opcua.server.HistoryManager._read_datavalue_history() - Code Metrics - Inspection of "Updated SQLite Historizing" - FreeOpcUa/python-opcua - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#156)

unknown

created 2016-04-11 17:45 UTC

_read_datavalue_history() A

↳ Parent: opcua.server.HistoryManager

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	7
CRAP Score	3.0175

Metric	Value
cc	3
dl	0
loc	21
ccs	7
cts	8
cp	0.875
crap	3.0175
rs	9.3142

from datetime import timedelta
from datetime import datetime

from opcua import Subscription
from opcua import ua


class HistoryStorageInterface(object):

    """
    Interface of a history backend.
    Must be implemented by backends
    """

    def new_historized_node(self, node_id, period, count=0):
        """
        Called when a new node is to be historized
        Returns None
        """
        raise NotImplementedError

    def save_node_value(self, node_id, datavalue):
        """
        Called when the value of a historized node has changed and should be saved in history
        Returns None
        """
        raise NotImplementedError

    def read_node_history(self, node_id, start, end, nb_values):
        """
        Called when a client make a history read request for a node
        if start or end is missing then nb_values is used to limit query
        nb_values is the max number of values to read. Ignored if 0
        Start time and end time are inclusive
        Returns a list of DataValues and a continuation point which
        is None if all nodes are read or the ServerTimeStamp of the last rejected DataValue
        """
        raise NotImplementedError

    def new_historized_event(self, event, period):
        """
        Called when historization of events is enabled on server side
        FIXME: we may need to store events per nodes in future...
        Returns None
        """
        raise NotImplementedError

    def save_event(self, event):
        """
        Called when a new event has been generated ans should be saved in history
        Returns None
        """
        raise NotImplementedError

    def read_event_history(self, start, end, evfilter):
        """
        Called when a client make a history read request for events
        Start time and end time are inclusive
        Returns a list of Events and a continuation point which
        is None if all events are read or the ServerTimeStamp of the last rejected event
        """
        raise NotImplementedError

    def stop(self):
        """
        Called when the server shuts down
        Can be used to close database connections etc.
        """
        raise NotImplementedError


# if you want to use an SQL based history uncomment this import and change the storage type of the history manager
# from opcua.server.history_sql import HistorySQLite


class HistoryDict(HistoryStorageInterface):
    """
    very minimal history backend storing data in memory using a Python dictionary
    """
    def __init__(self):
        self._datachanges = {}
        self._datachanges_period = {}
        self._events = {}

    def new_historized_node(self, node_id, period, count=0):
        self._datachanges[node_id] = []
        self._datachanges_period[node_id] = period, count

    def save_node_value(self, node_id, datavalue):
        data = self._datachanges[node_id]
        period, count = self._datachanges_period[node_id]
        data.append(datavalue)
        now = datetime.now()
        if period:
            while now - data[0].ServerTimestamp > period:
                data.pop(0)
        if count and len(data) > count:
            data = data[-count:]

    def read_node_history(self, node_id, start, end, nb_values):
        cont = None
        if node_id not in self._datachanges:
            print("Error attempt to read history for a node which is not historized")
            return [], cont
        else:
            if end is None:
                end = datetime.now() + timedelta(days=1)
            if start is None:
                start = ua.DateTimeMinValue
            results = [dv for dv in self._datachanges[node_id] if start <= dv.ServerTimestamp <= end]
            if nb_values:
                if start > ua.DateTimeMinValue and len(results) > nb_values:
                    cont = results[nb_values + 1].ServerTimestamp
                    results = results[:nb_values]
                else:
                    results = results[-nb_values:]
            return results, cont

    def new_historized_event(self, event, period):
        self._events = []

    def save_event(self, event):
        raise NotImplementedError

    def read_event_history(self, start, end, evfilter):
        raise NotImplementedError

    def stop(self):
        pass


class SubHandler(object):
    def __init__(self, storage):
        self.storage = storage

    def datachange_notification(self, node, val, data):
        self.storage.save_node_value(node.nodeid, data.monitored_item.Value)

    def event_notification(self, event):
        self.storage.save_event(event)


class HistoryManager(object):
    def __init__(self, iserver):
        self.iserver = iserver
        self.storage = HistoryDict()  # Change to HistorySQLite() for file based history
        self._sub = None
        self._handlers = {}

    def set_storage(self, storage):
        self.storage = storage

    def _create_subscription(self, handler):
        params = ua.CreateSubscriptionParameters()
        params.RequestedPublishingInterval = 10
        params.RequestedLifetimeCount = 3000
        params.RequestedMaxKeepAliveCount = 10000
        params.MaxNotificationsPerPublish = 0
        params.PublishingEnabled = True
        params.Priority = 0
        return Subscription(self.iserver.isession, params, handler)

    def historize(self, node, period=timedelta(days=7), count=0):
        if not self._sub:
            self._sub = self._create_subscription(SubHandler(self.storage))
        if node in self._handlers:
            raise ua.UaError("Node {} is already historized".format(node))
        self.storage.new_historized_node(node.nodeid, period, count)
        handler = self._sub.subscribe_data_change(node)
        self._handlers[node] = handler

    def dehistorize(self, node):
        self._sub.unsubscribe(self._handlers[node])
        del(self._handlers[node])

    def read_history(self, params):
        """
        Read history for a node
        This is the part AttributeService, but implemented as its own service
        since it requires more logic than other attribute service methods
        """
        results = []
        
        for rv in params.NodesToRead:
            res = self._read_history(params.HistoryReadDetails, rv)
            results.append(res)
        return results
        
    def _read_history(self, details, rv):
        """
        read history for a node
        """
        result = ua.HistoryReadResult()
        if isinstance(details, ua.ReadRawModifiedDetails):
            if details.IsReadModified:
                result.HistoryData = ua.HistoryModifiedData()
                # we do not support modified history by design so we return what we have
            else:
                result.HistoryData = ua.HistoryData()
            dv, cont = self._read_datavalue_history(rv, details)
            result.HistoryData.DataValues = dv
            result.ContinuationPoint = cont

        elif isinstance(details, ua.ReadEventDetails):
            result.HistoryData = ua.HistoryEvent()
            # FIXME: filter is a cumbersome type, maybe transform it something easier
            # to handle for storage
            result.HistoryData.Events = self.storage.read_event_history(details.StartTime,
                                                                        details.EndTime,
                                                                        details.Filter)
        else:
            # we do not currently support the other types, clients can process data themselves
            result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotImplemented)
        return result

    def _read_datavalue_history(self, rv, details):
        starttime = details.StartTime
        if rv.ContinuationPoint:
            # Spec says we should ignore details if cont point is present
            # but they also say we can use cont point as timestamp to enable stateless
            # implementation. This is contradictory, so we assume details is
            # send correctly with continuation point
            # starttime = bytes_to_datetime(rv.ContinuationPoint)
            starttime = ua.unpack_datetime(rv.ContinuationPoint)

        dv, cont = self.storage.read_node_history(rv.NodeId,
                                                  starttime,
                                                  details.EndTime,
                                                  details.NumValuesPerNode)
        if cont:
            # cont = datetime_to_bytes(dv[-1].ServerTimestamp)
            cont = ua.pack_datetime(dv[-1].ServerTimestamp)
        # FIXME, parse index range and filter out if necessary
        # rv.IndexRange
        # rv.DataEncoding # xml or binary, seems spec say we can ignore that one
        return dv, cont

    def update_history(self, params):
        """
        Update history for a node
        This is the part AttributeService, but implemented as its own service
        since it requires more logic than other attribute service methods
        """
        results = []
        for _ in params.HistoryUpdateDetails:
            result = ua.HistoryUpdateResult()
            # we do not accept to rewrite history
            result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotWritable)
            results.append(results)
        return results

    def stop(self):
        self.storage.stop()


1	1	from datetime import timedelta
2	1	from datetime import datetime
3
4	1	from opcua import Subscription
5	1	from opcua import ua
6
7
8	1	class HistoryStorageInterface(object):
9
10		"""
11		Interface of a history backend.
12		Must be implemented by backends
13		"""
14
15	1	def new_historized_node(self, node_id, period, count=0):
16		"""
17		Called when a new node is to be historized
18		Returns None
19		"""
20		raise NotImplementedError
21
22	1	def save_node_value(self, node_id, datavalue):
23		"""
24		Called when the value of a historized node has changed and should be saved in history
25		Returns None
26		"""
27		raise NotImplementedError
28
29	1	def read_node_history(self, node_id, start, end, nb_values):
30		"""
31		Called when a client make a history read request for a node
32		if start or end is missing then nb_values is used to limit query
33		nb_values is the max number of values to read. Ignored if 0
34		Start time and end time are inclusive
35		Returns a list of DataValues and a continuation point which
36		is None if all nodes are read or the ServerTimeStamp of the last rejected DataValue
37		"""
38		raise NotImplementedError
39
40	1	def new_historized_event(self, event, period):
41		"""
42		Called when historization of events is enabled on server side
43		FIXME: we may need to store events per nodes in future...
44		Returns None
45		"""
46		raise NotImplementedError
47
48	1	def save_event(self, event):
49		"""
50		Called when a new event has been generated ans should be saved in history
51		Returns None
52		"""
53		raise NotImplementedError
54
55	1	def read_event_history(self, start, end, evfilter):
56		"""
57		Called when a client make a history read request for events
58		Start time and end time are inclusive
59		Returns a list of Events and a continuation point which
60		is None if all events are read or the ServerTimeStamp of the last rejected event
61		"""
62		raise NotImplementedError
63
64	1	def stop(self):
65		"""
66		Called when the server shuts down
67		Can be used to close database connections etc.
68		"""
69		raise NotImplementedError
70
71
72		# if you want to use an SQL based history uncomment this import and change the storage type of the history manager
73		# from opcua.server.history_sql import HistorySQLite
74
75
76	1	class HistoryDict(HistoryStorageInterface):
77		"""
78		very minimal history backend storing data in memory using a Python dictionary
79		"""
80	1	def __init__(self):
81	1	self._datachanges = {}
82	1	self._datachanges_period = {}
83	1	self._events = {}
84
85	1	def new_historized_node(self, node_id, period, count=0):
86	1	self._datachanges[node_id] = []
87	1	self._datachanges_period[node_id] = period, count
88
89	1	def save_node_value(self, node_id, datavalue):
90	1	data = self._datachanges[node_id]
91	1	period, count = self._datachanges_period[node_id]
92	1	data.append(datavalue)
93	1	now = datetime.now()
94	1	if period:
95	1	while now - data[0].ServerTimestamp > period:
96		data.pop(0)
97	1	if count and len(data) > count:
98	1	data = data[-count:]
99
100	1	def read_node_history(self, node_id, start, end, nb_values):
101	1	cont = None
102	1	if node_id not in self._datachanges:
103		print("Error attempt to read history for a node which is not historized")
104		return [], cont
105		else:
106	1	if end is None:
107		end = datetime.now() + timedelta(days=1)
108	1	if start is None:
109		start = ua.DateTimeMinValue
110	1	results = [dv for dv in self._datachanges[node_id] if start <= dv.ServerTimestamp <= end]
111	1	if nb_values:
112	1	if start > ua.DateTimeMinValue and len(results) > nb_values:
113	1	cont = results[nb_values + 1].ServerTimestamp
114	1	results = results[:nb_values]
115		else:
116	1	results = results[-nb_values:]
117	1	return results, cont
118
119	1	def new_historized_event(self, event, period):
120		self._events = []
121
122	1	def save_event(self, event):
123		raise NotImplementedError
124
125	1	def read_event_history(self, start, end, evfilter):
126		raise NotImplementedError
127
128	1	def stop(self):
129	1	pass
130
131
132	1	class SubHandler(object):
133	1	def __init__(self, storage):
134	1	self.storage = storage
135
136	1	def datachange_notification(self, node, val, data):
137	1	self.storage.save_node_value(node.nodeid, data.monitored_item.Value)
138
139	1	def event_notification(self, event):
140		self.storage.save_event(event)
141
142
143	1	class HistoryManager(object):
144	1	def __init__(self, iserver):
145	1	self.iserver = iserver
146	1	self.storage = HistoryDict() # Change to HistorySQLite() for file based history
147	1	self._sub = None
148	1	self._handlers = {}
149
150	1	def set_storage(self, storage):
151		self.storage = storage
152
153	1	def _create_subscription(self, handler):
154	1	params = ua.CreateSubscriptionParameters()
155	1	params.RequestedPublishingInterval = 10
156	1	params.RequestedLifetimeCount = 3000
157	1	params.RequestedMaxKeepAliveCount = 10000
158	1	params.MaxNotificationsPerPublish = 0
159	1	params.PublishingEnabled = True
160	1	params.Priority = 0
161	1	return Subscription(self.iserver.isession, params, handler)
162
163	1	def historize(self, node, period=timedelta(days=7), count=0):
164	1	if not self._sub:
165	1	self._sub = self._create_subscription(SubHandler(self.storage))
166	1	if node in self._handlers:
167		raise ua.UaError("Node {} is already historized".format(node))
168	1	self.storage.new_historized_node(node.nodeid, period, count)
169	1	handler = self._sub.subscribe_data_change(node)
170	1	self._handlers[node] = handler
171
172	1	def dehistorize(self, node):
173	1	self._sub.unsubscribe(self._handlers[node])
174	1	del(self._handlers[node])
175
176	1	def read_history(self, params):
177		"""
178		Read history for a node
179		This is the part AttributeService, but implemented as its own service
180		since it requires more logic than other attribute service methods
181		"""
182	1	results = []
183
184	1	for rv in params.NodesToRead:
185	1	res = self._read_history(params.HistoryReadDetails, rv)
186	1	results.append(res)
187	1	return results
188
189	1	def _read_history(self, details, rv):
190		"""
191		read history for a node
192		"""
193	1	result = ua.HistoryReadResult()
194	1	if isinstance(details, ua.ReadRawModifiedDetails):
195	1	if details.IsReadModified:
196		result.HistoryData = ua.HistoryModifiedData()
197		# we do not support modified history by design so we return what we have
198		else:
199	1	result.HistoryData = ua.HistoryData()
200	1	dv, cont = self._read_datavalue_history(rv, details)
201	1	result.HistoryData.DataValues = dv
202	1	result.ContinuationPoint = cont
203
204		elif isinstance(details, ua.ReadEventDetails):
205		result.HistoryData = ua.HistoryEvent()
206		# FIXME: filter is a cumbersome type, maybe transform it something easier
207		# to handle for storage
208		result.HistoryData.Events = self.storage.read_event_history(details.StartTime,
209		details.EndTime,
210		details.Filter)
211		else:
212		# we do not currently support the other types, clients can process data themselves
213		result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotImplemented)
214	1	return result
215
216	1	def _read_datavalue_history(self, rv, details):
217	1	starttime = details.StartTime
218	1	if rv.ContinuationPoint:
219		# Spec says we should ignore details if cont point is present
220		# but they also say we can use cont point as timestamp to enable stateless
221		# implementation. This is contradictory, so we assume details is
222		# send correctly with continuation point
223		# starttime = bytes_to_datetime(rv.ContinuationPoint)
224		starttime = ua.unpack_datetime(rv.ContinuationPoint)
225
226	1	dv, cont = self.storage.read_node_history(rv.NodeId,
227		starttime,
228		details.EndTime,
229		details.NumValuesPerNode)
230	1	if cont:
231		# cont = datetime_to_bytes(dv[-1].ServerTimestamp)
232	1	cont = ua.pack_datetime(dv[-1].ServerTimestamp)
233		# FIXME, parse index range and filter out if necessary
234		# rv.IndexRange
235		# rv.DataEncoding # xml or binary, seems spec say we can ignore that one
236	1	return dv, cont
237
238	1	def update_history(self, params):
239		"""
240		Update history for a node
241		This is the part AttributeService, but implemented as its own service
242		since it requires more logic than other attribute service methods
243		"""
244		results = []
245		for _ in params.HistoryUpdateDetails:
246		result = ua.HistoryUpdateResult()
247		# we do not accept to rewrite history
248		result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotWritable)
249		results.append(results)
250		return results
251
252	1	def stop(self):
253		self.storage.stop()
254

FreeOpcUa / python-opcua

Pull Request — master (#156)

_read_datavalue_history() A

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