MAUVE Tracing

The MAUVE Tracing library defines trace structures embedded in MAUVE architectures. The tracing system uses LTTng.

MAUVE Tracing provides tracepoints to collect traces on MAUVE runtime internal elements, and tracepoints to add user-defined trace messages.

LTTng tracepoints

LTTng structures each tracepoint with a namespace, an event name, and fields. All the MAUVE traces are in the mauve namespace.

The tracepoints embedded in MAUVE Runtime are:

• component_start when a component is started; its fields are the component name and its clock value;
• state_execution_begin when the execution of a component's state starts; its fields are the component name, its clock value and the state name;
• state_execution_end when the execution of a component's state ends; its fields are the component name, its clock value and the state name.
• service_execution_begin when the execution of a resource's service starts; its fields are the resource name and the service name;
• service_execution_end when the execution of a resource's service ends; its fields are the resource name and the service name.

Activating trace collection

The structure of the LTTng components is available at http://lttng.org/docs/v2.9/#doc-plumbing.

Starting trace collection

To activate LTTng tracing and start collection, launch the following command:

rosrun mauve_tracing lttng-start [session]

Default session name is mauve. The trace is registered in ~/lttng-traces/<session>-<date>/.

Example: ~/lttng-traces/mauve-20170711-132012/.

If you want to filter the traces to be collected, look at the advanced LTTng usage.

Stoping trace collection

To stop trace collection and close the session, launch the following command:

rosrun mauve_tracing lttng-stop

Reading the traces

Once the trace session is destroyed, you can read the collected traces. LTTng links to several tools:

http://lttng.org/docs/v2.10/#doc-viewing-and-analyzing-your-traces

For instance, using babeltrace, you can have a readable form of the traces:

$ babeltrace ~/lttng-traces/mauve-20170711-132012/
(...)
[13:21:27.815739685] (+0.000010232) wdcsd002h mauve:state_execution_end: { cpu_id = 1 }, { name = "/B", clock = 1499772087803282475, state = "burn" }
[13:21:27.815740296] (+0.000000611) wdcsd002h mauve:state_execution_begin: { cpu_id = 1 }, { name = "/B", clock = 1499772087803282475, state = "sleep" }
[13:21:27.815751168] (+0.000010872) wdcsd002h mauve:state_execution_end: { cpu_id = 1 }, { name = "/A", clock = 1499772087803282475, state = "sleep" }
[13:21:27.815751650] (+0.000000482) wdcsd002h mauve:state_execution_begin: { cpu_id = 1 }, { name = "/A", clock = 1499772087803282475, state = "burn" }