class Storage
  def initialize(storage: {})
    @storage = storage
    @mutex = Mutex.new
  end

  def key?(key)
    with_lock { @storage.key?(key) }
  end

  def [](key)
    with_lock { @storage[key] }
  end

  def []=(key, value)
    with_lock { @storage[key] = value }
  end

  def delete(key)
    with_lock { @storage.delete(key) }
  end

  private

  def with_lock
    @mutex.synchronize do
      yield
    end
  end
end