Codereview request for 7183053: Optimize DoubleByte charset for String.getBytes()/new String(byte[]) (original) (raw)

Alan Bateman Alan.Bateman at oracle.com
Fri Jul 13 12:19:26 UTC 2012

On 11/07/2012 00:11, Xueming Shen wrote:

Hi,

In JDK7, the decoder and encoder implementation of most of our single-byte charsets and UTF-8 charset are optimized to implement the internal interfce sun.nio.cs.ArrayDecoder/ Encoder to provide a fastpath for String.getBytes(...) and new String(byte[]...) operations. I have an old blog regarding this optimization at https://blogs.oracle.com/xuemingshen/entry/fasternewstringbytescs This rfe, as the followup for above changes, is to implement ArrayDe/Encoder for most of the sun.nio.cs.ext.DoubleByte based double-byte charsets. Here is the webrev http://cr.openjdk.java.net/~sherman/7183053/webrev I've taken a pass over this and it's great to see DoubleByte.Decoder/Encoder implementing sun.nio.cs.ArrayDecoder/Encoder. The results looks good too, a small number of regressions (Big5 at len=32 for example) but this is a micro benchmark and I'm sure there are fluctuations. I don't see anything obviously wrong with the EBCDIC changes I'd need a history book to remember how the shifts between DBCS and SBCS. I think our tests our good for this area so I'm happy. One minor nit is the continue in both encode methods, I think it would be cleaner to use "else if (bb ..." instead.

I see in TestStringCoding.java that you've commented out the test that goes over the buffer limit - would I be correct to say that this isn't an issue and this happens with DB charsets today?

Ulf - you've got several patches to the double byte charsets and I wonder if you have cycles to try Sherman's patch with jdk8 to see if there is any more to be gained?

-Alan.

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