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- Subject: Re: avoiding copy - Luajit FFI
- From: Fabio Kaminski <fabiokaminski@...>
- Date: Tue, 7 Jun 2011 12:58:56 -0300
On Tue, Jun 7, 2011 at 12:53 PM, Justin Cormack
> On Tue, Jun 7, 2011 at 3:54 PM, Fabio Kaminski <email@example.com>
>> 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
>> 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?
>> 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
>> 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
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
no skinny C interface for now..