MemoryStore that supports expires_in

ExpiringMemoryStore.rb

class ExpiringMemoryStore < ActiveSupport::Cache::MemoryStore
  def read(name, options = nil)
    out = super(name, options)

    return if out.nil?
    return if out.first && out.first < Time.now
    return out.last
  end

  def write(name, value, options = {})
    expires_in = options.delete(:expires_in)
    expires_at = expires_in ? Time.now + expires_in : nil

    super(name, [expires_at, value], options)
  end
end


require File.dirname(__FILE__) + '/unit_test_helper'

class ExpiringMemoryStoreTest < Test::Unit::TestCase
  def test_store
    start = Time.now
    Time.stubs(:now).returns(start)

    store = ExpiringMemoryStore.new
    store.fetch(:my_key, :expires_in => 10) { 5 }
    assert_equal 5, store.read(:my_key)

    Time.stubs(:now).returns(start + 10)
    assert_equal 5, store.read(:my_key)

    Time.stubs(:now).returns(start + 11)
    assert_nil store.read(:my_key)
  end

  def test_store_without_expires_in
    store = ExpiringMemoryStore.new
    store.fetch(:my_key) { 5 }
    assert_equal 5, store.read(:my_key)
  end
end