bumpFromSelf method

void bumpFromSelf(int startNid, int delta)

Adds delta to the subtree-size cache at startNid and at every ancestor. Stops at kNoParentNid. O(depth).

Public so optimized callers (e.g. _purgeAndRemoveFromOrder Step 1) can do their own batched cache maintenance — pre-bumping ancestors before a downstream removal that they wrap in runWithSubtreeSizeUpdatesSuppressed. Most callers should rely on the inlined cache updates that fire automatically from the order mutators.

No-op when delta is zero.

Implementation

void bumpFromSelf(int startNid, int delta) {
  if (delta == 0) return;
  int cur = startNid;
  while (cur != kNoParentNid &&
      cur >= 0 &&
      cur < _subtreeSizeByNid.length) {
    // Refuse to mutate a freed slot. In debug, surface the violation;
    // in release, bail out — corrupting a freed slot causes downstream
    // visibility-cache bugs once the nid is recycled.
    if (_nids.keyOf(cur) == null) {
      assert(
        false,
        "VisibleOrderBuffer.bumpFromSelf walked through freed nid $cur "
        "from start nid $startNid (delta=$delta)",
      );
      break;
    }
    final next = _subtreeSizeByNid[cur] + delta;
    assert(
      next >= 0,
      "subtree-size would go negative at nid $cur "
      "(current=${_subtreeSizeByNid[cur]}, delta=$delta, "
      "key=${_nids.keyOf(cur)})",
    );
    _subtreeSizeByNid[cur] = next;
    cur = _parentByNidLookup(cur);
  }
}