On Wed, Feb 3, 2021 at 2:56 PM Lasse Collin <lasse.col...@tukaani.org> wrote:
>
> On 2021-02-01 Brett Okken wrote:
> > I have played with this quite a bit and have come up with a slightly
> > modified change which does not regress for the smallest of the sample
> > objects and shows a nice improvement for the 2 larger files.
>
> It seems to regress horribly if dist is zero. A file with a very long
> sequence of the same byte is good for testing.
>
Would this be a valid test of what you are describing?
final byte[] bytes = new byte[16 * 1024];
Arrays.fill(bytes, (byte) -75);
final byte[] compressed;
try(final ByteArrayOutputStream baos = new ByteArrayOutputStream();
final XZOutputStream xos = new XZOutputStream(baos,
new LZMA2Options()))
{
for (int i=0; i<10240; ++i) {
xos.write(bytes);
}
xos.finish();
compressed = baos.toByteArray();
}
The source is effectively 160MB of the same byte value.
I found a strange bit of behavior with this case in the compression.
In LZMAEncoderNormal.calcLongRepPrices, I am seeing a case where
int len2Limit = Math.min(niceLen, avail - len - 1);
results in -1, (avail and len are both 8). This results in calling
LZEncoder.getMatchLen with a lenLimit of -1. Is that expected?
When I was testing with java 8 and the ArrayUtil changes, this
resulted in an ArrayIndexOutBoundsException.
