当memcached命中时，如何获取caches_action设置过期标头? [英] How to get caches_action to set expires headers when there is a hit in memcached?

问题描述

我有一个缓存的动作

caches_action :my_action, :expires_in=>1.hours

，并使用

def my_action
   ...
   expires_in 1.hours
   send_data(...,:disposition => 'inline',:type => 'image/png',:filename => params[:title]+".png")
end

但是，当我查看由于memcached命中而产生的结果中的缓存控制响应标头时，我得到了:

However, when I look at the cache control response header from a result that is coming as the result of a memcached hit, I get this:

Cache-Control: private, max-age=0, must-revalidate

第一次回合，即当缓存中没有任何内容时，这就是我所期望的，即:

The first time round, i.e. when there is nothing in the cache, it is what I expect, i.e.:

Cache-Control: max-age=3600, private

看起来rails + memcached既没有缓存原始的响应头，也没有设置适当的头.结果是，即使结果(图像)没有变化，客户端也会每次都向服务器发出请求.尽管该操作在缓存中被命中后很快就完成了，但它仍然结束了再次发送所有数据的过程，我想避免这种情况.

It looks like rails+memcached is neither caching the original response headers, nor setting appropriate headers itself. The result is that the client makes a request to the server each time even when the result (an image) hasn't changed. Though the action completes quickly as it gets a hit in the cache, it still winds up sending all the data again, which I'd like to avoid.

我如何获取标头以执行正确的操作，以便客户端要么首先不发出请求，要么获得未修改"响应?

How do I get the headers to do the right thing so that the client either makes no request in the first place, or gets a 'not modified' response?

推荐答案

几天前，我遇到了同样的问题.调试看来，rails并未考虑caches_action的expires_in.

I had the very same problem a few days ago. Debugging it seems that rails is not taking into acount the expires_in for caches_action.

我发现有效的方法是将相同内容放入cache_path中.例如喜欢这样做

What I found that works is to put the same inside a cache_path. For example insted of doing

caches_action :monthly_sales_by_category, :expires_in => 10.minutes, :cache_path => proc { |c|
    category = c.params[:category]
    {:cat => category}
}

我所做的是以下

caches_action :monthly_sales_by_category, :cache_path => proc { |c|
    expires_in 10.minutes, :public => false
    category = c.params[:category]
    {:cat => category} 
}

并且像护身符一样工作.:)

And works like a charm. :)

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