SoW-2020-0002: Trace Hit Counters: trigger error reporting integration

[lttng-tools.git] / doc / examples / trigger-on-event / README.md

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+# Trigger notification example
+
+## Description
+This example is made-up of three executables.
+
+### `notification-client`
+
+```
+Usage: notification-client TRIGGER_NAME TRIGGER_NAME2 ...
+```
+
+A simple client that subscribes to the notifications emitted by the `TRIGGER_NAME` trigger.
+
+Multiple trigger names can be passed and subscribed to.
+
+
+### `instrumented-app`
+
+An application that emits the `trigger_example:my_event` event every 2 seconds.
+
+### `demo.sh`
+
+This script adds a trigger named `demo_trigger` which emits a notification when
+the user-space `trigger_example:my_event` event occurs.
+
+This script also adds a trigger named `demo_trigger_capture` which emits a
+notification when the user-space `trigger_example:my_event` event occurs and
+provides captured fields if present.
+
+Once the triggers have been setup, the notification-client is launched to print
+all notifications emitted by the `demo_trigger` and `demo_trigger_capture`
+trigger.
+
+## Building
+
+Simply run the included Makefile.
+
+## Running the example
+
+1) Launch a session daemon using:
+        ```
+        $ lttng-sessiond
+        ```
+2) Launch the `demo.sh` script
+3) Launch the `instrumented-app`
+
+The following output should be produced:
+
+```
+$ ./demo.sh
+Registering a notification trigger named "demo_trigger" for the trigger_example:my_event user-space event
+Trigger registered successfully.
+Trigger registered successfully.
+Subscribed to notifications of trigger "demo_trigger_capture"
+Subscribed to notifications of trigger "demo_trigger"
+[08-24-2020] 17:20:33.598221 - Received notification of event rule trigger "demo_trigger"
+[08-24-2020] 17:20:33.598855 - Received notification of event rule trigger "demo_trigger_capture"
+Captured field values:
+  Field: iteration Value: [Unsigned int] 0,
+  Field: does_not_exist Value: Capture unavailable,
+  Field: $ctx.vtid Value: [Unsigned int] 2302494,
+  Field: $ctx.procname Value: [String] instrumented-ap.
+[08-24-2020] 17:20:35.598556 - Received notification of event rule trigger "demo_trigger"
+[08-24-2020] 17:20:35.599293 - Received notification of event rule trigger "demo_trigger_capture"
+Captured field values:
+  Field: iteration Value: [Unsigned int] 1,
+  Field: does_not_exist Value: Capture unavailable,
+  Field: $ctx.vtid Value: [Unsigned int] 2302494,
+  Field: $ctx.procname Value: [String] instrumented-ap.
+[08-24-2020] 17:20:37.598977 - Received notification of event rule trigger "demo_trigger"
+[08-24-2020] 17:20:37.599676 - Received notification of event rule trigger "demo_trigger_capture"
+Captured field values:
+  Field: iteration Value: [Unsigned int] 2,
+  Field: does_not_exist Value: Capture unavailable,
+  Field: $ctx.vtid Value: [Unsigned int] 2302494,
+  Field: $ctx.procname Value: [String] instrumented-ap.
+[08-24-2020] 17:20:39.599430 - Received notification of event rule trigger "demo_trigger"
+[08-24-2020] 17:20:39.600178 - Received notification of event rule trigger "demo_trigger_capture"
+Captured field values:
+  Field: iteration Value: [Unsigned int] 3,
+  Field: does_not_exist Value: Capture unavailable,
+  Field: $ctx.vtid Value: [Unsigned int] 2302494,
+  Field: $ctx.procname Value: [String] instrumented-ap.
+...
+```
+
+```
+$ ./instrumented-app
+[08-24-2020] 17:20:33.597441 - Tracing event "trigger_example:my_event"
+[08-24-2020] 17:20:35.597703 - Tracing event "trigger_example:my_event"
+[08-24-2020] 17:20:37.597997 - Tracing event "trigger_example:my_event"
+...
+```
+
+