Function paho_mqtt_sys::MQTTAsync_setTraceCallback

pub unsafe extern "C" fn MQTTAsync_setTraceCallback(
    callback: MQTTAsync_traceCallback
)

This function sets the trace callback if needed. If set to NULL, no trace information will be returned. The default trace level is MQTTASYNC_TRACE_MINIMUM. @param callback a pointer to the function which will handle the trace information