Patch for Review: JvGetStringUTF and JvTempCString

[Bryce McKinlay]

On Tuesday, Aug 12, 2003, at 11:26 Pacific/Auckland, Mohan Embar wrote:

> Hi Tom & Bryce,
>
>> So maybe Mohan's class isn't needed after all...
>
> Like I said here:
>
> http://gcc.gnu.org/ml/java-patches/2003-q3/msg00311.html
>
> These three lines of code:
>
>   char *buf = (char *) __builtin_alloca (JvGetStringUTFLength (path) + 
> 1);
>   jsize total = JvGetStringUTFRegion (path, 0, path->length(), buf);
>   buf[total] = '\0';
>
> ...are like fingernails on a blackboard for me, and they're not
> limited to just natFile*.cc. I like the idea of encapsulating this
> by a class and doing any necessary cleanup in the destructor.

I totally agree that we have a problem here, I just wonder if this is 
the right solution. Two things that would make me like this better:

1. Can it be made to allocate only the space that it needs on the 
stack? Always allocating 500 bytes seems a bit wasteful. I wonder about 
large stack allocations since they will reduce the locality of the 
stack - increasing the chance of cache misses etc.

2. Can we use _Jv_AllocBytes rather than _Jv_Malloc/_Jv_Free in the 
need-to-allocate case? The former is *faster* given thread local 
allocation, possibly so even after accounting for the GC's marking 
overhead.

Regards

Bryce.