[Mesa-dev] [PATCH 02/21] glsl: protect locale_t with a mutex

[Chia-I Wu]

On Tue, May 6, 2014 at 6:04 AM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> On 05/05/2014 10:01 AM, Ian Romanick wrote:
>> On 05/04/2014 02:14 PM, Chia-I Wu wrote:
>>> On Sat, May 3, 2014 at 1:52 AM, Ian Romanick <idr at freedesktop.org> wrote:
>>>> On 04/22/2014 01:58 AM, Chia-I Wu wrote:
>>>>> There may be two contexts compiling shaders at the same time.  locale_t needs
>>>>> to be protected.
>>>>
>>>> Rather than calling glsl_initialize_strtod from other places in the
>>>> compiler, it seems better to use call_once from the strtof and strtod
>>>> functions.
>>> How about having a static object to call newlocale()/freelocale() in
>>> its constructor/destructor?  It will impose no overead on
>>> glsl_strtod(), at the expense of little wasted memory when the
>>> applications do not compile shaders.
>>
>> The problem I see with that is we don't know what order constructors on
>> global objects will occur.  Are we sure the contructor will be invoked
>> before we need the locale now and in the future?
>
> These functions are used during lexing to read floating point
> literals...without breaking on locales where the decimal point is a comma.
>
> All constructors have definitely been run by that point, and I can't
> imagine we'll ever need to call locale-independent strtof/strtod from
> other constructors.
They are also used by the IR reader.  But the IR reader is no longer
used to parse built-in functions or so.  We should be good as you
said.

Not that we need this, and I am not saying this with 100% confidence,
from my research on stackoverflow (instead of the standard, sorry), it
is the initialization order of static objects from different
translation units that are undefined.  If this locale_t_initializer
was defined statically in strtod.cpp, other static constructors
calling glsl_strtod() would actually work because, by the time
glsl_strtod() is called, locale_t_initializer is guaranteed to be
initialized.

Anyway, I should add some assert() just in case.

>
> --Ken
>



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