github.com/plusserver/webcache (go): Package webcache is a lightweight memory cache for go web servers that you can wrap around time consuming requests. The content type is []byte to allow a simple modification of the code.  If you have an long running function returning []byte which is called with every request  you can modify this to write the backend function into a CachedPage struct and update it only if the content is too old.  You can find a longer introduction and an example server at https://github.com/Nexinto/webcache
Keywords: golang