On Thu, 30 Nov 2023 23:30:20 GMT, Brian Burkhalter <b...@openjdk.org> wrote:
>> Pass `ByteArrayInputStream.buf ` directly to the `OutputStream` parameter of
>> `BAIS.transferTo` only if the target stream is in the `java.io` package.
>
> Brian Burkhalter has updated the pull request incrementally with one
> additional commit since the last revision:
>
> 8321053: Trust non-FilterOutputStreams in "java." packages
src/java.base/share/classes/java/io/ByteArrayInputStream.java line 211:
> 209: if (len > 0) {
> 210: byte[] tmp;
> 211: if (out.getClass().getPackageName().startsWith("java.") &&
Has anybody actually estimated or measured if such an exception is actually
useful / needed given the fact that System.arraycopy is fast native code and
most buffers used by java.io-located streams are just few KB? Just asking as it
could be the case that *interpreting* this Java bytecode could be slower than
executing some ASM ops to create a few-KB copy, and we *might* do an "premature
optimization" here.
src/java.base/share/classes/java/io/ByteArrayInputStream.java line 221:
> 219: int nbyte = Integer.min(len - nwritten,
> MAX_TRANSFER_SIZE);
> 220: if (tmp != null) {
> 221: System.arraycopy(buf, pos, tmp, 0, nbyte);
I assume the overall performance of transferTo will be faster if we use
System.arraycopy *only once* in line 215 to create a safe copy of the
*complete* buf instead of calling it multiple times in a loop to create copies
*per slice*. In that case we can omit the tmp == null case but simply use tmp =
buf, making the code in the loop if-free.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/16893#discussion_r1412118013
PR Review Comment: https://git.openjdk.org/jdk/pull/16893#discussion_r1412107929
