author | Matt Mackall <mpm@selenic.com> |
Tue, 10 Oct 2006 02:31:02 -0500 | |
changeset 3322 | 38be819a1225 |
parent 2858 | 345bac2bc4ec |
child 3686 | 4308f4cdc07b |
permissions | -rw-r--r-- |
161 | 1 |
# lock.py - simple locking scheme for mercurial |
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# |
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# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
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# |
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# This software may be used and distributed according to the terms |
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# of the GNU General Public License, incorporated herein by reference. |
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||
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make lock module use demandload.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1787
diff
changeset
|
8 |
from demandload import * |
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parents:
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diff
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|
9 |
demandload(globals(), 'errno os socket time util') |
161 | 10 |
|
2016
ff5c9a92f556
fix backtrace printed when cannot get lock.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
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|
11 |
class LockException(IOError): |
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parents:
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|
12 |
def __init__(self, errno, strerror, filename, desc): |
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parents:
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13 |
IOError.__init__(self, errno, strerror, filename) |
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parents:
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|
14 |
self.desc = desc |
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
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|
15 |
|
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e6e70450edb9
Raise a different exception when the lock is not available
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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diff
changeset
|
16 |
class LockHeld(LockException): |
2016
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parents:
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17 |
def __init__(self, errno, filename, desc, locker): |
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parents:
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|
18 |
LockException.__init__(self, errno, 'Lock held', filename, desc) |
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parents:
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self.locker = locker |
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parents:
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20 |
|
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Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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diff
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|
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class LockUnavailable(LockException): |
161 | 22 |
pass |
23 |
||
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Convert all classes to new-style classes by deriving them from object.
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class lock(object): |
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parents:
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25 |
# lock is symlink on platforms that support it, file on others. |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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26 |
|
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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|
27 |
# symlink is used because create of directory entry and contents |
d314a89fa4f1
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parents:
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# are atomic even over nfs. |
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parents:
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29 |
|
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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|
30 |
# old-style lock: symlink to pid |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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|
31 |
# new-style lock: symlink to hostname:pid |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
32 |
|
2016
ff5c9a92f556
fix backtrace printed when cannot get lock.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1877
diff
changeset
|
33 |
def __init__(self, file, timeout=-1, releasefn=None, desc=None): |
161 | 34 |
self.f = file |
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self.held = 0 |
|
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add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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36 |
self.timeout = timeout |
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add a releasefn keyword to lock.lock
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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37 |
self.releasefn = releasefn |
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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self.id = None |
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parents:
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self.host = None |
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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|
40 |
self.pid = None |
2016
ff5c9a92f556
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1877
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|
41 |
self.desc = desc |
161 | 42 |
self.lock() |
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def __del__(self): |
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self.release() |
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||
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def lock(self): |
|
1787
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Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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48 |
timeout = self.timeout |
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while 1: |
50 |
try: |
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self.trylock() |
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return 1 |
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except LockHeld, inst: |
|
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add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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changeset
|
54 |
if timeout != 0: |
161 | 55 |
time.sleep(1) |
1787
e431344e604c
add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
1753
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changeset
|
56 |
if timeout > 0: |
e431344e604c
add a timeout when a lock is held (default 1024 sec)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
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diff
changeset
|
57 |
timeout -= 1 |
161 | 58 |
continue |
2016
ff5c9a92f556
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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changeset
|
59 |
raise LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
ff5c9a92f556
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
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60 |
inst.locker) |
515 | 61 |
|
161 | 62 |
def trylock(self): |
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parents:
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63 |
if self.id is None: |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
64 |
self.host = socket.gethostname() |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
65 |
self.pid = os.getpid() |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
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66 |
self.id = '%s:%s' % (self.host, self.pid) |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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changeset
|
67 |
while not self.held: |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
68 |
try: |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
69 |
util.makelock(self.id, self.f) |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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changeset
|
70 |
self.held = 1 |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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changeset
|
71 |
except (OSError, IOError), why: |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
72 |
if why.errno == errno.EEXIST: |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
73 |
locker = self.testlock() |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
74 |
if locker: |
2016
ff5c9a92f556
fix backtrace printed when cannot get lock.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1877
diff
changeset
|
75 |
raise LockHeld(errno.EAGAIN, self.f, self.desc, |
ff5c9a92f556
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1877
diff
changeset
|
76 |
locker) |
1877
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
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77 |
else: |
2016
ff5c9a92f556
fix backtrace printed when cannot get lock.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1877
diff
changeset
|
78 |
raise LockUnavailable(why.errno, why.strerror, |
ff5c9a92f556
fix backtrace printed when cannot get lock.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1877
diff
changeset
|
79 |
why.filename, self.desc) |
1877
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
80 |
|
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
81 |
def testlock(self): |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
82 |
'''return id of locker if lock is valid, else None.''' |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
83 |
# if old-style lock, we cannot tell what machine locker is on. |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
84 |
# with new-style lock, if locker is on this machine, we can |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
85 |
# see if locker is alive. if locker is on this machine but |
d314a89fa4f1
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
86 |
# not alive, we can safely break lock. |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
87 |
locker = util.readlock(self.f) |
2579
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
88 |
try: |
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
89 |
host, pid = locker.split(":", 1) |
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
90 |
except ValueError: |
1877
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Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
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diff
changeset
|
91 |
return locker |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
92 |
if host != self.host: |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
93 |
return locker |
161 | 94 |
try: |
2579
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
95 |
pid = int(pid) |
1877
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
96 |
except: |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
97 |
return locker |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
98 |
if util.testpid(pid): |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
99 |
return locker |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
100 |
# if locker dead, break lock. must do this with another lock |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
101 |
# held, or can race and break valid lock. |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
102 |
try: |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
103 |
l = lock(self.f + '.break') |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
104 |
l.trylock() |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
105 |
os.unlink(self.f) |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
106 |
l.release() |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
107 |
except (LockHeld, LockUnavailable): |
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
108 |
return locker |
161 | 109 |
|
110 |
def release(self): |
|
111 |
if self.held: |
|
112 |
self.held = 0 |
|
1530
abfab59fce79
add a releasefn keyword to lock.lock
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
1062
diff
changeset
|
113 |
if self.releasefn: |
abfab59fce79
add a releasefn keyword to lock.lock
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
1062
diff
changeset
|
114 |
self.releasefn() |
503
c6a2e41c8c60
Fix troubles with clone and exception handling
mpm@selenic.com
parents:
429
diff
changeset
|
115 |
try: |
c6a2e41c8c60
Fix troubles with clone and exception handling
mpm@selenic.com
parents:
429
diff
changeset
|
116 |
os.unlink(self.f) |
c6a2e41c8c60
Fix troubles with clone and exception handling
mpm@selenic.com
parents:
429
diff
changeset
|
117 |
except: pass |
161 | 118 |