In practice we're talking on the order of a 10% performance gain from this optimization. So, it's not the end of the world if you write fields out-of-order. However, some users may rely on canonical ordering for other reasons, e.g. to be able to cryptographically sign messages, use their hashes as cache keys, etc.
On Thu, Aug 20, 2009 at 9:23 AM, roger peppe <rogpe...@gmail.com> wrote: > > 2009/8/20 Michael Poole <mdpo...@troilus.org>: > > roger peppe writes: > >> the documentation says, on writing fields in order: "This allows > >> parsing code to use optimizations > >> that rely on field numbers being in sequence." > >> > >> what optimizations might these be? > >> does the current implementation use any such optimizations? > >> what penalty do i pay by *not* writing fields in order? > > > > The C++ generator does this. If you look at some of the generated > > MergePartialFromCodedStream() methods, you can see how this is done. > > interesting, i hadn't noticed that. > > not an easy trick to pull in a language without goto, i'd think. > > tail recursion optimisation could make it possible, i suppose, > assuming the function call was cheaper than the switch. > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To post to this group, send email to protobuf@googlegroups.com To unsubscribe from this group, send email to protobuf+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/protobuf?hl=en -~----------~----~----~----~------~----~------~--~---
