root / lib / utils / wrapper.py @ dce20078
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1 | 7831fc5f | Michael Hanselmann | #
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2 | 7831fc5f | Michael Hanselmann | #
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3 | 7831fc5f | Michael Hanselmann | |
4 | 7831fc5f | Michael Hanselmann | # Copyright (C) 2006, 2007, 2010, 2011 Google Inc.
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5 | 7831fc5f | Michael Hanselmann | #
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6 | 7831fc5f | Michael Hanselmann | # This program is free software; you can redistribute it and/or modify
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7 | 7831fc5f | Michael Hanselmann | # it under the terms of the GNU General Public License as published by
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8 | 7831fc5f | Michael Hanselmann | # the Free Software Foundation; either version 2 of the License, or
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9 | 7831fc5f | Michael Hanselmann | # (at your option) any later version.
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10 | 7831fc5f | Michael Hanselmann | #
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11 | 7831fc5f | Michael Hanselmann | # This program is distributed in the hope that it will be useful, but
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12 | 7831fc5f | Michael Hanselmann | # WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | 7831fc5f | Michael Hanselmann | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 | 7831fc5f | Michael Hanselmann | # General Public License for more details.
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15 | 7831fc5f | Michael Hanselmann | #
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16 | 7831fc5f | Michael Hanselmann | # You should have received a copy of the GNU General Public License
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17 | 7831fc5f | Michael Hanselmann | # along with this program; if not, write to the Free Software
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18 | 7831fc5f | Michael Hanselmann | # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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19 | 7831fc5f | Michael Hanselmann | # 02110-1301, USA.
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20 | 7831fc5f | Michael Hanselmann | |
21 | 7831fc5f | Michael Hanselmann | """Utility functions wrapping other functions.
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22 | 7831fc5f | Michael Hanselmann |
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23 | 7831fc5f | Michael Hanselmann | """
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24 | 7831fc5f | Michael Hanselmann | |
25 | 7831fc5f | Michael Hanselmann | import time |
26 | 7831fc5f | Michael Hanselmann | import socket |
27 | 7831fc5f | Michael Hanselmann | import errno |
28 | 7831fc5f | Michael Hanselmann | import tempfile |
29 | 7831fc5f | Michael Hanselmann | import fcntl |
30 | 7831fc5f | Michael Hanselmann | import os |
31 | 7831fc5f | Michael Hanselmann | import select |
32 | 44c9b4fe | Michael Hanselmann | import logging |
33 | 7831fc5f | Michael Hanselmann | |
34 | 7831fc5f | Michael Hanselmann | |
35 | 7831fc5f | Michael Hanselmann | def TestDelay(duration): |
36 | 7831fc5f | Michael Hanselmann | """Sleep for a fixed amount of time.
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37 | 7831fc5f | Michael Hanselmann |
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38 | 7831fc5f | Michael Hanselmann | @type duration: float
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39 | 7831fc5f | Michael Hanselmann | @param duration: the sleep duration
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40 | 7831fc5f | Michael Hanselmann | @rtype: boolean
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41 | 7831fc5f | Michael Hanselmann | @return: False for negative value, True otherwise
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42 | 7831fc5f | Michael Hanselmann |
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43 | 7831fc5f | Michael Hanselmann | """
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44 | 7831fc5f | Michael Hanselmann | if duration < 0: |
45 | 7831fc5f | Michael Hanselmann | return False, "Invalid sleep duration" |
46 | 7831fc5f | Michael Hanselmann | time.sleep(duration) |
47 | 7831fc5f | Michael Hanselmann | return True, None |
48 | 7831fc5f | Michael Hanselmann | |
49 | 7831fc5f | Michael Hanselmann | |
50 | 7831fc5f | Michael Hanselmann | def CloseFdNoError(fd, retries=5): |
51 | 7831fc5f | Michael Hanselmann | """Close a file descriptor ignoring errors.
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52 | 7831fc5f | Michael Hanselmann |
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53 | 7831fc5f | Michael Hanselmann | @type fd: int
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54 | 7831fc5f | Michael Hanselmann | @param fd: the file descriptor
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55 | 7831fc5f | Michael Hanselmann | @type retries: int
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56 | 7831fc5f | Michael Hanselmann | @param retries: how many retries to make, in case we get any
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57 | 7831fc5f | Michael Hanselmann | other error than EBADF
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58 | 7831fc5f | Michael Hanselmann |
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59 | 7831fc5f | Michael Hanselmann | """
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60 | 7831fc5f | Michael Hanselmann | try:
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61 | 7831fc5f | Michael Hanselmann | os.close(fd) |
62 | 7831fc5f | Michael Hanselmann | except OSError, err: |
63 | 7831fc5f | Michael Hanselmann | if err.errno != errno.EBADF:
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64 | 7831fc5f | Michael Hanselmann | if retries > 0: |
65 | 7831fc5f | Michael Hanselmann | CloseFdNoError(fd, retries - 1)
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66 | 7831fc5f | Michael Hanselmann | # else either it's closed already or we're out of retries, so we
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67 | 7831fc5f | Michael Hanselmann | # ignore this and go on
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68 | 7831fc5f | Michael Hanselmann | |
69 | 7831fc5f | Michael Hanselmann | |
70 | 7831fc5f | Michael Hanselmann | def SetCloseOnExecFlag(fd, enable): |
71 | 7831fc5f | Michael Hanselmann | """Sets or unsets the close-on-exec flag on a file descriptor.
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72 | 7831fc5f | Michael Hanselmann |
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73 | 7831fc5f | Michael Hanselmann | @type fd: int
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74 | 7831fc5f | Michael Hanselmann | @param fd: File descriptor
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75 | 7831fc5f | Michael Hanselmann | @type enable: bool
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76 | 7831fc5f | Michael Hanselmann | @param enable: Whether to set or unset it.
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77 | 7831fc5f | Michael Hanselmann |
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78 | 7831fc5f | Michael Hanselmann | """
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79 | 7831fc5f | Michael Hanselmann | flags = fcntl.fcntl(fd, fcntl.F_GETFD) |
80 | 7831fc5f | Michael Hanselmann | |
81 | 7831fc5f | Michael Hanselmann | if enable:
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82 | 7831fc5f | Michael Hanselmann | flags |= fcntl.FD_CLOEXEC |
83 | 7831fc5f | Michael Hanselmann | else:
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84 | 7831fc5f | Michael Hanselmann | flags &= ~fcntl.FD_CLOEXEC |
85 | 7831fc5f | Michael Hanselmann | |
86 | 7831fc5f | Michael Hanselmann | fcntl.fcntl(fd, fcntl.F_SETFD, flags) |
87 | 7831fc5f | Michael Hanselmann | |
88 | 7831fc5f | Michael Hanselmann | |
89 | 7831fc5f | Michael Hanselmann | def SetNonblockFlag(fd, enable): |
90 | 7831fc5f | Michael Hanselmann | """Sets or unsets the O_NONBLOCK flag on on a file descriptor.
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91 | 7831fc5f | Michael Hanselmann |
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92 | 7831fc5f | Michael Hanselmann | @type fd: int
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93 | 7831fc5f | Michael Hanselmann | @param fd: File descriptor
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94 | 7831fc5f | Michael Hanselmann | @type enable: bool
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95 | 7831fc5f | Michael Hanselmann | @param enable: Whether to set or unset it
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96 | 7831fc5f | Michael Hanselmann |
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97 | 7831fc5f | Michael Hanselmann | """
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98 | 7831fc5f | Michael Hanselmann | flags = fcntl.fcntl(fd, fcntl.F_GETFL) |
99 | 7831fc5f | Michael Hanselmann | |
100 | 7831fc5f | Michael Hanselmann | if enable:
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101 | 7831fc5f | Michael Hanselmann | flags |= os.O_NONBLOCK |
102 | 7831fc5f | Michael Hanselmann | else:
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103 | 7831fc5f | Michael Hanselmann | flags &= ~os.O_NONBLOCK |
104 | 7831fc5f | Michael Hanselmann | |
105 | 7831fc5f | Michael Hanselmann | fcntl.fcntl(fd, fcntl.F_SETFL, flags) |
106 | 7831fc5f | Michael Hanselmann | |
107 | 7831fc5f | Michael Hanselmann | |
108 | 7831fc5f | Michael Hanselmann | def RetryOnSignal(fn, *args, **kwargs): |
109 | 7831fc5f | Michael Hanselmann | """Calls a function again if it failed due to EINTR.
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110 | 7831fc5f | Michael Hanselmann |
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111 | 7831fc5f | Michael Hanselmann | """
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112 | 7831fc5f | Michael Hanselmann | while True: |
113 | 7831fc5f | Michael Hanselmann | try:
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114 | 7831fc5f | Michael Hanselmann | return fn(*args, **kwargs)
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115 | 7831fc5f | Michael Hanselmann | except EnvironmentError, err: |
116 | 7831fc5f | Michael Hanselmann | if err.errno != errno.EINTR:
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117 | 7831fc5f | Michael Hanselmann | raise
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118 | 7831fc5f | Michael Hanselmann | except (socket.error, select.error), err:
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119 | 7831fc5f | Michael Hanselmann | # In python 2.6 and above select.error is an IOError, so it's handled
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120 | 7831fc5f | Michael Hanselmann | # above, in 2.5 and below it's not, and it's handled here.
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121 | 7831fc5f | Michael Hanselmann | if not (err.args and err.args[0] == errno.EINTR): |
122 | 7831fc5f | Michael Hanselmann | raise
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123 | 7831fc5f | Michael Hanselmann | |
124 | 7831fc5f | Michael Hanselmann | |
125 | 7831fc5f | Michael Hanselmann | def IgnoreProcessNotFound(fn, *args, **kwargs): |
126 | 7831fc5f | Michael Hanselmann | """Ignores ESRCH when calling a process-related function.
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127 | 7831fc5f | Michael Hanselmann |
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128 | 7831fc5f | Michael Hanselmann | ESRCH is raised when a process is not found.
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129 | 7831fc5f | Michael Hanselmann |
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130 | 7831fc5f | Michael Hanselmann | @rtype: bool
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131 | 7831fc5f | Michael Hanselmann | @return: Whether process was found
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132 | 7831fc5f | Michael Hanselmann |
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133 | 7831fc5f | Michael Hanselmann | """
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134 | 7831fc5f | Michael Hanselmann | try:
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135 | 7831fc5f | Michael Hanselmann | fn(*args, **kwargs) |
136 | 7831fc5f | Michael Hanselmann | except EnvironmentError, err: |
137 | 7831fc5f | Michael Hanselmann | # Ignore ESRCH
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138 | 7831fc5f | Michael Hanselmann | if err.errno == errno.ESRCH:
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139 | 7831fc5f | Michael Hanselmann | return False |
140 | 7831fc5f | Michael Hanselmann | raise
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141 | 7831fc5f | Michael Hanselmann | |
142 | 7831fc5f | Michael Hanselmann | return True |
143 | 7831fc5f | Michael Hanselmann | |
144 | 7831fc5f | Michael Hanselmann | |
145 | 7831fc5f | Michael Hanselmann | def IgnoreSignals(fn, *args, **kwargs): |
146 | 7831fc5f | Michael Hanselmann | """Tries to call a function ignoring failures due to EINTR.
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147 | 7831fc5f | Michael Hanselmann |
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148 | 7831fc5f | Michael Hanselmann | """
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149 | 7831fc5f | Michael Hanselmann | try:
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150 | 7831fc5f | Michael Hanselmann | return fn(*args, **kwargs)
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151 | 7831fc5f | Michael Hanselmann | except EnvironmentError, err: |
152 | 7831fc5f | Michael Hanselmann | if err.errno == errno.EINTR:
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153 | 7831fc5f | Michael Hanselmann | return None |
154 | 7831fc5f | Michael Hanselmann | else:
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155 | 7831fc5f | Michael Hanselmann | raise
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156 | 7831fc5f | Michael Hanselmann | except (select.error, socket.error), err:
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157 | 7831fc5f | Michael Hanselmann | # In python 2.6 and above select.error is an IOError, so it's handled
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158 | 7831fc5f | Michael Hanselmann | # above, in 2.5 and below it's not, and it's handled here.
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159 | 7831fc5f | Michael Hanselmann | if err.args and err.args[0] == errno.EINTR: |
160 | 7831fc5f | Michael Hanselmann | return None |
161 | 7831fc5f | Michael Hanselmann | else:
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162 | 7831fc5f | Michael Hanselmann | raise
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163 | 7831fc5f | Michael Hanselmann | |
164 | 7831fc5f | Michael Hanselmann | |
165 | 7831fc5f | Michael Hanselmann | def GetClosedTempfile(*args, **kwargs): |
166 | 7831fc5f | Michael Hanselmann | """Creates a temporary file and returns its path.
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167 | 7831fc5f | Michael Hanselmann |
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168 | 7831fc5f | Michael Hanselmann | """
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169 | 7831fc5f | Michael Hanselmann | (fd, path) = tempfile.mkstemp(*args, **kwargs) |
170 | 7831fc5f | Michael Hanselmann | CloseFdNoError(fd) |
171 | 7831fc5f | Michael Hanselmann | return path
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172 | 44c9b4fe | Michael Hanselmann | |
173 | 44c9b4fe | Michael Hanselmann | |
174 | 44c9b4fe | Michael Hanselmann | def ResetTempfileModule(): |
175 | 44c9b4fe | Michael Hanselmann | """Resets the random name generator of the tempfile module.
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176 | 44c9b4fe | Michael Hanselmann |
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177 | 44c9b4fe | Michael Hanselmann | This function should be called after C{os.fork} in the child process to
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178 | 44c9b4fe | Michael Hanselmann | ensure it creates a newly seeded random generator. Otherwise it would
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179 | 44c9b4fe | Michael Hanselmann | generate the same random parts as the parent process. If several processes
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180 | 44c9b4fe | Michael Hanselmann | race for the creation of a temporary file, this could lead to one not getting
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181 | 44c9b4fe | Michael Hanselmann | a temporary name.
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182 | 44c9b4fe | Michael Hanselmann |
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183 | 44c9b4fe | Michael Hanselmann | """
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184 | b459a848 | Andrea Spadaccini | # pylint: disable=W0212
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185 | 44c9b4fe | Michael Hanselmann | if hasattr(tempfile, "_once_lock") and hasattr(tempfile, "_name_sequence"): |
186 | 44c9b4fe | Michael Hanselmann | tempfile._once_lock.acquire() |
187 | 44c9b4fe | Michael Hanselmann | try:
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188 | 44c9b4fe | Michael Hanselmann | # Reset random name generator
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189 | 44c9b4fe | Michael Hanselmann | tempfile._name_sequence = None
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190 | 44c9b4fe | Michael Hanselmann | finally:
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191 | 44c9b4fe | Michael Hanselmann | tempfile._once_lock.release() |
192 | 44c9b4fe | Michael Hanselmann | else:
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193 | 44c9b4fe | Michael Hanselmann | logging.critical("The tempfile module misses at least one of the"
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194 | 44c9b4fe | Michael Hanselmann | " '_once_lock' and '_name_sequence' attributes") |