Alignment in the binary protocol

Dustin Sallings dustin at
Tue Mar 18 17:30:08 UTC 2008

On Mar 18, 2008, at 4:59, Trond Norbye wrote:

> Hi,
> I have been testing the binary protocol the last few days and I  
> would like to suggest that we swap the order some fields to solve  
> some alignment problems.
> The cas-id is a 64-bit datatype and will require 8-byte alignment on  
> some hardware, but it is placed on a 4-byte alignment in the get  
> response. The current get-response contains a 16 byte header  
> followed by the 4 byte flags-field causing the wrong alignment for  
> the cas id. If we swap the order on the two fields the cas-id will  
> get proper alignment, and we can access the field directly as an  
> uint64_t...
> To be consistent I suggest that we move the cas-id to the front in  
> the set/add/replace command as well. The attached patch implements  
> this.

	Hey, could I get  you to merge this with the current binary tree?  I  
did some cleanup work and it doesn't apply cleanly.  Since there are  
changes to how things work, I really want to make sure I preserve your  
intentions before doing client work.

	As I put no effort into considering 64-bit alignment, I don't have  
any issue with this.  Does anyone else?

Dustin Sallings

More information about the memcached mailing list