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@@ -1,251 +1,261 b'' | |||||
1 | # lock.py - simple advisory locking scheme for mercurial |
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1 | # lock.py - simple advisory locking scheme for mercurial | |
2 | # |
|
2 | # | |
3 | # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
|
3 | # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> | |
4 | # |
|
4 | # | |
5 | # This software may be used and distributed according to the terms of the |
|
5 | # This software may be used and distributed according to the terms of the | |
6 | # GNU General Public License version 2 or any later version. |
|
6 | # GNU General Public License version 2 or any later version. | |
7 |
|
7 | |||
8 | from __future__ import absolute_import |
|
8 | from __future__ import absolute_import | |
9 |
|
9 | |||
10 | import contextlib |
|
10 | import contextlib | |
11 | import errno |
|
11 | import errno | |
|
12 | import os | |||
12 | import socket |
|
13 | import socket | |
13 | import time |
|
14 | import time | |
14 | import warnings |
|
15 | import warnings | |
15 |
|
16 | |||
16 | from . import ( |
|
17 | from . import ( | |
17 | error, |
|
18 | error, | |
|
19 | pycompat, | |||
18 | util, |
|
20 | util, | |
19 | ) |
|
21 | ) | |
20 |
|
22 | |||
21 | def _getlockprefix(): |
|
23 | def _getlockprefix(): | |
22 | """Return a string which is used to differentiate pid namespaces |
|
24 | """Return a string which is used to differentiate pid namespaces | |
23 |
|
25 | |||
24 | It's useful to detect "dead" processes and remove stale locks with |
|
26 | It's useful to detect "dead" processes and remove stale locks with | |
25 | confidence. Typically it's just hostname. |
|
27 | confidence. Typically it's just hostname. On modern linux, we include an | |
|
28 | extra Linux-specific pid namespace identifier. | |||
26 | """ |
|
29 | """ | |
27 |
re |
|
30 | result = socket.gethostname() | |
|
31 | if pycompat.sysplatform.startswith('linux'): | |||
|
32 | try: | |||
|
33 | result += '/%x' % os.stat('/proc/self/ns/pid').st_ino | |||
|
34 | except OSError as ex: | |||
|
35 | if ex.errno not in (errno.ENOENT, errno.EACCES, errno.ENOTDIR): | |||
|
36 | raise | |||
|
37 | return result | |||
28 |
|
38 | |||
29 | class lock(object): |
|
39 | class lock(object): | |
30 | '''An advisory lock held by one process to control access to a set |
|
40 | '''An advisory lock held by one process to control access to a set | |
31 | of files. Non-cooperating processes or incorrectly written scripts |
|
41 | of files. Non-cooperating processes or incorrectly written scripts | |
32 | can ignore Mercurial's locking scheme and stomp all over the |
|
42 | can ignore Mercurial's locking scheme and stomp all over the | |
33 | repository, so don't do that. |
|
43 | repository, so don't do that. | |
34 |
|
44 | |||
35 | Typically used via localrepository.lock() to lock the repository |
|
45 | Typically used via localrepository.lock() to lock the repository | |
36 | store (.hg/store/) or localrepository.wlock() to lock everything |
|
46 | store (.hg/store/) or localrepository.wlock() to lock everything | |
37 | else under .hg/.''' |
|
47 | else under .hg/.''' | |
38 |
|
48 | |||
39 | # lock is symlink on platforms that support it, file on others. |
|
49 | # lock is symlink on platforms that support it, file on others. | |
40 |
|
50 | |||
41 | # symlink is used because create of directory entry and contents |
|
51 | # symlink is used because create of directory entry and contents | |
42 | # are atomic even over nfs. |
|
52 | # are atomic even over nfs. | |
43 |
|
53 | |||
44 | # old-style lock: symlink to pid |
|
54 | # old-style lock: symlink to pid | |
45 | # new-style lock: symlink to hostname:pid |
|
55 | # new-style lock: symlink to hostname:pid | |
46 |
|
56 | |||
47 | _host = None |
|
57 | _host = None | |
48 |
|
58 | |||
49 | def __init__(self, vfs, file, timeout=-1, releasefn=None, acquirefn=None, |
|
59 | def __init__(self, vfs, file, timeout=-1, releasefn=None, acquirefn=None, | |
50 | desc=None, inheritchecker=None, parentlock=None): |
|
60 | desc=None, inheritchecker=None, parentlock=None): | |
51 | self.vfs = vfs |
|
61 | self.vfs = vfs | |
52 | self.f = file |
|
62 | self.f = file | |
53 | self.held = 0 |
|
63 | self.held = 0 | |
54 | self.timeout = timeout |
|
64 | self.timeout = timeout | |
55 | self.releasefn = releasefn |
|
65 | self.releasefn = releasefn | |
56 | self.acquirefn = acquirefn |
|
66 | self.acquirefn = acquirefn | |
57 | self.desc = desc |
|
67 | self.desc = desc | |
58 | self._inheritchecker = inheritchecker |
|
68 | self._inheritchecker = inheritchecker | |
59 | self.parentlock = parentlock |
|
69 | self.parentlock = parentlock | |
60 | self._parentheld = False |
|
70 | self._parentheld = False | |
61 | self._inherited = False |
|
71 | self._inherited = False | |
62 | self.postrelease = [] |
|
72 | self.postrelease = [] | |
63 | self.pid = self._getpid() |
|
73 | self.pid = self._getpid() | |
64 | self.delay = self.lock() |
|
74 | self.delay = self.lock() | |
65 | if self.acquirefn: |
|
75 | if self.acquirefn: | |
66 | self.acquirefn() |
|
76 | self.acquirefn() | |
67 |
|
77 | |||
68 | def __enter__(self): |
|
78 | def __enter__(self): | |
69 | return self |
|
79 | return self | |
70 |
|
80 | |||
71 | def __exit__(self, exc_type, exc_value, exc_tb): |
|
81 | def __exit__(self, exc_type, exc_value, exc_tb): | |
72 | self.release() |
|
82 | self.release() | |
73 |
|
83 | |||
74 | def __del__(self): |
|
84 | def __del__(self): | |
75 | if self.held: |
|
85 | if self.held: | |
76 | warnings.warn("use lock.release instead of del lock", |
|
86 | warnings.warn("use lock.release instead of del lock", | |
77 | category=DeprecationWarning, |
|
87 | category=DeprecationWarning, | |
78 | stacklevel=2) |
|
88 | stacklevel=2) | |
79 |
|
89 | |||
80 | # ensure the lock will be removed |
|
90 | # ensure the lock will be removed | |
81 | # even if recursive locking did occur |
|
91 | # even if recursive locking did occur | |
82 | self.held = 1 |
|
92 | self.held = 1 | |
83 |
|
93 | |||
84 | self.release() |
|
94 | self.release() | |
85 |
|
95 | |||
86 | def _getpid(self): |
|
96 | def _getpid(self): | |
87 | # wrapper around util.getpid() to make testing easier |
|
97 | # wrapper around util.getpid() to make testing easier | |
88 | return util.getpid() |
|
98 | return util.getpid() | |
89 |
|
99 | |||
90 | def lock(self): |
|
100 | def lock(self): | |
91 | timeout = self.timeout |
|
101 | timeout = self.timeout | |
92 | while True: |
|
102 | while True: | |
93 | try: |
|
103 | try: | |
94 | self._trylock() |
|
104 | self._trylock() | |
95 | return self.timeout - timeout |
|
105 | return self.timeout - timeout | |
96 | except error.LockHeld as inst: |
|
106 | except error.LockHeld as inst: | |
97 | if timeout != 0: |
|
107 | if timeout != 0: | |
98 | time.sleep(1) |
|
108 | time.sleep(1) | |
99 | if timeout > 0: |
|
109 | if timeout > 0: | |
100 | timeout -= 1 |
|
110 | timeout -= 1 | |
101 | continue |
|
111 | continue | |
102 | raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
|
112 | raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, | |
103 | inst.locker) |
|
113 | inst.locker) | |
104 |
|
114 | |||
105 | def _trylock(self): |
|
115 | def _trylock(self): | |
106 | if self.held: |
|
116 | if self.held: | |
107 | self.held += 1 |
|
117 | self.held += 1 | |
108 | return |
|
118 | return | |
109 | if lock._host is None: |
|
119 | if lock._host is None: | |
110 | lock._host = _getlockprefix() |
|
120 | lock._host = _getlockprefix() | |
111 | lockname = '%s:%s' % (lock._host, self.pid) |
|
121 | lockname = '%s:%s' % (lock._host, self.pid) | |
112 | retry = 5 |
|
122 | retry = 5 | |
113 | while not self.held and retry: |
|
123 | while not self.held and retry: | |
114 | retry -= 1 |
|
124 | retry -= 1 | |
115 | try: |
|
125 | try: | |
116 | self.vfs.makelock(lockname, self.f) |
|
126 | self.vfs.makelock(lockname, self.f) | |
117 | self.held = 1 |
|
127 | self.held = 1 | |
118 | except (OSError, IOError) as why: |
|
128 | except (OSError, IOError) as why: | |
119 | if why.errno == errno.EEXIST: |
|
129 | if why.errno == errno.EEXIST: | |
120 | locker = self._readlock() |
|
130 | locker = self._readlock() | |
121 | # special case where a parent process holds the lock -- this |
|
131 | # special case where a parent process holds the lock -- this | |
122 | # is different from the pid being different because we do |
|
132 | # is different from the pid being different because we do | |
123 | # want the unlock and postrelease functions to be called, |
|
133 | # want the unlock and postrelease functions to be called, | |
124 | # but the lockfile to not be removed. |
|
134 | # but the lockfile to not be removed. | |
125 | if locker == self.parentlock: |
|
135 | if locker == self.parentlock: | |
126 | self._parentheld = True |
|
136 | self._parentheld = True | |
127 | self.held = 1 |
|
137 | self.held = 1 | |
128 | return |
|
138 | return | |
129 | locker = self._testlock(locker) |
|
139 | locker = self._testlock(locker) | |
130 | if locker is not None: |
|
140 | if locker is not None: | |
131 | raise error.LockHeld(errno.EAGAIN, |
|
141 | raise error.LockHeld(errno.EAGAIN, | |
132 | self.vfs.join(self.f), self.desc, |
|
142 | self.vfs.join(self.f), self.desc, | |
133 | locker) |
|
143 | locker) | |
134 | else: |
|
144 | else: | |
135 | raise error.LockUnavailable(why.errno, why.strerror, |
|
145 | raise error.LockUnavailable(why.errno, why.strerror, | |
136 | why.filename, self.desc) |
|
146 | why.filename, self.desc) | |
137 |
|
147 | |||
138 | def _readlock(self): |
|
148 | def _readlock(self): | |
139 | """read lock and return its value |
|
149 | """read lock and return its value | |
140 |
|
150 | |||
141 | Returns None if no lock exists, pid for old-style locks, and host:pid |
|
151 | Returns None if no lock exists, pid for old-style locks, and host:pid | |
142 | for new-style locks. |
|
152 | for new-style locks. | |
143 | """ |
|
153 | """ | |
144 | try: |
|
154 | try: | |
145 | return self.vfs.readlock(self.f) |
|
155 | return self.vfs.readlock(self.f) | |
146 | except (OSError, IOError) as why: |
|
156 | except (OSError, IOError) as why: | |
147 | if why.errno == errno.ENOENT: |
|
157 | if why.errno == errno.ENOENT: | |
148 | return None |
|
158 | return None | |
149 | raise |
|
159 | raise | |
150 |
|
160 | |||
151 | def _testlock(self, locker): |
|
161 | def _testlock(self, locker): | |
152 | if locker is None: |
|
162 | if locker is None: | |
153 | return None |
|
163 | return None | |
154 | try: |
|
164 | try: | |
155 | host, pid = locker.split(":", 1) |
|
165 | host, pid = locker.split(":", 1) | |
156 | except ValueError: |
|
166 | except ValueError: | |
157 | return locker |
|
167 | return locker | |
158 | if host != lock._host: |
|
168 | if host != lock._host: | |
159 | return locker |
|
169 | return locker | |
160 | try: |
|
170 | try: | |
161 | pid = int(pid) |
|
171 | pid = int(pid) | |
162 | except ValueError: |
|
172 | except ValueError: | |
163 | return locker |
|
173 | return locker | |
164 | if util.testpid(pid): |
|
174 | if util.testpid(pid): | |
165 | return locker |
|
175 | return locker | |
166 | # if locker dead, break lock. must do this with another lock |
|
176 | # if locker dead, break lock. must do this with another lock | |
167 | # held, or can race and break valid lock. |
|
177 | # held, or can race and break valid lock. | |
168 | try: |
|
178 | try: | |
169 | l = lock(self.vfs, self.f + '.break', timeout=0) |
|
179 | l = lock(self.vfs, self.f + '.break', timeout=0) | |
170 | self.vfs.unlink(self.f) |
|
180 | self.vfs.unlink(self.f) | |
171 | l.release() |
|
181 | l.release() | |
172 | except error.LockError: |
|
182 | except error.LockError: | |
173 | return locker |
|
183 | return locker | |
174 |
|
184 | |||
175 | def testlock(self): |
|
185 | def testlock(self): | |
176 | """return id of locker if lock is valid, else None. |
|
186 | """return id of locker if lock is valid, else None. | |
177 |
|
187 | |||
178 | If old-style lock, we cannot tell what machine locker is on. |
|
188 | If old-style lock, we cannot tell what machine locker is on. | |
179 | with new-style lock, if locker is on this machine, we can |
|
189 | with new-style lock, if locker is on this machine, we can | |
180 | see if locker is alive. If locker is on this machine but |
|
190 | see if locker is alive. If locker is on this machine but | |
181 | not alive, we can safely break lock. |
|
191 | not alive, we can safely break lock. | |
182 |
|
192 | |||
183 | The lock file is only deleted when None is returned. |
|
193 | The lock file is only deleted when None is returned. | |
184 |
|
194 | |||
185 | """ |
|
195 | """ | |
186 | locker = self._readlock() |
|
196 | locker = self._readlock() | |
187 | return self._testlock(locker) |
|
197 | return self._testlock(locker) | |
188 |
|
198 | |||
189 | @contextlib.contextmanager |
|
199 | @contextlib.contextmanager | |
190 | def inherit(self): |
|
200 | def inherit(self): | |
191 | """context for the lock to be inherited by a Mercurial subprocess. |
|
201 | """context for the lock to be inherited by a Mercurial subprocess. | |
192 |
|
202 | |||
193 | Yields a string that will be recognized by the lock in the subprocess. |
|
203 | Yields a string that will be recognized by the lock in the subprocess. | |
194 | Communicating this string to the subprocess needs to be done separately |
|
204 | Communicating this string to the subprocess needs to be done separately | |
195 | -- typically by an environment variable. |
|
205 | -- typically by an environment variable. | |
196 | """ |
|
206 | """ | |
197 | if not self.held: |
|
207 | if not self.held: | |
198 | raise error.LockInheritanceContractViolation( |
|
208 | raise error.LockInheritanceContractViolation( | |
199 | 'inherit can only be called while lock is held') |
|
209 | 'inherit can only be called while lock is held') | |
200 | if self._inherited: |
|
210 | if self._inherited: | |
201 | raise error.LockInheritanceContractViolation( |
|
211 | raise error.LockInheritanceContractViolation( | |
202 | 'inherit cannot be called while lock is already inherited') |
|
212 | 'inherit cannot be called while lock is already inherited') | |
203 | if self._inheritchecker is not None: |
|
213 | if self._inheritchecker is not None: | |
204 | self._inheritchecker() |
|
214 | self._inheritchecker() | |
205 | if self.releasefn: |
|
215 | if self.releasefn: | |
206 | self.releasefn() |
|
216 | self.releasefn() | |
207 | if self._parentheld: |
|
217 | if self._parentheld: | |
208 | lockname = self.parentlock |
|
218 | lockname = self.parentlock | |
209 | else: |
|
219 | else: | |
210 | lockname = '%s:%s' % (lock._host, self.pid) |
|
220 | lockname = '%s:%s' % (lock._host, self.pid) | |
211 | self._inherited = True |
|
221 | self._inherited = True | |
212 | try: |
|
222 | try: | |
213 | yield lockname |
|
223 | yield lockname | |
214 | finally: |
|
224 | finally: | |
215 | if self.acquirefn: |
|
225 | if self.acquirefn: | |
216 | self.acquirefn() |
|
226 | self.acquirefn() | |
217 | self._inherited = False |
|
227 | self._inherited = False | |
218 |
|
228 | |||
219 | def release(self): |
|
229 | def release(self): | |
220 | """release the lock and execute callback function if any |
|
230 | """release the lock and execute callback function if any | |
221 |
|
231 | |||
222 | If the lock has been acquired multiple times, the actual release is |
|
232 | If the lock has been acquired multiple times, the actual release is | |
223 | delayed to the last release call.""" |
|
233 | delayed to the last release call.""" | |
224 | if self.held > 1: |
|
234 | if self.held > 1: | |
225 | self.held -= 1 |
|
235 | self.held -= 1 | |
226 | elif self.held == 1: |
|
236 | elif self.held == 1: | |
227 | self.held = 0 |
|
237 | self.held = 0 | |
228 | if self._getpid() != self.pid: |
|
238 | if self._getpid() != self.pid: | |
229 | # we forked, and are not the parent |
|
239 | # we forked, and are not the parent | |
230 | return |
|
240 | return | |
231 | try: |
|
241 | try: | |
232 | if self.releasefn: |
|
242 | if self.releasefn: | |
233 | self.releasefn() |
|
243 | self.releasefn() | |
234 | finally: |
|
244 | finally: | |
235 | if not self._parentheld: |
|
245 | if not self._parentheld: | |
236 | try: |
|
246 | try: | |
237 | self.vfs.unlink(self.f) |
|
247 | self.vfs.unlink(self.f) | |
238 | except OSError: |
|
248 | except OSError: | |
239 | pass |
|
249 | pass | |
240 | # The postrelease functions typically assume the lock is not held |
|
250 | # The postrelease functions typically assume the lock is not held | |
241 | # at all. |
|
251 | # at all. | |
242 | if not self._parentheld: |
|
252 | if not self._parentheld: | |
243 | for callback in self.postrelease: |
|
253 | for callback in self.postrelease: | |
244 | callback() |
|
254 | callback() | |
245 | # Prevent double usage and help clear cycles. |
|
255 | # Prevent double usage and help clear cycles. | |
246 | self.postrelease = None |
|
256 | self.postrelease = None | |
247 |
|
257 | |||
248 | def release(*locks): |
|
258 | def release(*locks): | |
249 | for lock in locks: |
|
259 | for lock in locks: | |
250 | if lock is not None: |
|
260 | if lock is not None: | |
251 | lock.release() |
|
261 | lock.release() |
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