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