Hi Serguei,
On 23/12/2017 6:04 PM, serguei.spit...@oracle.com wrote:
Hi Egor and David,
Egor,
The fix looks good in general.
I've filed bug:
https://bugs.openjdk.java.net/browse/JDK-8194143
remove unneeded casts in LocationImpl and MirrorImpl classes
On 12/22/17 13:06, David Holmes wrote:
Hi Egor,
On 23/12/2017 1:32 AM, Egor Ushakov wrote:
Hi all,
could you please review and sponsor this small cleanup removing
unneeded casts in jdi LocationImpl and MirrorImpl.
They were preventing creating custom Location and Mirror
implementations used for tests and IDEA debugger impl.
http://cr.openjdk.java.net/~avu/egor.ushakov/cast_fix/
src/jdk.jdi/share/classes/com/sun/tools/jdi/LocationImpl.java
! public int compareTo(Location object) {
- LocationImpl other = (LocationImpl)object;
The existing code is somewhat suspect as the Location interface
implements Comparable but it does not specify what it means to compare
two Locations! That's a bug in itself.
Not sure, if it is really needed as it is abstract.
We could say: An implementation of the Location is expected to specify it.
That makes it impossible to compare different implementations of the
Location interface. The functionality has to be specified by the interface.
LocationImpl has decided how to compare two LocaltionImp's (but
doesn't even check they are in the same VirtualMachine!).
Nice catch!
Interesting...
Should comparing of locations from different mirrors be a no-op?
Not sure if it would be right to throw a VMMismatchException in such cases.
Not sure - without knowing why we need to compare Locations it's hard to
say.
Can we generalize that to accommodate other Location
implementations?Your change allows for this to happen, but it will
only work as expected if the other Location implementations use the
same comparison basis as LocationImpl - which is unspecified.
It is not clear, what you mean here.
What are the other Location implementations?
The ones that Egor is implementing and the reason for this bug report.
A JDI implementation normally has one base implementation of the Location.
What would be a need to have multiple?
Egor indicated it was for use in testing and the IDEA debugger. It's
apparent they have their own implementation of Location, but these
instances have to interact with the default LocationImpl implementations
- else this bug report would not be needed.
Cheers,
David
And different JDI implementations are not supposed to interact with each
other, are they?
src/jdk.jdi/share/classes/com/sun/tools/jdi/MirrorImpl.java
Change looks good. It would also seem that now this change is made
that this:
37 protected VirtualMachineImpl vm;
38
39 MirrorImpl(VirtualMachine aVm) {
40 super();
41
42 // Yes, its a bit of a hack. But by doing it this
43 // way, this is the only place we have to change
44 // typing to substitute a new impl.
45 vm = (VirtualMachineImpl)aVm;
might reduce to:
37 protected VirtualMachine vm;
38
39 MirrorImpl(VirtualMachine aVm) {
40 super();
41 vm = aVm;
if we no longer depend on it being VirtualMachineImpl ... and neither
do subclasses.
Good suggestion.
Thanks,
Serguei
David
-----
I do not have rights to create JDK bug report directly, please create
it if it is needed for the procedure.
Thanks!
