The previous architecture proved unable to support user expectations,
so the API has been rebuilt from first principles. Backward
compatibility cannot be maintained for this change.
Key changes include:
* Formerly the service-provided transition functions were allowed to
sleep, and the manager took care to not invoke them from ISR
context, instead returning an error if unable to initiate a
transition. In the new architecture transition functions are
required to work regardless of calling context: it is the service's
responsibility to guarantee the transition will proceed even if it
needs to be transferred to a thread. This eliminates state machine
complexities related to calling context.
* Constants identifying the visible state of the manager are exposed
to clients through both notification callbacks and a new monitor API
that allows clients to be notified of all state changes.
* Formerly the release operation was async, and would be delayed for the
last release to ensure a client would exist to be notified of any
failures. It is now synchronous.
* Formerly the cancel operation would fail on the last client associated
with a transition. The cancel operation is now synchronous.
* A helper function is provided to safely synchronously release a
request regardless of whether it has completed or is in progress,
satisfying the use case underlying #22974.
* The user-data parameter to asynchronous notification callbacks has
been removed as user data can be retrieved from the CONTAINER_OF
the client data.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
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