On 01/17/2013 05:30 PM, Andrew Hughes wrote:
----- Original Message -----
Hello,
Method sun.misc.Unsafe#copyMemory(Object,long,Object,long,long) is
used
in popular Snappy codec implementation [1, 2].
It's present in openjdk-7 and in late updates of Oracle jdk6. But
it's
missed in openjdk-6. Its native implementation is available in jdk6
hostspot [3], though. As far as I understood, it was removed from
jdk6
codebase during preparation to first jdk6 release [4]. I tried to
restore it in jdk6 sources (left hotspot untouched) and it seems to
work
well.
Can someone clarify, whether it's safe to patch sun.misc.Unsafe and
use
this method in jdk6?
[1] https://github.com/dain/snappy#snappy-in-java
[2]
https://github.com/dain/snappy/blob/01f0a37ca40196e08336532ea6d328eb3ed22b67/src/main/java/org/iq80/snappy/UnsafeMemory.java#L101
[3]
http://hg.openjdk.java.net/jdk6/jdk6/hotspot/file/cd74fab0a5e3/src/share/vm/prims/unsafe.cpp
[4]
http://hg.openjdk.java.net/jdk6/jdk6/jdk/diff/39e8fe7a0af1/src/share/classes/sun/misc/Unsafe.java
--
Regards,
Alex Kasko
It will be in HotSpot because the same HotSpot releases are shared between
6& 7 (well, they were until 6 stopped at hs20). Support for features in 8
will likewise appear in 7's HotSpot.
I can't see any reason why it couldn't be backported, but presumably there
was some reason it was removed.
Thanks for the clarification!
I'm afraid it's too late to propose any changes to jdk6, so I'll
continue using patched version.
--
Regards,
Alex Kasko
