# Copyright 2016-2017 IBM Corp. 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.
"""
Base definitions for resource classes.
Resource objects represent the real manageable resources in the systems managed
by the HMC.
"""
from __future__ import absolute_import
import time
from immutable_views import DictView
from ._logging import logged_api_call
from ._utils import repr_dict, repr_timestamp
__all__ = ['BaseResource']
[docs]class BaseResource(object):
"""
Abstract base class for resource classes (e.g. :class:`~zhmcclient.Cpc`)
representing manageable resources.
It defines the interface for the derived resource classes, and implements
methods that have a common implementation for the derived resource classes.
Objects of derived resource classes are representations of the actual
manageable resources in the HMC or in systems managed by the HMC.
Objects of derived resource classes should not be created by users of this
package by simply instantiating the derived resource classes. Instead, such
objects are created by this package and are returned to the user as a
result of methods such as :meth:`~zhmcclient.BaseManager.find` or
:meth:`~zhmcclient.BaseManager.list`. For this reason, the `__init__()`
method of this class and of its derived resource classes are considered
internal interfaces and their parameters are not documented and may change
incompatibly.
"""
def __init__(self, manager, uri, name, properties):
# This method intentionally has no docstring, because it is internal.
#
# Parameters:
# manager (subclass of :class:`~zhmcclient.BaseManager`):
# Manager object for this resource object (and for all resource
# objects of the same type in the scope of that manager).
# Must not be `None`.
# uri (string):
# Canonical URI path of the resource.
# Must not be `None`.
# name (string):
# Name of the resource.
# May be `None`.
# properties (dict):
# Properties for this resource object. May be `None` or empty.
# * Key: Name of the property.
# * Value: Value of the property.
# We want to surface precondition violations as early as possible,
# so we test those that are not surfaced through the init code:
assert manager is not None
assert uri is not None
self._manager = manager
self._uri = uri
self._properties = dict(properties) if properties else {}
if name is not None:
name_prop = self._manager._name_prop
if name_prop in self._properties:
assert self._properties[name_prop] == name
else:
self._properties[name_prop] = name
uri_prop = self._manager._uri_prop
if uri_prop in self._properties:
assert self._properties[uri_prop] == uri
else:
self._properties[uri_prop] = uri
self._properties_timestamp = int(time.time())
self._full_properties = False
@property
def properties(self):
"""
:class:`iv:immutable_views.DictView`: The properties of this resource
that are currently present in this Python object, as a dictionary.
* Key: Name of the property.
* Value: Value of the property.
The returned :class:`iv:immutable_views.DictView` object is an immutable
dictionary view that behaves like a standard Python :class:`dict`
except that it prevents any modifications to the dictionary.
See the respective 'Data model' sections in the :term:`HMC API` book
for a description of the resources along with their properties.
The dictionary contains either the full set of resource properties,
or a subset thereof, or can be empty in some cases.
Because the presence of properties in this dictionary depends on the
situation, the purpose of this dictionary is only for iterating
through the resource properties that are currently present.
Specific resource properties should be accessed via:
* The resource name, via the :attr:`~zhmcclient.BaseResource.name`
attribute.
* The resource URI, via the :attr:`~zhmcclient.BaseResource.uri`
attribute.
* Any resource property, via the
:meth:`~zhmcclient.BaseResource.get_property` or
:meth:`~zhmcclient.BaseResource.prop` methods.
Updates to property values can be done via the ``update_properties()``
method of the resource class. Which properties can be updated
is indicated with the 'w' qualifier in the data model of the resource
in the :term:`HMC API` book.
"""
return DictView(self._properties)
@property
def uri(self):
"""
string: The canonical URI path of the resource. Will not be `None`.
Example: ``/api/cpcs/12345``
"""
return self._uri
@property
def name(self):
"""
string: The name of the resource. Will not be `None`.
The resource name is unique across its sibling resources of the same
type and with the same parent resource.
Accessing this property will cause the properties of this resource
object to be updated from the HMC, if it does not yet contain the
property for the resource name.
"""
# pylint: disable=protected-access
# We avoid storing the name in an instance variable, because it can
# be modified via update_properties().
return self.get_property(self.manager._name_prop)
@property
def manager(self):
"""
Subclass of :class:`~zhmcclient.BaseManager`:
Manager object for this resource (and for all resources of the same
type in the scope of that manager). Will not be `None`.
"""
return self._manager
@property
def full_properties(self):
"""
A boolean indicating whether or not the resource properties in this
object are the full set of resource properties.
Note that listing resources and creating new resources produces objects
that have less than the full set of properties.
"""
return self._full_properties
@property
def properties_timestamp(self):
"""
The point in time of the last update of the resource properties cached
in this object, as Unix time (an integer that is the number of seconds
since the Unix epoch).
"""
return self._properties_timestamp
[docs] @logged_api_call
def pull_full_properties(self):
"""
Retrieve the full set of resource properties and cache them in this
object.
Authorization requirements:
* Object-access permission to this resource.
Raises:
:exc:`~zhmcclient.HTTPError`
:exc:`~zhmcclient.ParseError`
:exc:`~zhmcclient.AuthError`
:exc:`~zhmcclient.ConnectionError`
"""
full_properties = self.manager.session.get(self._uri)
self._properties = dict(full_properties)
self._properties_timestamp = int(time.time())
self._full_properties = True
[docs] @logged_api_call
def get_property(self, name):
"""
Return the value of a resource property.
If the resource property is not cached in this object yet, the full set
of resource properties is retrieved and cached in this object, and the
resource property is again attempted to be returned.
Authorization requirements:
* Object-access permission to this resource.
Parameters:
name (:term:`string`):
Name of the resource property, using the names defined in the
respective 'Data model' sections in the :term:`HMC API` book.
Returns:
The value of the resource property.
Raises:
KeyError: The resource property could not be found (also not in the
full set of resource properties).
:exc:`~zhmcclient.HTTPError`
:exc:`~zhmcclient.ParseError`
:exc:`~zhmcclient.AuthError`
:exc:`~zhmcclient.ConnectionError`
"""
try:
return self._properties[name]
except KeyError:
if self._full_properties:
raise
self.pull_full_properties()
return self._properties[name]
[docs] @logged_api_call
def prop(self, name, default=None):
"""
Return the value of a resource property, applying a default if it
does not exist.
If the resource property is not cached in this object yet, the full set
of resource properties is retrieved and cached in this object, and the
resource property is again attempted to be returned.
Authorization requirements:
* Object-access permission to this resource.
Parameters:
name (:term:`string`):
Name of the resource property, using the names defined in the
respective 'Data model' sections in the :term:`HMC API` book.
default:
Default value to be used, if the resource property does not exist.
Returns:
The value of the resource property.
Raises:
:exc:`~zhmcclient.HTTPError`
:exc:`~zhmcclient.ParseError`
:exc:`~zhmcclient.AuthError`
:exc:`~zhmcclient.ConnectionError`
"""
try:
return self.get_property(name)
except KeyError:
return default
[docs] def __str__(self):
"""
Return a human readable string representation of this resource.
Example result:
.. code-block:: text
Cpc(name=P0000S12,
object-uri=/api/cpcs/f1bc49af-f71a-3467-8def-3c186b5d9352,
status=service-required)
"""
properties_keys = self._properties.keys()
search_keys = ['status', 'object-uri', 'element-uri', 'name',
'type', 'class']
sorted_keys = sorted([k for k in properties_keys if k in search_keys])
info = ", ".join("%s=%r" % (k, self._properties[k])
for k in sorted_keys)
return "%s(%s)" % (self.__class__.__name__, info)
[docs] def __repr__(self):
"""
Return a string with the state of this resource, for debug purposes.
Note that the derived resource classes that have child resources
have their own ``__repr__()`` methods, because only they know which
child resources they have.
"""
ret = (
"{classname} at 0x{id:08x} (\n"
" _manager={_manager_classname} at 0x{_manager_id:08x},\n"
" _uri={_uri!r},\n"
" _full_properties={_full_properties!r},\n"
" _properties_timestamp={_properties_timestamp},\n"
" _properties={_properties}\n"
")".format(
classname=self.__class__.__name__,
id=id(self),
_manager_classname=self._manager.__class__.__name__,
_manager_id=id(self._manager),
_uri=self._uri,
_full_properties=self._full_properties,
_properties_timestamp=repr_timestamp(
self._properties_timestamp),
_properties=repr_dict(self._properties, indent=4),
))
return ret