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 = [redis server address]
41 DBAAS_SERVICE_PORT= [redis server port]
42 DBAAS_MASTER_NAME = [master Redis sentinel name]. Needed to set only if sentinel is in use.
43 DBAAS_SERVICE_SENTINEL_PORT = [Redis sentinel port number]. Needed to set only if sentinel
50 from ricsdl.syncstorage import SyncStorage
51 from ricsdl.exceptions import RejectedByBackend, NotConnected, BackendError
53 # There are two available methods for applications to handle notifications:
54 # - EVENT_LISTENER (true):
55 # - User calls sdl.start_event_listener() which will create an SDL managed
56 # event loop for handling messages.
57 # - EVENT_LISTENER (false):
58 # - User need to call sdl.handle_messages() which will return the message
60 # Note: In both cases, the given callback function will be executed.
63 # Constants used in the examples below.
65 MY_CHANNEL = "my_channel"
66 MY_LOCK = threading.Lock()
69 def _try_func_return(func):
71 Generic wrapper function to call SDL API function and handle exceptions if they are raised.
75 except RejectedByBackend as exp:
76 print(f'SDL function {func.__name__} failed: {str(exp)}')
77 # Permanent failure, just forward the exception
79 except (NotConnected, BackendError) as exp:
80 print(f'SDL function {func.__name__} failed for a temporal error: {str(exp)}')
81 # Here we could have a retry logic
84 def _try_func_callback_return(func):
85 """Generic wrapper function for testing SDL APIs with callback functions.
87 threading.Lock is unlocked in the callback function and threading.Lock is
88 only used to demonstrate that the callback function was called.
92 ret = _try_func_return(func)
93 while MY_LOCK.locked():
98 # Creates SDL instance. The call creates connection to the SDL database backend.
99 mysdl = _try_func_return(SyncStorage)
101 # Stores the last received channel and message
105 # Allows program to stop receive thread at the end of execution
109 def cb(channel: str, message: str):
110 """An example of function that will be called when an event is received.
112 This function sets last_cb_channel and last_cb_message as channel and
113 message respectively. This also unlocks the global lock variable.
116 channel: Channel where the message was received
117 message: Received message
119 global last_cb_channel, last_cb_message, MY_LOCK
120 last_cb_channel = channel
121 last_cb_message = message
127 """An example of a listener thread that continuously calls sdl.handle_events()."""
130 while not stop_thread:
131 message = mysdl.handle_events()
133 # You could process message here
137 # Subscribe to MY_CHANNEL. We expect that anytime we receive a message in the
138 # channel, cb function will be called.
139 _try_func_return(lambda: mysdl.subscribe_channel(MY_NS, cb, MY_CHANNEL))
141 # As mentioned above, there are two available methods for applications to
142 # handle notifications
144 _try_func_return(mysdl.start_event_listener)
146 thread = threading.Thread(target=listen_thread)
149 # Sets a value 'my_value' for a key 'my_key' under given namespace. Note that value
150 # type must be bytes and multiple key values can be set in one set function call.
151 _try_func_callback_return(
152 lambda: mysdl.set_and_publish(MY_NS, {MY_CHANNEL: "SET PUBLISH"}, {'my_key': b'my_value'}))
153 assert last_cb_channel == MY_CHANNEL and last_cb_message == "SET PUBLISH"
155 # Sets a value 'my_value2' for a key 'my_key' under given namespace only if the old value is
157 was_set = _try_func_callback_return(lambda: mysdl.set_if_and_publish(
158 MY_NS, {MY_CHANNEL: "SET IF PUBLISH"}, 'my_key', b'my_value', b'my_value2'))
159 assert was_set is True
160 assert last_cb_channel == MY_CHANNEL and last_cb_message == "SET IF PUBLISH"
161 # Try again. This time value 'my_value2' won't be set, because the key has already 'my_value2'
162 # value. Callback function will not be called here.
163 was_set = _try_func_return(lambda: mysdl.set_if_and_publish(MY_NS, {MY_CHANNEL: "SET IF PUBLISH"},
164 'my_key', b'my_value', b'my_value2'))
165 assert was_set is False
167 # Sets a value 'my_value' for a key 'my_key2' under given namespace only if the key doesn't exist.
168 # Note that value types must be bytes.
169 was_set = _try_func_callback_return(lambda: mysdl.set_if_not_exists_and_publish(
170 MY_NS, {MY_CHANNEL: "SET IF NOT PUBLISH"}, 'my_key2', b'my_value'))
171 assert was_set is True
172 assert last_cb_channel == MY_CHANNEL and last_cb_message == "SET IF NOT PUBLISH"
173 # Try again. This time the key 'my_key2' already exists. Callback function will not be called here.
174 was_set = _try_func_return(lambda: mysdl.set_if_not_exists_and_publish(
175 MY_NS, {MY_CHANNEL: "SET IF NOT PUBLISH"}, 'my_key2', b'my_value'))
176 assert was_set is False
178 # Removes a key 'my_key' under given namespace.
179 _try_func_callback_return(
180 lambda: mysdl.remove_and_publish(MY_NS, {MY_CHANNEL: "REMOVE PUBLISH"}, 'my_key'))
181 my_ret_dict = _try_func_return(lambda: mysdl.get(MY_NS, 'my_key'))
182 assert my_ret_dict == {}
183 assert last_cb_channel == MY_CHANNEL and last_cb_message == "REMOVE PUBLISH"
185 # Removes a key 'my_key' under given namespace only if the old value is 'my_value'.
186 was_removed = _try_func_callback_return(lambda: mysdl.remove_if_and_publish(
187 MY_NS, {MY_CHANNEL: "REMOVE IF PUBLISH"}, 'my_key2', b'my_value'))
188 assert was_removed is True
189 assert last_cb_channel == MY_CHANNEL and last_cb_message == "REMOVE IF PUBLISH"
190 # Try again to remove not anymore existing key 'my_key'. Callback function will not be called here.
191 was_removed = _try_func_return(lambda: mysdl.remove_if_and_publish(
192 MY_NS, {MY_CHANNEL: "REMOVE IF PUBLISH"}, 'my_key2', b'my_value'))
193 assert was_removed is False
195 # Removes all the keys under given namespace.
196 _try_func_return(lambda: mysdl.set(MY_NS, {'my_key': b'something'}))
197 my_ret_dict = _try_func_return(lambda: mysdl.get(MY_NS, {'my_key'}))
198 assert my_ret_dict != {}
200 _try_func_callback_return(
201 lambda: mysdl.remove_all_and_publish(MY_NS, {MY_CHANNEL: "REMOVE ALL PUBLISH"}))
202 my_ret_dict = _try_func_return(lambda: mysdl.get(MY_NS, {'my_key'}))
203 assert my_ret_dict == {}
204 assert last_cb_channel == MY_CHANNEL and last_cb_message == "REMOVE ALL PUBLISH"