Mercurial > hg
annotate mercurial/lock.py @ 5304:b85f7cc133cc
convert: avoid interpreting Windows path as CVS connection strings.
CVS connection strings regexp detect colons to separate protocols from path and login. Unfortunately, Windows paths contains colons and were interpreted as rsh connection strings.
author | Patrick Mezard <pmezard@gmail.com> |
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date | Fri, 14 Sep 2007 22:17:53 +0200 |
parents | abaee83ce0a6 |
children | 3e25a6eb5c9a |
rev | line source |
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161 | 1 # lock.py - simple locking scheme for mercurial |
2 # | |
2859 | 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 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 |
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37 self.id = None |
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38 self.host = None |
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39 self.pid = None |
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40 self.desc = desc |
161 | 41 self.lock() |
42 | |
43 def __del__(self): | |
44 self.release() | |
45 | |
46 def lock(self): | |
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47 timeout = self.timeout |
161 | 48 while 1: |
49 try: | |
50 self.trylock() | |
51 return 1 | |
52 except LockHeld, inst: | |
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53 if timeout != 0: |
161 | 54 time.sleep(1) |
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55 if timeout > 0: |
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56 timeout -= 1 |
161 | 57 continue |
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58 raise LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
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59 inst.locker) |
515 | 60 |
161 | 61 def trylock(self): |
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62 if self.id is None: |
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63 self.host = socket.gethostname() |
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64 self.pid = os.getpid() |
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65 self.id = '%s:%s' % (self.host, self.pid) |
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66 while not self.held: |
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67 try: |
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68 util.makelock(self.id, self.f) |
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69 self.held = 1 |
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70 except (OSError, IOError), why: |
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71 if why.errno == errno.EEXIST: |
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72 locker = self.testlock() |
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73 if locker is not None: |
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74 raise LockHeld(errno.EAGAIN, self.f, self.desc, |
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75 locker) |
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76 else: |
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77 raise LockUnavailable(why.errno, why.strerror, |
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78 why.filename, self.desc) |
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79 |
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80 def testlock(self): |
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81 """return id of locker if lock is valid, else None. |
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82 |
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83 If old-style lock, we cannot tell what machine locker is on. |
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84 with new-style lock, if locker is on this machine, we can |
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85 see if locker is alive. If locker is on this machine but |
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86 not alive, we can safely break lock. |
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87 |
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88 The lock file is only deleted when None is returned. |
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89 |
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90 """ |
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91 locker = util.readlock(self.f) |
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92 try: |
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93 host, pid = locker.split(":", 1) |
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94 except ValueError: |
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95 return locker |
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96 if host != self.host: |
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97 return locker |
161 | 98 try: |
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99 pid = int(pid) |
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100 except: |
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101 return locker |
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102 if util.testpid(pid): |
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103 return locker |
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104 # if locker dead, break lock. must do this with another lock |
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105 # held, or can race and break valid lock. |
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106 try: |
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107 l = lock(self.f + '.break') |
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108 l.trylock() |
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109 os.unlink(self.f) |
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110 l.release() |
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111 except (LockHeld, LockUnavailable): |
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112 return locker |
161 | 113 |
114 def release(self): | |
115 if self.held: | |
116 self.held = 0 | |
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117 if self.releasefn: |
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118 self.releasefn() |
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119 try: |
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120 os.unlink(self.f) |
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121 except: pass |
161 | 122 |