Mercurial > repos > guerler > springsuite

annotate planemo/lib/python3.7/site-packages/virtualenv/util/lock.py @ 1:56ad4e20f292 draft

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"planemo upload commit 6eee67778febed82ddd413c3ca40b3183a3898f1"
author guerler
date Fri, 31 Jul 2020 00:32:28 -0400
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1
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1 """holds locking functionality that works across processes"""
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2 from __future__ import absolute_import, unicode_literals
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3
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4 import logging
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5 import os
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6 from contextlib import contextmanager
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7 from threading import Lock, RLock
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8
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9 from filelock import FileLock, Timeout
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10
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11 from virtualenv.util.path import Path
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12
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13
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14 class _CountedFileLock(FileLock):
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15 def __init__(self, lock_file):
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16 parent = os.path.dirname(lock_file)
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17 if not os.path.exists(parent):
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18 try:
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19 os.makedirs(parent)
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20 except OSError:
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21 pass
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22 super(_CountedFileLock, self).__init__(lock_file)
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23 self.count = 0
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24 self.thread_safe = RLock()
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25
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26 def acquire(self, timeout=None, poll_intervall=0.05):
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27 with self.thread_safe:
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28 if self.count == 0:
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29 super(_CountedFileLock, self).acquire(timeout=timeout, poll_intervall=poll_intervall)
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30 self.count += 1
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31
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32 def release(self, force=False):
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33 with self.thread_safe:
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34 if self.count == 1:
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35 super(_CountedFileLock, self).release()
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36 self.count = max(self.count - 1, 0)
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37
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38
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39 _lock_store = {}
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40 _store_lock = Lock()
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41
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42
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43 class ReentrantFileLock(object):
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44 def __init__(self, folder):
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45 self._lock = None
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46 path = Path(folder)
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47 self.path = path.resolve() if path.exists() else path
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48
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49 def __repr__(self):
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50 return "{}({})".format(self.__class__.__name__, self.path)
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51
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52 def __div__(self, other):
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53 return ReentrantFileLock(self.path / other)
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54
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55 def __truediv__(self, other):
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56 return self.__div__(other)
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57
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58 def _create_lock(self, name=""):
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59 lock_file = str(self.path / "{}.lock".format(name))
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60 with _store_lock:
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61 if lock_file not in _lock_store:
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62 _lock_store[lock_file] = _CountedFileLock(lock_file)
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63 return _lock_store[lock_file]
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64
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65 @staticmethod
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66 def _del_lock(lock):
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67 with _store_lock:
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68 if lock is not None:
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69 with lock.thread_safe:
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70 if lock.count == 0:
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71 _lock_store.pop(lock.lock_file, None)
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72
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73 def __del__(self):
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74 self._del_lock(self._lock)
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75
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76 def __enter__(self):
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77 self._lock = self._create_lock()
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78 self._lock_file(self._lock)
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79
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80 def __exit__(self, exc_type, exc_val, exc_tb):
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81 self._release(self._lock)
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82
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83 def _lock_file(self, lock, no_block=False):
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84 # multiple processes might be trying to get a first lock... so we cannot check if this directory exist without
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85 # a lock, but that lock might then become expensive, and it's not clear where that lock should live.
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86 # Instead here we just ignore if we fail to create the directory.
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87 try:
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88 os.makedirs(str(self.path))
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89 except OSError:
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90 pass
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91 try:
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92 lock.acquire(0.0001)
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93 except Timeout:
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94 if no_block:
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95 raise
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96 logging.debug("lock file %s present, will block until released", lock.lock_file)
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97 lock.release() # release the acquire try from above
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98 lock.acquire()
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99
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100 @staticmethod
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101 def _release(lock):
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102 lock.release()
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103
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104 @contextmanager
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105 def lock_for_key(self, name, no_block=False):
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106 lock = self._create_lock(name)
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107 try:
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108 try:
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109 self._lock_file(lock, no_block)
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110 yield
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111 finally:
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112 self._release(lock)
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113 finally:
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114 self._del_lock(lock)
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115
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116
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117 __all__ = (
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118 "Timeout",
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119 "ReentrantFileLock",
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120 )