Polling

NihiloCore provides two complementary polling tools: UNihiloPollingTask for C++ and Blueprint use via a fluent callback API, and UNihiloPollingLibrary for a Blueprint latent node that suspends execution until a condition is met.

info

Polling is useful when you need to wait for a condition that has no event — for example, waiting for a subsystem to finish initializing, a replication flag to arrive on the client, or an async asset load to complete — without coupling the waiting code to the thing being waited on.

Polling Task

UNihiloPollingTask repeatedly evaluates a condition function on a fixed interval and fires a completion callback when it returns true. An optional timeout sets a hard deadline — if the condition hasn't been met by then, the timeout callback fires instead.

The condition is evaluated immediately on start before the first interval tick. If it is already true, the complete callback fires right away and no timers are started.

The task manages its own lifetime via AddToRoot — it keeps itself alive until the condition is met, the timeout fires, or it is cancelled. After any of these, it cleans up its timers, clears its delegates, and calls RemoveFromRoot. You do not need to store it in a UPROPERTY to keep it alive, though you may want to hold a reference if you intend to cancel it early.

C++ Usage

cpp

UNihiloPollingTask::Create(this, [this]()
{
	return [True condition here]
})
->WithInterval(0.1f)
->WithTimeout(10.0f)
->OnComplete([this]()
{
	[Runs when condition is met.]
});

Blueprint Usage

Use CreateBP with a FPollingConditionDynamic delegate instead of a native lambda. Chain WithInterval, WithTimeout, OnComplete, and OnTimeout the same way. In Blueprint, the completion and timeout events are exposed as OnConditionMet and OnTimeoutFired dynamic multicast delegates on the task object.

API

Function	Description
Create	Creates a new task with a native TFunction<bool()> condition. C++ only.
CreateBP	Creates a new task with a FPollingConditionDynamic delegate condition. Blueprint compatible.
WithInterval	Sets the polling interval in seconds. Must be called before the task starts. Returns this for chaining.
WithTimeout	Sets the maximum duration before the timeout callback fires. Optional. Must be called before the task starts. Returns this for chaining.
OnComplete	Sets the callback to fire when the condition returns true. Calling this starts the task if it hasn't started yet. Returns this for chaining.
OnTimeout	Sets the callback to fire if the timeout elapses before the condition is met. Calling this also starts the task if it hasn't started yet. Returns this for chaining.
Cancel	Stops polling and clears all timers and delegates without firing any callback.

Poll Until True (Latent Node)

PollUntilTrue in UNihiloPollingLibrary is a Blueprint latent function that suspends execution at a node until a boolean condition becomes true or a timeout is reached. It behaves like a Delay node but driven by a condition rather than a fixed duration.

The node takes a boolean variable by reference, an interval, and an optional timeout. It evaluates the boolean immediately on entry, then re-evaluates on every interval tick. When the condition is met or the timeout elapses, execution resumes with a ENihiloPollResult output — either Success or TimedOut — so you can branch on the outcome.

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The latent action guards against duplicate execution — if the node is somehow triggered again while already running (e.g. called from a Tick), the second call is ignored and the existing action continues unaffected.

For cases where you need callbacks or want to poll a computed expression rather than a plain boolean variable, use UNihiloPollingTask instead.