# fallback to regular behavior
return rgetattr(self, attr)
def __del__(self):
"""
Do not trust this get called. No guarantees given. Because of a funny
dance with the refs and the way the gc works, we should be calling the
close method explicitely.
"""
self.close()
|