SoW-2020-0002: Trace Hit Counters: trigger error reporting integration
[lttng-tools.git] / doc / examples / trigger-on-event / README.md
1 # Trigger notification example
2
3 ## Description
4 This example is made-up of three executables.
5
6 ### `notification-client`
7
8 ```
9 Usage: notification-client TRIGGER_NAME TRIGGER_NAME2 ...
10 ```
11
12 A simple client that subscribes to the notifications emitted by the `TRIGGER_NAME` trigger.
13
14 Multiple trigger names can be passed and subscribed to.
15
16
17 ### `instrumented-app`
18
19 An application that emits the `trigger_example:my_event` event every 2 seconds.
20
21 ### `demo.sh`
22
23 This script adds a trigger named `demo_trigger` which emits a notification when
24 the user-space `trigger_example:my_event` event occurs.
25
26 This script also adds a trigger named `demo_trigger_capture` which emits a
27 notification when the user-space `trigger_example:my_event` event occurs and
28 provides captured fields if present.
29
30 Once the triggers have been setup, the notification-client is launched to print
31 all notifications emitted by the `demo_trigger` and `demo_trigger_capture`
32 trigger.
33
34 ## Building
35
36 Simply run the included Makefile.
37
38 ## Running the example
39
40 1) Launch a session daemon using:
41 ```
42 $ lttng-sessiond
43 ```
44 2) Launch the `demo.sh` script
45 3) Launch the `instrumented-app`
46
47 The following output should be produced:
48
49 ```
50 $ ./demo.sh
51 Registering a notification trigger named "demo_trigger" for the trigger_example:my_event user-space event
52 Trigger registered successfully.
53 Trigger registered successfully.
54 Subscribed to notifications of trigger "demo_trigger_capture"
55 Subscribed to notifications of trigger "demo_trigger"
56 [08-24-2020] 17:20:33.598221 - Received notification of event rule trigger "demo_trigger"
57 [08-24-2020] 17:20:33.598855 - Received notification of event rule trigger "demo_trigger_capture"
58 Captured field values:
59 Field: iteration Value: [Unsigned int] 0,
60 Field: does_not_exist Value: Capture unavailable,
61 Field: $ctx.vtid Value: [Unsigned int] 2302494,
62 Field: $ctx.procname Value: [String] instrumented-ap.
63 [08-24-2020] 17:20:35.598556 - Received notification of event rule trigger "demo_trigger"
64 [08-24-2020] 17:20:35.599293 - Received notification of event rule trigger "demo_trigger_capture"
65 Captured field values:
66 Field: iteration Value: [Unsigned int] 1,
67 Field: does_not_exist Value: Capture unavailable,
68 Field: $ctx.vtid Value: [Unsigned int] 2302494,
69 Field: $ctx.procname Value: [String] instrumented-ap.
70 [08-24-2020] 17:20:37.598977 - Received notification of event rule trigger "demo_trigger"
71 [08-24-2020] 17:20:37.599676 - Received notification of event rule trigger "demo_trigger_capture"
72 Captured field values:
73 Field: iteration Value: [Unsigned int] 2,
74 Field: does_not_exist Value: Capture unavailable,
75 Field: $ctx.vtid Value: [Unsigned int] 2302494,
76 Field: $ctx.procname Value: [String] instrumented-ap.
77 [08-24-2020] 17:20:39.599430 - Received notification of event rule trigger "demo_trigger"
78 [08-24-2020] 17:20:39.600178 - Received notification of event rule trigger "demo_trigger_capture"
79 Captured field values:
80 Field: iteration Value: [Unsigned int] 3,
81 Field: does_not_exist Value: Capture unavailable,
82 Field: $ctx.vtid Value: [Unsigned int] 2302494,
83 Field: $ctx.procname Value: [String] instrumented-ap.
84 ...
85 ```
86
87 ```
88 $ ./instrumented-app
89 [08-24-2020] 17:20:33.597441 - Tracing event "trigger_example:my_event"
90 [08-24-2020] 17:20:35.597703 - Tracing event "trigger_example:my_event"
91 [08-24-2020] 17:20:37.597997 - Tracing event "trigger_example:my_event"
92 ...
93 ```
94
95
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