Re: Comparing Pika-syle and JNI-style Shiro Kawai 15 Jan 2004 02:28 UTC

>From: Tom Lord <>
Subject: Re: Comparing Pika-syle and JNI-style
Date: Wed, 14 Jan 2004 18:35:43 -0800 (PST)

>     > As Per noted, Boehm GC avoids this if configured with "interior
>     > pointer" flag.
> Ok, but that doesn't help if the data is separately allocated.

If you're accessing the data chunk and no reference except
from the scheme_value local variable points to the string header,
then the string header can be collected, but that doesn't matter
(since you don't need it anyway).

> Or, for that matter, if my pointer is pointed past the end of the
> string but I'm indexing at a negative offset from it.

You can point the next address past the end of chunk and still the
chunk is retained, since in C it is a valid pointer usage.
(you can change this behavior by configuration option, though).

> The whole thing just plays way too fast and loose with C semantics to
> be acceptable for critical systems.

Yup.   I don't object to this feeling.   I just wanted to be precise
about the facts.