Mercurial > hg > mercurial-crew-with-dirclash
annotate mercurial/lock.py @ 5483:0c43f87baba3 default tip
Fix file-changed-to-dir and dir-to-file commits (issue660).
Allow adding to dirstate files that clash with previously existing
but marked for removal. Protect from reintroducing clashes by revert.
This change doesn't address related issues with update. Current
workaround is to do "clean" update by manually removing conflicting
files/dirs from working directory.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Sat, 27 Oct 2007 16:27:55 +0400 |
parents | 8933b8ea871a |
children |
rev | line source |
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161 | 1 # lock.py - simple locking scheme for mercurial |
2 # | |
2858 | 3 # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
161 | 4 # |
5 # This software may be used and distributed according to the terms | |
6 # of the GNU General Public License, incorporated herein by reference. | |
7 | |
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8 import errno, os, socket, time, util |
161 | 9 |
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10 class LockException(IOError): |
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11 def __init__(self, errno, strerror, filename, desc): |
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12 IOError.__init__(self, errno, strerror, filename) |
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13 self.desc = desc |
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14 |
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15 class LockHeld(LockException): |
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16 def __init__(self, errno, filename, desc, locker): |
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17 LockException.__init__(self, errno, 'Lock held', filename, desc) |
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18 self.locker = locker |
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19 |
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20 class LockUnavailable(LockException): |
161 | 21 pass |
22 | |
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23 class lock(object): |
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24 # lock is symlink on platforms that support it, file on others. |
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25 |
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26 # symlink is used because create of directory entry and contents |
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27 # are atomic even over nfs. |
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28 |
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29 # old-style lock: symlink to pid |
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30 # new-style lock: symlink to hostname:pid |
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31 |
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32 _host = None |
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33 |
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34 def __init__(self, file, timeout=-1, releasefn=None, desc=None): |
161 | 35 self.f = file |
36 self.held = 0 | |
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37 self.timeout = timeout |
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38 self.releasefn = releasefn |
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39 self.desc = desc |
161 | 40 self.lock() |
41 | |
42 def __del__(self): | |
43 self.release() | |
44 | |
45 def lock(self): | |
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46 timeout = self.timeout |
161 | 47 while 1: |
48 try: | |
49 self.trylock() | |
50 return 1 | |
51 except LockHeld, inst: | |
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52 if timeout != 0: |
161 | 53 time.sleep(1) |
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54 if timeout > 0: |
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55 timeout -= 1 |
161 | 56 continue |
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57 raise LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
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58 inst.locker) |
515 | 59 |
161 | 60 def trylock(self): |
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61 if lock._host is None: |
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62 lock._host = socket.gethostname() |
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63 lockname = '%s:%s' % (lock._host, os.getpid()) |
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64 while not self.held: |
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65 try: |
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66 util.makelock(lockname, self.f) |
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67 self.held = 1 |
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68 except (OSError, IOError), why: |
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69 if why.errno == errno.EEXIST: |
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70 locker = self.testlock() |
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71 if locker is not None: |
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72 raise LockHeld(errno.EAGAIN, self.f, self.desc, |
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73 locker) |
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74 else: |
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75 raise LockUnavailable(why.errno, why.strerror, |
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76 why.filename, self.desc) |
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77 |
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78 def testlock(self): |
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79 """return id of locker if lock is valid, else None. |
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80 |
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81 If old-style lock, we cannot tell what machine locker is on. |
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82 with new-style lock, if locker is on this machine, we can |
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83 see if locker is alive. If locker is on this machine but |
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84 not alive, we can safely break lock. |
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85 |
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86 The lock file is only deleted when None is returned. |
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87 |
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88 """ |
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89 locker = util.readlock(self.f) |
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90 try: |
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91 host, pid = locker.split(":", 1) |
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92 except ValueError: |
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93 return locker |
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94 if host != lock._host: |
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95 return locker |
161 | 96 try: |
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97 pid = int(pid) |
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98 except: |
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99 return locker |
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100 if util.testpid(pid): |
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101 return locker |
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102 # if locker dead, break lock. must do this with another lock |
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103 # held, or can race and break valid lock. |
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104 try: |
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105 l = lock(self.f + '.break') |
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106 l.trylock() |
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107 os.unlink(self.f) |
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108 l.release() |
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109 except (LockHeld, LockUnavailable): |
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110 return locker |
161 | 111 |
112 def release(self): | |
113 if self.held: | |
114 self.held = 0 | |
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115 if self.releasefn: |
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116 self.releasefn() |
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117 try: |
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118 os.unlink(self.f) |
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119 except: pass |
161 | 120 |