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
193
194
195
196
197
198
199
200
201
202
203
204
205
206
|
# Vendored up-to-date copy of locket.py
# Based on https://github.com/mwilliamson/locket.py/pull/8
# flake8: noqa
import time
import errno
import threading
import weakref
__all__ = ["lock_file"]
try:
import fcntl
except ImportError:
try:
import ctypes
import ctypes.wintypes
import msvcrt
except ImportError:
raise ImportError(
"Platform not supported (failed to import fcntl, ctypes, msvcrt)"
)
else:
_kernel32 = ctypes.WinDLL("kernel32", use_last_error=True)
_WinAPI_LockFile = _kernel32.LockFile
_WinAPI_LockFile.restype = ctypes.wintypes.BOOL
_WinAPI_LockFile.argtypes = [ctypes.wintypes.HANDLE] + [
ctypes.wintypes.DWORD
] * 4
_WinAPI_UnlockFile = _kernel32.UnlockFile
_WinAPI_UnlockFile.restype = ctypes.wintypes.BOOL
_WinAPI_UnlockFile.argtypes = [ctypes.wintypes.HANDLE] + [
ctypes.wintypes.DWORD
] * 4
_lock_file_blocking_available = False
def _lock_file_non_blocking(file_):
res = _WinAPI_LockFile(msvcrt.get_osfhandle(file_.fileno()), 0, 0, 1, 0)
if res:
return True
else:
err = ctypes.get_last_error()
# 33 = ERROR_LOCK_VIOLATION
if err != 33:
raise ctypes.WinError(err)
return False
def _unlock_file(file_):
_WinAPI_UnlockFile(msvcrt.get_osfhandle(file_.fileno()), 0, 0, 1, 0)
else:
_lock_file_blocking_available = True
def _lock_file_blocking(file_):
fcntl.flock(file_.fileno(), fcntl.LOCK_EX)
def _lock_file_non_blocking(file_):
try:
fcntl.flock(file_.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
return True
except IOError as error:
if error.errno in [errno.EACCES, errno.EAGAIN]:
return False
else:
raise
def _unlock_file(file_):
fcntl.flock(file_.fileno(), fcntl.LOCK_UN)
_locks_lock = threading.Lock()
_locks = weakref.WeakValueDictionary()
def lock_file(path, **kwargs):
_locks_lock.acquire()
try:
lock = _locks.get(path)
if lock is None:
lock = _create_lock_file(path)
_locks[path] = lock
finally:
_locks_lock.release()
return _Locker(lock, **kwargs)
def _create_lock_file(path):
thread_lock = _ThreadLock(path)
file_lock = _LockFile(path)
return _LockSet([thread_lock, file_lock])
class LockError(Exception):
pass
def _acquire_non_blocking(acquire, timeout, retry_period, path):
if retry_period is None:
retry_period = 0.05
start_time = time.time()
while True:
success = acquire()
if success:
return
elif timeout is not None and time.time() - start_time > timeout:
raise LockError("Couldn't lock {0}".format(path))
else:
time.sleep(retry_period)
class _LockSet:
def __init__(self, locks):
self._locks = locks
def acquire(self, timeout, retry_period):
acquired_locks = []
try:
for lock in self._locks:
lock.acquire(timeout, retry_period)
acquired_locks.append(lock)
except:
for acquired_lock in reversed(acquired_locks):
# TODO: handle exceptions
acquired_lock.release()
raise
def release(self):
for lock in reversed(self._locks):
# TODO: Handle exceptions
lock.release()
class _ThreadLock:
def __init__(self, path):
self._path = path
self._lock = threading.Lock()
def acquire(self, timeout=None, retry_period=None):
if timeout is None:
self._lock.acquire()
else:
_acquire_non_blocking(
acquire=lambda: self._lock.acquire(False),
timeout=timeout,
retry_period=retry_period,
path=self._path,
)
def release(self):
self._lock.release()
class _LockFile:
def __init__(self, path):
self._path = path
self._file = None
self._thread_lock = threading.Lock()
def acquire(self, timeout=None, retry_period=None):
if self._file is None:
self._file = open(self._path, "wb")
if timeout is None and _lock_file_blocking_available:
_lock_file_blocking(self._file)
else:
_acquire_non_blocking(
acquire=lambda: _lock_file_non_blocking(self._file),
timeout=timeout,
retry_period=retry_period,
path=self._path,
)
def release(self):
_unlock_file(self._file)
self._file.close()
self._file = None
class _Locker:
"""
A lock wrapper to always apply the given *timeout* and *retry_period*
to acquire() calls.
"""
def __init__(self, lock, timeout=None, retry_period=None):
self._lock = lock
self._timeout = timeout
self._retry_period = retry_period
def acquire(self):
self._lock.acquire(self._timeout, self._retry_period)
def release(self):
self._lock.release()
def __enter__(self):
self.acquire()
return self
def __exit__(self, *args):
self.release()
|
