Manuel M. T. Chakravarty
chak at cse.unsw.edu.au
Mon Dec 4 20:49:02 EST 2000
Fergus Henderson <fjh at cs.mu.oz.au> wrote,
> On 04-Dec-2000, Marcin 'Qrczak' Kowalczyk <qrczak at knm.org.pl> wrote:
> > Mon, 4 Dec 2000 04:15:28 -0800, Simon Marlow <simonmar at microsoft.com> pisze:
> > > Ok, so the malloc/free is the most expensive part. I'm moderately
> > > surprised:) Perhaps we could do a better job, but we'll never do
> > > better than ByteArrays as long as the bracket is required.
> > BTW, withCString in my implementation which handles charsets does not
> > use alloca but malloc. It's because we don't know the length of the
> > resulting char until we convert it, so we cannot preallocate it.
> > We must guess an initial size and realloc the array as needed.
> I don't know the details of withCString, so this might not be
> applicable, but an alternative that is likely to be more efficient is
> to use a static or alloca()'ed buffer for the initial try, and if it
> doesn't fit then switch to using malloc()/realloc().
> At the end, you can check whether the final buffer pointer is equal to
> the original fixed-size static or alloca()'ed buffer, and only free it
> if it is not. Or you can keep a separate boolean flag.
Would have to be alloca'ed; otherwise, Concurrent would kill
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