Re: collapsed_forwarding and ICP

From: Henrik Nordstrom <>
Date: Fri, 06 Feb 2009 01:18:16 +0100

fre 2009-02-06 klockan 10:07 +1100 skrev Mark Nottingham:
> If I have a peer and it has collapsed_forwarding on, at what point
> will it return an ICP_HIT to me? E.g.,
> 1) As soon as there's an outstanding (therefore collapsed) request for
> it?
> 2) As soon as there's a cacheable response in-flight for it?
> 3) Only when the entire response is in-cache?
> My reading of the code is that it's #1. Do I have this right?


> If that's the case:
> - On the plus side, this helps collapse requests across peers.


> - On the down side, it seems like there's the potential for requests
> to go to peers, only to find that the response is uncacheable.

Yes, and the slower the origin is to respond the more you'll see of

Should be trivial to add a tuning knob to ICP for this. The "not yet
known if they may be cached" objects have a special KEY_EARLY_PUBLIC
flag set. See icpCheckUdpHit() for a suitable spot. htcpCheckHit would
also need the same.

Received on Fri Feb 06 2009 - 00:18:22 MST

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