root / ncclient / operations / rpc.py @ 6a2dfeb4
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# Copyright 2009 Shikhar Bhushan
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from threading import Event, Lock |
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from uuid import uuid1 |
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from ncclient import content |
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from ncclient.transport import SessionListener |
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from errors import OperationError, TimeoutExpiredError, MissingCapabilityError |
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import logging |
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logger = logging.getLogger('ncclient.operations.rpc')
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class RPCReply: |
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"""Represents an *<rpc-reply>*. Only concerns itself with whether the
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operation was successful.
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.. note::
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If the reply has not yet been parsed there is an implicit, one-time
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parsing overhead to accessing the attributes defined by this class and
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any subclasses.
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"""
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def __init__(self, raw): |
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self._raw = raw
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self._parsed = False |
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self._root = None |
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self._errors = []
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def __repr__(self): |
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return self._raw |
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def _parsing_hook(self, root): |
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"""Subclass can implement.
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:type root: :class:`~xml.etree.ElementTree.Element`
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"""
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pass
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def parse(self): |
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"""Parse the *<rpc-reply>*"""
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if self._parsed: |
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return
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root = self._root = content.xml2ele(self._raw) # <rpc-reply> element |
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# per rfc 4741 an <ok/> tag is sent when there are no errors or warnings
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ok = content.find(root, 'ok', nslist=[content.BASE_NS, content.CISCO_BS])
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if ok is not None: |
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logger.debug('parsed [%s]' % ok.tag)
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else: # create RPCError objects from <rpc-error> elements |
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error = content.find(root, 'rpc-error', nslist=[content.BASE_NS, content.CISCO_BS])
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if error is not None: |
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logger.debug('parsed [%s]' % error.tag)
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for err in root.getiterator(error.tag): |
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# process a particular <rpc-error>
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d = {} |
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for err_detail in err.getchildren(): # <error-type> etc.. |
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tag = content.unqualify(err_detail.tag) |
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if tag != 'error-info': |
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d[tag] = err_detail.text.strip() |
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else:
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d[tag] = content.ele2xml(err_detail) |
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self._errors.append(RPCError(d))
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self._parsing_hook(root)
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self._parsed = True |
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@property
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def xml(self): |
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"*<rpc-reply>* as returned"
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return self._raw |
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@property
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def ok(self): |
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"Boolean value indicating if there were no errors."
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if not self._parsed: |
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self.parse()
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return not self._errors # empty list => false |
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@property
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def error(self): |
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"""Short for :attr:`errors` [0]; :const:`None` if there were no errors.
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"""
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if not self._parsed: |
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self.parse()
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if self._errors: |
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return self._errors[0] |
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else:
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return None |
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@property
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def errors(self): |
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"""`list` of :class:`RPCError` objects. Will be empty if there were no
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*<rpc-error>* elements in reply.
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"""
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if not self._parsed: |
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self.parse()
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return self._errors |
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class RPCError(OperationError): # raise it if you like |
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"""Represents an *<rpc-error>*. It is an instance of :exc:`OperationError`
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so it can be raised like any other exception."""
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def __init__(self, err_dict): |
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self._dict = err_dict
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if self.message is not None: |
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OperationError.__init__(self, self.message) |
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else:
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OperationError.__init__(self)
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@property
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def type(self): |
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"`string` represeting *error-type* element"
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return self.get('error-type', None) |
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@property
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def severity(self): |
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"`string` represeting *error-severity* element"
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return self.get('error-severity', None) |
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@property
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def tag(self): |
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"`string` represeting *error-tag* element"
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return self.get('error-tag', None) |
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@property
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def path(self): |
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"`string` or :const:`None`; represeting *error-path* element"
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return self.get('error-path', None) |
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@property
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def message(self): |
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"`string` or :const:`None`; represeting *error-message* element"
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return self.get('error-message', None) |
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@property
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def info(self): |
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"`string` or :const:`None`, represeting *error-info* element"
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return self.get('error-info', None) |
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## dictionary interface
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__getitem__ = lambda self, key: self._dict.__getitem__(key) |
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__iter__ = lambda self: self._dict.__iter__() |
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__contains__ = lambda self, key: self._dict.__contains__(key) |
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keys = lambda self: self._dict.keys() |
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get = lambda self, key, default: self._dict.get(key, default) |
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iteritems = lambda self: self._dict.iteritems() |
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iterkeys = lambda self: self._dict.iterkeys() |
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itervalues = lambda self: self._dict.itervalues() |
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values = lambda self: self._dict.values() |
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items = lambda self: self._dict.items() |
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__repr__ = lambda self: repr(self._dict) |
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class RPCReplyListener(SessionListener): |
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# internal use
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# one instance per session
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def __new__(cls, session): |
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instance = session.get_listener_instance(cls) |
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if instance is None: |
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instance = object.__new__(cls)
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instance._lock = Lock() |
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instance._id2rpc = {} |
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instance._pipelined = session.can_pipeline |
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session.add_listener(instance) |
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return instance
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def register(self, id, rpc): |
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with self._lock: |
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self._id2rpc[id] = rpc |
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def callback(self, root, raw): |
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tag, attrs = root |
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if content.unqualify(tag) != 'rpc-reply': |
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return
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rpc = None
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for key in attrs: |
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if content.unqualify(key) == 'message-id': |
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id = attrs[key] |
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try:
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with self._lock: |
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rpc = self._id2rpc.pop(id) |
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except KeyError: |
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logger.warning('no object registered for message-id: [%s]' % id) |
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except Exception as e: |
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logger.debug('error - %r' % e)
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break
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else:
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if not self._pipelined: |
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with self._lock: |
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assert(len(self._id2rpc) == 1) |
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rpc = self._id2rpc.values()[0] |
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self._id2rpc.clear()
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else:
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logger.warning('<rpc-reply> without message-id received: %s' % raw)
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logger.debug('delivering to %r' % rpc)
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rpc.deliver_reply(raw) |
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def errback(self, err): |
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try:
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for rpc in self._id2rpc.values(): |
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rpc.deliver_error(err) |
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finally:
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self._id2rpc.clear()
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class RPC(object): |
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"""Base class for all operations.
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Directly corresponds to *<rpc>* requests. Handles making the request, and
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taking delivery of the reply.
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"""
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# : Subclasses can specify their dependencies on capabilities. List of URI's
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# or abbreviated names, e.g. ':writable-running'. These are verified at the
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# time of object creation. If the capability is not available, a
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# :exc:`MissingCapabilityError` is raised.
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DEPENDS = [] |
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# : Subclasses can specify a different reply class, but it must be a
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# subclass of :class:`RPCReply`.
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REPLY_CLS = RPCReply |
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def __init__(self, session, async=False, timeout=None): |
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self._session = session
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try:
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for cap in self.DEPENDS: |
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self._assert(cap)
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except AttributeError: |
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pass
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self._async = async
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self._timeout = timeout
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# keeps things simple instead of having a class attr that has to be locked
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self._id = uuid1().urn
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# RPCReplyListener itself makes sure there isn't more than one instance -- i.e. multiton
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self._listener = RPCReplyListener(session)
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self._listener.register(self._id, self) |
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self._reply = None |
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self._error = None |
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self._event = Event()
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def _build(self, opspec): |
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# internal
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spec = { |
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'tag': 'rpc', |
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'attrib': {
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'xmlns': content.BASE_NS,
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'message-id': self._id |
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}, |
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'subtree': [ opspec ]
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} |
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return content.dtree2xml(spec)
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def _request(self, op): |
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"""Subclasses call this method to make the RPC request.
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In asynchronous mode, returns an :class:`~threading.Event` which is set
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when the reply has been received or an error occured. It is prudent,
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therefore, to check the :attr:`error` attribute before accesing
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:attr:`reply`.
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Otherwise, waits until the reply is received and returns
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:class:`RPCReply`.
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:arg opspec: :ref:`dtree` for the operation
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:type opspec: :obj:`dict` or :obj:`string` or :class:`~xml.etree.ElementTree.Element`
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:rtype: :class:`~threading.Event` or :class:`RPCReply`
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"""
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logger.debug('request %r with opsepc=%r' % (self, op)) |
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req = self._build(op)
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self._session.send(req)
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if self._async: |
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logger.debug('async, returning event')
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return self._event |
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else:
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logger.debug('sync, will wait for timeout=%r' % self._timeout) |
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self._event.wait(self._timeout) |
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if self._event.isSet(): |
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if self._error: |
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raise self._error |
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self._reply.parse()
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return self._reply |
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else:
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raise TimeoutExpiredError
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def request(self, *args, **kwds): |
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"""Subclasses implement this method. Here, the operation is constructed
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in :ref:`dtree`, and the result of :meth:`_request` returned."""
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raise NotImplementedError |
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def _delivery_hook(self): |
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"""Subclasses can implement this method. Will be called after
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initialising the :attr:`reply` or :attr:`error` attribute and before
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setting the :attr:`event`"""
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pass
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def _assert(self, capability): |
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"""Subclasses can use this method to verify that a capability is available
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with the NETCONF server, before making a request that requires it. A
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:exc:`MissingCapabilityError` will be raised if the capability is not
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available."""
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if capability not in self._session.server_capabilities: |
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raise MissingCapabilityError('Server does not support [%s]' % cap) |
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def deliver_reply(self, raw): |
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# internal use
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self._reply = self.REPLY_CLS(raw) |
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self._delivery_hook()
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self._event.set()
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def deliver_error(self, err): |
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# internal use
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self._error = err
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self._delivery_hook()
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self._event.set()
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@property
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def reply(self): |
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":class:`RPCReply` element if reply has been received or :const:`None`"
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return self._reply |
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@property
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def error(self): |
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""":exc:`Exception` type if an error occured or :const:`None`.
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This attribute should be checked if the request was made asynchronously,
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so that it can be determined if :attr:`event` being set is because of a
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reply or error.
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.. note::
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This represents an error which prevented a reply from being
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received. An *<rpc-error>* does not fall in that category -- see
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:class:`RPCReply` for that.
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"""
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return self._error |
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@property
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def id(self): |
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"The *message-id* for this RPC"
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return self._id |
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@property
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def session(self): |
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"""The :class:`~ncclient.transport.Session` object associated with this
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RPC"""
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return self._session |
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@property
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def event(self): |
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""":class:`~threading.Event` that is set when reply has been received or
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error occured."""
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return self._event |
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def set_async(self, async=True): |
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"""Set asynchronous mode for this RPC."""
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self._async = async
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if async and not session.can_pipeline: |
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raise UserWarning('Asynchronous mode not supported for this device/session') |
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def set_timeout(self, timeout): |
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"""Set the timeout for synchronous waiting defining how long the RPC
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request will block on a reply before raising an error."""
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self._timeout = timeout
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#: Whether this RPC is asynchronous
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async = property(fget=lambda self: self._async, fset=set_async) |
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#: Timeout for synchronous waiting
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timeout = property(fget=lambda self: self._timeout, fset=set_timeout) |