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Update coordinator now allows retriggering

· 2 min read
Joakim Plate

The update coordinator with debouncer active will now accept a request for an update while an update is currently in progress. The request will be queued up to be performed after the current update finishes.

Consider the following case:

async def _update():
    a = await get_a()
    # A: User or other logic request a new update here through async_schedule_update()
    b = await get_b()
    return (a,b)

A user or code that request an updates at timestamp A expects that the entities linked will all get new data from that time. However, since we previously ignored that request, entities would have data for the value of a that is from a time before the update request that was ignored.

To make sure we avoid this case, the update coordinator will now schedule an additional update, if a request is received while currently executing an update.

A side effect of this is that it is now possible to schedule an update from inside an update function of the coordinator. That is useful if for example a connection is lost mid update, and we want all entities to indicate directly as unavailable, yet we want to attempt a re-connect as quick as possible but do that in the next update cycle.