Thanks Mandy. I also appreciate you noticing (off-list) that I can
remove the extra space in "Class <?>" in several places. I have updated
webrev.4 in place.
dl
On 11/2/18 1:55 PM, Mandy Chung wrote:
Hi Dean,
I reviewed webrev.4 version. It looks good. Happy to see moving the
doPrivileged support to Java and the performance improvement.
On 10/31/18 3:23 PM, dean.l...@oracle.com wrote:
https://bugs.openjdk.java.net/browse/JDK-8212605
http://cr.openjdk.java.net/~dlong/8212605/webrev.1
This change implements AccessController.doPrivileged in Java. This
gives a performance improvement while also being useful to Project
Loom by removing the Java --> native --> Java transition. One reason
doPrivileged has historically been in native is because of the need
to guarantee the cleanup of the privileged context when doPrivileged
returns. To do that in Java, the information that
AccessController.getContext needs is pushed onto the Java stack as
arguments to a method that getContext will recognize during its stack
walk. This allows us to remove the native privileged stack while
guaranteeing that the privileged context goes away when the method
returns.
Tested with tier1-tier3 hotspot and jdk tests and JCK
api/java_security tests. For the first few rounds of testing, I kept
the old native privileged stack and compared the results of the old
and new implementations for each getContext call, which did catch
some early bugs. The changes were also examined by internal security
experts and run through additional internal security tests.
The improvement on this [1] doPrivileged microbenchmark is
approximate 50x.
There is no attempt to optimize getContext() or security permission
checks in this change, however, this is intended to be a first step
towards other possible improvements, for example those proposed here
[2].
FYI. Sean and I also did some experiment to replace
JVM_GetStackAccessControlContext with StackWalker some time ago.
Another potential area to move the code from VM to Java for the future
as David explored and probably involves performance work in the stack
walker.
Mandy
