Well,
I deleted my Harmony tree, I'll refetch it tonight and check.
--benson
On Mon, Jan 25, 2010 at 8:26 AM, Dawid Weiss <dawid.we...@gmail.com> wrote:
> Hi Benson (and others),
>
> Say, when you moved the code from Apache Harmony, did you modify it
> along the way, or is it what's found in the Harmony's
> source code? I'm asking because we're still hitting those array out of
> bounds exceptions sometimes. They are tough to isolate, so I reverted
> to white-box code inspection. There is a repeated snippet of code that
> just isn't right to me, look here:
>
> comparison = comp.compare(c, partitionIndex);
> while (c >= b && comparison >= 0) {
> if (comparison == 0) {
> if (c == partitionIndex) {
> partitionIndex = d;
> } else if (d == partitionIndex) {
> partitionIndex = c;
> }
> swap.swap(c, d);
>
> d--;
> }
> c--;
> comparison = comp.compare(c, partitionIndex);
> }
>
> doing eager comparison counting is wrong because variable c _can go
> below _b_ (which can be the start index or zero). To keep
> the invariants correct, the code should read as follows:
>
> int comparison;
> while (c >= b && (comparison = comp.compare(c, partitionIndex)) >= 0) {
> if (comparison == 0) {
> if (c == partitionIndex) {
> partitionIndex = d;
> } else if (d == partitionIndex) {
> partitionIndex = c;
> }
> swap.swap(c, d);
>
> d--;
> }
> c--;
> }
>
> Note that I did not analyze the whole logic flow of qsort in this
> ported code, but just looking at the code above it seems
> that c can indeed go beyond the marker limit.
>
> What do you think? A bug or am I just being dim?
>
> Dawid
>
