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#!/usr/bin/env python
#coding=utf8
'''
The current living objects database.
'''
from datetime import datetime, timedelta
import logging
from threading import RLock
from tql import TqlObject
from exceptions import AlreadyRegistered
DEFAULT_TTL = 0
TTL_SERVER_DELTA = 2 # Delta to apply for all tags
class ObjectsDB(object):
'''
The object database.
This class abstract the access to the current living objects database. The
database store a list of :class:`TqlObject` instances, each defining an
object with its tags.
Objects are registered by :meth:`register` method, and removed by
:meth:`unregister` method. You can update the tags of registered objects
with :meth:`update` method. A call to :meth:`all` method give you the
complete list of objects with an automatic update before to return it.
.. note:
All calls to the :class:`ObjectDB` are thread-safe.
'''
def __init__(self, server):
# The server to use to complete database:
self._server = server
# The object database:
self._objects = {} # Dict of oid -> TqlObject instances
# The TTL database:
self._ttls = {} # (obj_id, tag) -> time of death
# The access lock of the object database:
self._lock = RLock()
# The list of received message while update:
self._msgs = []
def update(self, ids=None, tags=None, tags_novalue=None):
'''
Update the database according to the TTL values.
:param ids: list of ids to update (or None for all)
:param tags: list of tags to update (or None for all)
:param tags_noval: list of tags to update (only the name, not the
attached value, None for all)
'''
with self._lock:
self._update(ids, tags, tags_novalue)
self._process_responses()
def _update(self, ids=None, tags=None, tags_novalue=None):
'''
First step of the database update process.
This methods make essentially two things:
* Calculate the final list of tags to get and to check
* Send the request to each client involved in the update
.. warning:
The call to this method is not threadsafe and must be done only
by :meth:`update` method.
'''
self._msgs = []
# Cast input to the right type:
if tags is not None:
tags = set(tags)
if tags_novalue is not None:
tags_novalue = set(tags_novalue)
if tags is not None:
tags_novalue -= tags
if ids is not None:
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# The main-loop, we will pop each object id from the set and
# process it:
while ids:
oid = ids.pop()
obj = self._objects.get(oid)
assert obj is not None, 'object not found'
if '__parent' in obj:
# Current object is proxified by a parent:
parent = obj['__parent']
self._update_object(parent, tags, tags_novalue)
# Parent is removed from the list if it present (because
# it has been updated):
if parent['id'] in ids:
ids.remove(parent['id'])
# Search for sibling objects:
sg = set((o for o in ids if o.startswith('%s.' % parent['id'])))
ids -= sg
for sibling in sg:
sibling = self.get_by_id(sibling)
self._update_object(sibling, tags, tags_novalue)
else:
# Current object is a standard node:
self._update_object(obj, tags, tags_novalue)
def _process_responses(self):
'''
Process the responses received from clients.
'''
msgs = self._server.manager.wait(frozenset(self._msgs), timeout=10)
now = datetime.now()
for msg in msgs:
if msg.get('error') is not None:
logging.error('Error from client while getting tags')
else:
returned = msg['return']
obj = msg['data']
assert isinstance(returned, dict), 'returned tags is not a dict'
assert isinstance(obj, TqlObject), 'data obj is not TqlObject'
if '__parent' in obj:
user_tags = obj['__parent']['__user_defined_tags']
else:
user_tags = obj['__user_defined_tags']
for name, attrs in returned.iteritems():
obj[name] = attrs.get('value')
# Update the ttl
ttl = attrs.get('ttl', DEFAULT_TTL)
if ttl == -1:
tod = datetime.max
else:
ttl += TTL_SERVER_DELTA
dt = timedelta(seconds=ttl)
tod = now + dt
self._ttls[(obj['id'], name)] = tod
obj.update(user_tags)
def _update_object(self, obj, tags, tags_novalue):
'''
Calculate the list of tags to request for a client, and send the
request to the client.
'''
parent = obj.get('__parent')
if parent is None:
user_tags = self._server.conf.show(obj['id'])['tags']
obj['__user_defined_tags'] = user_tags
client_id = obj['id']
else:
user_tags = parent['__user_defined_tags']
client_id = parent['id']
if tags is not None:
tags -= set(user_tags)
if tags_novalue is not None:
tags_novalue -= set(user_tags)
try:
client = self._server.get_connection(client_id)
except KeyError:
pass
else:
# The client is connected:
if parent is None:
obj.update(client.get_tags())
# First, check if each tag is not already cached:
now = datetime.now()
if tags is not None:
for tag in tags.copy():
if now < self._ttls.get((obj['id'], tag), now):
tags.remove(tag)
# Cast as jsonizable type:
tags = tuple(tags)
if tags_novalue is not None:
for tag in tags_novalue.copy():
if now < self._ttls.get((obj['id'], tag), now):
tags_novalue.remove(tag)
# Cast as jsonizable type:
tags_novalue = tuple(tags_novalue)
# Ask tags to the node:
if (tags is None or tags) or (tags_novalue is None or tags_novalue):
self._request_tags(obj, client, tags, tags_novalue)
def _request_tags(self, obj, client, tags, tags_novalue):
'''
Send the request to the client.
'''
if '__parent' in obj:
subid = obj['id'].partition('.')[2]
msg_id = client.connection.async_call('sub_tags', subid, tags,
tags_novalue, _data=obj)
else:
msg_id = client.connection.async_call('get_tags', tags,
tags_novalue, _data=obj)
self._msgs.append(msg_id)
def get_by_id(self, oid):
'''
Get an registered object by its id.
:param oid: the complete oid of the object to get
:return: a :class:`TqlObject` instance
'''
return self._objects[oid]
def register(self, obj):
'''
Populate the database with the specified object. All the tags specified
in the passed object will be declared as infite TTL.
'''
with self._lock:
if 'id' not in obj:
raise ValueError('id tag must exists on the object')
elif obj['id'] in self._objects:
raise AlreadyRegistered('The object is already registered')
else:
self._objects[obj['id']] = obj
def unregister(self, obj_id):
'''
Remove an object from the manager by its id.
'''
with self._lock:
if obj_id in self._objects:
self.unregister_children(obj_id)
del self._objects[obj_id]
else:
raise ValueError('The object is not registered')
def unregister_children(self, obj_id):
'''
Remove all children of an object.
'''
with self._lock:
if obj_id in self._objects:
parent = self._objects[obj_id]
for key, obj in self._objects.items():
if obj.get('__parent') is parent:
del self._objects[key]
else:
raise ValueError('The object %r is not registered' % obj_id)
def get_ids(self):
'''
Get the set of all the first level ids.
'''
ids = set()
for oid in self._objects:
parid = oid.partition('.')[0]
ids.add(parid)
return ids
def all(self, tags, to_check):
'''
Get all the objects registered on the server with specified tags.
'''
self.update(tags=tags, tags_novalue=to_check)
for obj in self._objects.values():
yield obj
def some(self, ids, tags=set(), to_check=set()):
'''
Get specified objects registed on the server with specified tags.
'''
self.update(ids, tags=tags, tags_novalue=to_check)
for obj_id in ids:
yield self._objects[obj_id]