Function producerUpdateValueVersion

packages/core/primitives/signals/src/graph.ts:309–334

(node: ReactiveNode)

 * Ensure this producer's `version` is up-to-date.
 */
export function producerUpdateValueVersion(node: ReactiveNode): void {
  if (consumerIsLive(node) && !node.dirty) {
    // A live consumer will be marked dirty by producers, so a clean state means that its version
    // is guaranteed to be up-to-date.
    return;
  }

  if (!node.dirty && node.lastCleanEpoch === epoch) {
    // Even non-live consumers can skip polling if they previously found themselves to be clean at
    // the current epoch, since their dependencies could not possibly have changed (such a change
    // would've increased the epoch).
    return;
  }

  if (!node.producerMustRecompute(node) && !consumerPollProducersForChange(node)) {
    // None of our producers report a change since the last time they were read, so no
    // recomputation of our value is necessary, and we can consider ourselves clean.
    producerMarkClean(node);
    return;
  }

  node.producerRecomputeValue(node);

  // After recomputing the value, we're no longer dirty.
  producerMarkClean(node);
}

/**
 * Propagate a dirty notification to live consumers of this producer.