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1 | 162c1c1f | Guido Trotter | #
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2 | 162c1c1f | Guido Trotter | #
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3 | 162c1c1f | Guido Trotter | |
4 | 162c1c1f | Guido Trotter | # Copyright (C) 2006, 2007 Google Inc.
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5 | 162c1c1f | Guido Trotter | #
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6 | 162c1c1f | Guido Trotter | # This program is free software; you can redistribute it and/or modify
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7 | 162c1c1f | Guido Trotter | # it under the terms of the GNU General Public License as published by
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8 | 162c1c1f | Guido Trotter | # the Free Software Foundation; either version 2 of the License, or
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9 | 162c1c1f | Guido Trotter | # (at your option) any later version.
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10 | 162c1c1f | Guido Trotter | #
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11 | 162c1c1f | Guido Trotter | # This program is distributed in the hope that it will be useful, but
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12 | 162c1c1f | Guido Trotter | # WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | 162c1c1f | Guido Trotter | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 | 162c1c1f | Guido Trotter | # General Public License for more details.
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15 | 162c1c1f | Guido Trotter | #
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16 | 162c1c1f | Guido Trotter | # You should have received a copy of the GNU General Public License
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17 | 162c1c1f | Guido Trotter | # along with this program; if not, write to the Free Software
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18 | 162c1c1f | Guido Trotter | # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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19 | 162c1c1f | Guido Trotter | # 02110-1301, USA.
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20 | 162c1c1f | Guido Trotter | |
21 | 162c1c1f | Guido Trotter | """Module implementing the Ganeti locking code."""
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22 | 162c1c1f | Guido Trotter | |
23 | c70d2d9b | Iustin Pop | # pylint: disable-msg=W0212
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24 | c70d2d9b | Iustin Pop | |
25 | c70d2d9b | Iustin Pop | # W0212 since e.g. LockSet methods use (a lot) the internals of
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26 | c70d2d9b | Iustin Pop | # SharedLock
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27 | 162c1c1f | Guido Trotter | |
28 | d76167a5 | Michael Hanselmann | import os |
29 | d76167a5 | Michael Hanselmann | import select |
30 | 162c1c1f | Guido Trotter | import threading |
31 | d76167a5 | Michael Hanselmann | import time |
32 | d76167a5 | Michael Hanselmann | import errno |
33 | 84e344d4 | Michael Hanselmann | |
34 | a95fd5d7 | Guido Trotter | from ganeti import errors |
35 | 7ee7c0c7 | Guido Trotter | from ganeti import utils |
36 | 162c1c1f | Guido Trotter | |
37 | 162c1c1f | Guido Trotter | |
38 | 42a999d1 | Guido Trotter | def ssynchronized(lock, shared=0): |
39 | 42a999d1 | Guido Trotter | """Shared Synchronization decorator.
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40 | 42a999d1 | Guido Trotter |
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41 | 42a999d1 | Guido Trotter | Calls the function holding the given lock, either in exclusive or shared
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42 | 42a999d1 | Guido Trotter | mode. It requires the passed lock to be a SharedLock (or support its
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43 | 42a999d1 | Guido Trotter | semantics).
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44 | 42a999d1 | Guido Trotter |
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45 | 42a999d1 | Guido Trotter | """
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46 | 42a999d1 | Guido Trotter | def wrap(fn): |
47 | 42a999d1 | Guido Trotter | def sync_function(*args, **kwargs): |
48 | 42a999d1 | Guido Trotter | lock.acquire(shared=shared) |
49 | 42a999d1 | Guido Trotter | try:
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50 | 42a999d1 | Guido Trotter | return fn(*args, **kwargs)
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51 | 42a999d1 | Guido Trotter | finally:
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52 | 42a999d1 | Guido Trotter | lock.release() |
53 | 42a999d1 | Guido Trotter | return sync_function
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54 | 42a999d1 | Guido Trotter | return wrap
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55 | 42a999d1 | Guido Trotter | |
56 | 42a999d1 | Guido Trotter | |
57 | 7e8841bd | Michael Hanselmann | class RunningTimeout(object): |
58 | 7e8841bd | Michael Hanselmann | """Class to calculate remaining timeout when doing several operations.
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59 | 7e8841bd | Michael Hanselmann |
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60 | 7e8841bd | Michael Hanselmann | """
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61 | 7e8841bd | Michael Hanselmann | __slots__ = [ |
62 | 7e8841bd | Michael Hanselmann | "_allow_negative",
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63 | 7e8841bd | Michael Hanselmann | "_start_time",
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64 | 7e8841bd | Michael Hanselmann | "_time_fn",
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65 | 7e8841bd | Michael Hanselmann | "_timeout",
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66 | 7e8841bd | Michael Hanselmann | ] |
67 | 7e8841bd | Michael Hanselmann | |
68 | 7e8841bd | Michael Hanselmann | def __init__(self, timeout, allow_negative, _time_fn=time.time): |
69 | 7e8841bd | Michael Hanselmann | """Initializes this class.
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70 | 7e8841bd | Michael Hanselmann |
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71 | 7e8841bd | Michael Hanselmann | @type timeout: float
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72 | 7e8841bd | Michael Hanselmann | @param timeout: Timeout duration
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73 | 7e8841bd | Michael Hanselmann | @type allow_negative: bool
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74 | 7e8841bd | Michael Hanselmann | @param allow_negative: Whether to return values below zero
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75 | 7e8841bd | Michael Hanselmann | @param _time_fn: Time function for unittests
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76 | 7e8841bd | Michael Hanselmann |
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77 | 7e8841bd | Michael Hanselmann | """
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78 | 7e8841bd | Michael Hanselmann | object.__init__(self) |
79 | 7e8841bd | Michael Hanselmann | |
80 | 7e8841bd | Michael Hanselmann | if timeout is not None and timeout < 0.0: |
81 | 7e8841bd | Michael Hanselmann | raise ValueError("Timeout must not be negative") |
82 | 7e8841bd | Michael Hanselmann | |
83 | 7e8841bd | Michael Hanselmann | self._timeout = timeout
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84 | 7e8841bd | Michael Hanselmann | self._allow_negative = allow_negative
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85 | 7e8841bd | Michael Hanselmann | self._time_fn = _time_fn
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86 | 7e8841bd | Michael Hanselmann | |
87 | 7e8841bd | Michael Hanselmann | self._start_time = None |
88 | 7e8841bd | Michael Hanselmann | |
89 | 7e8841bd | Michael Hanselmann | def Remaining(self): |
90 | 7e8841bd | Michael Hanselmann | """Returns the remaining timeout.
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91 | 7e8841bd | Michael Hanselmann |
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92 | 7e8841bd | Michael Hanselmann | """
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93 | 7e8841bd | Michael Hanselmann | if self._timeout is None: |
94 | 7e8841bd | Michael Hanselmann | return None |
95 | 7e8841bd | Michael Hanselmann | |
96 | 7e8841bd | Michael Hanselmann | # Get start time on first calculation
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97 | 7e8841bd | Michael Hanselmann | if self._start_time is None: |
98 | 7e8841bd | Michael Hanselmann | self._start_time = self._time_fn() |
99 | 7e8841bd | Michael Hanselmann | |
100 | 7e8841bd | Michael Hanselmann | # Calculate remaining time
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101 | 7e8841bd | Michael Hanselmann | remaining_timeout = self._start_time + self._timeout - self._time_fn() |
102 | 7e8841bd | Michael Hanselmann | |
103 | 7e8841bd | Michael Hanselmann | if not self._allow_negative: |
104 | 7e8841bd | Michael Hanselmann | # Ensure timeout is always >= 0
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105 | 7e8841bd | Michael Hanselmann | return max(0.0, remaining_timeout) |
106 | 7e8841bd | Michael Hanselmann | |
107 | 7e8841bd | Michael Hanselmann | return remaining_timeout
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108 | 7e8841bd | Michael Hanselmann | |
109 | 7e8841bd | Michael Hanselmann | |
110 | 34cb5617 | Guido Trotter | class _SingleNotifyPipeConditionWaiter(object): |
111 | 34cb5617 | Guido Trotter | """Helper class for SingleNotifyPipeCondition
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112 | d76167a5 | Michael Hanselmann |
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113 | d76167a5 | Michael Hanselmann | """
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114 | d76167a5 | Michael Hanselmann | __slots__ = [ |
115 | d76167a5 | Michael Hanselmann | "_fd",
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116 | d76167a5 | Michael Hanselmann | "_poller",
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117 | d76167a5 | Michael Hanselmann | ] |
118 | d76167a5 | Michael Hanselmann | |
119 | 34cb5617 | Guido Trotter | def __init__(self, poller, fd): |
120 | 34cb5617 | Guido Trotter | """Constructor for _SingleNotifyPipeConditionWaiter
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121 | d76167a5 | Michael Hanselmann |
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122 | d76167a5 | Michael Hanselmann | @type poller: select.poll
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123 | d76167a5 | Michael Hanselmann | @param poller: Poller object
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124 | d76167a5 | Michael Hanselmann | @type fd: int
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125 | d76167a5 | Michael Hanselmann | @param fd: File descriptor to wait for
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126 | d76167a5 | Michael Hanselmann |
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127 | d76167a5 | Michael Hanselmann | """
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128 | d76167a5 | Michael Hanselmann | object.__init__(self) |
129 | d76167a5 | Michael Hanselmann | self._poller = poller
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130 | d76167a5 | Michael Hanselmann | self._fd = fd
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131 | d76167a5 | Michael Hanselmann | |
132 | d76167a5 | Michael Hanselmann | def __call__(self, timeout): |
133 | d76167a5 | Michael Hanselmann | """Wait for something to happen on the pipe.
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134 | d76167a5 | Michael Hanselmann |
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135 | d76167a5 | Michael Hanselmann | @type timeout: float or None
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136 | d76167a5 | Michael Hanselmann | @param timeout: Timeout for waiting (can be None)
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137 | d76167a5 | Michael Hanselmann |
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138 | d76167a5 | Michael Hanselmann | """
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139 | f4e673fb | Michael Hanselmann | running_timeout = RunningTimeout(timeout, True)
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140 | f4e673fb | Michael Hanselmann | |
141 | f4e673fb | Michael Hanselmann | while True: |
142 | f4e673fb | Michael Hanselmann | remaining_time = running_timeout.Remaining() |
143 | f4e673fb | Michael Hanselmann | |
144 | b44b0141 | Michael Hanselmann | if remaining_time is not None: |
145 | b44b0141 | Michael Hanselmann | if remaining_time < 0.0: |
146 | b44b0141 | Michael Hanselmann | break
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147 | d76167a5 | Michael Hanselmann | |
148 | 413b7472 | Michael Hanselmann | # Our calculation uses seconds, poll() wants milliseconds
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149 | b44b0141 | Michael Hanselmann | remaining_time *= 1000
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150 | b44b0141 | Michael Hanselmann | |
151 | b44b0141 | Michael Hanselmann | try:
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152 | b44b0141 | Michael Hanselmann | result = self._poller.poll(remaining_time)
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153 | d76167a5 | Michael Hanselmann | except EnvironmentError, err: |
154 | d76167a5 | Michael Hanselmann | if err.errno != errno.EINTR:
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155 | d76167a5 | Michael Hanselmann | raise
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156 | d76167a5 | Michael Hanselmann | result = None
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157 | d76167a5 | Michael Hanselmann | |
158 | d76167a5 | Michael Hanselmann | # Check whether we were notified
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159 | d76167a5 | Michael Hanselmann | if result and result[0][0] == self._fd: |
160 | d76167a5 | Michael Hanselmann | break
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161 | d76167a5 | Michael Hanselmann | |
162 | d76167a5 | Michael Hanselmann | |
163 | 2419060d | Guido Trotter | class _BaseCondition(object): |
164 | 2419060d | Guido Trotter | """Base class containing common code for conditions.
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165 | 2419060d | Guido Trotter |
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166 | 2419060d | Guido Trotter | Some of this code is taken from python's threading module.
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167 | 2419060d | Guido Trotter |
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168 | 2419060d | Guido Trotter | """
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169 | 2419060d | Guido Trotter | __slots__ = [ |
170 | 2419060d | Guido Trotter | "_lock",
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171 | 2419060d | Guido Trotter | "acquire",
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172 | 2419060d | Guido Trotter | "release",
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173 | 2419060d | Guido Trotter | ] |
174 | 2419060d | Guido Trotter | |
175 | 2419060d | Guido Trotter | def __init__(self, lock): |
176 | 2419060d | Guido Trotter | """Constructor for _BaseCondition.
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177 | 2419060d | Guido Trotter |
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178 | 69b99987 | Michael Hanselmann | @type lock: threading.Lock
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179 | 2419060d | Guido Trotter | @param lock: condition base lock
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180 | 2419060d | Guido Trotter |
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181 | 2419060d | Guido Trotter | """
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182 | 2419060d | Guido Trotter | object.__init__(self) |
183 | 2419060d | Guido Trotter | |
184 | 2419060d | Guido Trotter | # Recursive locks are not supported
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185 | 2419060d | Guido Trotter | assert not hasattr(lock, "_acquire_restore") |
186 | 2419060d | Guido Trotter | assert not hasattr(lock, "_release_save") |
187 | 2419060d | Guido Trotter | |
188 | 2419060d | Guido Trotter | self._lock = lock
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189 | 2419060d | Guido Trotter | |
190 | 2419060d | Guido Trotter | # Export the lock's acquire() and release() methods
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191 | 2419060d | Guido Trotter | self.acquire = lock.acquire
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192 | 2419060d | Guido Trotter | self.release = lock.release
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193 | 2419060d | Guido Trotter | |
194 | 2419060d | Guido Trotter | def _is_owned(self): |
195 | 2419060d | Guido Trotter | """Check whether lock is owned by current thread.
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196 | 2419060d | Guido Trotter |
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197 | 2419060d | Guido Trotter | """
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198 | 2419060d | Guido Trotter | if self._lock.acquire(0): |
199 | 2419060d | Guido Trotter | self._lock.release()
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200 | 2419060d | Guido Trotter | return False |
201 | 2419060d | Guido Trotter | |
202 | 2419060d | Guido Trotter | return True |
203 | 2419060d | Guido Trotter | |
204 | 2419060d | Guido Trotter | def _check_owned(self): |
205 | 2419060d | Guido Trotter | """Raise an exception if the current thread doesn't own the lock.
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206 | 2419060d | Guido Trotter |
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207 | 2419060d | Guido Trotter | """
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208 | 2419060d | Guido Trotter | if not self._is_owned(): |
209 | 2419060d | Guido Trotter | raise RuntimeError("cannot work with un-aquired lock") |
210 | 2419060d | Guido Trotter | |
211 | 2419060d | Guido Trotter | |
212 | 34cb5617 | Guido Trotter | class SingleNotifyPipeCondition(_BaseCondition): |
213 | 34cb5617 | Guido Trotter | """Condition which can only be notified once.
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214 | d76167a5 | Michael Hanselmann |
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215 | 34cb5617 | Guido Trotter | This condition class uses pipes and poll, internally, to be able to wait for
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216 | 34cb5617 | Guido Trotter | notification with a timeout, without resorting to polling. It is almost
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217 | 34cb5617 | Guido Trotter | compatible with Python's threading.Condition, with the following differences:
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218 | 34cb5617 | Guido Trotter | - notifyAll can only be called once, and no wait can happen after that
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219 | 34cb5617 | Guido Trotter | - notify is not supported, only notifyAll
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220 | d76167a5 | Michael Hanselmann |
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221 | d76167a5 | Michael Hanselmann | """
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222 | 34cb5617 | Guido Trotter | |
223 | 34cb5617 | Guido Trotter | __slots__ = _BaseCondition.__slots__ + [ |
224 | d76167a5 | Michael Hanselmann | "_poller",
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225 | d76167a5 | Michael Hanselmann | "_read_fd",
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226 | d76167a5 | Michael Hanselmann | "_write_fd",
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227 | d76167a5 | Michael Hanselmann | "_nwaiters",
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228 | 34cb5617 | Guido Trotter | "_notified",
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229 | d76167a5 | Michael Hanselmann | ] |
230 | d76167a5 | Michael Hanselmann | |
231 | 34cb5617 | Guido Trotter | _waiter_class = _SingleNotifyPipeConditionWaiter |
232 | d76167a5 | Michael Hanselmann | |
233 | 34cb5617 | Guido Trotter | def __init__(self, lock): |
234 | 34cb5617 | Guido Trotter | """Constructor for SingleNotifyPipeCondition
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235 | d76167a5 | Michael Hanselmann |
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236 | d76167a5 | Michael Hanselmann | """
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237 | 34cb5617 | Guido Trotter | _BaseCondition.__init__(self, lock)
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238 | d76167a5 | Michael Hanselmann | self._nwaiters = 0 |
239 | 34cb5617 | Guido Trotter | self._notified = False |
240 | 34cb5617 | Guido Trotter | self._read_fd = None |
241 | 34cb5617 | Guido Trotter | self._write_fd = None |
242 | 34cb5617 | Guido Trotter | self._poller = None |
243 | d76167a5 | Michael Hanselmann | |
244 | 34cb5617 | Guido Trotter | def _check_unnotified(self): |
245 | 69b99987 | Michael Hanselmann | """Throws an exception if already notified.
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246 | 69b99987 | Michael Hanselmann |
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247 | 69b99987 | Michael Hanselmann | """
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248 | 34cb5617 | Guido Trotter | if self._notified: |
249 | 34cb5617 | Guido Trotter | raise RuntimeError("cannot use already notified condition") |
250 | d76167a5 | Michael Hanselmann | |
251 | 34cb5617 | Guido Trotter | def _Cleanup(self): |
252 | 34cb5617 | Guido Trotter | """Cleanup open file descriptors, if any.
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253 | d76167a5 | Michael Hanselmann |
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254 | d76167a5 | Michael Hanselmann | """
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255 | 34cb5617 | Guido Trotter | if self._read_fd is not None: |
256 | 34cb5617 | Guido Trotter | os.close(self._read_fd)
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257 | 34cb5617 | Guido Trotter | self._read_fd = None |
258 | d76167a5 | Michael Hanselmann | |
259 | 34cb5617 | Guido Trotter | if self._write_fd is not None: |
260 | 34cb5617 | Guido Trotter | os.close(self._write_fd)
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261 | 34cb5617 | Guido Trotter | self._write_fd = None |
262 | 34cb5617 | Guido Trotter | self._poller = None |
263 | d76167a5 | Michael Hanselmann | |
264 | 34cb5617 | Guido Trotter | def wait(self, timeout=None): |
265 | 34cb5617 | Guido Trotter | """Wait for a notification.
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266 | d76167a5 | Michael Hanselmann |
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267 | 34cb5617 | Guido Trotter | @type timeout: float or None
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268 | 34cb5617 | Guido Trotter | @param timeout: Waiting timeout (can be None)
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269 | d76167a5 | Michael Hanselmann |
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270 | d76167a5 | Michael Hanselmann | """
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271 | 34cb5617 | Guido Trotter | self._check_owned()
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272 | 34cb5617 | Guido Trotter | self._check_unnotified()
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273 | d76167a5 | Michael Hanselmann | |
274 | 34cb5617 | Guido Trotter | self._nwaiters += 1 |
275 | 34cb5617 | Guido Trotter | try:
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276 | 34cb5617 | Guido Trotter | if self._poller is None: |
277 | 34cb5617 | Guido Trotter | (self._read_fd, self._write_fd) = os.pipe() |
278 | 34cb5617 | Guido Trotter | self._poller = select.poll()
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279 | 34cb5617 | Guido Trotter | self._poller.register(self._read_fd, select.POLLHUP) |
280 | d76167a5 | Michael Hanselmann | |
281 | 34cb5617 | Guido Trotter | wait_fn = self._waiter_class(self._poller, self._read_fd) |
282 | 34cb5617 | Guido Trotter | self.release()
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283 | 34cb5617 | Guido Trotter | try:
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284 | 34cb5617 | Guido Trotter | # Wait for notification
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285 | 34cb5617 | Guido Trotter | wait_fn(timeout) |
286 | 34cb5617 | Guido Trotter | finally:
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287 | 34cb5617 | Guido Trotter | # Re-acquire lock
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288 | 34cb5617 | Guido Trotter | self.acquire()
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289 | 34cb5617 | Guido Trotter | finally:
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290 | 34cb5617 | Guido Trotter | self._nwaiters -= 1 |
291 | 34cb5617 | Guido Trotter | if self._nwaiters == 0: |
292 | 34cb5617 | Guido Trotter | self._Cleanup()
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293 | d76167a5 | Michael Hanselmann | |
294 | 7260cfbe | Iustin Pop | def notifyAll(self): # pylint: disable-msg=C0103 |
295 | d76167a5 | Michael Hanselmann | """Close the writing side of the pipe to notify all waiters.
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296 | d76167a5 | Michael Hanselmann |
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297 | d76167a5 | Michael Hanselmann | """
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298 | 34cb5617 | Guido Trotter | self._check_owned()
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299 | 34cb5617 | Guido Trotter | self._check_unnotified()
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300 | 34cb5617 | Guido Trotter | self._notified = True |
301 | d76167a5 | Michael Hanselmann | if self._write_fd is not None: |
302 | d76167a5 | Michael Hanselmann | os.close(self._write_fd)
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303 | d76167a5 | Michael Hanselmann | self._write_fd = None |
304 | d76167a5 | Michael Hanselmann | |
305 | d76167a5 | Michael Hanselmann | |
306 | 34cb5617 | Guido Trotter | class PipeCondition(_BaseCondition): |
307 | 48dabc6a | Michael Hanselmann | """Group-only non-polling condition with counters.
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308 | 48dabc6a | Michael Hanselmann |
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309 | 48dabc6a | Michael Hanselmann | This condition class uses pipes and poll, internally, to be able to wait for
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310 | 48dabc6a | Michael Hanselmann | notification with a timeout, without resorting to polling. It is almost
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311 | 48dabc6a | Michael Hanselmann | compatible with Python's threading.Condition, but only supports notifyAll and
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312 | 48dabc6a | Michael Hanselmann | non-recursive locks. As an additional features it's able to report whether
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313 | 48dabc6a | Michael Hanselmann | there are any waiting threads.
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314 | 48dabc6a | Michael Hanselmann |
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315 | 48dabc6a | Michael Hanselmann | """
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316 | 2419060d | Guido Trotter | __slots__ = _BaseCondition.__slots__ + [ |
317 | 48dabc6a | Michael Hanselmann | "_nwaiters",
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318 | 34cb5617 | Guido Trotter | "_single_condition",
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319 | 48dabc6a | Michael Hanselmann | ] |
320 | 48dabc6a | Michael Hanselmann | |
321 | 34cb5617 | Guido Trotter | _single_condition_class = SingleNotifyPipeCondition |
322 | 48dabc6a | Michael Hanselmann | |
323 | 48dabc6a | Michael Hanselmann | def __init__(self, lock): |
324 | 48dabc6a | Michael Hanselmann | """Initializes this class.
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325 | 48dabc6a | Michael Hanselmann |
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326 | 48dabc6a | Michael Hanselmann | """
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327 | 2419060d | Guido Trotter | _BaseCondition.__init__(self, lock)
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328 | 48dabc6a | Michael Hanselmann | self._nwaiters = 0 |
329 | 34cb5617 | Guido Trotter | self._single_condition = self._single_condition_class(self._lock) |
330 | 48dabc6a | Michael Hanselmann | |
331 | 48dabc6a | Michael Hanselmann | def wait(self, timeout=None): |
332 | 48dabc6a | Michael Hanselmann | """Wait for a notification.
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333 | 48dabc6a | Michael Hanselmann |
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334 | 48dabc6a | Michael Hanselmann | @type timeout: float or None
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335 | 48dabc6a | Michael Hanselmann | @param timeout: Waiting timeout (can be None)
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336 | 48dabc6a | Michael Hanselmann |
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337 | 48dabc6a | Michael Hanselmann | """
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338 | 48dabc6a | Michael Hanselmann | self._check_owned()
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339 | 48dabc6a | Michael Hanselmann | |
340 | 48dabc6a | Michael Hanselmann | # Keep local reference to the pipe. It could be replaced by another thread
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341 | 48dabc6a | Michael Hanselmann | # notifying while we're waiting.
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342 | 34cb5617 | Guido Trotter | my_condition = self._single_condition
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343 | 48dabc6a | Michael Hanselmann | |
344 | 48dabc6a | Michael Hanselmann | assert self._nwaiters >= 0 |
345 | 48dabc6a | Michael Hanselmann | self._nwaiters += 1 |
346 | 48dabc6a | Michael Hanselmann | try:
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347 | 34cb5617 | Guido Trotter | my_condition.wait(timeout) |
348 | 48dabc6a | Michael Hanselmann | finally:
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349 | 48dabc6a | Michael Hanselmann | assert self._nwaiters > 0 |
350 | 48dabc6a | Michael Hanselmann | self._nwaiters -= 1 |
351 | 48dabc6a | Michael Hanselmann | |
352 | 7260cfbe | Iustin Pop | def notifyAll(self): # pylint: disable-msg=C0103 |
353 | 48dabc6a | Michael Hanselmann | """Notify all currently waiting threads.
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354 | 48dabc6a | Michael Hanselmann |
|
355 | 48dabc6a | Michael Hanselmann | """
|
356 | 48dabc6a | Michael Hanselmann | self._check_owned()
|
357 | 34cb5617 | Guido Trotter | self._single_condition.notifyAll()
|
358 | 34cb5617 | Guido Trotter | self._single_condition = self._single_condition_class(self._lock) |
359 | 48dabc6a | Michael Hanselmann | |
360 | 48dabc6a | Michael Hanselmann | def has_waiting(self): |
361 | 48dabc6a | Michael Hanselmann | """Returns whether there are active waiters.
|
362 | 48dabc6a | Michael Hanselmann |
|
363 | 48dabc6a | Michael Hanselmann | """
|
364 | 48dabc6a | Michael Hanselmann | self._check_owned()
|
365 | 48dabc6a | Michael Hanselmann | |
366 | 48dabc6a | Michael Hanselmann | return bool(self._nwaiters) |
367 | 48dabc6a | Michael Hanselmann | |
368 | 48dabc6a | Michael Hanselmann | |
369 | 84e344d4 | Michael Hanselmann | class _CountingCondition(object): |
370 | 84e344d4 | Michael Hanselmann | """Wrapper for Python's built-in threading.Condition class.
|
371 | 84e344d4 | Michael Hanselmann |
|
372 | 84e344d4 | Michael Hanselmann | This wrapper keeps a count of active waiters. We can't access the internal
|
373 | 84e344d4 | Michael Hanselmann | "__waiters" attribute of threading.Condition because it's not thread-safe.
|
374 | 84e344d4 | Michael Hanselmann |
|
375 | 84e344d4 | Michael Hanselmann | """
|
376 | 84e344d4 | Michael Hanselmann | __slots__ = [ |
377 | 84e344d4 | Michael Hanselmann | "_cond",
|
378 | 84e344d4 | Michael Hanselmann | "_nwaiters",
|
379 | 84e344d4 | Michael Hanselmann | ] |
380 | 84e344d4 | Michael Hanselmann | |
381 | 84e344d4 | Michael Hanselmann | def __init__(self, lock): |
382 | 84e344d4 | Michael Hanselmann | """Initializes this class.
|
383 | 84e344d4 | Michael Hanselmann |
|
384 | 84e344d4 | Michael Hanselmann | """
|
385 | 84e344d4 | Michael Hanselmann | object.__init__(self) |
386 | 84e344d4 | Michael Hanselmann | self._cond = threading.Condition(lock=lock)
|
387 | 84e344d4 | Michael Hanselmann | self._nwaiters = 0 |
388 | 84e344d4 | Michael Hanselmann | |
389 | 7260cfbe | Iustin Pop | def notifyAll(self): # pylint: disable-msg=C0103 |
390 | 84e344d4 | Michael Hanselmann | """Notifies the condition.
|
391 | 84e344d4 | Michael Hanselmann |
|
392 | 84e344d4 | Michael Hanselmann | """
|
393 | 84e344d4 | Michael Hanselmann | return self._cond.notifyAll() |
394 | 84e344d4 | Michael Hanselmann | |
395 | 84e344d4 | Michael Hanselmann | def wait(self, timeout=None): |
396 | 84e344d4 | Michael Hanselmann | """Waits for the condition to be notified.
|
397 | 84e344d4 | Michael Hanselmann |
|
398 | 84e344d4 | Michael Hanselmann | @type timeout: float or None
|
399 | 34cb5617 | Guido Trotter | @param timeout: Waiting timeout (can be None)
|
400 | 84e344d4 | Michael Hanselmann |
|
401 | 84e344d4 | Michael Hanselmann | """
|
402 | 84e344d4 | Michael Hanselmann | assert self._nwaiters >= 0 |
403 | 84e344d4 | Michael Hanselmann | |
404 | 84e344d4 | Michael Hanselmann | self._nwaiters += 1 |
405 | 84e344d4 | Michael Hanselmann | try:
|
406 | 84e344d4 | Michael Hanselmann | return self._cond.wait(timeout=timeout) |
407 | 84e344d4 | Michael Hanselmann | finally:
|
408 | 84e344d4 | Michael Hanselmann | self._nwaiters -= 1 |
409 | 84e344d4 | Michael Hanselmann | |
410 | 84e344d4 | Michael Hanselmann | def has_waiting(self): |
411 | 84e344d4 | Michael Hanselmann | """Returns whether there are active waiters.
|
412 | 84e344d4 | Michael Hanselmann |
|
413 | 84e344d4 | Michael Hanselmann | """
|
414 | 84e344d4 | Michael Hanselmann | return bool(self._nwaiters) |
415 | 84e344d4 | Michael Hanselmann | |
416 | 84e344d4 | Michael Hanselmann | |
417 | 84e344d4 | Michael Hanselmann | class SharedLock(object): |
418 | 162c1c1f | Guido Trotter | """Implements a shared lock.
|
419 | 162c1c1f | Guido Trotter |
|
420 | 162c1c1f | Guido Trotter | Multiple threads can acquire the lock in a shared way, calling
|
421 | 162c1c1f | Guido Trotter | acquire_shared(). In order to acquire the lock in an exclusive way threads
|
422 | 162c1c1f | Guido Trotter | can call acquire_exclusive().
|
423 | 162c1c1f | Guido Trotter |
|
424 | 162c1c1f | Guido Trotter | The lock prevents starvation but does not guarantee that threads will acquire
|
425 | 162c1c1f | Guido Trotter | the shared lock in the order they queued for it, just that they will
|
426 | 162c1c1f | Guido Trotter | eventually do so.
|
427 | 162c1c1f | Guido Trotter |
|
428 | 162c1c1f | Guido Trotter | """
|
429 | 84e344d4 | Michael Hanselmann | __slots__ = [ |
430 | 84e344d4 | Michael Hanselmann | "__active_shr_c",
|
431 | 84e344d4 | Michael Hanselmann | "__inactive_shr_c",
|
432 | 84e344d4 | Michael Hanselmann | "__deleted",
|
433 | 84e344d4 | Michael Hanselmann | "__exc",
|
434 | 84e344d4 | Michael Hanselmann | "__lock",
|
435 | 84e344d4 | Michael Hanselmann | "__pending",
|
436 | 84e344d4 | Michael Hanselmann | "__shr",
|
437 | 84e344d4 | Michael Hanselmann | ] |
438 | 84e344d4 | Michael Hanselmann | |
439 | 34cb5617 | Guido Trotter | __condition_class = PipeCondition |
440 | 84e344d4 | Michael Hanselmann | |
441 | 162c1c1f | Guido Trotter | def __init__(self): |
442 | 84e344d4 | Michael Hanselmann | """Construct a new SharedLock.
|
443 | 84e344d4 | Michael Hanselmann |
|
444 | 84e344d4 | Michael Hanselmann | """
|
445 | 84e344d4 | Michael Hanselmann | object.__init__(self) |
446 | 84e344d4 | Michael Hanselmann | |
447 | 84e344d4 | Michael Hanselmann | # Internal lock
|
448 | 162c1c1f | Guido Trotter | self.__lock = threading.Lock()
|
449 | 162c1c1f | Guido Trotter | |
450 | 84e344d4 | Michael Hanselmann | # Queue containing waiting acquires
|
451 | 84e344d4 | Michael Hanselmann | self.__pending = []
|
452 | 84e344d4 | Michael Hanselmann | |
453 | 84e344d4 | Michael Hanselmann | # Active and inactive conditions for shared locks
|
454 | 84e344d4 | Michael Hanselmann | self.__active_shr_c = self.__condition_class(self.__lock) |
455 | 84e344d4 | Michael Hanselmann | self.__inactive_shr_c = self.__condition_class(self.__lock) |
456 | 84e344d4 | Michael Hanselmann | |
457 | 84e344d4 | Michael Hanselmann | # Current lock holders
|
458 | 162c1c1f | Guido Trotter | self.__shr = set() |
459 | 162c1c1f | Guido Trotter | self.__exc = None |
460 | 162c1c1f | Guido Trotter | |
461 | a95fd5d7 | Guido Trotter | # is this lock in the deleted state?
|
462 | a95fd5d7 | Guido Trotter | self.__deleted = False |
463 | a95fd5d7 | Guido Trotter | |
464 | 84e344d4 | Michael Hanselmann | def __check_deleted(self): |
465 | 84e344d4 | Michael Hanselmann | """Raises an exception if the lock has been deleted.
|
466 | 84e344d4 | Michael Hanselmann |
|
467 | 84e344d4 | Michael Hanselmann | """
|
468 | 84e344d4 | Michael Hanselmann | if self.__deleted: |
469 | 84e344d4 | Michael Hanselmann | raise errors.LockError("Deleted lock") |
470 | 84e344d4 | Michael Hanselmann | |
471 | 162c1c1f | Guido Trotter | def __is_sharer(self): |
472 | 84e344d4 | Michael Hanselmann | """Is the current thread sharing the lock at this time?
|
473 | 84e344d4 | Michael Hanselmann |
|
474 | 84e344d4 | Michael Hanselmann | """
|
475 | 162c1c1f | Guido Trotter | return threading.currentThread() in self.__shr |
476 | 162c1c1f | Guido Trotter | |
477 | 162c1c1f | Guido Trotter | def __is_exclusive(self): |
478 | 84e344d4 | Michael Hanselmann | """Is the current thread holding the lock exclusively at this time?
|
479 | 84e344d4 | Michael Hanselmann |
|
480 | 84e344d4 | Michael Hanselmann | """
|
481 | 162c1c1f | Guido Trotter | return threading.currentThread() == self.__exc |
482 | 162c1c1f | Guido Trotter | |
483 | 162c1c1f | Guido Trotter | def __is_owned(self, shared=-1): |
484 | 162c1c1f | Guido Trotter | """Is the current thread somehow owning the lock at this time?
|
485 | 162c1c1f | Guido Trotter |
|
486 | 162c1c1f | Guido Trotter | This is a private version of the function, which presumes you're holding
|
487 | 162c1c1f | Guido Trotter | the internal lock.
|
488 | 162c1c1f | Guido Trotter |
|
489 | 162c1c1f | Guido Trotter | """
|
490 | 162c1c1f | Guido Trotter | if shared < 0: |
491 | 162c1c1f | Guido Trotter | return self.__is_sharer() or self.__is_exclusive() |
492 | 162c1c1f | Guido Trotter | elif shared:
|
493 | 162c1c1f | Guido Trotter | return self.__is_sharer() |
494 | 162c1c1f | Guido Trotter | else:
|
495 | 162c1c1f | Guido Trotter | return self.__is_exclusive() |
496 | 162c1c1f | Guido Trotter | |
497 | 162c1c1f | Guido Trotter | def _is_owned(self, shared=-1): |
498 | 162c1c1f | Guido Trotter | """Is the current thread somehow owning the lock at this time?
|
499 | 162c1c1f | Guido Trotter |
|
500 | c41eea6e | Iustin Pop | @param shared:
|
501 | c41eea6e | Iustin Pop | - < 0: check for any type of ownership (default)
|
502 | c41eea6e | Iustin Pop | - 0: check for exclusive ownership
|
503 | c41eea6e | Iustin Pop | - > 0: check for shared ownership
|
504 | 162c1c1f | Guido Trotter |
|
505 | 162c1c1f | Guido Trotter | """
|
506 | 162c1c1f | Guido Trotter | self.__lock.acquire()
|
507 | 162c1c1f | Guido Trotter | try:
|
508 | 84e344d4 | Michael Hanselmann | return self.__is_owned(shared=shared) |
509 | 162c1c1f | Guido Trotter | finally:
|
510 | 162c1c1f | Guido Trotter | self.__lock.release()
|
511 | 162c1c1f | Guido Trotter | |
512 | 84e344d4 | Michael Hanselmann | def _count_pending(self): |
513 | 84e344d4 | Michael Hanselmann | """Returns the number of pending acquires.
|
514 | a95fd5d7 | Guido Trotter |
|
515 | 84e344d4 | Michael Hanselmann | @rtype: int
|
516 | a95fd5d7 | Guido Trotter |
|
517 | a95fd5d7 | Guido Trotter | """
|
518 | 84e344d4 | Michael Hanselmann | self.__lock.acquire()
|
519 | 84e344d4 | Michael Hanselmann | try:
|
520 | 84e344d4 | Michael Hanselmann | return len(self.__pending) |
521 | 84e344d4 | Michael Hanselmann | finally:
|
522 | 84e344d4 | Michael Hanselmann | self.__lock.release()
|
523 | a95fd5d7 | Guido Trotter | |
524 | 84e344d4 | Michael Hanselmann | def __do_acquire(self, shared): |
525 | 84e344d4 | Michael Hanselmann | """Actually acquire the lock.
|
526 | 84e344d4 | Michael Hanselmann |
|
527 | 84e344d4 | Michael Hanselmann | """
|
528 | 84e344d4 | Michael Hanselmann | if shared:
|
529 | 84e344d4 | Michael Hanselmann | self.__shr.add(threading.currentThread())
|
530 | 84e344d4 | Michael Hanselmann | else:
|
531 | 84e344d4 | Michael Hanselmann | self.__exc = threading.currentThread()
|
532 | a95fd5d7 | Guido Trotter | |
533 | 84e344d4 | Michael Hanselmann | def __can_acquire(self, shared): |
534 | 84e344d4 | Michael Hanselmann | """Determine whether lock can be acquired.
|
535 | a95fd5d7 | Guido Trotter |
|
536 | a95fd5d7 | Guido Trotter | """
|
537 | 84e344d4 | Michael Hanselmann | if shared:
|
538 | 84e344d4 | Michael Hanselmann | return self.__exc is None |
539 | 84e344d4 | Michael Hanselmann | else:
|
540 | 84e344d4 | Michael Hanselmann | return len(self.__shr) == 0 and self.__exc is None |
541 | a95fd5d7 | Guido Trotter | |
542 | 84e344d4 | Michael Hanselmann | def __is_on_top(self, cond): |
543 | 84e344d4 | Michael Hanselmann | """Checks whether the passed condition is on top of the queue.
|
544 | a95fd5d7 | Guido Trotter |
|
545 | 84e344d4 | Michael Hanselmann | The caller must make sure the queue isn't empty.
|
546 | a95fd5d7 | Guido Trotter |
|
547 | 84e344d4 | Michael Hanselmann | """
|
548 | 84e344d4 | Michael Hanselmann | return self.__pending[0] == cond |
549 | 4d686df8 | Guido Trotter | |
550 | a66bd91b | Michael Hanselmann | def __acquire_unlocked(self, shared, timeout): |
551 | 84e344d4 | Michael Hanselmann | """Acquire a shared lock.
|
552 | 9216a9f7 | Michael Hanselmann |
|
553 | 84e344d4 | Michael Hanselmann | @param shared: whether to acquire in shared mode; by default an
|
554 | 84e344d4 | Michael Hanselmann | exclusive lock will be acquired
|
555 | 84e344d4 | Michael Hanselmann | @param timeout: maximum waiting time before giving up
|
556 | 9216a9f7 | Michael Hanselmann |
|
557 | 9216a9f7 | Michael Hanselmann | """
|
558 | 84e344d4 | Michael Hanselmann | self.__check_deleted()
|
559 | 9216a9f7 | Michael Hanselmann | |
560 | 84e344d4 | Michael Hanselmann | # We cannot acquire the lock if we already have it
|
561 | 84e344d4 | Michael Hanselmann | assert not self.__is_owned(), "double acquire() on a non-recursive lock" |
562 | 84e344d4 | Michael Hanselmann | |
563 | 84e344d4 | Michael Hanselmann | # Check whether someone else holds the lock or there are pending acquires.
|
564 | 84e344d4 | Michael Hanselmann | if not self.__pending and self.__can_acquire(shared): |
565 | 84e344d4 | Michael Hanselmann | # Apparently not, can acquire lock directly.
|
566 | 84e344d4 | Michael Hanselmann | self.__do_acquire(shared)
|
567 | 84e344d4 | Michael Hanselmann | return True |
568 | 9216a9f7 | Michael Hanselmann | |
569 | 84e344d4 | Michael Hanselmann | if shared:
|
570 | 84e344d4 | Michael Hanselmann | wait_condition = self.__active_shr_c
|
571 | 9216a9f7 | Michael Hanselmann | |
572 | 84e344d4 | Michael Hanselmann | # Check if we're not yet in the queue
|
573 | 84e344d4 | Michael Hanselmann | if wait_condition not in self.__pending: |
574 | 84e344d4 | Michael Hanselmann | self.__pending.append(wait_condition)
|
575 | 84e344d4 | Michael Hanselmann | else:
|
576 | 84e344d4 | Michael Hanselmann | wait_condition = self.__condition_class(self.__lock) |
577 | 84e344d4 | Michael Hanselmann | # Always add to queue
|
578 | 84e344d4 | Michael Hanselmann | self.__pending.append(wait_condition)
|
579 | 84e344d4 | Michael Hanselmann | |
580 | 84e344d4 | Michael Hanselmann | try:
|
581 | 84e344d4 | Michael Hanselmann | # Wait until we become the topmost acquire in the queue or the timeout
|
582 | 84e344d4 | Michael Hanselmann | # expires.
|
583 | 84e344d4 | Michael Hanselmann | while not (self.__is_on_top(wait_condition) and |
584 | 84e344d4 | Michael Hanselmann | self.__can_acquire(shared)):
|
585 | 84e344d4 | Michael Hanselmann | # Wait for notification
|
586 | 84e344d4 | Michael Hanselmann | wait_condition.wait(timeout) |
587 | 84e344d4 | Michael Hanselmann | self.__check_deleted()
|
588 | 84e344d4 | Michael Hanselmann | |
589 | 84e344d4 | Michael Hanselmann | # A lot of code assumes blocking acquires always succeed. Loop
|
590 | 84e344d4 | Michael Hanselmann | # internally for that case.
|
591 | 84e344d4 | Michael Hanselmann | if timeout is not None: |
592 | 84e344d4 | Michael Hanselmann | break
|
593 | 84e344d4 | Michael Hanselmann | |
594 | 84e344d4 | Michael Hanselmann | if self.__is_on_top(wait_condition) and self.__can_acquire(shared): |
595 | 84e344d4 | Michael Hanselmann | self.__do_acquire(shared)
|
596 | 84e344d4 | Michael Hanselmann | return True |
597 | 9216a9f7 | Michael Hanselmann | finally:
|
598 | 84e344d4 | Michael Hanselmann | # Remove condition from queue if there are no more waiters
|
599 | 84e344d4 | Michael Hanselmann | if not wait_condition.has_waiting() and not self.__deleted: |
600 | 84e344d4 | Michael Hanselmann | self.__pending.remove(wait_condition)
|
601 | 9216a9f7 | Michael Hanselmann | |
602 | 84e344d4 | Michael Hanselmann | return False |
603 | 9216a9f7 | Michael Hanselmann | |
604 | 008b92fa | Michael Hanselmann | def acquire(self, shared=0, timeout=None, test_notify=None): |
605 | 162c1c1f | Guido Trotter | """Acquire a shared lock.
|
606 | 162c1c1f | Guido Trotter |
|
607 | 84e344d4 | Michael Hanselmann | @type shared: int
|
608 | c41eea6e | Iustin Pop | @param shared: whether to acquire in shared mode; by default an
|
609 | c41eea6e | Iustin Pop | exclusive lock will be acquired
|
610 | 84e344d4 | Michael Hanselmann | @type timeout: float
|
611 | 84e344d4 | Michael Hanselmann | @param timeout: maximum waiting time before giving up
|
612 | 008b92fa | Michael Hanselmann | @type test_notify: callable or None
|
613 | 008b92fa | Michael Hanselmann | @param test_notify: Special callback function for unittesting
|
614 | 162c1c1f | Guido Trotter |
|
615 | 162c1c1f | Guido Trotter | """
|
616 | 162c1c1f | Guido Trotter | self.__lock.acquire()
|
617 | 162c1c1f | Guido Trotter | try:
|
618 | 008b92fa | Michael Hanselmann | # We already got the lock, notify now
|
619 | 008b92fa | Michael Hanselmann | if __debug__ and callable(test_notify): |
620 | 008b92fa | Michael Hanselmann | test_notify() |
621 | 008b92fa | Michael Hanselmann | |
622 | 84e344d4 | Michael Hanselmann | return self.__acquire_unlocked(shared, timeout) |
623 | 162c1c1f | Guido Trotter | finally:
|
624 | 162c1c1f | Guido Trotter | self.__lock.release()
|
625 | 162c1c1f | Guido Trotter | |
626 | 162c1c1f | Guido Trotter | def release(self): |
627 | 162c1c1f | Guido Trotter | """Release a Shared Lock.
|
628 | 162c1c1f | Guido Trotter |
|
629 | 162c1c1f | Guido Trotter | You must have acquired the lock, either in shared or in exclusive mode,
|
630 | 162c1c1f | Guido Trotter | before calling this function.
|
631 | 162c1c1f | Guido Trotter |
|
632 | 162c1c1f | Guido Trotter | """
|
633 | 162c1c1f | Guido Trotter | self.__lock.acquire()
|
634 | 162c1c1f | Guido Trotter | try:
|
635 | 84e344d4 | Michael Hanselmann | assert self.__is_exclusive() or self.__is_sharer(), \ |
636 | 84e344d4 | Michael Hanselmann | "Cannot release non-owned lock"
|
637 | 84e344d4 | Michael Hanselmann | |
638 | 162c1c1f | Guido Trotter | # Autodetect release type
|
639 | 162c1c1f | Guido Trotter | if self.__is_exclusive(): |
640 | 162c1c1f | Guido Trotter | self.__exc = None |
641 | 84e344d4 | Michael Hanselmann | else:
|
642 | 162c1c1f | Guido Trotter | self.__shr.remove(threading.currentThread())
|
643 | 162c1c1f | Guido Trotter | |
644 | 84e344d4 | Michael Hanselmann | # Notify topmost condition in queue
|
645 | 84e344d4 | Michael Hanselmann | if self.__pending: |
646 | 84e344d4 | Michael Hanselmann | first_condition = self.__pending[0] |
647 | 84e344d4 | Michael Hanselmann | first_condition.notifyAll() |
648 | 4d686df8 | Guido Trotter | |
649 | 84e344d4 | Michael Hanselmann | if first_condition == self.__active_shr_c: |
650 | 84e344d4 | Michael Hanselmann | self.__active_shr_c = self.__inactive_shr_c |
651 | 84e344d4 | Michael Hanselmann | self.__inactive_shr_c = first_condition
|
652 | 162c1c1f | Guido Trotter | |
653 | 162c1c1f | Guido Trotter | finally:
|
654 | 162c1c1f | Guido Trotter | self.__lock.release()
|
655 | 162c1c1f | Guido Trotter | |
656 | 84e344d4 | Michael Hanselmann | def delete(self, timeout=None): |
657 | a95fd5d7 | Guido Trotter | """Delete a Shared Lock.
|
658 | a95fd5d7 | Guido Trotter |
|
659 | a95fd5d7 | Guido Trotter | This operation will declare the lock for removal. First the lock will be
|
660 | a95fd5d7 | Guido Trotter | acquired in exclusive mode if you don't already own it, then the lock
|
661 | a95fd5d7 | Guido Trotter | will be put in a state where any future and pending acquire() fail.
|
662 | a95fd5d7 | Guido Trotter |
|
663 | 84e344d4 | Michael Hanselmann | @type timeout: float
|
664 | 84e344d4 | Michael Hanselmann | @param timeout: maximum waiting time before giving up
|
665 | a95fd5d7 | Guido Trotter |
|
666 | a95fd5d7 | Guido Trotter | """
|
667 | a95fd5d7 | Guido Trotter | self.__lock.acquire()
|
668 | a95fd5d7 | Guido Trotter | try:
|
669 | 84e344d4 | Michael Hanselmann | assert not self.__is_sharer(), "Cannot delete() a lock while sharing it" |
670 | 84e344d4 | Michael Hanselmann | |
671 | 84e344d4 | Michael Hanselmann | self.__check_deleted()
|
672 | a95fd5d7 | Guido Trotter | |
673 | 84e344d4 | Michael Hanselmann | # The caller is allowed to hold the lock exclusively already.
|
674 | 84e344d4 | Michael Hanselmann | acquired = self.__is_exclusive()
|
675 | a95fd5d7 | Guido Trotter | |
676 | 84e344d4 | Michael Hanselmann | if not acquired: |
677 | a66bd91b | Michael Hanselmann | acquired = self.__acquire_unlocked(0, timeout) |
678 | a66bd91b | Michael Hanselmann | |
679 | a66bd91b | Michael Hanselmann | assert self.__is_exclusive() and not self.__is_sharer(), \ |
680 | a66bd91b | Michael Hanselmann | "Lock wasn't acquired in exclusive mode"
|
681 | 84e344d4 | Michael Hanselmann | |
682 | 84e344d4 | Michael Hanselmann | if acquired:
|
683 | 84e344d4 | Michael Hanselmann | self.__deleted = True |
684 | 84e344d4 | Michael Hanselmann | self.__exc = None |
685 | a95fd5d7 | Guido Trotter | |
686 | 84e344d4 | Michael Hanselmann | # Notify all acquires. They'll throw an error.
|
687 | 84e344d4 | Michael Hanselmann | while self.__pending: |
688 | 84e344d4 | Michael Hanselmann | self.__pending.pop().notifyAll()
|
689 | a95fd5d7 | Guido Trotter | |
690 | 84e344d4 | Michael Hanselmann | return acquired
|
691 | a95fd5d7 | Guido Trotter | finally:
|
692 | a95fd5d7 | Guido Trotter | self.__lock.release()
|
693 | a95fd5d7 | Guido Trotter | |
694 | aaae9bc0 | Guido Trotter | |
695 | f12eadb3 | Iustin Pop | # Whenever we want to acquire a full LockSet we pass None as the value
|
696 | 5bbd3f7f | Michael Hanselmann | # to acquire. Hide this behind this nicely named constant.
|
697 | e310b019 | Guido Trotter | ALL_SET = None
|
698 | e310b019 | Guido Trotter | |
699 | e310b019 | Guido Trotter | |
700 | 5aab242c | Michael Hanselmann | class _AcquireTimeout(Exception): |
701 | 5aab242c | Michael Hanselmann | """Internal exception to abort an acquire on a timeout.
|
702 | 5aab242c | Michael Hanselmann |
|
703 | 5aab242c | Michael Hanselmann | """
|
704 | 5aab242c | Michael Hanselmann | |
705 | 5aab242c | Michael Hanselmann | |
706 | aaae9bc0 | Guido Trotter | class LockSet: |
707 | aaae9bc0 | Guido Trotter | """Implements a set of locks.
|
708 | aaae9bc0 | Guido Trotter |
|
709 | aaae9bc0 | Guido Trotter | This abstraction implements a set of shared locks for the same resource type,
|
710 | aaae9bc0 | Guido Trotter | distinguished by name. The user can lock a subset of the resources and the
|
711 | aaae9bc0 | Guido Trotter | LockSet will take care of acquiring the locks always in the same order, thus
|
712 | aaae9bc0 | Guido Trotter | preventing deadlock.
|
713 | aaae9bc0 | Guido Trotter |
|
714 | aaae9bc0 | Guido Trotter | All the locks needed in the same set must be acquired together, though.
|
715 | aaae9bc0 | Guido Trotter |
|
716 | aaae9bc0 | Guido Trotter | """
|
717 | aaae9bc0 | Guido Trotter | def __init__(self, members=None): |
718 | aaae9bc0 | Guido Trotter | """Constructs a new LockSet.
|
719 | aaae9bc0 | Guido Trotter |
|
720 | c41eea6e | Iustin Pop | @param members: initial members of the set
|
721 | aaae9bc0 | Guido Trotter |
|
722 | aaae9bc0 | Guido Trotter | """
|
723 | aaae9bc0 | Guido Trotter | # Used internally to guarantee coherency.
|
724 | aaae9bc0 | Guido Trotter | self.__lock = SharedLock()
|
725 | aaae9bc0 | Guido Trotter | |
726 | aaae9bc0 | Guido Trotter | # The lockdict indexes the relationship name -> lock
|
727 | aaae9bc0 | Guido Trotter | # The order-of-locking is implied by the alphabetical order of names
|
728 | aaae9bc0 | Guido Trotter | self.__lockdict = {}
|
729 | aaae9bc0 | Guido Trotter | |
730 | aaae9bc0 | Guido Trotter | if members is not None: |
731 | aaae9bc0 | Guido Trotter | for name in members: |
732 | aaae9bc0 | Guido Trotter | self.__lockdict[name] = SharedLock()
|
733 | aaae9bc0 | Guido Trotter | |
734 | aaae9bc0 | Guido Trotter | # The owner dict contains the set of locks each thread owns. For
|
735 | aaae9bc0 | Guido Trotter | # performance each thread can access its own key without a global lock on
|
736 | aaae9bc0 | Guido Trotter | # this structure. It is paramount though that *no* other type of access is
|
737 | aaae9bc0 | Guido Trotter | # done to this structure (eg. no looping over its keys). *_owner helper
|
738 | aaae9bc0 | Guido Trotter | # function are defined to guarantee access is correct, but in general never
|
739 | aaae9bc0 | Guido Trotter | # do anything different than __owners[threading.currentThread()], or there
|
740 | aaae9bc0 | Guido Trotter | # will be trouble.
|
741 | aaae9bc0 | Guido Trotter | self.__owners = {}
|
742 | aaae9bc0 | Guido Trotter | |
743 | aaae9bc0 | Guido Trotter | def _is_owned(self): |
744 | aaae9bc0 | Guido Trotter | """Is the current thread a current level owner?"""
|
745 | aaae9bc0 | Guido Trotter | return threading.currentThread() in self.__owners |
746 | aaae9bc0 | Guido Trotter | |
747 | b2dabfd6 | Guido Trotter | def _add_owned(self, name=None): |
748 | aaae9bc0 | Guido Trotter | """Note the current thread owns the given lock"""
|
749 | b2dabfd6 | Guido Trotter | if name is None: |
750 | b2dabfd6 | Guido Trotter | if not self._is_owned(): |
751 | b2dabfd6 | Guido Trotter | self.__owners[threading.currentThread()] = set() |
752 | aaae9bc0 | Guido Trotter | else:
|
753 | b2dabfd6 | Guido Trotter | if self._is_owned(): |
754 | b2dabfd6 | Guido Trotter | self.__owners[threading.currentThread()].add(name)
|
755 | b2dabfd6 | Guido Trotter | else:
|
756 | b2dabfd6 | Guido Trotter | self.__owners[threading.currentThread()] = set([name]) |
757 | b2dabfd6 | Guido Trotter | |
758 | b2dabfd6 | Guido Trotter | def _del_owned(self, name=None): |
759 | aaae9bc0 | Guido Trotter | """Note the current thread owns the given lock"""
|
760 | aaae9bc0 | Guido Trotter | |
761 | e4335b5b | Michael Hanselmann | assert not (name is None and self.__lock._is_owned()), \ |
762 | e4335b5b | Michael Hanselmann | "Cannot hold internal lock when deleting owner status"
|
763 | e4335b5b | Michael Hanselmann | |
764 | b2dabfd6 | Guido Trotter | if name is not None: |
765 | b2dabfd6 | Guido Trotter | self.__owners[threading.currentThread()].remove(name)
|
766 | b2dabfd6 | Guido Trotter | |
767 | b2dabfd6 | Guido Trotter | # Only remove the key if we don't hold the set-lock as well
|
768 | b2dabfd6 | Guido Trotter | if (not self.__lock._is_owned() and |
769 | b2dabfd6 | Guido Trotter | not self.__owners[threading.currentThread()]): |
770 | aaae9bc0 | Guido Trotter | del self.__owners[threading.currentThread()] |
771 | aaae9bc0 | Guido Trotter | |
772 | aaae9bc0 | Guido Trotter | def _list_owned(self): |
773 | aaae9bc0 | Guido Trotter | """Get the set of resource names owned by the current thread"""
|
774 | aaae9bc0 | Guido Trotter | if self._is_owned(): |
775 | aaae9bc0 | Guido Trotter | return self.__owners[threading.currentThread()].copy() |
776 | aaae9bc0 | Guido Trotter | else:
|
777 | aaae9bc0 | Guido Trotter | return set() |
778 | aaae9bc0 | Guido Trotter | |
779 | 5aab242c | Michael Hanselmann | def _release_and_delete_owned(self): |
780 | 5aab242c | Michael Hanselmann | """Release and delete all resources owned by the current thread"""
|
781 | 5aab242c | Michael Hanselmann | for lname in self._list_owned(): |
782 | 56452af7 | Michael Hanselmann | lock = self.__lockdict[lname]
|
783 | 56452af7 | Michael Hanselmann | if lock._is_owned():
|
784 | 56452af7 | Michael Hanselmann | lock.release() |
785 | 5aab242c | Michael Hanselmann | self._del_owned(name=lname)
|
786 | 5aab242c | Michael Hanselmann | |
787 | aaae9bc0 | Guido Trotter | def __names(self): |
788 | aaae9bc0 | Guido Trotter | """Return the current set of names.
|
789 | aaae9bc0 | Guido Trotter |
|
790 | aaae9bc0 | Guido Trotter | Only call this function while holding __lock and don't iterate on the
|
791 | aaae9bc0 | Guido Trotter | result after releasing the lock.
|
792 | aaae9bc0 | Guido Trotter |
|
793 | aaae9bc0 | Guido Trotter | """
|
794 | 0cf257c5 | Guido Trotter | return self.__lockdict.keys() |
795 | aaae9bc0 | Guido Trotter | |
796 | aaae9bc0 | Guido Trotter | def _names(self): |
797 | aaae9bc0 | Guido Trotter | """Return a copy of the current set of elements.
|
798 | aaae9bc0 | Guido Trotter |
|
799 | aaae9bc0 | Guido Trotter | Used only for debugging purposes.
|
800 | cdb08f44 | Michael Hanselmann |
|
801 | aaae9bc0 | Guido Trotter | """
|
802 | d4803c24 | Guido Trotter | # If we don't already own the set-level lock acquired
|
803 | d4803c24 | Guido Trotter | # we'll get it and note we need to release it later.
|
804 | d4803c24 | Guido Trotter | release_lock = False
|
805 | d4803c24 | Guido Trotter | if not self.__lock._is_owned(): |
806 | d4803c24 | Guido Trotter | release_lock = True
|
807 | d4803c24 | Guido Trotter | self.__lock.acquire(shared=1) |
808 | aaae9bc0 | Guido Trotter | try:
|
809 | aaae9bc0 | Guido Trotter | result = self.__names()
|
810 | aaae9bc0 | Guido Trotter | finally:
|
811 | d4803c24 | Guido Trotter | if release_lock:
|
812 | d4803c24 | Guido Trotter | self.__lock.release()
|
813 | 0cf257c5 | Guido Trotter | return set(result) |
814 | aaae9bc0 | Guido Trotter | |
815 | 5aab242c | Michael Hanselmann | def acquire(self, names, timeout=None, shared=0, test_notify=None): |
816 | aaae9bc0 | Guido Trotter | """Acquire a set of resource locks.
|
817 | aaae9bc0 | Guido Trotter |
|
818 | c41eea6e | Iustin Pop | @param names: the names of the locks which shall be acquired
|
819 | c41eea6e | Iustin Pop | (special lock names, or instance/node names)
|
820 | c41eea6e | Iustin Pop | @param shared: whether to acquire in shared mode; by default an
|
821 | c41eea6e | Iustin Pop | exclusive lock will be acquired
|
822 | 5aab242c | Michael Hanselmann | @type timeout: float or None
|
823 | 5e0a6daf | Michael Hanselmann | @param timeout: Maximum time to acquire all locks
|
824 | 5aab242c | Michael Hanselmann | @type test_notify: callable or None
|
825 | 5aab242c | Michael Hanselmann | @param test_notify: Special callback function for unittesting
|
826 | aaae9bc0 | Guido Trotter |
|
827 | 5aab242c | Michael Hanselmann | @return: Set of all locks successfully acquired or None in case of timeout
|
828 | aaae9bc0 | Guido Trotter |
|
829 | c41eea6e | Iustin Pop | @raise errors.LockError: when any lock we try to acquire has
|
830 | c41eea6e | Iustin Pop | been deleted before we succeed. In this case none of the
|
831 | c41eea6e | Iustin Pop | locks requested will be acquired.
|
832 | aaae9bc0 | Guido Trotter |
|
833 | aaae9bc0 | Guido Trotter | """
|
834 | 5aab242c | Michael Hanselmann | assert timeout is None or timeout >= 0.0 |
835 | aaae9bc0 | Guido Trotter | |
836 | aaae9bc0 | Guido Trotter | # Check we don't already own locks at this level
|
837 | aaae9bc0 | Guido Trotter | assert not self._is_owned(), "Cannot acquire locks in the same set twice" |
838 | aaae9bc0 | Guido Trotter | |
839 | 5aab242c | Michael Hanselmann | # We need to keep track of how long we spent waiting for a lock. The
|
840 | 5aab242c | Michael Hanselmann | # timeout passed to this function is over all lock acquires.
|
841 | 7e8841bd | Michael Hanselmann | running_timeout = RunningTimeout(timeout, False)
|
842 | 5aab242c | Michael Hanselmann | |
843 | 806e20fd | Guido Trotter | try:
|
844 | 76e2f08a | Michael Hanselmann | if names is not None: |
845 | 5aab242c | Michael Hanselmann | # Support passing in a single resource to acquire rather than many
|
846 | 5aab242c | Michael Hanselmann | if isinstance(names, basestring): |
847 | 5aab242c | Michael Hanselmann | names = [names] |
848 | 5aab242c | Michael Hanselmann | |
849 | 76e2f08a | Michael Hanselmann | return self.__acquire_inner(names, False, shared, |
850 | 7e8841bd | Michael Hanselmann | running_timeout.Remaining, test_notify) |
851 | 76e2f08a | Michael Hanselmann | |
852 | 76e2f08a | Michael Hanselmann | else:
|
853 | 76e2f08a | Michael Hanselmann | # If no names are given acquire the whole set by not letting new names
|
854 | 76e2f08a | Michael Hanselmann | # being added before we release, and getting the current list of names.
|
855 | 76e2f08a | Michael Hanselmann | # Some of them may then be deleted later, but we'll cope with this.
|
856 | 76e2f08a | Michael Hanselmann | #
|
857 | 76e2f08a | Michael Hanselmann | # We'd like to acquire this lock in a shared way, as it's nice if
|
858 | 76e2f08a | Michael Hanselmann | # everybody else can use the instances at the same time. If are
|
859 | 76e2f08a | Michael Hanselmann | # acquiring them exclusively though they won't be able to do this
|
860 | 76e2f08a | Michael Hanselmann | # anyway, though, so we'll get the list lock exclusively as well in
|
861 | 76e2f08a | Michael Hanselmann | # order to be able to do add() on the set while owning it.
|
862 | 76e2f08a | Michael Hanselmann | if not self.__lock.acquire(shared=shared, |
863 | 7e8841bd | Michael Hanselmann | timeout=running_timeout.Remaining()): |
864 | 76e2f08a | Michael Hanselmann | raise _AcquireTimeout()
|
865 | 76e2f08a | Michael Hanselmann | try:
|
866 | 76e2f08a | Michael Hanselmann | # note we own the set-lock
|
867 | 76e2f08a | Michael Hanselmann | self._add_owned()
|
868 | 76e2f08a | Michael Hanselmann | |
869 | 76e2f08a | Michael Hanselmann | return self.__acquire_inner(self.__names(), True, shared, |
870 | 7e8841bd | Michael Hanselmann | running_timeout.Remaining, test_notify) |
871 | 76e2f08a | Michael Hanselmann | except:
|
872 | 76e2f08a | Michael Hanselmann | # We shouldn't have problems adding the lock to the owners list, but
|
873 | 76e2f08a | Michael Hanselmann | # if we did we'll try to release this lock and re-raise exception.
|
874 | 76e2f08a | Michael Hanselmann | # Of course something is going to be really wrong, after this.
|
875 | 5aab242c | Michael Hanselmann | self.__lock.release()
|
876 | 76e2f08a | Michael Hanselmann | self._del_owned()
|
877 | 76e2f08a | Michael Hanselmann | raise
|
878 | 5aab242c | Michael Hanselmann | |
879 | 5aab242c | Michael Hanselmann | except _AcquireTimeout:
|
880 | 5aab242c | Michael Hanselmann | return None |
881 | aaae9bc0 | Guido Trotter | |
882 | 76e2f08a | Michael Hanselmann | def __acquire_inner(self, names, want_all, shared, timeout_fn, test_notify): |
883 | 7e8841bd | Michael Hanselmann | """Inner logic for acquiring a number of locks.
|
884 | 7e8841bd | Michael Hanselmann |
|
885 | 7e8841bd | Michael Hanselmann | @param names: Names of the locks to be acquired
|
886 | 7e8841bd | Michael Hanselmann | @param want_all: Whether all locks in the set should be acquired
|
887 | 7e8841bd | Michael Hanselmann | @param shared: Whether to acquire in shared mode
|
888 | 7e8841bd | Michael Hanselmann | @param timeout_fn: Function returning remaining timeout
|
889 | 7e8841bd | Michael Hanselmann | @param test_notify: Special callback function for unittesting
|
890 | 76e2f08a | Michael Hanselmann |
|
891 | 76e2f08a | Michael Hanselmann | """
|
892 | 76e2f08a | Michael Hanselmann | acquire_list = [] |
893 | 76e2f08a | Michael Hanselmann | |
894 | 76e2f08a | Michael Hanselmann | # First we look the locks up on __lockdict. We have no way of being sure
|
895 | 76e2f08a | Michael Hanselmann | # they will still be there after, but this makes it a lot faster should
|
896 | 71e1863e | Michael Hanselmann | # just one of them be the already wrong. Using a sorted sequence to prevent
|
897 | 71e1863e | Michael Hanselmann | # deadlocks.
|
898 | 71e1863e | Michael Hanselmann | for lname in sorted(utils.UniqueSequence(names)): |
899 | 76e2f08a | Michael Hanselmann | try:
|
900 | 76e2f08a | Michael Hanselmann | lock = self.__lockdict[lname] # raises KeyError if lock is not there |
901 | 76e2f08a | Michael Hanselmann | except KeyError: |
902 | 76e2f08a | Michael Hanselmann | if want_all:
|
903 | 76e2f08a | Michael Hanselmann | # We are acquiring all the set, it doesn't matter if this particular
|
904 | 76e2f08a | Michael Hanselmann | # element is not there anymore.
|
905 | 76e2f08a | Michael Hanselmann | continue
|
906 | 76e2f08a | Michael Hanselmann | |
907 | 76e2f08a | Michael Hanselmann | raise errors.LockError("Non-existing lock in set (%s)" % lname) |
908 | 76e2f08a | Michael Hanselmann | |
909 | 9b154270 | Michael Hanselmann | acquire_list.append((lname, lock)) |
910 | 9b154270 | Michael Hanselmann | |
911 | 76e2f08a | Michael Hanselmann | # This will hold the locknames we effectively acquired.
|
912 | 76e2f08a | Michael Hanselmann | acquired = set()
|
913 | 76e2f08a | Michael Hanselmann | |
914 | 76e2f08a | Michael Hanselmann | try:
|
915 | 76e2f08a | Michael Hanselmann | # Now acquire_list contains a sorted list of resources and locks we
|
916 | 76e2f08a | Michael Hanselmann | # want. In order to get them we loop on this (private) list and
|
917 | 76e2f08a | Michael Hanselmann | # acquire() them. We gave no real guarantee they will still exist till
|
918 | 76e2f08a | Michael Hanselmann | # this is done but .acquire() itself is safe and will alert us if the
|
919 | 76e2f08a | Michael Hanselmann | # lock gets deleted.
|
920 | 76e2f08a | Michael Hanselmann | for (lname, lock) in acquire_list: |
921 | 76e2f08a | Michael Hanselmann | if __debug__ and callable(test_notify): |
922 | 76e2f08a | Michael Hanselmann | test_notify_fn = lambda: test_notify(lname)
|
923 | 76e2f08a | Michael Hanselmann | else:
|
924 | 76e2f08a | Michael Hanselmann | test_notify_fn = None
|
925 | 76e2f08a | Michael Hanselmann | |
926 | 76e2f08a | Michael Hanselmann | timeout = timeout_fn() |
927 | 76e2f08a | Michael Hanselmann | |
928 | 76e2f08a | Michael Hanselmann | try:
|
929 | 76e2f08a | Michael Hanselmann | # raises LockError if the lock was deleted
|
930 | 76e2f08a | Michael Hanselmann | acq_success = lock.acquire(shared=shared, timeout=timeout, |
931 | 76e2f08a | Michael Hanselmann | test_notify=test_notify_fn) |
932 | 76e2f08a | Michael Hanselmann | except errors.LockError:
|
933 | 76e2f08a | Michael Hanselmann | if want_all:
|
934 | 76e2f08a | Michael Hanselmann | # We are acquiring all the set, it doesn't matter if this
|
935 | 76e2f08a | Michael Hanselmann | # particular element is not there anymore.
|
936 | 76e2f08a | Michael Hanselmann | continue
|
937 | 76e2f08a | Michael Hanselmann | |
938 | 76e2f08a | Michael Hanselmann | raise errors.LockError("Non-existing lock in set (%s)" % lname) |
939 | 76e2f08a | Michael Hanselmann | |
940 | 76e2f08a | Michael Hanselmann | if not acq_success: |
941 | 76e2f08a | Michael Hanselmann | # Couldn't get lock or timeout occurred
|
942 | 76e2f08a | Michael Hanselmann | if timeout is None: |
943 | 76e2f08a | Michael Hanselmann | # This shouldn't happen as SharedLock.acquire(timeout=None) is
|
944 | 76e2f08a | Michael Hanselmann | # blocking.
|
945 | 76e2f08a | Michael Hanselmann | raise errors.LockError("Failed to get lock %s" % lname) |
946 | 76e2f08a | Michael Hanselmann | |
947 | 76e2f08a | Michael Hanselmann | raise _AcquireTimeout()
|
948 | 76e2f08a | Michael Hanselmann | |
949 | 76e2f08a | Michael Hanselmann | try:
|
950 | 76e2f08a | Michael Hanselmann | # now the lock cannot be deleted, we have it!
|
951 | 76e2f08a | Michael Hanselmann | self._add_owned(name=lname)
|
952 | 76e2f08a | Michael Hanselmann | acquired.add(lname) |
953 | 76e2f08a | Michael Hanselmann | |
954 | 76e2f08a | Michael Hanselmann | except:
|
955 | 76e2f08a | Michael Hanselmann | # We shouldn't have problems adding the lock to the owners list, but
|
956 | 76e2f08a | Michael Hanselmann | # if we did we'll try to release this lock and re-raise exception.
|
957 | 76e2f08a | Michael Hanselmann | # Of course something is going to be really wrong after this.
|
958 | 76e2f08a | Michael Hanselmann | if lock._is_owned():
|
959 | 76e2f08a | Michael Hanselmann | lock.release() |
960 | 76e2f08a | Michael Hanselmann | raise
|
961 | 76e2f08a | Michael Hanselmann | |
962 | 76e2f08a | Michael Hanselmann | except:
|
963 | 76e2f08a | Michael Hanselmann | # Release all owned locks
|
964 | 76e2f08a | Michael Hanselmann | self._release_and_delete_owned()
|
965 | 76e2f08a | Michael Hanselmann | raise
|
966 | 76e2f08a | Michael Hanselmann | |
967 | 0cc00929 | Guido Trotter | return acquired
|
968 | aaae9bc0 | Guido Trotter | |
969 | aaae9bc0 | Guido Trotter | def release(self, names=None): |
970 | aaae9bc0 | Guido Trotter | """Release a set of resource locks, at the same level.
|
971 | aaae9bc0 | Guido Trotter |
|
972 | aaae9bc0 | Guido Trotter | You must have acquired the locks, either in shared or in exclusive mode,
|
973 | aaae9bc0 | Guido Trotter | before releasing them.
|
974 | aaae9bc0 | Guido Trotter |
|
975 | c41eea6e | Iustin Pop | @param names: the names of the locks which shall be released
|
976 | c41eea6e | Iustin Pop | (defaults to all the locks acquired at that level).
|
977 | aaae9bc0 | Guido Trotter |
|
978 | aaae9bc0 | Guido Trotter | """
|
979 | aaae9bc0 | Guido Trotter | assert self._is_owned(), "release() on lock set while not owner" |
980 | aaae9bc0 | Guido Trotter | |
981 | aaae9bc0 | Guido Trotter | # Support passing in a single resource to release rather than many
|
982 | aaae9bc0 | Guido Trotter | if isinstance(names, basestring): |
983 | aaae9bc0 | Guido Trotter | names = [names] |
984 | aaae9bc0 | Guido Trotter | |
985 | aaae9bc0 | Guido Trotter | if names is None: |
986 | aaae9bc0 | Guido Trotter | names = self._list_owned()
|
987 | aaae9bc0 | Guido Trotter | else:
|
988 | aaae9bc0 | Guido Trotter | names = set(names)
|
989 | aaae9bc0 | Guido Trotter | assert self._list_owned().issuperset(names), ( |
990 | aaae9bc0 | Guido Trotter | "release() on unheld resources %s" %
|
991 | aaae9bc0 | Guido Trotter | names.difference(self._list_owned()))
|
992 | aaae9bc0 | Guido Trotter | |
993 | 3b7ed473 | Guido Trotter | # First of all let's release the "all elements" lock, if set.
|
994 | 3b7ed473 | Guido Trotter | # After this 'add' can work again
|
995 | 3b7ed473 | Guido Trotter | if self.__lock._is_owned(): |
996 | 3b7ed473 | Guido Trotter | self.__lock.release()
|
997 | b2dabfd6 | Guido Trotter | self._del_owned()
|
998 | 3b7ed473 | Guido Trotter | |
999 | aaae9bc0 | Guido Trotter | for lockname in names: |
1000 | aaae9bc0 | Guido Trotter | # If we are sure the lock doesn't leave __lockdict without being
|
1001 | aaae9bc0 | Guido Trotter | # exclusively held we can do this...
|
1002 | aaae9bc0 | Guido Trotter | self.__lockdict[lockname].release()
|
1003 | b2dabfd6 | Guido Trotter | self._del_owned(name=lockname)
|
1004 | aaae9bc0 | Guido Trotter | |
1005 | aaae9bc0 | Guido Trotter | def add(self, names, acquired=0, shared=0): |
1006 | aaae9bc0 | Guido Trotter | """Add a new set of elements to the set
|
1007 | aaae9bc0 | Guido Trotter |
|
1008 | c41eea6e | Iustin Pop | @param names: names of the new elements to add
|
1009 | c41eea6e | Iustin Pop | @param acquired: pre-acquire the new resource?
|
1010 | c41eea6e | Iustin Pop | @param shared: is the pre-acquisition shared?
|
1011 | aaae9bc0 | Guido Trotter |
|
1012 | aaae9bc0 | Guido Trotter | """
|
1013 | d2aff862 | Guido Trotter | # Check we don't already own locks at this level
|
1014 | d2aff862 | Guido Trotter | assert not self._is_owned() or self.__lock._is_owned(shared=0), \ |
1015 | d2aff862 | Guido Trotter | "Cannot add locks if the set is only partially owned, or shared"
|
1016 | 3b7ed473 | Guido Trotter | |
1017 | aaae9bc0 | Guido Trotter | # Support passing in a single resource to add rather than many
|
1018 | aaae9bc0 | Guido Trotter | if isinstance(names, basestring): |
1019 | aaae9bc0 | Guido Trotter | names = [names] |
1020 | aaae9bc0 | Guido Trotter | |
1021 | ab62526c | Guido Trotter | # If we don't already own the set-level lock acquired in an exclusive way
|
1022 | 3b7ed473 | Guido Trotter | # we'll get it and note we need to release it later.
|
1023 | 3b7ed473 | Guido Trotter | release_lock = False
|
1024 | 3b7ed473 | Guido Trotter | if not self.__lock._is_owned(): |
1025 | 3b7ed473 | Guido Trotter | release_lock = True
|
1026 | 3b7ed473 | Guido Trotter | self.__lock.acquire()
|
1027 | 3b7ed473 | Guido Trotter | |
1028 | aaae9bc0 | Guido Trotter | try:
|
1029 | 0cf257c5 | Guido Trotter | invalid_names = set(self.__names()).intersection(names) |
1030 | aaae9bc0 | Guido Trotter | if invalid_names:
|
1031 | aaae9bc0 | Guido Trotter | # This must be an explicit raise, not an assert, because assert is
|
1032 | aaae9bc0 | Guido Trotter | # turned off when using optimization, and this can happen because of
|
1033 | aaae9bc0 | Guido Trotter | # concurrency even if the user doesn't want it.
|
1034 | aaae9bc0 | Guido Trotter | raise errors.LockError("duplicate add() (%s)" % invalid_names) |
1035 | aaae9bc0 | Guido Trotter | |
1036 | aaae9bc0 | Guido Trotter | for lockname in names: |
1037 | aaae9bc0 | Guido Trotter | lock = SharedLock() |
1038 | aaae9bc0 | Guido Trotter | |
1039 | aaae9bc0 | Guido Trotter | if acquired:
|
1040 | aaae9bc0 | Guido Trotter | lock.acquire(shared=shared) |
1041 | aaae9bc0 | Guido Trotter | # now the lock cannot be deleted, we have it!
|
1042 | aaae9bc0 | Guido Trotter | try:
|
1043 | b2dabfd6 | Guido Trotter | self._add_owned(name=lockname)
|
1044 | aaae9bc0 | Guido Trotter | except:
|
1045 | aaae9bc0 | Guido Trotter | # We shouldn't have problems adding the lock to the owners list,
|
1046 | aaae9bc0 | Guido Trotter | # but if we did we'll try to release this lock and re-raise
|
1047 | aaae9bc0 | Guido Trotter | # exception. Of course something is going to be really wrong,
|
1048 | aaae9bc0 | Guido Trotter | # after this. On the other hand the lock hasn't been added to the
|
1049 | aaae9bc0 | Guido Trotter | # __lockdict yet so no other threads should be pending on it. This
|
1050 | aaae9bc0 | Guido Trotter | # release is just a safety measure.
|
1051 | aaae9bc0 | Guido Trotter | lock.release() |
1052 | aaae9bc0 | Guido Trotter | raise
|
1053 | aaae9bc0 | Guido Trotter | |
1054 | aaae9bc0 | Guido Trotter | self.__lockdict[lockname] = lock
|
1055 | aaae9bc0 | Guido Trotter | |
1056 | aaae9bc0 | Guido Trotter | finally:
|
1057 | 3b7ed473 | Guido Trotter | # Only release __lock if we were not holding it previously.
|
1058 | 3b7ed473 | Guido Trotter | if release_lock:
|
1059 | 3b7ed473 | Guido Trotter | self.__lock.release()
|
1060 | aaae9bc0 | Guido Trotter | |
1061 | aaae9bc0 | Guido Trotter | return True |
1062 | aaae9bc0 | Guido Trotter | |
1063 | 5e0a6daf | Michael Hanselmann | def remove(self, names): |
1064 | aaae9bc0 | Guido Trotter | """Remove elements from the lock set.
|
1065 | aaae9bc0 | Guido Trotter |
|
1066 | aaae9bc0 | Guido Trotter | You can either not hold anything in the lockset or already hold a superset
|
1067 | aaae9bc0 | Guido Trotter | of the elements you want to delete, exclusively.
|
1068 | aaae9bc0 | Guido Trotter |
|
1069 | c41eea6e | Iustin Pop | @param names: names of the resource to remove.
|
1070 | aaae9bc0 | Guido Trotter |
|
1071 | 5aab242c | Michael Hanselmann | @return: a list of locks which we removed; the list is always
|
1072 | c41eea6e | Iustin Pop | equal to the names list if we were holding all the locks
|
1073 | c41eea6e | Iustin Pop | exclusively
|
1074 | aaae9bc0 | Guido Trotter |
|
1075 | aaae9bc0 | Guido Trotter | """
|
1076 | aaae9bc0 | Guido Trotter | # Support passing in a single resource to remove rather than many
|
1077 | aaae9bc0 | Guido Trotter | if isinstance(names, basestring): |
1078 | aaae9bc0 | Guido Trotter | names = [names] |
1079 | aaae9bc0 | Guido Trotter | |
1080 | aaae9bc0 | Guido Trotter | # If we own any subset of this lock it must be a superset of what we want
|
1081 | aaae9bc0 | Guido Trotter | # to delete. The ownership must also be exclusive, but that will be checked
|
1082 | aaae9bc0 | Guido Trotter | # by the lock itself.
|
1083 | aaae9bc0 | Guido Trotter | assert not self._is_owned() or self._list_owned().issuperset(names), ( |
1084 | aaae9bc0 | Guido Trotter | "remove() on acquired lockset while not owning all elements")
|
1085 | aaae9bc0 | Guido Trotter | |
1086 | 3f404fc5 | Guido Trotter | removed = [] |
1087 | aaae9bc0 | Guido Trotter | |
1088 | aaae9bc0 | Guido Trotter | for lname in names: |
1089 | aaae9bc0 | Guido Trotter | # Calling delete() acquires the lock exclusively if we don't already own
|
1090 | aaae9bc0 | Guido Trotter | # it, and causes all pending and subsequent lock acquires to fail. It's
|
1091 | aaae9bc0 | Guido Trotter | # fine to call it out of order because delete() also implies release(),
|
1092 | aaae9bc0 | Guido Trotter | # and the assertion above guarantees that if we either already hold
|
1093 | aaae9bc0 | Guido Trotter | # everything we want to delete, or we hold none.
|
1094 | aaae9bc0 | Guido Trotter | try:
|
1095 | aaae9bc0 | Guido Trotter | self.__lockdict[lname].delete()
|
1096 | 3f404fc5 | Guido Trotter | removed.append(lname) |
1097 | aaae9bc0 | Guido Trotter | except (KeyError, errors.LockError): |
1098 | aaae9bc0 | Guido Trotter | # This cannot happen if we were already holding it, verify:
|
1099 | aaae9bc0 | Guido Trotter | assert not self._is_owned(), "remove failed while holding lockset" |
1100 | aaae9bc0 | Guido Trotter | else:
|
1101 | aaae9bc0 | Guido Trotter | # If no LockError was raised we are the ones who deleted the lock.
|
1102 | aaae9bc0 | Guido Trotter | # This means we can safely remove it from lockdict, as any further or
|
1103 | aaae9bc0 | Guido Trotter | # pending delete() or acquire() will fail (and nobody can have the lock
|
1104 | aaae9bc0 | Guido Trotter | # since before our call to delete()).
|
1105 | aaae9bc0 | Guido Trotter | #
|
1106 | aaae9bc0 | Guido Trotter | # This is done in an else clause because if the exception was thrown
|
1107 | aaae9bc0 | Guido Trotter | # it's the job of the one who actually deleted it.
|
1108 | aaae9bc0 | Guido Trotter | del self.__lockdict[lname] |
1109 | aaae9bc0 | Guido Trotter | # And let's remove it from our private list if we owned it.
|
1110 | aaae9bc0 | Guido Trotter | if self._is_owned(): |
1111 | b2dabfd6 | Guido Trotter | self._del_owned(name=lname)
|
1112 | aaae9bc0 | Guido Trotter | |
1113 | 3f404fc5 | Guido Trotter | return removed
|
1114 | aaae9bc0 | Guido Trotter | |
1115 | 7ee7c0c7 | Guido Trotter | |
1116 | 7ee7c0c7 | Guido Trotter | # Locking levels, must be acquired in increasing order.
|
1117 | 7ee7c0c7 | Guido Trotter | # Current rules are:
|
1118 | 7ee7c0c7 | Guido Trotter | # - at level LEVEL_CLUSTER resides the Big Ganeti Lock (BGL) which must be
|
1119 | 7ee7c0c7 | Guido Trotter | # acquired before performing any operation, either in shared or in exclusive
|
1120 | 7ee7c0c7 | Guido Trotter | # mode. acquiring the BGL in exclusive mode is discouraged and should be
|
1121 | 7ee7c0c7 | Guido Trotter | # avoided.
|
1122 | 7ee7c0c7 | Guido Trotter | # - at levels LEVEL_NODE and LEVEL_INSTANCE reside node and instance locks.
|
1123 | 7ee7c0c7 | Guido Trotter | # If you need more than one node, or more than one instance, acquire them at
|
1124 | 7ee7c0c7 | Guido Trotter | # the same time.
|
1125 | 7ee7c0c7 | Guido Trotter | LEVEL_CLUSTER = 0
|
1126 | 04e1bfaf | Guido Trotter | LEVEL_INSTANCE = 1
|
1127 | 04e1bfaf | Guido Trotter | LEVEL_NODE = 2
|
1128 | 7ee7c0c7 | Guido Trotter | |
1129 | 7ee7c0c7 | Guido Trotter | LEVELS = [LEVEL_CLUSTER, |
1130 | 04e1bfaf | Guido Trotter | LEVEL_INSTANCE, |
1131 | 04e1bfaf | Guido Trotter | LEVEL_NODE] |
1132 | 7ee7c0c7 | Guido Trotter | |
1133 | 7ee7c0c7 | Guido Trotter | # Lock levels which are modifiable
|
1134 | 7ee7c0c7 | Guido Trotter | LEVELS_MOD = [LEVEL_NODE, LEVEL_INSTANCE] |
1135 | 7ee7c0c7 | Guido Trotter | |
1136 | ea205dbc | Michael Hanselmann | LEVEL_NAMES = { |
1137 | ea205dbc | Michael Hanselmann | LEVEL_CLUSTER: "cluster",
|
1138 | ea205dbc | Michael Hanselmann | LEVEL_INSTANCE: "instance",
|
1139 | ea205dbc | Michael Hanselmann | LEVEL_NODE: "node",
|
1140 | ea205dbc | Michael Hanselmann | } |
1141 | ea205dbc | Michael Hanselmann | |
1142 | 08a6c581 | Guido Trotter | # Constant for the big ganeti lock
|
1143 | 7ee7c0c7 | Guido Trotter | BGL = 'BGL'
|
1144 | 7ee7c0c7 | Guido Trotter | |
1145 | 7ee7c0c7 | Guido Trotter | |
1146 | 7ee7c0c7 | Guido Trotter | class GanetiLockManager: |
1147 | 7ee7c0c7 | Guido Trotter | """The Ganeti Locking Library
|
1148 | 7ee7c0c7 | Guido Trotter |
|
1149 | 5bbd3f7f | Michael Hanselmann | The purpose of this small library is to manage locking for ganeti clusters
|
1150 | 7ee7c0c7 | Guido Trotter | in a central place, while at the same time doing dynamic checks against
|
1151 | 7ee7c0c7 | Guido Trotter | possible deadlocks. It will also make it easier to transition to a different
|
1152 | 7ee7c0c7 | Guido Trotter | lock type should we migrate away from python threads.
|
1153 | 7ee7c0c7 | Guido Trotter |
|
1154 | 7ee7c0c7 | Guido Trotter | """
|
1155 | 7ee7c0c7 | Guido Trotter | _instance = None
|
1156 | 7ee7c0c7 | Guido Trotter | |
1157 | 7ee7c0c7 | Guido Trotter | def __init__(self, nodes=None, instances=None): |
1158 | 7ee7c0c7 | Guido Trotter | """Constructs a new GanetiLockManager object.
|
1159 | 7ee7c0c7 | Guido Trotter |
|
1160 | 4e07ec8c | Guido Trotter | There should be only a GanetiLockManager object at any time, so this
|
1161 | 4e07ec8c | Guido Trotter | function raises an error if this is not the case.
|
1162 | 7ee7c0c7 | Guido Trotter |
|
1163 | c41eea6e | Iustin Pop | @param nodes: list of node names
|
1164 | c41eea6e | Iustin Pop | @param instances: list of instance names
|
1165 | 7ee7c0c7 | Guido Trotter |
|
1166 | 7ee7c0c7 | Guido Trotter | """
|
1167 | c41eea6e | Iustin Pop | assert self.__class__._instance is None, \ |
1168 | c41eea6e | Iustin Pop | "double GanetiLockManager instance"
|
1169 | c41eea6e | Iustin Pop | |
1170 | 7ee7c0c7 | Guido Trotter | self.__class__._instance = self |
1171 | 7ee7c0c7 | Guido Trotter | |
1172 | 7ee7c0c7 | Guido Trotter | # The keyring contains all the locks, at their level and in the correct
|
1173 | 7ee7c0c7 | Guido Trotter | # locking order.
|
1174 | 7ee7c0c7 | Guido Trotter | self.__keyring = {
|
1175 | 7ee7c0c7 | Guido Trotter | LEVEL_CLUSTER: LockSet([BGL]), |
1176 | 7ee7c0c7 | Guido Trotter | LEVEL_NODE: LockSet(nodes), |
1177 | 7ee7c0c7 | Guido Trotter | LEVEL_INSTANCE: LockSet(instances), |
1178 | 7ee7c0c7 | Guido Trotter | } |
1179 | 7ee7c0c7 | Guido Trotter | |
1180 | 7ee7c0c7 | Guido Trotter | def _names(self, level): |
1181 | 7ee7c0c7 | Guido Trotter | """List the lock names at the given level.
|
1182 | 7ee7c0c7 | Guido Trotter |
|
1183 | c41eea6e | Iustin Pop | This can be used for debugging/testing purposes.
|
1184 | c41eea6e | Iustin Pop |
|
1185 | c41eea6e | Iustin Pop | @param level: the level whose list of locks to get
|
1186 | 7ee7c0c7 | Guido Trotter |
|
1187 | 7ee7c0c7 | Guido Trotter | """
|
1188 | 7ee7c0c7 | Guido Trotter | assert level in LEVELS, "Invalid locking level %s" % level |
1189 | 7ee7c0c7 | Guido Trotter | return self.__keyring[level]._names() |
1190 | 7ee7c0c7 | Guido Trotter | |
1191 | 7ee7c0c7 | Guido Trotter | def _is_owned(self, level): |
1192 | 7ee7c0c7 | Guido Trotter | """Check whether we are owning locks at the given level
|
1193 | 7ee7c0c7 | Guido Trotter |
|
1194 | 7ee7c0c7 | Guido Trotter | """
|
1195 | 7ee7c0c7 | Guido Trotter | return self.__keyring[level]._is_owned() |
1196 | 7ee7c0c7 | Guido Trotter | |
1197 | d4f4b3e7 | Guido Trotter | is_owned = _is_owned |
1198 | d4f4b3e7 | Guido Trotter | |
1199 | 7ee7c0c7 | Guido Trotter | def _list_owned(self, level): |
1200 | 7ee7c0c7 | Guido Trotter | """Get the set of owned locks at the given level
|
1201 | 7ee7c0c7 | Guido Trotter |
|
1202 | 7ee7c0c7 | Guido Trotter | """
|
1203 | 7ee7c0c7 | Guido Trotter | return self.__keyring[level]._list_owned() |
1204 | 7ee7c0c7 | Guido Trotter | |
1205 | 7ee7c0c7 | Guido Trotter | def _upper_owned(self, level): |
1206 | 7ee7c0c7 | Guido Trotter | """Check that we don't own any lock at a level greater than the given one.
|
1207 | 7ee7c0c7 | Guido Trotter |
|
1208 | 7ee7c0c7 | Guido Trotter | """
|
1209 | 7ee7c0c7 | Guido Trotter | # This way of checking only works if LEVELS[i] = i, which we check for in
|
1210 | 7ee7c0c7 | Guido Trotter | # the test cases.
|
1211 | 7ee7c0c7 | Guido Trotter | return utils.any((self._is_owned(l) for l in LEVELS[level + 1:])) |
1212 | 7ee7c0c7 | Guido Trotter | |
1213 | fe267188 | Iustin Pop | def _BGL_owned(self): # pylint: disable-msg=C0103 |
1214 | 7ee7c0c7 | Guido Trotter | """Check if the current thread owns the BGL.
|
1215 | 7ee7c0c7 | Guido Trotter |
|
1216 | 7ee7c0c7 | Guido Trotter | Both an exclusive or a shared acquisition work.
|
1217 | 7ee7c0c7 | Guido Trotter |
|
1218 | 7ee7c0c7 | Guido Trotter | """
|
1219 | 7ee7c0c7 | Guido Trotter | return BGL in self.__keyring[LEVEL_CLUSTER]._list_owned() |
1220 | 7ee7c0c7 | Guido Trotter | |
1221 | c70d2d9b | Iustin Pop | @staticmethod
|
1222 | c70d2d9b | Iustin Pop | def _contains_BGL(level, names): # pylint: disable-msg=C0103 |
1223 | c41eea6e | Iustin Pop | """Check if the level contains the BGL.
|
1224 | c41eea6e | Iustin Pop |
|
1225 | c41eea6e | Iustin Pop | Check if acting on the given level and set of names will change
|
1226 | c41eea6e | Iustin Pop | the status of the Big Ganeti Lock.
|
1227 | 7ee7c0c7 | Guido Trotter |
|
1228 | 7ee7c0c7 | Guido Trotter | """
|
1229 | 7ee7c0c7 | Guido Trotter | return level == LEVEL_CLUSTER and (names is None or BGL in names) |
1230 | 7ee7c0c7 | Guido Trotter | |
1231 | 5e0a6daf | Michael Hanselmann | def acquire(self, level, names, timeout=None, shared=0): |
1232 | 7ee7c0c7 | Guido Trotter | """Acquire a set of resource locks, at the same level.
|
1233 | 7ee7c0c7 | Guido Trotter |
|
1234 | c41eea6e | Iustin Pop | @param level: the level at which the locks shall be acquired;
|
1235 | 5bbd3f7f | Michael Hanselmann | it must be a member of LEVELS.
|
1236 | c41eea6e | Iustin Pop | @param names: the names of the locks which shall be acquired
|
1237 | c41eea6e | Iustin Pop | (special lock names, or instance/node names)
|
1238 | c41eea6e | Iustin Pop | @param shared: whether to acquire in shared mode; by default
|
1239 | c41eea6e | Iustin Pop | an exclusive lock will be acquired
|
1240 | 5e0a6daf | Michael Hanselmann | @type timeout: float
|
1241 | 5e0a6daf | Michael Hanselmann | @param timeout: Maximum time to acquire all locks
|
1242 | 7ee7c0c7 | Guido Trotter |
|
1243 | 7ee7c0c7 | Guido Trotter | """
|
1244 | 7ee7c0c7 | Guido Trotter | assert level in LEVELS, "Invalid locking level %s" % level |
1245 | 7ee7c0c7 | Guido Trotter | |
1246 | 7ee7c0c7 | Guido Trotter | # Check that we are either acquiring the Big Ganeti Lock or we already own
|
1247 | 7ee7c0c7 | Guido Trotter | # it. Some "legacy" opcodes need to be sure they are run non-concurrently
|
1248 | 7ee7c0c7 | Guido Trotter | # so even if we've migrated we need to at least share the BGL to be
|
1249 | 7ee7c0c7 | Guido Trotter | # compatible with them. Of course if we own the BGL exclusively there's no
|
1250 | 7ee7c0c7 | Guido Trotter | # point in acquiring any other lock, unless perhaps we are half way through
|
1251 | 7ee7c0c7 | Guido Trotter | # the migration of the current opcode.
|
1252 | 7ee7c0c7 | Guido Trotter | assert (self._contains_BGL(level, names) or self._BGL_owned()), ( |
1253 | 7ee7c0c7 | Guido Trotter | "You must own the Big Ganeti Lock before acquiring any other")
|
1254 | 7ee7c0c7 | Guido Trotter | |
1255 | 7ee7c0c7 | Guido Trotter | # Check we don't own locks at the same or upper levels.
|
1256 | 21a6c826 | Guido Trotter | assert not self._upper_owned(level), ("Cannot acquire locks at a level" |
1257 | 7ee7c0c7 | Guido Trotter | " while owning some at a greater one")
|
1258 | 7ee7c0c7 | Guido Trotter | |
1259 | 7ee7c0c7 | Guido Trotter | # Acquire the locks in the set.
|
1260 | 5e0a6daf | Michael Hanselmann | return self.__keyring[level].acquire(names, shared=shared, timeout=timeout) |
1261 | 7ee7c0c7 | Guido Trotter | |
1262 | 7ee7c0c7 | Guido Trotter | def release(self, level, names=None): |
1263 | 7ee7c0c7 | Guido Trotter | """Release a set of resource locks, at the same level.
|
1264 | 7ee7c0c7 | Guido Trotter |
|
1265 | c41eea6e | Iustin Pop | You must have acquired the locks, either in shared or in exclusive
|
1266 | c41eea6e | Iustin Pop | mode, before releasing them.
|
1267 | 7ee7c0c7 | Guido Trotter |
|
1268 | c41eea6e | Iustin Pop | @param level: the level at which the locks shall be released;
|
1269 | 5bbd3f7f | Michael Hanselmann | it must be a member of LEVELS
|
1270 | c41eea6e | Iustin Pop | @param names: the names of the locks which shall be released
|
1271 | c41eea6e | Iustin Pop | (defaults to all the locks acquired at that level)
|
1272 | 7ee7c0c7 | Guido Trotter |
|
1273 | 7ee7c0c7 | Guido Trotter | """
|
1274 | 7ee7c0c7 | Guido Trotter | assert level in LEVELS, "Invalid locking level %s" % level |
1275 | 7ee7c0c7 | Guido Trotter | assert (not self._contains_BGL(level, names) or |
1276 | 7ee7c0c7 | Guido Trotter | not self._upper_owned(LEVEL_CLUSTER)), ( |
1277 | 7ee7c0c7 | Guido Trotter | "Cannot release the Big Ganeti Lock while holding something"
|
1278 | e4335b5b | Michael Hanselmann | " at upper levels (%r)" %
|
1279 | 1f864b60 | Iustin Pop | (utils.CommaJoin(["%s=%r" % (LEVEL_NAMES[i], self._list_owned(i)) |
1280 | 1f864b60 | Iustin Pop | for i in self.__keyring.keys()]), )) |
1281 | 7ee7c0c7 | Guido Trotter | |
1282 | 7ee7c0c7 | Guido Trotter | # Release will complain if we don't own the locks already
|
1283 | 7ee7c0c7 | Guido Trotter | return self.__keyring[level].release(names) |
1284 | 7ee7c0c7 | Guido Trotter | |
1285 | 7ee7c0c7 | Guido Trotter | def add(self, level, names, acquired=0, shared=0): |
1286 | 7ee7c0c7 | Guido Trotter | """Add locks at the specified level.
|
1287 | 7ee7c0c7 | Guido Trotter |
|
1288 | c41eea6e | Iustin Pop | @param level: the level at which the locks shall be added;
|
1289 | 5bbd3f7f | Michael Hanselmann | it must be a member of LEVELS_MOD.
|
1290 | c41eea6e | Iustin Pop | @param names: names of the locks to acquire
|
1291 | c41eea6e | Iustin Pop | @param acquired: whether to acquire the newly added locks
|
1292 | c41eea6e | Iustin Pop | @param shared: whether the acquisition will be shared
|
1293 | c41eea6e | Iustin Pop |
|
1294 | 7ee7c0c7 | Guido Trotter | """
|
1295 | 7ee7c0c7 | Guido Trotter | assert level in LEVELS_MOD, "Invalid or immutable level %s" % level |
1296 | 7ee7c0c7 | Guido Trotter | assert self._BGL_owned(), ("You must own the BGL before performing other" |
1297 | 7ee7c0c7 | Guido Trotter | " operations")
|
1298 | 7ee7c0c7 | Guido Trotter | assert not self._upper_owned(level), ("Cannot add locks at a level" |
1299 | 7ee7c0c7 | Guido Trotter | " while owning some at a greater one")
|
1300 | 7ee7c0c7 | Guido Trotter | return self.__keyring[level].add(names, acquired=acquired, shared=shared) |
1301 | 7ee7c0c7 | Guido Trotter | |
1302 | 5e0a6daf | Michael Hanselmann | def remove(self, level, names): |
1303 | 7ee7c0c7 | Guido Trotter | """Remove locks from the specified level.
|
1304 | 7ee7c0c7 | Guido Trotter |
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1305 | c41eea6e | Iustin Pop | You must either already own the locks you are trying to remove
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1306 | c41eea6e | Iustin Pop | exclusively or not own any lock at an upper level.
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1307 | 7ee7c0c7 | Guido Trotter |
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1308 | c41eea6e | Iustin Pop | @param level: the level at which the locks shall be removed;
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1309 | c41eea6e | Iustin Pop | it must be a member of LEVELS_MOD
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1310 | c41eea6e | Iustin Pop | @param names: the names of the locks which shall be removed
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1311 | c41eea6e | Iustin Pop | (special lock names, or instance/node names)
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1312 | 7ee7c0c7 | Guido Trotter |
|
1313 | 7ee7c0c7 | Guido Trotter | """
|
1314 | 7ee7c0c7 | Guido Trotter | assert level in LEVELS_MOD, "Invalid or immutable level %s" % level |
1315 | 7ee7c0c7 | Guido Trotter | assert self._BGL_owned(), ("You must own the BGL before performing other" |
1316 | 7ee7c0c7 | Guido Trotter | " operations")
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1317 | f12eadb3 | Iustin Pop | # Check we either own the level or don't own anything from here
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1318 | f12eadb3 | Iustin Pop | # up. LockSet.remove() will check the case in which we don't own
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1319 | f12eadb3 | Iustin Pop | # all the needed resources, or we have a shared ownership.
|
1320 | 7ee7c0c7 | Guido Trotter | assert self._is_owned(level) or not self._upper_owned(level), ( |
1321 | 7ee7c0c7 | Guido Trotter | "Cannot remove locks at a level while not owning it or"
|
1322 | 7ee7c0c7 | Guido Trotter | " owning some at a greater one")
|
1323 | 5e0a6daf | Michael Hanselmann | return self.__keyring[level].remove(names) |