On 8/29/10 10:16 AM, martin f krafft wrote:
>
> What I think BackupPC is doing right now is:
>
> 1. It starts receiving a file
>
> 2. After a certain time, it has enough information to take a guess
> at the corresponding pool file, and opens it.
>
> 3. What seems to happen now is weird: the FileIO method fileDeltaRxNext is
> called repeatedly, but at the same time, the client keeps sending data,
> not
> checksums.
I haven't followed the code, but I think the idea is that if the file - or
maybe
the difference from the existing guessed match - fits in memory it doesn't need
to write a tmp file before writing to the pool. I'm not sure if the rsync
protocol allows switching from 'no file' on the receiving side to having
checksums to match in mid-file even if the initial filename is correct and not
a
hash collision.
> Here's what I think should happen instead:
>
> As soon as at least one candidate file in the pool is found:
>
> 1. Keep the received data (2×128k) in memory;
>
> 2. Somehow convince the peer that we actually have the file and that
> it should continue sending block checksums, or however the rsync
> protocol actually works;
Not sure this is possible, and even if it is you still have to deal with hash
collisions detected later.
> Does this make sense?
Only on bandwidth-restricted connections. On a LAN you can usually transfer as
fast as the remote can read the file anyway.
--
Les Mikesell
lesmikes...@gmail.com
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