SoW-2019-0002: Dynamic Snapshot
[lttng-tools.git] / doc / examples / trigger-on-event / README.md
1 # Trigger notification exemple
2
3 ## Description
4 This exemple is made-up of three executables.
5
6 ### `notification-client`
7
8 ```
9 Usage: notification-client TRIGGER_NAME
10 ```
11
12 A simple client that subscribes to the notifications emitted by the `TRIGGER_NAME` trigger.
13
14 ### `instrumented-app`
15
16 An application that emits the `trigger_exemple:my_event` event every 2 seconds.
17
18 ### `demo.sh`
19
20 This script adds a trigger named `demo_trigger` which emits a notification when the user-space `trigger_exemple:my_event` event occurs.
21
22 Once the trigger has been setup, the notification-client is launched to print all notifications emitted by the `demo_trigger` trigger.
23
24 ## Building
25
26 Simply run the included Makefile.
27
28 ## Running the exemple
29
30 1) Launch a session daemon using:
31 ```
32 $ lttng-sessiond
33 ```
34 2) Launch the `demo.sh` script
35 3) Launch the `instrumented-app`
36
37 The following output should be produced:
38
39 ```
40 $ ./demo.sh
41 Registering a notification trigger named "demo_trigger" for the trigger_exemple:my_event user-space event
42 Trigger registered successfully.
43 Subscribed to notifications of trigger "demo_trigger"
44 [02-14-2020] 18:13:34.779766 - Received notification of event rule trigger "demo_trigger"
45 [02-14-2020] 18:13:36.779888 - Received notification of event rule trigger "demo_trigger"
46 [02-14-2020] 18:13:38.780514 - Received notification of event rule trigger "demo_trigger"
47 [02-14-2020] 18:13:40.780656 - Received notification of event rule trigger "demo_trigger"
48 ```
49
50 ```
51 $ ./instrumented-app
52 [02-14-2020] 18:13:34.779433 - Tracing event "trigger_exemple:my_event"
53 [02-14-2020] 18:13:36.779693 - Tracing event "trigger_exemple:my_event"
54 [02-14-2020] 18:13:38.780010 - Tracing event "trigger_exemple:my_event"
55 [02-14-2020] 18:13:40.780286 - Tracing event "trigger_exemple:my_event"
56 ```
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