diff --git a/marconi/openstack/common/excutils.py b/marconi/openstack/common/excutils.py new file mode 100644 index 000000000..806a70a66 --- /dev/null +++ b/marconi/openstack/common/excutils.py @@ -0,0 +1,101 @@ +# vim: tabstop=4 shiftwidth=4 softtabstop=4 + +# 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 marconi.openstack.common.gettextutils import _ # noqa + + +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 + """ + def __init__(self): + self.reraise = True + + 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: + logging.error(_('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 = unicode(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( + _('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 diff --git a/marconi/openstack/common/fileutils.py b/marconi/openstack/common/fileutils.py new file mode 100644 index 000000000..3a8ee4626 --- /dev/null +++ b/marconi/openstack/common/fileutils.py @@ -0,0 +1,111 @@ +# vim: tabstop=4 shiftwidth=4 softtabstop=4 + +# 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 + +from marconi.openstack.common import excutils +from marconi.openstack.common.gettextutils import _ # noqa +from marconi.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 file(*args, **kwargs) diff --git a/marconi/openstack/common/gettextutils.py b/marconi/openstack/common/gettextutils.py index 2cefb5d73..1d98c5a81 100644 --- a/marconi/openstack/common/gettextutils.py +++ b/marconi/openstack/common/gettextutils.py @@ -26,10 +26,13 @@ Usual usage in an openstack.common module: import copy import gettext -import logging.handlers +import logging import os import re -import UserString +try: + import UserString as _userString +except ImportError: + import collections as _userString from babel import localedata import six @@ -37,11 +40,27 @@ import six _localedir = os.environ.get('marconi'.upper() + '_LOCALEDIR') _t = gettext.translation('marconi', localedir=_localedir, fallback=True) -_AVAILABLE_LANGUAGES = [] +_AVAILABLE_LANGUAGES = {} +USE_LAZY = False + + +def enable_lazy(): + """Convenience function for configuring _() to use lazy gettext + + Call this at the start of execution to enable the gettextutils._ + function to use lazy gettext functionality. This is useful if + your project is importing _ directly instead of using the + gettextutils.install() way of importing the _ function. + """ + global USE_LAZY + USE_LAZY = True def _(msg): - return _t.ugettext(msg) + if USE_LAZY: + return Message(msg, 'marconi') + else: + return _t.ugettext(msg) def install(domain, lazy=False): @@ -95,7 +114,7 @@ def install(domain, lazy=False): unicode=True) -class Message(UserString.UserString, object): +class Message(_userString.UserString, object): """Class used to encapsulate translatable messages.""" def __init__(self, msg, domain): # _msg is the gettext msgid and should never change @@ -236,7 +255,7 @@ class Message(UserString.UserString, object): if name in ops: return getattr(self.data, name) else: - return UserString.UserString.__getattribute__(self, name) + return _userString.UserString.__getattribute__(self, name) def get_available_languages(domain): @@ -244,8 +263,8 @@ def get_available_languages(domain): :param domain: the domain to get languages for """ - if _AVAILABLE_LANGUAGES: - return _AVAILABLE_LANGUAGES + if domain in _AVAILABLE_LANGUAGES: + return copy.copy(_AVAILABLE_LANGUAGES[domain]) localedir = '%s_LOCALEDIR' % domain.upper() find = lambda x: gettext.find(domain, @@ -254,7 +273,7 @@ def get_available_languages(domain): # NOTE(mrodden): en_US should always be available (and first in case # order matters) since our in-line message strings are en_US - _AVAILABLE_LANGUAGES.append('en_US') + language_list = ['en_US'] # NOTE(luisg): Babel <1.0 used a function called list(), which was # renamed to locale_identifiers() in >=1.0, the requirements master list # requires >=0.9.6, uncapped, so defensively work with both. We can remove @@ -264,13 +283,14 @@ def get_available_languages(domain): locale_identifiers = list_identifiers() for i in locale_identifiers: if find(i) is not None: - _AVAILABLE_LANGUAGES.append(i) - return _AVAILABLE_LANGUAGES + language_list.append(i) + _AVAILABLE_LANGUAGES[domain] = language_list + return copy.copy(language_list) def get_localized_message(message, user_locale): """Gets a localized version of the given message in the given locale.""" - if (isinstance(message, Message)): + if isinstance(message, Message): if user_locale: message.locale = user_locale return unicode(message) diff --git a/marconi/openstack/common/jsonutils.py b/marconi/openstack/common/jsonutils.py index c7b92d105..b9646107f 100644 --- a/marconi/openstack/common/jsonutils.py +++ b/marconi/openstack/common/jsonutils.py @@ -38,14 +38,18 @@ import functools import inspect import itertools import json -import types -import xmlrpclib +try: + import xmlrpclib +except ImportError: + # NOTE(jd): xmlrpclib is not shipped with Python 3 + xmlrpclib = None -import netaddr import six +from marconi.openstack.common import importutils from marconi.openstack.common import timeutils +netaddr = importutils.try_import("netaddr") _nasty_type_tests = [inspect.ismodule, inspect.isclass, inspect.ismethod, inspect.isfunction, inspect.isgeneratorfunction, @@ -53,7 +57,8 @@ _nasty_type_tests = [inspect.ismodule, inspect.isclass, inspect.ismethod, inspect.iscode, inspect.isbuiltin, inspect.isroutine, inspect.isabstract] -_simple_types = (types.NoneType, int, basestring, bool, float, long) +_simple_types = (six.string_types + six.integer_types + + (type(None), bool, float)) def to_primitive(value, convert_instances=False, convert_datetime=True, @@ -125,7 +130,7 @@ def to_primitive(value, convert_instances=False, convert_datetime=True, # It's not clear why xmlrpclib created their own DateTime type, but # for our purposes, make it a datetime type which is explicitly # handled - if isinstance(value, xmlrpclib.DateTime): + if xmlrpclib and isinstance(value, xmlrpclib.DateTime): value = datetime.datetime(*tuple(value.timetuple())[:6]) if convert_datetime and isinstance(value, datetime.datetime): @@ -138,7 +143,7 @@ def to_primitive(value, convert_instances=False, convert_datetime=True, # Likely an instance of something. Watch for cycles. # Ignore class member vars. return recursive(value.__dict__, level=level + 1) - elif isinstance(value, netaddr.IPAddress): + elif netaddr and isinstance(value, netaddr.IPAddress): return six.text_type(value) else: if any(test(value) for test in _nasty_type_tests): diff --git a/marconi/openstack/common/lockutils.py b/marconi/openstack/common/lockutils.py new file mode 100644 index 000000000..4227e0a79 --- /dev/null +++ b/marconi/openstack/common/lockutils.py @@ -0,0 +1,277 @@ +# vim: tabstop=4 shiftwidth=4 softtabstop=4 + +# 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 functools +import os +import threading +import time +import weakref + +from oslo.config import cfg + +from marconi.openstack.common import fileutils +from marconi.openstack.common.gettextutils import _ # noqa +from marconi.openstack.common import local +from marconi.openstack.common import log as logging + + +LOG = logging.getLogger(__name__) + + +util_opts = [ + cfg.BoolOpt('disable_process_locking', default=False, + help='Whether to disable inter-process locks'), + cfg.StrOpt('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 _InterProcessLock(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 __enter__(self): + 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() + return self + 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 + + def __exit__(self, exc_type, exc_val, exc_tb): + try: + self.unlock() + self.lockfile.close() + except IOError: + LOG.exception(_("Could not release the acquired lock `%s`"), + self.fname) + + def trylock(self): + raise NotImplementedError() + + def unlock(self): + raise NotImplementedError() + + +class _WindowsLock(_InterProcessLock): + 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 _PosixLock(_InterProcessLock): + def trylock(self): + fcntl.lockf(self.lockfile, fcntl.LOCK_EX | fcntl.LOCK_NB) + + def unlock(self): + fcntl.lockf(self.lockfile, fcntl.LOCK_UN) + + +if os.name == 'nt': + import msvcrt + InterProcessLock = _WindowsLock +else: + import fcntl + InterProcessLock = _PosixLock + +_semaphores = weakref.WeakValueDictionary() + + +@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 a method decorated with @synchronized('mylock', + external=True), only one of them will execute at a time. + + :param lock_path: The lock_path keyword argument is used to specify a + special location for external lock files to live. If nothing is set, then + CONF.lock_path is used as a default. + """ + # NOTE(soren): If we ever go natively threaded, this will be racy. + # See http://stackoverflow.com/questions/5390569/dyn + # amically-allocating-and-destroying-mutexes + sem = _semaphores.get(name, threading.Semaphore()) + if name not in _semaphores: + # this check is not racy - we're already holding ref locally + # so GC won't remove the item and there was no IO switch + # (only valid in greenthreads) + _semaphores[name] = sem + + with sem: + LOG.debug(_('Got semaphore "%(lock)s"'), {'lock': name}) + + # NOTE(mikal): I know this looks odd + if not hasattr(local.strong_store, 'locks_held'): + local.strong_store.locks_held = [] + local.strong_store.locks_held.append(name) + + try: + if external and not CONF.disable_process_locking: + LOG.debug(_('Attempting to grab file lock "%(lock)s"'), + {'lock': name}) + + # We need a copy of lock_path because it is non-local + local_lock_path = lock_path or CONF.lock_path + if not local_lock_path: + raise cfg.RequiredOptError('lock_path') + + if not os.path.exists(local_lock_path): + fileutils.ensure_tree(local_lock_path) + LOG.info(_('Created lock path: %s'), local_lock_path) + + def add_prefix(name, prefix): + if not prefix: + return name + sep = '' if prefix.endswith('-') else '-' + return '%s%s%s' % (prefix, sep, name) + + # NOTE(mikal): the lock name cannot contain directory + # separators + lock_file_name = add_prefix(name.replace(os.sep, '_'), + lock_file_prefix) + + lock_file_path = os.path.join(local_lock_path, lock_file_name) + + try: + lock = InterProcessLock(lock_file_path) + with lock as lock: + LOG.debug(_('Got file lock "%(lock)s" at %(path)s'), + {'lock': name, 'path': lock_file_path}) + yield lock + finally: + LOG.debug(_('Released file lock "%(lock)s" at %(path)s'), + {'lock': name, 'path': lock_file_path}) + else: + yield sem + + finally: + local.strong_store.locks_held.remove(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): + with lock(name, lock_file_prefix, external, lock_path): + LOG.debug(_('Got semaphore / lock "%(function)s"'), + {'function': f.__name__}) + return f(*args, **kwargs) + + 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) diff --git a/openstack-common.conf b/openstack-common.conf index 352530449..d5813d723 100644 --- a/openstack-common.conf +++ b/openstack-common.conf @@ -1,7 +1,10 @@ [DEFAULT] +module=excutils +module=fileutils module=gettextutils module=importutils module=jsonutils +module=lockutils module=log module=setup module=timeutils