author | Pierre-Yves David <pierre-yves.david@ens-lyon.org> |
Thu, 03 Nov 2016 05:10:14 +0100 | |
changeset 30280 | 0269ab4f4371 |
parent 28959 | 518c3e392f75 |
child 30920 | dc9f086c7691 |
permissions | -rw-r--r-- |
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# lock.py - simple advisory 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 of the |
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# GNU General Public License version 2 or any later version. |
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|
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from __future__ import absolute_import |
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import contextlib |
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import errno |
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import socket |
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import time |
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import warnings |
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|
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from . import ( |
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error, |
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util, |
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) |
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|
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class lock(object): |
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'''An advisory lock held by one process to control access to a set |
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of files. Non-cooperating processes or incorrectly written scripts |
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can ignore Mercurial's locking scheme and stomp all over the |
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repository, so don't do that. |
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|
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Typically used via localrepository.lock() to lock the repository |
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store (.hg/store/) or localrepository.wlock() to lock everything |
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else under .hg/.''' |
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# lock is symlink on platforms that support it, file on others. |
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# symlink is used because create of directory entry and contents |
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# are atomic even over nfs. |
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# old-style lock: symlink to pid |
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# new-style lock: symlink to hostname:pid |
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_host = None |
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def __init__(self, vfs, file, timeout=-1, releasefn=None, acquirefn=None, |
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desc=None, inheritchecker=None, parentlock=None): |
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self.vfs = vfs |
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self.f = file |
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self.held = 0 |
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self.timeout = timeout |
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self.releasefn = releasefn |
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self.acquirefn = acquirefn |
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self.desc = desc |
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self._inheritchecker = inheritchecker |
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self.parentlock = parentlock |
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self._parentheld = False |
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self._inherited = False |
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self.postrelease = [] |
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self.pid = self._getpid() |
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self.delay = self.lock() |
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if self.acquirefn: |
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self.acquirefn() |
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def __enter__(self): |
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return self |
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def __exit__(self, exc_type, exc_value, exc_tb): |
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self.release() |
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def __del__(self): |
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if self.held: |
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warnings.warn("use lock.release instead of del lock", |
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category=DeprecationWarning, |
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stacklevel=2) |
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|
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# ensure the lock will be removed |
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# even if recursive locking did occur |
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self.held = 1 |
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self.release() |
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||
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def _getpid(self): |
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# wrapper around util.getpid() to make testing easier |
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return util.getpid() |
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def lock(self): |
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timeout = self.timeout |
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while True: |
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try: |
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self._trylock() |
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return self.timeout - timeout |
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except error.LockHeld as inst: |
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if timeout != 0: |
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time.sleep(1) |
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if timeout > 0: |
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timeout -= 1 |
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continue |
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raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
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inst.locker) |
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def _trylock(self): |
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if self.held: |
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self.held += 1 |
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return |
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if lock._host is None: |
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lock._host = socket.gethostname() |
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lockname = '%s:%s' % (lock._host, self.pid) |
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retry = 5 |
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while not self.held and retry: |
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retry -= 1 |
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try: |
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self.vfs.makelock(lockname, self.f) |
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self.held = 1 |
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except (OSError, IOError) as why: |
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if why.errno == errno.EEXIST: |
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locker = self._readlock() |
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# special case where a parent process holds the lock -- this |
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# is different from the pid being different because we do |
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# want the unlock and postrelease functions to be called, |
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# but the lockfile to not be removed. |
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if locker == self.parentlock: |
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self._parentheld = True |
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self.held = 1 |
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return |
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locker = self._testlock(locker) |
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if locker is not None: |
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raise error.LockHeld(errno.EAGAIN, |
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|
124 |
self.vfs.join(self.f), self.desc, |
7640 | 125 |
locker) |
1877
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diff
changeset
|
126 |
else: |
7640 | 127 |
raise error.LockUnavailable(why.errno, why.strerror, |
128 |
why.filename, self.desc) |
|
1877
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parents:
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diff
changeset
|
129 |
|
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diff
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|
130 |
def _readlock(self): |
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parents:
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changeset
|
131 |
"""read lock and return its value |
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parents:
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diff
changeset
|
132 |
|
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|
133 |
Returns None if no lock exists, pid for old-style locks, and host:pid |
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diff
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|
134 |
for new-style locks. |
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|
135 |
""" |
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changeset
|
136 |
try: |
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parents:
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diff
changeset
|
137 |
return self.vfs.readlock(self.f) |
9664d32bd6cb
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parents:
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diff
changeset
|
138 |
except (OSError, IOError) as why: |
9664d32bd6cb
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parents:
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diff
changeset
|
139 |
if why.errno == errno.ENOENT: |
9664d32bd6cb
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parents:
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diff
changeset
|
140 |
return None |
9664d32bd6cb
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parents:
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diff
changeset
|
141 |
raise |
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parents:
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diff
changeset
|
142 |
|
26291
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parents:
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diff
changeset
|
143 |
def _testlock(self, locker): |
26290
9664d32bd6cb
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parents:
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changeset
|
144 |
if locker is None: |
9664d32bd6cb
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parents:
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diff
changeset
|
145 |
return None |
2579
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
146 |
try: |
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
147 |
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
|
148 |
except ValueError: |
1877
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parents:
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diff
changeset
|
149 |
return locker |
4947
3e25a6eb5c9a
lock.py: cache hostname, but not pid, in case we fork
Bryan O'Sullivan <bos@serpentine.com>
parents:
3877
diff
changeset
|
150 |
if host != lock._host: |
1877
d314a89fa4f1
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parents:
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diff
changeset
|
151 |
return locker |
161 | 152 |
try: |
2579
0875cda033fd
use __contains__, index or split instead of str.find
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
2016
diff
changeset
|
153 |
pid = int(pid) |
9685
a820cd39d415
lock: catch specific exceptions
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
9680
diff
changeset
|
154 |
except ValueError: |
1877
d314a89fa4f1
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parents:
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diff
changeset
|
155 |
return locker |
d314a89fa4f1
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parents:
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diff
changeset
|
156 |
if util.testpid(pid): |
d314a89fa4f1
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parents:
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diff
changeset
|
157 |
return locker |
d314a89fa4f1
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parents:
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diff
changeset
|
158 |
# if locker dead, break lock. must do this with another lock |
d314a89fa4f1
change lock format to let us detect and break stale locks.
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parents:
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diff
changeset
|
159 |
# held, or can race and break valid lock. |
d314a89fa4f1
change lock format to let us detect and break stale locks.
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parents:
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diff
changeset
|
160 |
try: |
20091
abfe6a8e619b
lock: take both vfs and lock file path relative to vfs to access via vfs
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents:
19927
diff
changeset
|
161 |
l = lock(self.vfs, self.f + '.break', timeout=0) |
abfe6a8e619b
lock: take both vfs and lock file path relative to vfs to access via vfs
FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
parents:
19927
diff
changeset
|
162 |
self.vfs.unlink(self.f) |
1877
d314a89fa4f1
change lock format to let us detect and break stale locks.
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parents:
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diff
changeset
|
163 |
l.release() |
7640 | 164 |
except error.LockError: |
1877
d314a89fa4f1
change lock format to let us detect and break stale locks.
Vadim Gelfer <vadim.gelfer@gmail.com>
parents:
1836
diff
changeset
|
165 |
return locker |
161 | 166 |
|
26291
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
167 |
def testlock(self): |
1d33842c5b3e
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parents:
26290
diff
changeset
|
168 |
"""return id of locker if lock is valid, else None. |
1d33842c5b3e
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parents:
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diff
changeset
|
169 |
|
1d33842c5b3e
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parents:
26290
diff
changeset
|
170 |
If old-style lock, we cannot tell what machine locker is on. |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
171 |
with new-style lock, if locker is on this machine, we can |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
172 |
see if locker is alive. If locker is on this machine but |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
173 |
not alive, we can safely break lock. |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
174 |
|
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
175 |
The lock file is only deleted when None is returned. |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
176 |
|
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
177 |
""" |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
178 |
locker = self._readlock() |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
179 |
return self._testlock(locker) |
1d33842c5b3e
lock: factor out lock testing into a separate function
Siddharth Agarwal <sid0@fb.com>
parents:
26290
diff
changeset
|
180 |
|
26473
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
181 |
@contextlib.contextmanager |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
182 |
def inherit(self): |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
183 |
"""context for the lock to be inherited by a Mercurial subprocess. |
26357
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
184 |
|
26473
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
185 |
Yields a string that will be recognized by the lock in the subprocess. |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
186 |
Communicating this string to the subprocess needs to be done separately |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
187 |
-- typically by an environment variable. |
26357
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
188 |
""" |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
189 |
if not self.held: |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
190 |
raise error.LockInheritanceContractViolation( |
26473
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
191 |
'inherit can only be called while lock is held') |
26357
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
192 |
if self._inherited: |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
193 |
raise error.LockInheritanceContractViolation( |
26473
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
194 |
'inherit cannot be called while lock is already inherited') |
26498
e8564e04382d
lock: add a way to prevent locks from being inherited
Siddharth Agarwal <sid0@fb.com>
parents:
26474
diff
changeset
|
195 |
if self._inheritchecker is not None: |
e8564e04382d
lock: add a way to prevent locks from being inherited
Siddharth Agarwal <sid0@fb.com>
parents:
26474
diff
changeset
|
196 |
self._inheritchecker() |
26357
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
197 |
if self.releasefn: |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
198 |
self.releasefn() |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
199 |
if self._parentheld: |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
200 |
lockname = self.parentlock |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
201 |
else: |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
202 |
lockname = '%s:%s' % (lock._host, self.pid) |
6979a1369185
lock: add a method to prepare the lock for inheritance
Siddharth Agarwal <sid0@fb.com>
parents:
26356
diff
changeset
|
203 |
self._inherited = True |
26473
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
204 |
try: |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
205 |
yield lockname |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
206 |
finally: |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
207 |
if self.acquirefn: |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
208 |
self.acquirefn() |
5f94e64f182c
lock: turn prepinherit/reacquire into a single context manager
Siddharth Agarwal <sid0@fb.com>
parents:
26387
diff
changeset
|
209 |
self._inherited = False |
26358
de5a52e5eb9e
lock: add a method to reacquire the lock after subprocesses exit
Siddharth Agarwal <sid0@fb.com>
parents:
26357
diff
changeset
|
210 |
|
161 | 211 |
def release(self): |
15583
926a06f7a353
lock: add mechanism to register post release callback
Pierre-Yves David <pierre-yves.david@ens-lyon.org>
parents:
14494
diff
changeset
|
212 |
"""release the lock and execute callback function if any |
926a06f7a353
lock: add mechanism to register post release callback
Pierre-Yves David <pierre-yves.david@ens-lyon.org>
parents:
14494
diff
changeset
|
213 |
|
17537 | 214 |
If the lock has been acquired multiple times, the actual release is |
17510 | 215 |
delayed to the last release call.""" |
8108
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
216 |
if self.held > 1: |
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
217 |
self.held -= 1 |
9680
8cea86d73887
lock: use '==' instead of 'is' for integer equality ('is' may not work)
Benoit Boissinot <benoit.boissinot@ens-lyon.org>
parents:
9309
diff
changeset
|
218 |
elif self.held == 1: |
161 | 219 |
self.held = 0 |
26383
0fceb34806e1
lock: add a wrapper to os.getpid() to make testing easier
Siddharth Agarwal <sid0@fb.com>
parents:
26359
diff
changeset
|
220 |
if self._getpid() != self.pid: |
18907
af9fa8d4c939
lock: if we fork, ensure that only the parent releases
Bryan O'Sullivan <bryano@fb.com>
parents:
17683
diff
changeset
|
221 |
# we forked, and are not the parent |
af9fa8d4c939
lock: if we fork, ensure that only the parent releases
Bryan O'Sullivan <bryano@fb.com>
parents:
17683
diff
changeset
|
222 |
return |
503
c6a2e41c8c60
Fix troubles with clone and exception handling
mpm@selenic.com
parents:
429
diff
changeset
|
223 |
try: |
23032
f484be02bd35
lock: while releasing, unlink lockfile even if the release function throws
Siddharth Agarwal <sid0@fb.com>
parents:
20380
diff
changeset
|
224 |
if self.releasefn: |
f484be02bd35
lock: while releasing, unlink lockfile even if the release function throws
Siddharth Agarwal <sid0@fb.com>
parents:
20380
diff
changeset
|
225 |
self.releasefn() |
f484be02bd35
lock: while releasing, unlink lockfile even if the release function throws
Siddharth Agarwal <sid0@fb.com>
parents:
20380
diff
changeset
|
226 |
finally: |
26359
c545d51c901e
lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26358
diff
changeset
|
227 |
if not self._parentheld: |
c545d51c901e
lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26358
diff
changeset
|
228 |
try: |
c545d51c901e
lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26358
diff
changeset
|
229 |
self.vfs.unlink(self.f) |
c545d51c901e
lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26358
diff
changeset
|
230 |
except OSError: |
c545d51c901e
lock.release: do not unlink inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26358
diff
changeset
|
231 |
pass |
26474
431094a3b21f
lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26473
diff
changeset
|
232 |
# The postrelease functions typically assume the lock is not held |
431094a3b21f
lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26473
diff
changeset
|
233 |
# at all. |
431094a3b21f
lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26473
diff
changeset
|
234 |
if not self._parentheld: |
431094a3b21f
lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26473
diff
changeset
|
235 |
for callback in self.postrelease: |
431094a3b21f
lock.release: don't call postrelease functions for inherited locks
Siddharth Agarwal <sid0@fb.com>
parents:
26473
diff
changeset
|
236 |
callback() |
28959
518c3e392f75
lock: clear postrelease hooks list after usage
Gregory Szorc <gregory.szorc@gmail.com>
parents:
28027
diff
changeset
|
237 |
# Prevent double usage and help clear cycles. |
518c3e392f75
lock: clear postrelease hooks list after usage
Gregory Szorc <gregory.szorc@gmail.com>
parents:
28027
diff
changeset
|
238 |
self.postrelease = None |
161 | 239 |
|
8108
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
240 |
def release(*locks): |
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
241 |
for lock in locks: |
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
242 |
if lock is not None: |
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
243 |
lock.release() |