Mercurial > hg
annotate mercurial/lock.py @ 17509:f7767f52e9eb
spelling: recursion
author | timeless@mozdev.org |
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date | Fri, 17 Aug 2012 13:58:18 -0700 |
parents | cc24e4ed3e0c |
children | e7cfe3587ea4 7c44b703657b 829919ef894a |
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9309
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localrepo: document the locking scheme a little better
Greg Ward <greg-hg@gerg.ca>
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1 # lock.py - simple advisory locking scheme for mercurial |
161 | 2 # |
2859 | 3 # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
161 | 4 # |
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5 # This software may be used and distributed according to the terms of the |
10263 | 6 # GNU General Public License version 2 or any later version. |
161 | 7 |
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8 import util, error |
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9 import errno, os, socket, time |
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10 import warnings |
161 | 11 |
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12 class lock(object): |
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13 '''An advisory lock held by one process to control access to a set |
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14 of files. Non-cooperating processes or incorrectly written scripts |
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15 can ignore Mercurial's locking scheme and stomp all over the |
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16 repository, so don't do that. |
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17 |
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localrepo: document the locking scheme a little better
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18 Typically used via localrepository.lock() to lock the repository |
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19 store (.hg/store/) or localrepository.wlock() to lock everything |
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20 else under .hg/.''' |
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21 |
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22 # lock is symlink on platforms that support it, file on others. |
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23 |
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24 # symlink is used because create of directory entry and contents |
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25 # are atomic even over nfs. |
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26 |
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27 # old-style lock: symlink to pid |
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28 # new-style lock: symlink to hostname:pid |
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29 |
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30 _host = None |
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31 |
2016
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fix backtrace printed when cannot get lock.
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32 def __init__(self, file, timeout=-1, releasefn=None, desc=None): |
161 | 33 self.f = file |
34 self.held = 0 | |
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35 self.timeout = timeout |
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36 self.releasefn = releasefn |
2016
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37 self.desc = desc |
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38 self.postrelease = [] |
161 | 39 self.lock() |
40 | |
41 def __del__(self): | |
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42 if self.held: |
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43 warnings.warn("use lock.release instead of del lock", |
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44 category=DeprecationWarning, |
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45 stacklevel=2) |
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46 |
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47 # ensure the lock will be removed |
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48 # even if recursive locking did occur |
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49 self.held = 1 |
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50 |
161 | 51 self.release() |
52 | |
53 def lock(self): | |
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54 timeout = self.timeout |
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check-code: flag 0/1 used as constant Boolean expression
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55 while True: |
161 | 56 try: |
57 self.trylock() | |
58 return 1 | |
7640 | 59 except error.LockHeld, inst: |
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60 if timeout != 0: |
161 | 61 time.sleep(1) |
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62 if timeout > 0: |
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63 timeout -= 1 |
161 | 64 continue |
7640 | 65 raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
66 inst.locker) | |
515 | 67 |
161 | 68 def trylock(self): |
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69 if self.held: |
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70 self.held += 1 |
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71 return |
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72 if lock._host is None: |
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73 lock._host = socket.gethostname() |
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74 lockname = '%s:%s' % (lock._host, os.getpid()) |
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75 while not self.held: |
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76 try: |
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77 util.makelock(lockname, self.f) |
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78 self.held = 1 |
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79 except (OSError, IOError), why: |
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80 if why.errno == errno.EEXIST: |
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81 locker = self.testlock() |
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82 if locker is not None: |
7640 | 83 raise error.LockHeld(errno.EAGAIN, self.f, self.desc, |
84 locker) | |
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85 else: |
7640 | 86 raise error.LockUnavailable(why.errno, why.strerror, |
87 why.filename, self.desc) | |
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88 |
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89 def testlock(self): |
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90 """return id of locker if lock is valid, else None. |
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91 |
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92 If old-style lock, we cannot tell what machine locker is on. |
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93 with new-style lock, if locker is on this machine, we can |
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94 see if locker is alive. If locker is on this machine but |
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95 not alive, we can safely break lock. |
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96 |
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97 The lock file is only deleted when None is returned. |
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98 |
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99 """ |
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100 locker = util.readlock(self.f) |
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101 try: |
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102 host, pid = locker.split(":", 1) |
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103 except ValueError: |
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104 return locker |
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105 if host != lock._host: |
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106 return locker |
161 | 107 try: |
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108 pid = int(pid) |
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109 except ValueError: |
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110 return locker |
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111 if util.testpid(pid): |
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112 return locker |
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113 # if locker dead, break lock. must do this with another lock |
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114 # held, or can race and break valid lock. |
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115 try: |
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116 l = lock(self.f + '.break', timeout=0) |
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117 util.unlink(self.f) |
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118 l.release() |
7640 | 119 except error.LockError: |
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120 return locker |
161 | 121 |
122 def release(self): | |
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123 """release the lock and execute callback function if any |
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124 |
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125 If the lock have been aquired multiple time, the actual release is |
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126 delayed to the last relase call.""" |
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127 if self.held > 1: |
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128 self.held -= 1 |
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129 elif self.held == 1: |
161 | 130 self.held = 0 |
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131 if self.releasefn: |
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132 self.releasefn() |
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133 try: |
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134 util.unlink(self.f) |
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135 except OSError: |
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136 pass |
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137 for callback in self.postrelease: |
15583
926a06f7a353
lock: add mechanism to register post release callback
Pierre-Yves David <pierre-yves.david@ens-lyon.org>
parents:
14494
diff
changeset
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138 callback() |
161 | 139 |
8108
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
140 def release(*locks): |
a26d33749bd8
made repo locks recursive and deprecate refcounting based lock releasing
Ronny Pfannschmidt <Ronny.Pfannschmidt@gmx.de>
parents:
7640
diff
changeset
|
141 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
|
142 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
|
143 lock.release() |