openstack/mistral
Code Issues Proposed changes

Add lockutils to openstack/common

Browse Source 
* This is step 1 needed for moving to testr
 * Module lockutils.py is needed by testr

Partially implements bp mistral-speedup-tests

Change-Id: Ic233da39f7266b8bf4ef862c89de02add259be50
This commit is contained in:
Nikolay Mahotkin
2014-06-02 17:20:33 +04:00
parent 03db18e484
commit 697a69d0eb
5 changed files with 726 additions and 0 deletions
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113
mistral/openstack/common/excutils.py Normal file
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# Copyright 2011 OpenStack Foundation.
# Copyright 2012, Red Hat, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Exception related utilities.
"""
import logging
import sys
import time
import traceback
import six
from mistral.openstack.common.gettextutils import _LE
class save_and_reraise_exception(object):
"""Save current exception, run some code and then re-raise.
In some cases the exception context can be cleared, resulting in None
being attempted to be re-raised after an exception handler is run. This
can happen when eventlet switches greenthreads or when running an
exception handler, code raises and catches an exception. In both
cases the exception context will be cleared.
To work around this, we save the exception state, run handler code, and
then re-raise the original exception. If another exception occurs, the
saved exception is logged and the new exception is re-raised.
In some cases the caller may not want to re-raise the exception, and
for those circumstances this context provides a reraise flag that
can be used to suppress the exception. For example::
except Exception:
with save_and_reraise_exception() as ctxt:
decide_if_need_reraise()
if not should_be_reraised:
ctxt.reraise = False
If another exception occurs and reraise flag is False,
the saved exception will not be logged.
If the caller wants to raise new exception during exception handling
he/she sets reraise to False initially with an ability to set it back to
True if needed::
except Exception:
with save_and_reraise_exception(reraise=False) as ctxt:
[if statements to determine whether to raise a new exception]
# Not raising a new exception, so reraise
ctxt.reraise = True
"""
def __init__(self, reraise=True):
self.reraise = reraise
def __enter__(self):
self.type_, self.value, self.tb, = sys.exc_info()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if exc_type is not None:
if self.reraise:
logging.error(_LE('Original exception being dropped: %s'),
traceback.format_exception(self.type_,
self.value,
self.tb))
return False
if self.reraise:
six.reraise(self.type_, self.value, self.tb)
def forever_retry_uncaught_exceptions(infunc):
def inner_func(*args, **kwargs):
last_log_time = 0
last_exc_message = None
exc_count = 0
while True:
try:
return infunc(*args, **kwargs)
except Exception as exc:
this_exc_message = six.u(str(exc))
if this_exc_message == last_exc_message:
exc_count += 1
else:
exc_count = 1
# Do not log any more frequently than once a minute unless
# the exception message changes
cur_time = int(time.time())
if (cur_time - last_log_time > 60 or
this_exc_message != last_exc_message):
logging.exception(
_LE('Unexpected exception occurred %d time(s)... '
'retrying.') % exc_count)
last_log_time = cur_time
last_exc_message = this_exc_message
exc_count = 0
# This should be a very rare event. In case it isn't, do
# a sleep.
time.sleep(1)
return inner_func

135
mistral/openstack/common/fileutils.py Normal file
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# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import contextlib
import errno
import os
import tempfile
from mistral.openstack.common import excutils
from mistral.openstack.common import log as logging
LOG = logging.getLogger(__name__)
_FILE_CACHE = {}
def ensure_tree(path):
"""Create a directory (and any ancestor directories required)
:param path: Directory to create
"""
try:
os.makedirs(path)
except OSError as exc:
if exc.errno == errno.EEXIST:
if not os.path.isdir(path):
raise
else:
raise
def read_cached_file(filename, force_reload=False):
"""Read from a file if it has been modified.
:param force_reload: Whether to reload the file.
:returns: A tuple with a boolean specifying if the data is fresh
or not.
"""
global _FILE_CACHE
if force_reload and filename in _FILE_CACHE:
del _FILE_CACHE[filename]
reloaded = False
mtime = os.path.getmtime(filename)
cache_info = _FILE_CACHE.setdefault(filename, {})
if not cache_info or mtime > cache_info.get('mtime', 0):
LOG.debug("Reloading cached file %s" % filename)
with open(filename) as fap:
cache_info['data'] = fap.read()
cache_info['mtime'] = mtime
reloaded = True
return (reloaded, cache_info['data'])
def delete_if_exists(path, remove=os.unlink):
"""Delete a file, but ignore file not found error.
:param path: File to delete
:param remove: Optional function to remove passed path
"""
try:
remove(path)
except OSError as e:
if e.errno != errno.ENOENT:
raise
@contextlib.contextmanager
def remove_path_on_error(path, remove=delete_if_exists):
"""Protect code that wants to operate on PATH atomically.
Any exception will cause PATH to be removed.
:param path: File to work with
:param remove: Optional function to remove passed path
"""
try:
yield
except Exception:
with excutils.save_and_reraise_exception():
remove(path)
def file_open(*args, **kwargs):
"""Open file
see built-in file() documentation for more details
Note: The reason this is kept in a separate module is to easily
be able to provide a stub module that doesn't alter system
state at all (for unit tests)
"""
return open(*args, **kwargs)
def write_to_tempfile(content, path=None, suffix='', prefix='tmp'):
"""Create temporary file or use existing file.
This util is needed for creating temporary file with
specified content, suffix and prefix. If path is not None,
it will be used for writing content. If the path doesn't
exist it'll be created.
:param content: content for temporary file.
:param path: same as parameter 'dir' for mkstemp
:param suffix: same as parameter 'suffix' for mkstemp
:param prefix: same as parameter 'prefix' for mkstemp
For example: it can be used in database tests for creating
configuration files.
"""
if path:
ensure_tree(path)
(fd, path) = tempfile.mkstemp(suffix=suffix, dir=path, prefix=prefix)
try:
os.write(fd, content)
finally:
os.close(fd)
return path

378
mistral/openstack/common/lockutils.py Normal file
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# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import contextlib
import errno
import fcntl
import functools
import os
import shutil
import subprocess
import sys
import tempfile
import threading
import time
import weakref
from oslo.config import cfg
from mistral.openstack.common import fileutils
from mistral.openstack.common.gettextutils import _, _LE, _LI
from mistral.openstack.common import log as logging
LOG = logging.getLogger(__name__)
util_opts = [
cfg.BoolOpt('disable_process_locking', default=False,
help='Enables or disables inter-process locks.'),
cfg.StrOpt('lock_path',
default=os.environ.get("MISTRAL_LOCK_PATH"),
help='Directory to use for lock files.')
]
CONF = cfg.CONF
CONF.register_opts(util_opts)
def set_defaults(lock_path):
cfg.set_defaults(util_opts, lock_path=lock_path)
class _FileLock(object):
"""Lock implementation which allows multiple locks, working around
issues like bugs.debian.org/cgi-bin/bugreport.cgi?bug=632857 and does
not require any cleanup. Since the lock is always held on a file
descriptor rather than outside of the process, the lock gets dropped
automatically if the process crashes, even if __exit__ is not executed.
There are no guarantees regarding usage by multiple green threads in a
single process here. This lock works only between processes. Exclusive
access between local threads should be achieved using the semaphores
in the @synchronized decorator.
Note these locks are released when the descriptor is closed, so it's not
safe to close the file descriptor while another green thread holds the
lock. Just opening and closing the lock file can break synchronisation,
so lock files must be accessed only using this abstraction.
"""
def __init__(self, name):
self.lockfile = None
self.fname = name
def acquire(self):
basedir = os.path.dirname(self.fname)
if not os.path.exists(basedir):
fileutils.ensure_tree(basedir)
LOG.info(_LI('Created lock path: %s'), basedir)
self.lockfile = open(self.fname, 'w')
while True:
try:
# Using non-blocking locks since green threads are not
# patched to deal with blocking locking calls.
# Also upon reading the MSDN docs for locking(), it seems
# to have a laughable 10 attempts "blocking" mechanism.
self.trylock()
LOG.debug('Got file lock "%s"', self.fname)
return True
except IOError as e:
if e.errno in (errno.EACCES, errno.EAGAIN):
# external locks synchronise things like iptables
# updates - give it some time to prevent busy spinning
time.sleep(0.01)
else:
raise threading.ThreadError(_("Unable to acquire lock on"
" `%(filename)s` due to"
" %(exception)s") %
{
'filename': self.fname,
'exception': e,
})
def __enter__(self):
self.acquire()
return self
def release(self):
try:
self.unlock()
self.lockfile.close()
LOG.debug('Released file lock "%s"', self.fname)
except IOError:
LOG.exception(_LE("Could not release the acquired lock `%s`"),
self.fname)
def __exit__(self, exc_type, exc_val, exc_tb):
self.release()
def exists(self):
return os.path.exists(self.fname)
def trylock(self):
raise NotImplementedError()
def unlock(self):
raise NotImplementedError()
class _WindowsLock(_FileLock):
def trylock(self):
msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_NBLCK, 1)
def unlock(self):
msvcrt.locking(self.lockfile.fileno(), msvcrt.LK_UNLCK, 1)
class _FcntlLock(_FileLock):
def trylock(self):
fcntl.lockf(self.lockfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
def unlock(self):
fcntl.lockf(self.lockfile, fcntl.LOCK_UN)
class _PosixLock(object):
def __init__(self, name):
# Hash the name because it's not valid to have POSIX semaphore
# names with things like / in them. Then use base64 to encode
# the digest() instead taking the hexdigest() because the
# result is shorter and most systems can't have shm sempahore
# names longer than 31 characters.
h = hashlib.sha1()
h.update(name.encode('ascii'))
self.name = str((b'/' + base64.urlsafe_b64encode(
h.digest())).decode('ascii'))
def acquire(self, timeout=None):
self.semaphore = posix_ipc.Semaphore(self.name,
flags=posix_ipc.O_CREAT,
initial_value=1)
self.semaphore.acquire(timeout)
return self
def __enter__(self):
self.acquire()
return self
def release(self):
self.semaphore.release()
self.semaphore.close()
def __exit__(self, exc_type, exc_val, exc_tb):
self.release()
def exists(self):
try:
semaphore = posix_ipc.Semaphore(self.name)
except posix_ipc.ExistentialError:
return False
else:
semaphore.close()
return True
if os.name == 'nt':
import msvcrt
InterProcessLock = _WindowsLock
FileLock = _WindowsLock
else:
import base64
import hashlib
import posix_ipc
InterProcessLock = _PosixLock
FileLock = _FcntlLock
_semaphores = weakref.WeakValueDictionary()
_semaphores_lock = threading.Lock()
def _get_lock_path(name, lock_file_prefix, lock_path=None):
# NOTE(mikal): the lock name cannot contain directory
# separators
name = name.replace(os.sep, '_')
if lock_file_prefix:
sep = '' if lock_file_prefix.endswith('-') else '-'
name = '%s%s%s' % (lock_file_prefix, sep, name)
local_lock_path = lock_path or CONF.lock_path
if not local_lock_path:
# NOTE(bnemec): Create a fake lock path for posix locks so we don't
# unnecessarily raise the RequiredOptError below.
if InterProcessLock is not _PosixLock:
raise cfg.RequiredOptError('lock_path')
local_lock_path = 'posixlock:/'
return os.path.join(local_lock_path, name)
def external_lock(name, lock_file_prefix=None, lock_path=None):
LOG.debug('Attempting to grab external lock "%(lock)s"',
{'lock': name})
lock_file_path = _get_lock_path(name, lock_file_prefix, lock_path)
# NOTE(bnemec): If an explicit lock_path was passed to us then it
# means the caller is relying on file-based locking behavior, so
# we can't use posix locks for those calls.
if lock_path:
return FileLock(lock_file_path)
return InterProcessLock(lock_file_path)
def remove_external_lock_file(name, lock_file_prefix=None):
"""Remove a external lock file when it's not used anymore
This will be helpful when we have a lot of lock files
"""
with internal_lock(name):
lock_file_path = _get_lock_path(name, lock_file_prefix)
try:
os.remove(lock_file_path)
except OSError:
LOG.info(_LI('Failed to remove file %(file)s'),
{'file': lock_file_path})
def internal_lock(name):
with _semaphores_lock:
try:
sem = _semaphores[name]
except KeyError:
sem = threading.Semaphore()
_semaphores[name] = sem
LOG.debug('Got semaphore "%(lock)s"', {'lock': name})
return sem
@contextlib.contextmanager
def lock(name, lock_file_prefix=None, external=False, lock_path=None):
"""Context based lock
This function yields a `threading.Semaphore` instance (if we don't use
eventlet.monkey_patch(), else `semaphore.Semaphore`) unless external is
True, in which case, it'll yield an InterProcessLock instance.
:param lock_file_prefix: The lock_file_prefix argument is used to provide
lock files on disk with a meaningful prefix.
:param external: The external keyword argument denotes whether this lock
should work across multiple processes. This means that if two different
workers both run a method decorated with @synchronized('mylock',
external=True), only one of them will execute at a time.
"""
int_lock = internal_lock(name)
with int_lock:
if external and not CONF.disable_process_locking:
ext_lock = external_lock(name, lock_file_prefix, lock_path)
with ext_lock:
yield ext_lock
else:
yield int_lock
LOG.debug('Released semaphore "%(lock)s"', {'lock': name})
def synchronized(name, lock_file_prefix=None, external=False, lock_path=None):
"""Synchronization decorator.
Decorating a method like so::
@synchronized('mylock')
def foo(self, *args):
...
ensures that only one thread will execute the foo method at a time.
Different methods can share the same lock::
@synchronized('mylock')
def foo(self, *args):
...
@synchronized('mylock')
def bar(self, *args):
...
This way only one of either foo or bar can be executing at a time.
"""
def wrap(f):
@functools.wraps(f)
def inner(*args, **kwargs):
try:
with lock(name, lock_file_prefix, external, lock_path):
LOG.debug('Got semaphore / lock "%(function)s"',
{'function': f.__name__})
return f(*args, **kwargs)
finally:
LOG.debug('Semaphore / lock released "%(function)s"',
{'function': f.__name__})
return inner
return wrap
def synchronized_with_prefix(lock_file_prefix):
"""Partial object generator for the synchronization decorator.
Redefine @synchronized in each project like so::
(in nova/utils.py)
from nova.openstack.common import lockutils
synchronized = lockutils.synchronized_with_prefix('nova-')
(in nova/foo.py)
from nova import utils
@utils.synchronized('mylock')
def bar(self, *args):
...
The lock_file_prefix argument is used to provide lock files on disk with a
meaningful prefix.
"""
return functools.partial(synchronized, lock_file_prefix=lock_file_prefix)
def main(argv):
"""Create a dir for locks and pass it to command from arguments
If you run this:
python -m openstack.common.lockutils python setup.py testr <etc>
a temporary directory will be created for all your locks and passed to all
your tests in an environment variable. The temporary dir will be deleted
afterwards and the return value will be preserved.
"""
lock_dir = tempfile.mkdtemp()
os.environ["MISTRAL_LOCK_PATH"] = lock_dir
try:
ret_val = subprocess.call(argv[1:])
finally:
shutil.rmtree(lock_dir, ignore_errors=True)
return ret_val
if __name__ == '__main__':
sys.exit(main(sys.argv))

99
mistral/openstack/common/test.py Normal file
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@@ -0,0 +1,99 @@
# Copyright (c) 2013 Hewlett-Packard Development Company, L.P.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
##############################################################################
##############################################################################
##
## DO NOT MODIFY THIS FILE
##
## This file is being graduated to the oslotest library. Please make all
## changes there, and only backport critical fixes here. - dhellmann
##
##############################################################################
##############################################################################
"""Common utilities used in testing"""
import logging
import os
import tempfile
import fixtures
import testtools
_TRUE_VALUES = ('True', 'true', '1', 'yes')
_LOG_FORMAT = "%(levelname)8s [%(name)s] %(message)s"
class BaseTestCase(testtools.TestCase):
def setUp(self):
super(BaseTestCase, self).setUp()
self._set_timeout()
self._fake_output()
self._fake_logs()
self.useFixture(fixtures.NestedTempfile())
self.useFixture(fixtures.TempHomeDir())
self.tempdirs = []
def _set_timeout(self):
test_timeout = os.environ.get('OS_TEST_TIMEOUT', 0)
try:
test_timeout = int(test_timeout)
except ValueError:
# If timeout value is invalid do not set a timeout.
test_timeout = 0
if test_timeout > 0:
self.useFixture(fixtures.Timeout(test_timeout, gentle=True))
def _fake_output(self):
if os.environ.get('OS_STDOUT_CAPTURE') in _TRUE_VALUES:
stdout = self.useFixture(fixtures.StringStream('stdout')).stream
self.useFixture(fixtures.MonkeyPatch('sys.stdout', stdout))
if os.environ.get('OS_STDERR_CAPTURE') in _TRUE_VALUES:
stderr = self.useFixture(fixtures.StringStream('stderr')).stream
self.useFixture(fixtures.MonkeyPatch('sys.stderr', stderr))
def _fake_logs(self):
if os.environ.get('OS_DEBUG') in _TRUE_VALUES:
level = logging.DEBUG
else:
level = logging.INFO
capture_logs = os.environ.get('OS_LOG_CAPTURE') in _TRUE_VALUES
if capture_logs:
self.useFixture(
fixtures.FakeLogger(
format=_LOG_FORMAT,
level=level,
nuke_handlers=capture_logs,
)
)
else:
logging.basicConfig(format=_LOG_FORMAT, level=level)
def create_tempfiles(self, files, ext='.conf'):
tempfiles = []
for (basename, contents) in files:
if not os.path.isabs(basename):
(fd, path) = tempfile.mkstemp(prefix=basename, suffix=ext)
else:
path = basename + ext
fd = os.open(path, os.O_CREAT | os.O_WRONLY)
tempfiles.append(path)
try:
os.write(fd, contents)
finally:
os.close(fd)
return tempfiles

1
openstack-common.conf
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@@ -8,6 +8,7 @@ module=db.sqlalchemy.session
module=db.sqlalchemy.migration
module=log
module=jsonutils
module=lockutils
module=loopingcall
module=periodic_task
module=threadgroup