1 # Copyright (c) 2020 Samsung Electronics
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
16 # This source code is part of the near-RT RIC (RAN Intelligent Controller)
17 # platform project (RICP).
20 """Examples on how to use Shared Data Layer (SDL) notification feature.
22 Execution of these examples requires:
23 * Following Redis extension commands have been installed to runtime environment:
31 Redis v4.0 or greater is required. Older versions do not support extension modules.
32 Implementation of above commands is produced by RIC DBaaS:
33 https://gerrit.o-ran-sc.org/r/admin/repos/ric-plt/dbaas
34 In official RIC deployments these commands are installed by `dbaas` service to Redis
36 In development environment you may want install commands manually to pod/container, which is
38 * Following environment variables are needed to set to the pod/container where the application
39 utilizing SDL is going to be run.
40 DBAAS_SERVICE_HOST = [DB service address]
41 DBAAS_SERVICE_PORT= [DB service port]
42 DBAAS_MASTER_NAME = [DB name]. Needed to set only if Redis sentinel is used to provide high
43 availability for Redis DB solution.
44 DBAAS_SERVICE_SENTINEL_PORT = [Redis sentinel port number]. Needed to set only if Redis
46 DBASS_CLUSTER_ADDR_LIST = [list of DB service addresses]. Is set only if more than one
47 Redis sentinel groups are in use.
48 In official RIC deployments four first environment variables are defined in Helm configMaps
49 of the DBaaS and these configurations can be loaded automatically as environment variables
50 into application pods via `envFrom dbaas-appconfig` statement in an application Helm Charts.
51 The last environment variable is not for time being in use in official RIC deployments, only
52 in Nokia SEP deployments.
58 from ricsdl.syncstorage import SyncStorage
59 from ricsdl.exceptions import RejectedByBackend, NotConnected, BackendError
60 from typing import (Union, List)
62 # There are two available methods for applications to handle notifications:
63 # - EVENT_LISTENER (true):
64 # - User calls sdl.start_event_listener() which will create an SDL managed
65 # event loop for handling messages.
66 # - EVENT_LISTENER (false):
67 # - User need to call sdl.handle_events() which will return the message
69 # Note: In both cases, the given callback function will be executed.
72 # Constants used in the examples below.
74 MY_CHANNEL = "my_channel"
75 MY_LOCK = threading.Lock()
78 def _try_func_return(func):
80 Generic wrapper function to call SDL API function and handle exceptions if they are raised.
84 except RejectedByBackend as exp:
85 print(f'SDL function {func.__name__} failed: {str(exp)}')
86 # Permanent failure, just forward the exception
88 except (NotConnected, BackendError) as exp:
89 print(f'SDL function {func.__name__} failed for a temporal error: {str(exp)}')
90 # Here we could have a retry logic
93 def _try_func_callback_return(func):
94 """Generic wrapper function for testing SDL APIs with callback functions.
96 threading.Lock is unlocked in the callback function and threading.Lock is
97 only used to demonstrate that the callback function was called.
101 ret = _try_func_return(func)
102 while MY_LOCK.locked():
107 # Creates SDL instance. The call creates connection to the SDL database backend.
108 mysdl = _try_func_return(SyncStorage)
110 # Stores the last received channel and message
114 # Allows program to stop receive thread at the end of execution
118 def cb(channel: str, message: List[str]):
119 """An example of function that will be called when an event list is received.
121 This function sets last_cb_channel and last_cb_message as channel and
122 message respectively. This also unlocks the global lock variable.
125 channel: Channel where the message was received
126 message: Received message
128 global last_cb_channel, last_cb_message, MY_LOCK
129 last_cb_channel = channel
130 last_cb_message = message
136 """An example of a listener thread that continuously calls sdl.handle_events()."""
139 while not stop_thread:
140 message = mysdl.handle_events()
142 # You could process message here
146 # Subscribe to MY_CHANNEL. We expect that anytime we receive a message in the
147 # channel, cb function will be called.
148 _try_func_return(lambda: mysdl.subscribe_channel(MY_NS, cb, MY_CHANNEL))
150 # As mentioned above, there are two available methods for applications to
151 # handle notifications
153 _try_func_return(mysdl.start_event_listener)
155 thread = threading.Thread(target=listen_thread)
158 # Sets a value 'my_value' for a key 'my_key' under given namespace. Note that value
159 # type must be bytes and multiple key values can be set in one set function call.
160 _try_func_callback_return(
161 lambda: mysdl.set_and_publish(MY_NS, {MY_CHANNEL: "SET PUBLISH"}, {'my_key': b'my_value'}))
162 assert last_cb_channel == MY_CHANNEL and last_cb_message[0] == "SET PUBLISH"
164 # Sets a value 'my_value' for a key 'my_key' under given namespace. Note that value
165 # type must be bytes and multiple key values can be set in one set function call.
166 # Function publishes two events into one channel.
167 _try_func_callback_return(
168 lambda: mysdl.set_and_publish(MY_NS, {MY_CHANNEL: ["SET PUBLISH1", "SET PUBLISH2"]}, {'my_key': b'my_value'}))
169 assert last_cb_channel == MY_CHANNEL and last_cb_message == ["SET PUBLISH1", "SET PUBLISH2"]
171 # Sets a value 'my_value2' for a key 'my_key' under given namespace only if the old value is
173 was_set = _try_func_callback_return(lambda: mysdl.set_if_and_publish(
174 MY_NS, {MY_CHANNEL: "SET IF PUBLISH"}, 'my_key', b'my_value', b'my_value2'))
175 assert was_set is True
176 assert last_cb_channel == MY_CHANNEL and last_cb_message[0] == "SET IF PUBLISH"
177 # Try again. This time value 'my_value2' won't be set, because the key has already 'my_value2'
178 # value. Callback function will not be called here.
179 was_set = _try_func_return(lambda: mysdl.set_if_and_publish(MY_NS, {MY_CHANNEL: "SET IF PUBLISH"},
180 'my_key', b'my_value', b'my_value2'))
181 assert was_set is False
183 # Sets a value 'my_value' for a key 'my_key2' under given namespace only if the key doesn't exist.
184 # Note that value types must be bytes.
185 was_set = _try_func_callback_return(lambda: mysdl.set_if_not_exists_and_publish(
186 MY_NS, {MY_CHANNEL: "SET IF NOT PUBLISH"}, 'my_key2', b'my_value'))
187 assert was_set is True
188 assert last_cb_channel == MY_CHANNEL and last_cb_message[0] == "SET IF NOT PUBLISH"
189 # Try again. This time the key 'my_key2' already exists. Callback function will not be called here.
190 was_set = _try_func_return(lambda: mysdl.set_if_not_exists_and_publish(
191 MY_NS, {MY_CHANNEL: "SET IF NOT PUBLISH"}, 'my_key2', b'my_value'))
192 assert was_set is False
194 # Removes a key 'my_key' under given namespace.
195 _try_func_callback_return(
196 lambda: mysdl.remove_and_publish(MY_NS, {MY_CHANNEL: "REMOVE PUBLISH"}, 'my_key'))
197 my_ret_dict = _try_func_return(lambda: mysdl.get(MY_NS, 'my_key'))
198 assert my_ret_dict == {}
199 assert last_cb_channel == MY_CHANNEL and last_cb_message[0] == "REMOVE PUBLISH"
201 # Removes a key 'my_key' under given namespace only if the old value is 'my_value'.
202 was_removed = _try_func_callback_return(lambda: mysdl.remove_if_and_publish(
203 MY_NS, {MY_CHANNEL: "REMOVE IF PUBLISH"}, 'my_key2', b'my_value'))
204 assert was_removed is True
205 assert last_cb_channel == MY_CHANNEL and last_cb_message[0] == "REMOVE IF PUBLISH"
206 # Try again to remove not anymore existing key 'my_key'. Callback function will not be called here.
207 was_removed = _try_func_return(lambda: mysdl.remove_if_and_publish(
208 MY_NS, {MY_CHANNEL: "REMOVE IF PUBLISH"}, 'my_key2', b'my_value'))
209 assert was_removed is False
211 # Removes all the keys under given namespace.
212 _try_func_return(lambda: mysdl.set(MY_NS, {'my_key': b'something'}))
213 my_ret_dict = _try_func_return(lambda: mysdl.get(MY_NS, {'my_key'}))
214 assert my_ret_dict != {}
216 _try_func_callback_return(
217 lambda: mysdl.remove_all_and_publish(MY_NS, {MY_CHANNEL: "REMOVE ALL PUBLISH"}))
218 my_ret_dict = _try_func_return(lambda: mysdl.get(MY_NS, {'my_key'}))
219 assert my_ret_dict == {}
220 assert last_cb_channel == MY_CHANNEL and last_cb_message[0] == "REMOVE ALL PUBLISH"