This commit introduces a new member variable `mRouterRoleAllowed` in
the `Mle` class to cache the evaluation of whether the device is
currently permitted to operate as a router.
Previously, the `IsRouterEligible()` method evaluated several
conditions (e.g., `IsFullThreadDevice()`, `mRouterEligible` config,
and various fields in `SecurityPolicy`) every time it was called.
Since this method is invoked frequently across different `Mle`
operations, re-evaluating these conditions repeatedly was
inefficient.
The new `mRouterRoleAllowed` variable caches the final computed
result. It is updated via the `UpdateRouterRoleAllowed()` method
whenever any underlying input changes, such as:
- `Mle` starting.
- Configuration parameter updates (e.g., `SetRouterEligible()`).
- Security policy changes from the `KeyManager`.
This change centralizes the logic for handling role permission updates
into a single location (`UpdateRouterRoleAllowed()`). By
consolidating the actions taken when the allowed state changes, the
codebase is cleaner and easier to maintain and update.
It also provides a clearer conceptual distinction between the user's
router configuration (`mRouterEligible`) and the effective state
used by the device.
Abtin Keshavarzian
221a9cbbb0