module Aws::RefreshingCredentials

def credentials
  refresh_if_near_expiration!
  @credentials
end

def initialize(options = {})
  @mutex = Mutex.new
  @before_refresh = options.delete(:before_refresh) if Hash === options
  @before_refresh.call(self) if @before_refresh
  refresh
end

def near_expiration?(expiration_length)
  if @expiration
    # Are we within expiration?
    (Time.now.to_i + expiration_length) > @expiration.to_i
  else
    true
  end
end

def refresh!
  @mutex.synchronize do
    @before_refresh.call(self) if @before_refresh
    refresh
  end
end

def refresh_if_near_expiration!
  # Note: This check is an optimization. Rather than acquire the mutex on every #refresh_if_near_expiration
  # call, we check before doing so, and then we check within the mutex to avoid a race condition.
  # See issue: https://github.com/aws/aws-sdk-ruby/issues/2641 for more info.
  if near_expiration?(SYNC_EXPIRATION_LENGTH)
    @mutex.synchronize do
      if near_expiration?(SYNC_EXPIRATION_LENGTH)
        @before_refresh.call(self) if @before_refresh
        refresh
      end
    end
  elsif @async_refresh && near_expiration?(ASYNC_EXPIRATION_LENGTH)
    unless @mutex.locked?
      Thread.new do
        @mutex.synchronize do
          if near_expiration?(ASYNC_EXPIRATION_LENGTH)
            @before_refresh.call(self) if @before_refresh
            refresh
          end
        end
      end
    end
  end
end