chore: Update openstack.common, add lockutils

This patch updates openstack.common to HEAD and also adds
lockutils to openstack-common.conf in anticipation of
pulling in the cache module when it lands.

Change-Id: I714e03c4eba9e98b92144f2b2f227799d104f1bd

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

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)

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)

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):

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)

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