class ara::diag::Indicator

The interface serves for the structured querying and monitoring of vehicle diagnostic indicators within the AUTOSAR Adaptive Platform. Applications instantiate the object via a modeled identifier and can retrieve the current status via an asynchronous query method [SWS_DM_00744]. In addition, a user-defined callback function can be registered that receives status updates directly upon changes [SWS_DM_00745]. As an essential boundary condition, the instance is strictly bound to a port, neither copyable nor movable, and requires synchronization against concurrent calls during registration as well as destruction.

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Context

The ara::diag::Indicator class acts in the Adaptive Platform module diag as the central representation of the DiagnosticIndicatorInterface [SWS_DM_00742]. Its core task is to enable applications to access diagnostic indicators such as warning lamps or function indicators (for example, a Malfunction Indicator Light, MIL).

Essentially three components participate in the interaction: a consuming adaptive application (such as an instrument cluster or an HMI service), the instance of ara::diag::Indicator as a local interface endpoint, and the Diagnostic Management daemon (DM). The latter processes the vehicle-wide diagnostic events and UDS DTC states and provides the underlying diagnostic functionality [SWS_DM_00744].

Context diagram: Interaction partners of the ara::diag::Indicator interface between application logic and Diagnostic Management daemon. Sources: [SWS_DM_00742], [SWS_DM_00744].

Lifecycle

Creation of an ara::diag::Indicator object takes place explicitly by passing an ara::core::InstanceSpecifier to the constructor [SWS_DM_00742]. This identifier binds the object to an PortPrototype defined in the design model, which must strictly be typed as DiagnosticIndicatorInterface [SWS_DM_00742].

With regard to ownership and object semantics, ara::diag::Indicator is designed as a strict single instance: neither copying nor moving is permitted. Accordingly, copy constructor [SWS_DM_01629], move constructor [SWS_DM_01630], copy assignment operator [SWS_DM_01627], and move assignment operator [SWS_DM_01628] are declared as deleted (=delete).

The lifecycle ends with the call of the destructor ~Indicator() [SWS_DM_00743]. While constructor and status query are specified as thread-safe [SWS_DM_00742], [SWS_DM_00744], the destructor is not thread-safe [SWS_DM_00743]. The calling application must therefore ensure that no concurrent method calls or notifier executions take place during destruction.

Usage Path

After successful initialization, the class supports two complementary usage models for determining the indicator state:

• Event-driven notification: A callback function of type IndicatorStatusTypeNotifier can be registered via SetNotifier() [SWS_DM_00745], [SWS_DM_02129]. As soon as the status of the indicator changes, the runtime environment calls this notifier. A consecutive call of SetNotifier() overwrites the previously registered handler [SWS_DM_00745]. Since SetNotifier() is not thread-safe, registration must be synchronized externally [SWS_DM_00745]. Presumably, the notifier is executed in the context of a background thread of Diagnostic Management, which is why no time-consuming blocking operations should occur within it. Question Q-c27898ecefb8006f (open)
• Targeted query: The current state can be actively queried at any time via GetIndicatorState() [SWS_DM_00744]. The method is thread-safe and returns a ara::core::Future<IndicatorStatusType> [SWS_DM_00744]. Interpretation: The asynchronous provisioning via a future indicates that the query is internally delegated via inter-process communication (IPC) to the central Diagnostic Management daemon. Question Q-61a650bd8ab7fc04 (open)

Sequence diagram: Typical sequence of instantiation, notifier registration, state query, and object destruction. Sources: [SWS_DM_00742], [SWS_DM_00744], [SWS_DM_00745], [SWS_DM_00743].

Error Scenarios

Error conditions can occur both during the initialization phase and at runtime:

• Configuration violations during construction: The constructor reports modeling inconsistencies in the form of defined violations [SWS_DM_00742]. These include InstanceSpecifierMappingIntegrityViolation (the identifier cannot be resolved or does not reference a port), PortInterfaceMappingViolation (the referenced port is not typed by an DiagnosticIndicatorInterface), ProcessMappingViolation (no matching modeled process available for the runtime instance), and InstanceSpecifierAlreadyInUseViolation (the identifier is already used by another instance in the process) [SWS_DM_00742].
• Failure of diagnostic functions: If the execution of GetIndicatorState() fails, the error code DiagErrc::kServiceNotAvailable is transported via the returned future [SWS_DM_00744]. This occurs when essential functions of Diagnostic Management are not available at call time [SWS_DM_00744].
• Concurrent accesses: Since SetNotifier() [SWS_DM_00745] and the destructor [SWS_DM_00743] are not thread-safe, unprotected concurrent access leads to undefined runtime behavior.