/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py is in python-bzrlib 2.7.0-2ubuntu3.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 | # Copyright (C) 2009, 2010 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
"""Helpers for managing cleanup functions and the errors they might raise.
The usual way to run cleanup code in Python is::
try:
do_something()
finally:
cleanup_something()
However if both `do_something` and `cleanup_something` raise an exception
Python will forget the original exception and propagate the one from
cleanup_something. Unfortunately, this is almost always much less useful than
the original exception.
If you want to be certain that the first, and only the first, error is raised,
then use::
operation = OperationWithCleanups(do_something)
operation.add_cleanup(cleanup_something)
operation.run_simple()
This is more inconvenient (because you need to make every try block a
function), but will ensure that the first error encountered is the one raised,
while also ensuring all cleanups are run. See OperationWithCleanups for more
details.
"""
from __future__ import absolute_import
from collections import deque
import sys
from bzrlib import (
debug,
trace,
)
def _log_cleanup_error(exc):
trace.mutter('Cleanup failed:')
trace.log_exception_quietly()
if 'cleanup' in debug.debug_flags:
trace.warning('bzr: warning: Cleanup failed: %s', exc)
def _run_cleanup(func, *args, **kwargs):
"""Run func(*args, **kwargs), logging but not propagating any error it
raises.
:returns: True if func raised no errors, else False.
"""
try:
func(*args, **kwargs)
except KeyboardInterrupt:
raise
except Exception, exc:
_log_cleanup_error(exc)
return False
return True
def _run_cleanups(funcs):
"""Run a series of cleanup functions."""
for func, args, kwargs in funcs:
_run_cleanup(func, *args, **kwargs)
class ObjectWithCleanups(object):
"""A mixin for objects that hold a cleanup list.
Subclass or client code can call add_cleanup and then later `cleanup_now`.
"""
def __init__(self):
self.cleanups = deque()
def add_cleanup(self, cleanup_func, *args, **kwargs):
"""Add a cleanup to run.
Cleanups may be added at any time.
Cleanups will be executed in LIFO order.
"""
self.cleanups.appendleft((cleanup_func, args, kwargs))
def cleanup_now(self):
_run_cleanups(self.cleanups)
self.cleanups.clear()
class OperationWithCleanups(ObjectWithCleanups):
"""A way to run some code with a dynamic cleanup list.
This provides a way to add cleanups while the function-with-cleanups is
running.
Typical use::
operation = OperationWithCleanups(some_func)
operation.run(args...)
where `some_func` is::
def some_func(operation, args, ...):
do_something()
operation.add_cleanup(something)
# etc
Note that the first argument passed to `some_func` will be the
OperationWithCleanups object. To invoke `some_func` without that, use
`run_simple` instead of `run`.
"""
def __init__(self, func):
super(OperationWithCleanups, self).__init__()
self.func = func
def run(self, *args, **kwargs):
return _do_with_cleanups(
self.cleanups, self.func, self, *args, **kwargs)
def run_simple(self, *args, **kwargs):
return _do_with_cleanups(
self.cleanups, self.func, *args, **kwargs)
def _do_with_cleanups(cleanup_funcs, func, *args, **kwargs):
"""Run `func`, then call all the cleanup_funcs.
All the cleanup_funcs are guaranteed to be run. The first exception raised
by func or any of the cleanup_funcs is the one that will be propagted by
this function (subsequent errors are caught and logged).
Conceptually similar to::
try:
return func(*args, **kwargs)
finally:
for cleanup, cargs, ckwargs in cleanup_funcs:
cleanup(*cargs, **ckwargs)
It avoids several problems with using try/finally directly:
* an exception from func will not be obscured by a subsequent exception
from a cleanup.
* an exception from a cleanup will not prevent other cleanups from
running (but the first exception encountered is still the one
propagated).
Unike `_run_cleanup`, `_do_with_cleanups` can propagate an exception from a
cleanup, but only if there is no exception from func.
"""
# As correct as Python 2.4 allows.
try:
result = func(*args, **kwargs)
except:
# We have an exception from func already, so suppress cleanup errors.
_run_cleanups(cleanup_funcs)
raise
else:
# No exception from func, so allow the first exception from
# cleanup_funcs to propagate if one occurs (but only after running all
# of them).
exc_info = None
for cleanup, c_args, c_kwargs in cleanup_funcs:
# XXX: Hmm, if KeyboardInterrupt arrives at exactly this line, we
# won't run all cleanups... perhaps we should temporarily install a
# SIGINT handler?
if exc_info is None:
try:
cleanup(*c_args, **c_kwargs)
except:
# This is the first cleanup to fail, so remember its
# details.
exc_info = sys.exc_info()
else:
# We already have an exception to propagate, so log any errors
# but don't propagate them.
_run_cleanup(cleanup, *c_args, **kwargs)
if exc_info is not None:
try:
raise exc_info[0], exc_info[1], exc_info[2]
finally:
del exc_info
# No error, so we can return the result
return result
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