Re: avoiding copy - Luajit FFI

[Fabio Kaminski <fabiokaminski@...>]

On Tue, Jun 7, 2011 at 12:53 PM, Justin Cormack
<justin@specialbusservice.com> wrote:
> On Tue, Jun 7, 2011 at 3:54 PM, Fabio Kaminski <fabiokaminski@gmail.com>
> wrote:
>>
>> Hi Folks,
>>
>> Im trying to get less memory copy as possible with luajit FFI, and in
>> the api to get your hands in a (void *) or (char *) pointer
>> is copying it through "ffi.string()" wich in turns, will create a lua
>> string..
>>
>> my first question: why cant ffi.string() reuse the given pointer.. vm
>> design? avoid concurrency races  from the C side?
>>
>> the c api "lua_pushlstring()" works the same way?
>>
>> second:
>>
>> When you simply need to push a string or even a file buffer thats
>> fine, but if whe are talking about things like byte buffers over a
>> network
>> those copy would make it loose a lot of performance in the long run..
>> even creating a bytebuffer on the C side and passing only the
>> requested byte string on the lua api side..
>>
>> Anyone has found a way (writing c logic or not) to avoid those copies?
>>
>
> Only call ffi.string when you absolutely need to, the rest of the time you
> can just pass around the raw buffers. You can just allocate them with
> ffi.new.
> Justin
>
>

Yeah, thats the way to go.. create more C abstraction  (and black
boxes from lua app perspective) and try to switch C/Lua VM the least
as possible..

no skinny C interface for now..