Enum FiberUpdatePriority

Namespace

Velvet

Assembly

Velvet.Docs.dll

Lane priority for a scheduled re-render. The lane is chosen from the scheduling context, not passed as an argument. A UseDeferredValue derivation asks for the Transition lane directly, and a StartTransition call asks for the Urgent lane directly for the render that shows its isPending. A hook-driven state update is classified from its context, tested in this order: the Transition lane while a StartTransition callback is running and has not yet suspended; failing that, the Urgent lane while a discrete event handler runs; failing that, the Normal lane. A starved Transition lane is promoted to Normal. Lower numeric values indicate higher priority; a fiber's lane queue drains lowest-value-first.

public enum FiberUpdatePriority

Fields

Normal = 1

Default priority for state updates that are not part of a transition. A starved Transition lane is promoted to it, coalescing with the very traffic that kept preempting it, so the starved work commits with the next Normal drain instead of waiting behind it. Belongs to FiberBatchScheduler's Immediate tier (drained by DrainImmediate / registered via ScheduleImmediate).

Transition = 2

Lowest priority. Taken by the updates a StartTransition callback schedules before it first suspends, and by UseDeferredValue derivations. Its flush runs in a later panel scheduler pass than the request that queued it, within the bound FiberBatchScheduler.ScheduleDelayed describes, behind any higher-priority lanes still queued, which commit first, and once it has been starved for a fixed number of flushes it is promoted to Normal — draining in that same flush, or right after any co-pending Urgent drains; isPending survives until the promoted work commits. Belongs to FiberBatchScheduler's Delayed tier (enrolled through ScheduleDelayed, which registers the drains that commit it) until a starvation promotion moves it to the Immediate tier.

Urgent = 0

Highest priority. Drains ahead of every other lane within a fiber's lane queue. Belongs to FiberBatchScheduler's Immediate tier (drained by DrainImmediate / registered via ScheduleImmediate), alongside Normal.