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# Copyright (c) 2015 IBM, 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.
"""Glance Store capability"""
import logging
import threading
import enum
from oslo_utils import reflection
from glance_store import exceptions
from glance_store.i18n import _LW
_STORE_CAPABILITES_UPDATE_SCHEDULING_BOOK = {}
_STORE_CAPABILITES_UPDATE_SCHEDULING_LOCK = threading.Lock()
LOG = logging.getLogger(__name__)
class BitMasks(enum.IntEnum):
NONE = 0b00000000
ALL = 0b11111111
READ_ACCESS = 0b00000001
# Included READ_ACCESS
READ_OFFSET = 0b00000011
# Included READ_ACCESS
READ_CHUNK = 0b00000101
# READ_OFFSET | READ_CHUNK
READ_RANDOM = 0b00000111
WRITE_ACCESS = 0b00001000
# Included WRITE_ACCESS
WRITE_OFFSET = 0b00011000
# Included WRITE_ACCESS
WRITE_CHUNK = 0b00101000
# WRITE_OFFSET | WRITE_CHUNK
WRITE_RANDOM = 0b00111000
# READ_ACCESS | WRITE_ACCESS
RW_ACCESS = 0b00001001
# READ_OFFSET | WRITE_OFFSET
RW_OFFSET = 0b00011011
# READ_CHUNK | WRITE_CHUNK
RW_CHUNK = 0b00101101
# RW_OFFSET | RW_CHUNK
RW_RANDOM = 0b00111111
# driver is stateless and can be reused safely
DRIVER_REUSABLE = 0b01000000
class StoreCapability(object):
def __init__(self):
# Set static store capabilities base on
# current driver implementation.
self._capabilities = getattr(self.__class__, "_CAPABILITIES", 0)
@property
def capabilities(self):
return self._capabilities
@staticmethod
def contains(x, y):
return x & y == y
def update_capabilities(self):
"""
Update dynamic storage capabilities based on current
driver configuration and backend status when needed.
As a hook, the function will be triggered in two cases:
calling once after store driver get configured, it was
used to update dynamic storage capabilities based on
current driver configuration, or calling when the
capabilities checking of an operation failed every time,
this was used to refresh dynamic storage capabilities
based on backend status then.
This function shouldn't raise any exception out.
"""
LOG.debug(("Store %s doesn't support updating dynamic "
"storage capabilities. Please overwrite "
"'update_capabilities' method of the store to "
"implement updating logics if needed.") %
reflection.get_class_name(self))
def is_capable(self, *capabilities):
"""
Check if requested capability(s) are supported by
current driver instance.
:param capabilities: required capability(s).
"""
caps = 0
for cap in capabilities:
caps |= int(cap)
return self.contains(self.capabilities, caps)
def set_capabilities(self, *dynamic_capabilites):
"""
Set dynamic storage capabilities based on current
driver configuration and backend status.
:param dynamic_capabilites: dynamic storage capability(s).
"""
for cap in dynamic_capabilites:
self._capabilities |= int(cap)
def unset_capabilities(self, *dynamic_capabilites):
"""
Unset dynamic storage capabilities.
:param dynamic_capabilites: dynamic storage capability(s).
"""
caps = 0
for cap in dynamic_capabilites:
caps |= int(cap)
# TODO(zhiyan): Cascaded capability removal is
# skipped currently, we can add it back later
# when a concrete requirement comes out.
# For example, when removing READ_ACCESS, all
# read related capabilities need to be removed
# together, e.g. READ_RANDOM.
self._capabilities &= ~caps
def check(store_op_fun):
def op_checker(store, *args, **kwargs):
get_capabilities = [
BitMasks.READ_ACCESS,
BitMasks.READ_OFFSET if kwargs.get('offset') else BitMasks.NONE,
BitMasks.READ_CHUNK if kwargs.get('chunk_size') else BitMasks.NONE
]
op_cap_map = {
'get': get_capabilities,
'add': [BitMasks.WRITE_ACCESS],
'delete': [BitMasks.WRITE_ACCESS]}
op_exec_map = {
'get': (exceptions.StoreRandomGetNotSupported
if kwargs.get('offset') or kwargs.get('chunk_size') else
exceptions.StoreGetNotSupported),
'add': exceptions.StoreAddDisabled,
'delete': exceptions.StoreDeleteNotSupported}
op = store_op_fun.__name__.lower()
try:
req_cap = op_cap_map[op]
except KeyError:
LOG.warning(_LW('The capability of operation "%s" '
'could not be checked.'), op)
else:
if not store.is_capable(*req_cap):
kwargs.setdefault('offset', 0)
kwargs.setdefault('chunk_size', None)
raise op_exec_map[op](**kwargs)
return store_op_fun(store, *args, **kwargs)
return op_checker
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