如何使httplib2缓存为只读？

Question

The following code creates Http object with caching enabled:

http = httplib2.Http('cache')
r, b = http.request('http://google.com')

The following code creates Http object with caching enabled and if the resource has already been in the cache, its never requested again:

http = httplib2.Http('cache')
r, b = http.request('http://google.com',
        headers={'cache-control':'min-fresh=-1000000000'})

How do I modify these two samples for the cache is used but never updated?

Thanks

Answer 1

You can pass a cache into the Http object you construct, if it implements these methods :

 Cache.get(key) Cache.set(key, value) Cache.delete(key) 

Wrap an instance of FileCache with an object that you retain a reference to. After your initial requests, change its behaviour so that get continues to work and set delegates to delete (so you never return a stale value).