binary protocol notes from the facebook hackathon

Paul Querna chip at
Tue Jul 10 16:38:37 UTC 2007

Brad Fitzpatrick wrote:
> COMMANDS:  (for cmd byte)
>   get    - single key get (no more multi-get; clients should pipeline)
>   getq   - like get, but quiet.  that is, no cache miss, return nothing.
>       Note: clients should implement multi-get (still important for
>             reducing network roundtrips!) as n pipelined requests, the
>             first n-1 being getq, the last being a regular
>             get.  that way you're guaranteed to get a response, and
>             you know when the server's done.  you can also do the naive
>             thing and send n pipelined gets, but then you could potentially
>             get back a lot of "NOT_FOUND!" error code packets.

This is missing the discussion about the GETQ putting the server into
'cork' mode, and any non-GETQ would uncork it.  This would allow the
server to optimize its own IO without nearly as much pain.

Also, as a client author, I really would prefer just having a NOOP or
ECHO command at end of the bulk GETQ, rather than having to special case
the last request. I guess I could just send a GET for a stats key or
something, but that seems weird.


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