Transport connection caches must go.
robey at lag.net
Tue May 23 19:15:40 BST 2006
On 23 May 2006, at 7:51, John A Meinel wrote:
> The reason we have per-transport caches, is because we cache different
> things for each transport. And the key for the cache may be
> different. I
> personally don't like that the ftp cache includes the password in its
> key, as I don't like to remember passwords.
> We could cache the Transport objects themselves (say based on the
> portion of the URL), and then have get_transport() do a clone() if
> is a matching netloc.
> And then we would add a transport.flush_cache() function, which
> could be
> called by the test suite.
I like a variation of this idea.
We only really want to check for reuse against currently-open
transports, right? So what if we added a method to Transport to ask
if it can clone itself for an url? Like so:
new_transport = old_transport.try_clone(url)
If the URL is incompatible (you asked an sftp transport to clone an
http url), it returns None.
So you just keep a set of currently-open transports (weakref?) and
when you want to open a new one, you iterate through the old ones and
give them a chance to clone if they can. The default Transport
implementation would always return None, but transports could add a
handler as an optimization.
That way you don't need a cache, you just need to track open
transports and give them a chance to reuse their connections at a
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