#
# Copyright © 2015 eNovance
#
# 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 datetime
import errno
import functools
import hashlib
import logging
import os
import shutil
import tempfile
import threading
import weakref
import fasteners
from oslo_utils import fileutils
from oslo_utils import timeutils
import voluptuous
import tooz
from tooz import coordination
from tooz import locking
from tooz import utils
LOG = logging.getLogger(__name__)
class _Barrier:
def __init__(self):
self.cond = threading.Condition()
self.owner = None
self.shared = False
self.ref = 0
@contextlib.contextmanager
def _translate_failures():
try:
yield
except (OSError, voluptuous.Invalid) as e:
utils.raise_with_cause(tooz.ToozError, str(e), cause=e)
def _convert_from_old_format(data):
# NOTE(sileht): previous version of the driver was storing str as-is
# making impossible to read from python3 something written with python2
# version of the lib.
# Now everything is stored with explicit type bytes or unicode. This
# convert the old format to the new one to maintain compat of already
# deployed file.
# example of potential old python2 payload:
# {b"member_id": b"member"}
# {b"member_id": u"member"}
# example of potential old python3 payload:
# {u"member_id": b"member"}
# {u"member_id": u"member"}
if b"member_id" in data or b"group_id" in data:
data = {k.decode("utf8"): v for k, v in data.items()}
# About member_id and group_id valuse if the file have been written
# with python2 and in the old format, we can't known with python3
# if we need to decode the value or not. Python3 see bytes blob
# We keep it as-is and pray, this have a good change to break if
# the application was using str in python2 and unicode in python3
# The member file is often overridden so it's should be fine
# But the group file can be very old, so we
# now have to update it each time create_group is called
return data
def _lock_me(lock):
def wrapper(func):
@functools.wraps(func)
def decorator(*args, **kwargs):
with lock:
return func(*args, **kwargs)
return decorator
return wrapper
class FileLock(locking.Lock):
"""A file based lock."""
def __init__(self, path, barrier, member_id):
super().__init__(path)
self.acquired = False
self._lock = fasteners.InterProcessLock(path)
self._barrier = barrier
self._member_id = member_id
self.ref = 0
def is_still_owner(self):
return self.acquired
def acquire(self, blocking=True, shared=False, timeout=None):
blocking, timeout = utils.convert_blocking(blocking, timeout)
watch = timeutils.StopWatch(duration=timeout)
watch.start()
# Make the shared barrier ours first.
with self._barrier.cond:
while self._barrier.owner is not None:
if (shared and self._barrier.shared):
break
if not blocking or watch.expired():
return False
self._barrier.cond.wait(watch.leftover(return_none=True))
self._barrier.owner = (threading.current_thread().ident,
os.getpid(), self._member_id)
self._barrier.shared = shared
self._barrier.ref += 1
self.ref += 1
# Ok at this point we are now working in a thread safe manner,
# and now we can try to get the actual lock...
gotten = False
try:
gotten = self._lock.acquire(
blocking=blocking,
# Since the barrier waiting may have
# taken a long time, we have to use
# the leftover (and not the original).
timeout=watch.leftover(return_none=True))
finally:
# NOTE(harlowja): do this in a finally block to **ensure** that
# we release the barrier if something bad happens...
if not gotten:
# Release the barrier to let someone else have a go at it...
with self._barrier.cond:
self._barrier.owner = None
self._barrier.ref = 0
self._barrier.shared = False
self._barrier.cond.notify_all()
self.acquired = gotten
return gotten
def release(self):
if not self.acquired:
return False
with self._barrier.cond:
self._barrier.ref -= 1
self.ref -= 1
if not self.ref:
self.acquired = False
if not self._barrier.ref:
self._barrier.owner = None
self._lock.release()
self._barrier.cond.notify_all()
return True
def __del__(self):
if self.acquired:
LOG.warning("Unreleased lock %s garbage collected", self.name)
[docs]
class FileDriver(coordination.CoordinationDriverCachedRunWatchers,
coordination.CoordinationDriverWithExecutor):
"""A file based driver.
This driver uses files and directories (and associated file locks) to
provide the coordination driver semantics and required API(s). It **is**
missing some functionality but in the future these not implemented API(s)
will be filled in.
The File driver connection URI should look like::
file://DIRECTORY[?timeout=TIMEOUT]
DIRECTORY is the location that should be used to store lock files.
TIMEOUT defaults to 10.
General recommendations/usage considerations:
- It does **not** automatically delete members from
groups of processes that have died, manual cleanup will be needed
for those types of failures.
- It is **not** distributed (or recommended to be used in those
situations, so the developer using this should really take that into
account when applying this driver in there app).
"""
CHARACTERISTICS = (
coordination.Characteristics.NON_TIMEOUT_BASED,
coordination.Characteristics.DISTRIBUTED_ACROSS_THREADS,
coordination.Characteristics.DISTRIBUTED_ACROSS_PROCESSES,
)
"""
Tuple of :py:class:`~tooz.coordination.Characteristics` introspectable
enum member(s) that can be used to interogate how this driver works.
"""
HASH_ROUTINE = 'sha1'
"""This routine is used to hash a member (or group) id into a filesystem
safe name that can be used for member lookup and group joining."""
_barriers = weakref.WeakValueDictionary()
"""
Barriers shared among all file driver locks, this is required
since interprocess locking is not thread aware, so we must add the
thread awareness on-top of it instead.
"""
[docs]
def __init__(self, member_id, parsed_url, options):
"""Initialize the file driver."""
super().__init__(member_id, parsed_url, options)
self._dir = parsed_url.path
self._group_dir = os.path.join(self._dir, 'groups')
self._tmpdir = os.path.join(self._dir, 'tmp')
self._driver_lock_path = os.path.join(self._dir, '.driver_lock')
self._driver_lock = self._get_raw_lock(self._driver_lock_path,
self._member_id)
self._reserved_dirs = [self._dir, self._group_dir, self._tmpdir]
self._reserved_paths = list(self._reserved_dirs)
self._reserved_paths.append(self._driver_lock_path)
self._safe_member_id = self._make_filesystem_safe(member_id)
self._timeout = int(self._options.get('timeout', 10))
@classmethod
def _get_raw_lock(cls, path, member_id):
lock_barrier = cls._barriers.setdefault(path, _Barrier())
return FileLock(path, lock_barrier, member_id)
[docs]
def get_lock(self, name):
path = utils.safe_abs_path(self._dir, name.decode())
if path in self._reserved_paths:
raise ValueError("Unable to create a lock using"
" reserved path '%s' for lock"
" with name '%s'" % (path, name))
return self._get_raw_lock(path, self._member_id)
@classmethod
def _make_filesystem_safe(cls, item):
item = utils.to_binary(item, encoding="utf8")
return hashlib.new(cls.HASH_ROUTINE, item).hexdigest()
def _start(self):
super()._start()
for a_dir in self._reserved_dirs:
try:
fileutils.ensure_tree(a_dir)
except OSError as e:
raise coordination.ToozConnectionError(e)
def _update_group_metadata(self, path, group_id):
details = {
'group_id': utils.to_binary(group_id, encoding="utf8")
}
details['encoded'] = details["group_id"] != group_id
details_blob = utils.dumps(details)
fd, name = tempfile.mkstemp("tooz", dir=self._tmpdir)
with os.fdopen(fd, "wb") as fh:
fh.write(details_blob)
os.rename(name, path)
[docs]
def create_group(self, group_id):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
group_meta_path = os.path.join(group_dir, '.metadata')
def _do_create_group():
if os.path.exists(os.path.join(group_dir, ".metadata")):
# NOTE(sileht): We update the group metadata even
# they are already good, so ensure dict key are convert
# to unicode in case of the file have been written with
# tooz < 1.36
self._update_group_metadata(group_meta_path, group_id)
raise coordination.GroupAlreadyExist(group_id)
else:
fileutils.ensure_tree(group_dir)
self._update_group_metadata(group_meta_path, group_id)
fut = self._executor.submit(_do_create_group)
return FileFutureResult(fut)
[docs]
def join_group(self, group_id, capabilities=b""):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
me_path = os.path.join(group_dir, "%s.raw" % self._safe_member_id)
@_lock_me(self._driver_lock)
def _do_join_group():
if not os.path.exists(os.path.join(group_dir, ".metadata")):
raise coordination.GroupNotCreated(group_id)
if os.path.isfile(me_path):
raise coordination.MemberAlreadyExist(group_id,
self._member_id)
details = {
'capabilities': capabilities,
'joined_on': datetime.datetime.now(),
'member_id': utils.to_binary(self._member_id,
encoding="utf-8")
}
details['encoded'] = details["member_id"] != self._member_id
details_blob = utils.dumps(details)
with open(me_path, "wb") as fh:
fh.write(details_blob)
self._joined_groups.add(group_id)
fut = self._executor.submit(_do_join_group)
return FileFutureResult(fut)
[docs]
def leave_group(self, group_id):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
me_path = os.path.join(group_dir, "%s.raw" % self._safe_member_id)
@_lock_me(self._driver_lock)
def _do_leave_group():
if not os.path.exists(os.path.join(group_dir, ".metadata")):
raise coordination.GroupNotCreated(group_id)
try:
os.unlink(me_path)
except OSError as e:
if e.errno != errno.ENOENT:
raise
else:
raise coordination.MemberNotJoined(group_id,
self._member_id)
else:
self._joined_groups.discard(group_id)
fut = self._executor.submit(_do_leave_group)
return FileFutureResult(fut)
_SCHEMAS = {
'group': voluptuous.Schema({
voluptuous.Required('group_id'): voluptuous.Any(str, bytes),
# NOTE(sileht): tooz <1.36 was creating file without this
voluptuous.Optional('encoded'): bool,
}),
'member': voluptuous.Schema({
voluptuous.Required('member_id'): voluptuous.Any(str, bytes),
voluptuous.Required('joined_on'): datetime.datetime,
# NOTE(sileht): tooz <1.36 was creating file without this
voluptuous.Optional('encoded'): bool,
}, extra=voluptuous.ALLOW_EXTRA),
}
def _load_and_validate(self, blob, schema_key):
data = utils.loads(blob)
data = _convert_from_old_format(data)
schema = self._SCHEMAS[schema_key]
return schema(data)
def _read_member_id(self, path):
with open(path, 'rb') as fh:
details = self._load_and_validate(fh.read(), 'member')
if details.get("encoded"):
return details['member_id'].decode("utf-8")
return details['member_id']
[docs]
def get_members(self, group_id):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
@_lock_me(self._driver_lock)
def _do_get_members():
if not os.path.isdir(group_dir):
raise coordination.GroupNotCreated(group_id)
members = set()
try:
entries = os.listdir(group_dir)
except OSError as e:
# Did someone manage to remove it before we got here...
if e.errno != errno.ENOENT:
raise
else:
for entry in entries:
if not entry.endswith('.raw'):
continue
entry_path = os.path.join(group_dir, entry)
try:
m_time = datetime.datetime.fromtimestamp(
os.stat(entry_path).st_mtime)
current_time = datetime.datetime.now()
delta_time = timeutils.delta_seconds(m_time,
current_time)
if delta_time >= 0 and delta_time <= self._timeout:
member_id = self._read_member_id(entry_path)
else:
continue
except OSError as e:
if e.errno != errno.ENOENT:
raise
else:
members.add(member_id)
return members
fut = self._executor.submit(_do_get_members)
return FileFutureResult(fut)
[docs]
def get_member_capabilities(self, group_id, member_id):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
safe_member_id = self._make_filesystem_safe(member_id)
member_path = os.path.join(group_dir, "%s.raw" % safe_member_id)
@_lock_me(self._driver_lock)
def _do_get_member_capabilities():
try:
with open(member_path, "rb") as fh:
contents = fh.read()
except OSError as e:
if e.errno == errno.ENOENT:
if not os.path.isdir(group_dir):
raise coordination.GroupNotCreated(group_id)
else:
raise coordination.MemberNotJoined(group_id,
member_id)
else:
raise
else:
details = self._load_and_validate(contents, 'member')
return details.get("capabilities")
fut = self._executor.submit(_do_get_member_capabilities)
return FileFutureResult(fut)
[docs]
def delete_group(self, group_id):
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
@_lock_me(self._driver_lock)
def _do_delete_group():
try:
entries = os.listdir(group_dir)
except OSError as e:
if e.errno == errno.ENOENT:
raise coordination.GroupNotCreated(group_id)
else:
raise
else:
if len(entries) > 1:
raise coordination.GroupNotEmpty(group_id)
elif len(entries) == 1 and entries != ['.metadata']:
raise tooz.ToozError(
"Unexpected path '%s' found in"
" group directory '%s' (expected to only find"
" a '.metadata' path)" % (entries[0], group_dir))
else:
try:
shutil.rmtree(group_dir)
except OSError as e:
if e.errno != errno.ENOENT:
raise
fut = self._executor.submit(_do_delete_group)
return FileFutureResult(fut)
def _read_group_id(self, path):
with open(path, 'rb') as fh:
details = self._load_and_validate(fh.read(), 'group')
if details.get("encoded"):
return details['group_id'].decode("utf-8")
return details['group_id']
[docs]
def get_groups(self):
def _do_get_groups():
groups = []
for entry in os.listdir(self._group_dir):
path = os.path.join(self._group_dir, entry, '.metadata')
try:
groups.append(self._read_group_id(path))
except OSError as e:
if e.errno != errno.ENOENT:
raise
return groups
fut = self._executor.submit(_do_get_groups)
return FileFutureResult(fut)
[docs]
def heartbeat(self):
for group_id in self._joined_groups:
safe_group_id = self._make_filesystem_safe(group_id)
group_dir = os.path.join(self._group_dir, safe_group_id)
member_path = os.path.join(group_dir, "%s.raw" %
self._safe_member_id)
@_lock_me(self._driver_lock)
def _do_heartbeat():
try:
os.utime(member_path, None)
except OSError as err:
if err.errno != errno.ENOENT:
raise
_do_heartbeat()
return self._timeout
[docs]
@staticmethod
def watch_elected_as_leader(group_id, callback):
raise tooz.NotImplemented
[docs]
@staticmethod
def unwatch_elected_as_leader(group_id, callback):
raise tooz.NotImplemented
FileFutureResult = functools.partial(coordination.CoordinatorResult,
failure_translator=_translate_failures)
