class Google::Cloud::Env::LazyDict

def lookup_key key
  # Optimization: check for key existence and return quickly without
  # grabbing the mutex. This works because keys are never deleted.
  return @key_values[key] if @key_values.key? key
  @mutex.synchronize do
    if @key_values.key? key
      @key_values[key]
    else
      retries =
        if @retries.respond_to? :reset_dup
          @retries.reset_dup
        elsif @retries.respond_to? :call
          @retries.call
        end
      @key_values[key] = LazyValue.new retries: retries, &@compute_handler
    end
  end
end