Ignore googlebot for Rack::Cache?

I'm using Rack::Cache, and google search bot triggers all my cache misses, so my cache is always full of pages that don't actuall开发者_C百科y represent the most popular ones on my site, I can't seem to find how to ignore an IP or useragent for caching, has anyone had this problem before?

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You could check for Googlebot in the user-agent string and skip caching if it is.

Search agent strings: http://www.smart-it-consulting.com/internet/google/googlebot-spoofer/