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@@ -1,156 +1,165 b'' | |||
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1 | 1 | # lock.py - simple advisory locking scheme for mercurial |
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2 | 2 | # |
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3 | 3 | # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
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4 | 4 | # |
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5 | 5 | # This software may be used and distributed according to the terms of the |
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6 | 6 | # GNU General Public License version 2 or any later version. |
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7 | 7 | |
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8 | import util, error | |
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9 | import errno, os, socket, time | |
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8 | from __future__ import absolute_import | |
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9 | ||
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10 | import errno | |
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11 | import os | |
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12 | import socket | |
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13 | import time | |
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10 | 14 | import warnings |
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11 | 15 | |
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16 | from . import ( | |
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17 | error, | |
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18 | util, | |
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19 | ) | |
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20 | ||
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12 | 21 | class lock(object): |
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13 | 22 | '''An advisory lock held by one process to control access to a set |
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14 | 23 | of files. Non-cooperating processes or incorrectly written scripts |
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15 | 24 | can ignore Mercurial's locking scheme and stomp all over the |
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16 | 25 | repository, so don't do that. |
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17 | 26 | |
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18 | 27 | Typically used via localrepository.lock() to lock the repository |
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19 | 28 | store (.hg/store/) or localrepository.wlock() to lock everything |
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20 | 29 | else under .hg/.''' |
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21 | 30 | |
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22 | 31 | # lock is symlink on platforms that support it, file on others. |
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23 | 32 | |
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24 | 33 | # symlink is used because create of directory entry and contents |
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25 | 34 | # are atomic even over nfs. |
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26 | 35 | |
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27 | 36 | # old-style lock: symlink to pid |
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28 | 37 | # new-style lock: symlink to hostname:pid |
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29 | 38 | |
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30 | 39 | _host = None |
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31 | 40 | |
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32 | 41 | def __init__(self, vfs, file, timeout=-1, releasefn=None, desc=None): |
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33 | 42 | self.vfs = vfs |
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34 | 43 | self.f = file |
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35 | 44 | self.held = 0 |
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36 | 45 | self.timeout = timeout |
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37 | 46 | self.releasefn = releasefn |
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38 | 47 | self.desc = desc |
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39 | 48 | self.postrelease = [] |
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40 | 49 | self.pid = os.getpid() |
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41 | 50 | self.delay = self.lock() |
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42 | 51 | |
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43 | 52 | def __del__(self): |
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44 | 53 | if self.held: |
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45 | 54 | warnings.warn("use lock.release instead of del lock", |
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46 | 55 | category=DeprecationWarning, |
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47 | 56 | stacklevel=2) |
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48 | 57 | |
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49 | 58 | # ensure the lock will be removed |
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50 | 59 | # even if recursive locking did occur |
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51 | 60 | self.held = 1 |
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52 | 61 | |
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53 | 62 | self.release() |
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54 | 63 | |
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55 | 64 | def lock(self): |
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56 | 65 | timeout = self.timeout |
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57 | 66 | while True: |
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58 | 67 | try: |
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59 | 68 | self.trylock() |
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60 | 69 | return self.timeout - timeout |
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61 | 70 | except error.LockHeld as inst: |
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62 | 71 | if timeout != 0: |
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63 | 72 | time.sleep(1) |
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64 | 73 | if timeout > 0: |
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65 | 74 | timeout -= 1 |
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66 | 75 | continue |
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67 | 76 | raise error.LockHeld(errno.ETIMEDOUT, inst.filename, self.desc, |
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68 | 77 | inst.locker) |
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69 | 78 | |
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70 | 79 | def trylock(self): |
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71 | 80 | if self.held: |
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72 | 81 | self.held += 1 |
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73 | 82 | return |
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74 | 83 | if lock._host is None: |
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75 | 84 | lock._host = socket.gethostname() |
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76 | 85 | lockname = '%s:%s' % (lock._host, self.pid) |
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77 | 86 | while not self.held: |
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78 | 87 | try: |
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79 | 88 | self.vfs.makelock(lockname, self.f) |
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80 | 89 | self.held = 1 |
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81 | 90 | except (OSError, IOError) as why: |
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82 | 91 | if why.errno == errno.EEXIST: |
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83 | 92 | locker = self.testlock() |
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84 | 93 | if locker is not None: |
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85 | 94 | raise error.LockHeld(errno.EAGAIN, |
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86 | 95 | self.vfs.join(self.f), self.desc, |
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87 | 96 | locker) |
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88 | 97 | else: |
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89 | 98 | raise error.LockUnavailable(why.errno, why.strerror, |
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90 | 99 | why.filename, self.desc) |
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91 | 100 | |
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92 | 101 | def testlock(self): |
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93 | 102 | """return id of locker if lock is valid, else None. |
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94 | 103 | |
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95 | 104 | If old-style lock, we cannot tell what machine locker is on. |
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96 | 105 | with new-style lock, if locker is on this machine, we can |
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97 | 106 | see if locker is alive. If locker is on this machine but |
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98 | 107 | not alive, we can safely break lock. |
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99 | 108 | |
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100 | 109 | The lock file is only deleted when None is returned. |
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101 | 110 | |
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102 | 111 | """ |
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103 | 112 | try: |
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104 | 113 | locker = self.vfs.readlock(self.f) |
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105 | 114 | except (OSError, IOError) as why: |
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106 | 115 | if why.errno == errno.ENOENT: |
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107 | 116 | return None |
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108 | 117 | raise |
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109 | 118 | try: |
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110 | 119 | host, pid = locker.split(":", 1) |
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111 | 120 | except ValueError: |
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112 | 121 | return locker |
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113 | 122 | if host != lock._host: |
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114 | 123 | return locker |
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115 | 124 | try: |
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116 | 125 | pid = int(pid) |
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117 | 126 | except ValueError: |
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118 | 127 | return locker |
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119 | 128 | if util.testpid(pid): |
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120 | 129 | return locker |
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121 | 130 | # if locker dead, break lock. must do this with another lock |
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122 | 131 | # held, or can race and break valid lock. |
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123 | 132 | try: |
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124 | 133 | l = lock(self.vfs, self.f + '.break', timeout=0) |
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125 | 134 | self.vfs.unlink(self.f) |
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126 | 135 | l.release() |
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127 | 136 | except error.LockError: |
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128 | 137 | return locker |
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129 | 138 | |
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130 | 139 | def release(self): |
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131 | 140 | """release the lock and execute callback function if any |
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132 | 141 | |
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133 | 142 | If the lock has been acquired multiple times, the actual release is |
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134 | 143 | delayed to the last release call.""" |
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135 | 144 | if self.held > 1: |
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136 | 145 | self.held -= 1 |
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137 | 146 | elif self.held == 1: |
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138 | 147 | self.held = 0 |
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139 | 148 | if os.getpid() != self.pid: |
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140 | 149 | # we forked, and are not the parent |
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141 | 150 | return |
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142 | 151 | try: |
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143 | 152 | if self.releasefn: |
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144 | 153 | self.releasefn() |
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145 | 154 | finally: |
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146 | 155 | try: |
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147 | 156 | self.vfs.unlink(self.f) |
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148 | 157 | except OSError: |
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149 | 158 | pass |
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150 | 159 | for callback in self.postrelease: |
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151 | 160 | callback() |
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152 | 161 | |
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153 | 162 | def release(*locks): |
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154 | 163 | for lock in locks: |
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155 | 164 | if lock is not None: |
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156 | 165 | lock.release() |
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