increment method

Future<int> increment([
  1. int amount = 1
])

Increments the counter by amount (default is 1).

This method increases the current counter value by the specified amount. It ensures that the operation is thread-safe by using a lock.

Returns the updated counter value.

Implementation

Future<int> increment([int amount = 1]) {
  return _lock.synchronized(() async {
    final current = await get(); // already calls _ensureFresh inside lock
    final updated = current + amount;
    await value.set(updated);
    return updated;
  });
}