Function applyDeferBlockStateWithScheduling

packages/core/src/defer/rendering.ts:325–377

* Extends the `applyDeferBlockState` with timer-based scheduling. * This function becomes available on a page if there are defer blocks * that use `after` or `minimum` parameters in the `@loading` or * `@placeholder` blocks.

(
  newState: DeferBlockState,
  lDetails: LDeferBlockDetails,
  lContainer: LContainer,
  tNode: TNode,
  hostLView: LView<unknown>,
)

 * `@placeholder` blocks.
 */
function applyDeferBlockStateWithScheduling(
  newState: DeferBlockState,
  lDetails: LDeferBlockDetails,
  lContainer: LContainer,
  tNode: TNode,
  hostLView: LView<unknown>,
) {
  const now = Date.now();
  const hostTView = hostLView[TVIEW];
  const tDetails = getTDeferBlockDetails(hostTView, tNode);

  if (lDetails[STATE_IS_FROZEN_UNTIL] === null || lDetails[STATE_IS_FROZEN_UNTIL] <= now) {
    lDetails[STATE_IS_FROZEN_UNTIL] = null;

    const loadingAfter = getLoadingBlockAfter(tDetails);
    const inLoadingAfterPhase = lDetails[LOADING_AFTER_CLEANUP_FN] !== null;
    if (newState === DeferBlockState.Loading && loadingAfter !== null && !inLoadingAfterPhase) {
      // Trying to render loading, but it has an `after` config,
      // so schedule an update action after a timeout.
      lDetails[NEXT_DEFER_BLOCK_STATE] = newState;
      const cleanupFn = scheduleDeferBlockUpdate(
        loadingAfter,
        lDetails,
        tNode,
        lContainer,
        hostLView,
      );
      lDetails[LOADING_AFTER_CLEANUP_FN] = cleanupFn;
    } else {
      // If we transition to a complete or an error state and there is a pending
      // operation to render loading after a timeout - invoke a cleanup operation,
      // which stops the timer.
      if (newState > DeferBlockState.Loading && inLoadingAfterPhase) {
        lDetails[LOADING_AFTER_CLEANUP_FN]!();
        lDetails[LOADING_AFTER_CLEANUP_FN] = null;
        lDetails[NEXT_DEFER_BLOCK_STATE] = null;
      }

      applyDeferBlockState(newState, lDetails, lContainer, tNode, hostLView);

      const duration = getMinimumDurationForState(tDetails, newState);
      if (duration !== null) {
        lDetails[STATE_IS_FROZEN_UNTIL] = now + duration;
        scheduleDeferBlockUpdate(duration, lDetails, tNode, lContainer, hostLView);
      }
    }
  } else {
    // We are still rendering the previous state.
    // Update the `NEXT_DEFER_BLOCK_STATE`, which would be
    // picked up once it's time to transition to the next state.
    lDetails[NEXT_DEFER_BLOCK_STATE] = newState;
  }
}

/**
 * Schedules an update operation after a specified timeout.