projects / lttng-tools.git / blame
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| 2463b787 JR |
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 |