Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[Alex Menkov]

+1 for webrev.05

--alex

On 09/28/2018 04:25, serguei.spit...@oracle.com wrote:

Hi Jc,

I agree it can be refactored later so I'm Okay with the current webrev.

Thanks,
Serguei

On 9/27/18 8:57 PM, JC Beyler wrote:

Hi Serguei,

Exactly, I'm taking the lazy approach and just doing the ones I need. 
Ideally I will find a better means to wrap around the methods without 
having to redefine all of them but I've looked around and nothing 
seems really perfect even with heavy utilization of C++ templates. 
Perhaps I can use some macro definitions to make the code easier to be 
generated but I did not want to go in either direction now, instead 
preferring to keep it simple and direct.


If you agree, as we add more methods we can always refactor this at 
some point if someone (or us) finds a better solution to this but that 
is an internal problem to the exception checking class and won't 
affect the tests.


Does that sound reasonable?

Let me know,
Jc

On Thu, Sep 27, 2018 at 8:00 PM > wrote:


Hi Jc,

Sorry for being late to the party.
The webrev5 looks good to me.
I don't think you have to try to fix the build system.
Avoiding using unique_ptr is good enough.

Do I understand it right that the ExceptionCheckingJniEnv class
is going to enhanced with more JNI functions?
I'm wonder if it can be anyhow generalized to avoid this.

Thanks,
Serguei
**

On 9/27/18 2:33 PM, JC Beyler wrote:

Hi all,

Sorry to come back to this so late in the game, but somehow when
I synced my hg clone (or the issue was always there and it is a
flaky build), it seems that something in the build might have
changed? Basically now it seems that the build is adding flags
that makes my usage of unique_ptr fail.

I "think" it is due to the build adding the gnu++98 standard (But
this has been there for a while it seems so most likely a
side-effect is it is being now used):

    CXXSTD_CXXFLAG="-std=gnu++98"
FLAGS_CXX_COMPILER_CHECK_ARGUMENTS(ARGUMENT: [$CXXSTD_CXXFLAG
-Werror],
IF_FALSE: [CXXSTD_CXXFLAG=""])

(from:

https://hg.openjdk.java.net/jdk/jdk/file/dade6dd87bb4/make/autoconf/flags-cflags.m4)
but I'm not sure.

When I remove that flag, my g++ goes to a more recent standard
and unique_ptr works.

So I now have to ask you all:
  1) Should we try to fix the build system to at least have C++11
for the C++ tests, then my webrev.04 can stay as is but has to
wait for that to happen
  2) Should we push a new version that does not use unique_ptr?
That solution would look like the following webrev:
http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.05/


Sorry for the last minute rug pull,
Jc

On Thu, Sep 27, 2018 at 11:32 AM Mikael Vidstedt
mailto:mikael.vidst...@oracle.com>>
wrote:


Very, very nice! Thanks for adding the comment and renaming
the class! Ship it!

Cheers,
Mikael



On Sep 27, 2018, at 10:45 AM, JC Beyler mailto:jcbey...@google.com>> wrote:

Hi Mikael and David,

@David: I thought it was implicit but did not want to
presume on this one because my goal is to start propagating
this new class in the test base and get the checks to be
done implicitly so I was probably being over-cautious
@Mikael: done and done, what do you think of the comment
here :

http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.04/test/hotspot/jtreg/vmTestbase/nsk/share/jni/ExceptionCheckingJniEnv.hpp.html



For all, the new webrev is here:
Webrev:
http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.04/

Bug: https://bugs.openjdk.java.net/browse/JDK-8210842

Thanks,
Jc

On Thu, Sep 27, 2018 at 6:03 AM David Holmes
mailto:david.hol...@oracle.com>>
wrote:

Sorry Jc, I thought my LGTM was implicit. :)

Thanks,
David

On 26/09/2018 11:52 PM, JC Beyler wrote:
> Ping on this, anybody have time to do a review and
give a LGTM? Or David
> if you have time and will to provide an explicit LGTM :)
>
> Thanks,
> Jc
>
> On Mon, Sep 24, 2018 at 9:18 AM JC Beyler
mailto:jcbey...@google.com>
> >> wrote:
>
>     Hi David,
>
>     Sounds good to me, Alex gave me one LGTM, so it
seems I'm waiting
>     for an explicit LGTM from y

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[Martin Buchholz]

Some of us have lobbied to make openjdk source C++11, but it's not yet.

If you're brave, you can try to change that flag to -std=gnu++11

On Thu, Sep 27, 2018 at 2:33 PM, JC Beyler  wrote:
> Hi all,
>
> Sorry to come back to this so late in the game, but somehow when I synced my
> hg clone (or the issue was always there and it is a flaky build), it seems
> that something in the build might have changed? Basically now it seems that
> the build is adding flags that makes my usage of unique_ptr fail.
>
> I "think" it is due to the build adding the gnu++98 standard (But this has
> been there for a while it seems so most likely a side-effect is it is being
> now used):
>
> CXXSTD_CXXFLAG="-std=gnu++98"
> FLAGS_CXX_COMPILER_CHECK_ARGUMENTS(ARGUMENT: [$CXXSTD_CXXFLAG -Werror],
> IF_FALSE: [CXXSTD_CXXFLAG=""])
>
> (from:
> https://hg.openjdk.java.net/jdk/jdk/file/dade6dd87bb4/make/autoconf/flags-cflags.m4)
> but I'm not sure.
>
> When I remove that flag, my g++ goes to a more recent standard and
> unique_ptr works.
>
> So I now have to ask you all:
>   1) Should we try to fix the build system to at least have C++11 for the
> C++ tests, then my webrev.04 can stay as is but has to wait for that to
> happen
>   2) Should we push a new version that does not use unique_ptr? That
> solution would look like the following webrev:
>  http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.05/
>
> Sorry for the last minute rug pull,
> Jc
>
> On Thu, Sep 27, 2018 at 11:32 AM Mikael Vidstedt
>  wrote:
>>
>>
>> Very, very nice! Thanks for adding the comment and renaming the class!
>> Ship it!
>>
>> Cheers,
>> Mikael
>>
>>
>> On Sep 27, 2018, at 10:45 AM, JC Beyler  wrote:
>>
>> Hi Mikael and David,
>>
>> @David: I thought it was implicit but did not want to presume on this one
>> because my goal is to start propagating this new class in the test base and
>> get the checks to be done implicitly so I was probably being over-cautious
>> @Mikael: done and done, what do you think of the comment here :
>> http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.04/test/hotspot/jtreg/vmTestbase/nsk/share/jni/ExceptionCheckingJniEnv.hpp.html
>>
>> For all, the new webrev is here:
>> Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.04/
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
>>
>> Thanks,
>> Jc
>>
>> On Thu, Sep 27, 2018 at 6:03 AM David Holmes 
>> wrote:
>>>
>>> Sorry Jc, I thought my LGTM was implicit. :)
>>>
>>> Thanks,
>>> David
>>>
>>> On 26/09/2018 11:52 PM, JC Beyler wrote:
>>> > Ping on this, anybody have time to do a review and give a LGTM? Or
>>> > David
>>> > if you have time and will to provide an explicit LGTM :)
>>> >
>>> > Thanks,
>>> > Jc
>>> >
>>> > On Mon, Sep 24, 2018 at 9:18 AM JC Beyler >> > > wrote:
>>> >
>>> > Hi David,
>>> >
>>> > Sounds good to me, Alex gave me one LGTM, so it seems I'm waiting
>>> > for an explicit LGTM from you or from someone else on this list to
>>> > do a review.
>>> >
>>> > Thanks again for your help,
>>> > Jc
>>> >
>>> > On Sun, Sep 23, 2018 at 9:22 AM David Holmes
>>> > mailto:david.hol...@oracle.com>> wrote:
>>> >
>>> > Hi Jc,
>>> >
>>> > I don't think it is an issue for this to go ahead. If the
>>> > static
>>> > analysis tool has an issue then we can either find out how to
>>> > teach it
>>> > about this code structure, or else flag the issues as false
>>> > positives.
>>> > I'd be relying on one of the serviceability team here to handle
>>> > that if
>>> > the problem arises.
>>> >
>>> > Thanks,
>>> > David
>>> >
>>> > On 23/09/2018 12:17 PM, JC Beyler wrote:
>>> >  > Hi David,
>>> >  >
>>> >  > No worries with the time to answer; I appreciate the review!
>>> >  >
>>> >  > That's a fair point. Is it possible to "describe" to the
>>> > static analysis
>>> >  > tool to "trust" calls made in the SafeJNIEnv class?
>>> >  >
>>> >  > Otherwise, do you have any idea on how to go forward? For
>>> > what it's
>>> >  > worth, this current webrev does not try to replace exception
>>> > checking
>>> >  > with the SafeJNIEnv (it actually adds it), so for now the
>>> >  > question/solution could be delayed. I could continue working
>>> > on this in
>>> >  > the scope of both the nsk/gc/lock/jniref code base and the
>>> > NSK_VERIFIER
>>> >  > macro removal and we can look at how to tackle the cases
>>> > where the tests
>>> >  > are actually calling exception checking (I know my
>>> > heapmonitor does for
>>> >  > example).
>>> >  >
>>> >  > Let me know what you think and thanks for the review,
>>> >  > Jc
>>> >  >
>>> >  >
>>> >  > On Sun, Sep 23, 2018 at 6:48 AM David Holmes
>>>

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[David Holmes]

Hi Jc,

This seems fine to me. I'll leave it to you and Mikael to wrestle out 
the naming.


Thanks,
David

On 27/09/2018 1:45 PM, JC Beyler wrote:

Hi Mikael and David,

@David: I thought it was implicit but did not want to presume on this 
one because my goal is to start propagating this new class in the test 
base and get the checks to be done implicitly so I was probably being 
over-cautious
@Mikael: done and done, what do you think of the comment here : 
http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.04/test/hotspot/jtreg/vmTestbase/nsk/share/jni/ExceptionCheckingJniEnv.hpp.html 



For all, the new webrev is here:
Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.04/ 


Bug: https://bugs.openjdk.java.net/browse/JDK-8210842

Thanks,
Jc

On Thu, Sep 27, 2018 at 6:03 AM David Holmes > wrote:


Sorry Jc, I thought my LGTM was implicit. :)

Thanks,
David

On 26/09/2018 11:52 PM, JC Beyler wrote:
 > Ping on this, anybody have time to do a review and give a LGTM?
Or David
 > if you have time and will to provide an explicit LGTM :)
 >
 > Thanks,
 > Jc
 >
 > On Mon, Sep 24, 2018 at 9:18 AM JC Beyler mailto:jcbey...@google.com>
 > >> wrote:
 >
 >     Hi David,
 >
 >     Sounds good to me, Alex gave me one LGTM, so it seems I'm waiting
 >     for an explicit LGTM from you or from someone else on this
list to
 >     do a review.
 >
 >     Thanks again for your help,
 >     Jc
 >
 >     On Sun, Sep 23, 2018 at 9:22 AM David Holmes
 >     mailto:david.hol...@oracle.com>
>>
wrote:
 >
 >         Hi Jc,
 >
 >         I don't think it is an issue for this to go ahead. If the
static
 >         analysis tool has an issue then we can either find out how to
 >         teach it
 >         about this code structure, or else flag the issues as false
 >         positives.
 >         I'd be relying on one of the serviceability team here to
handle
 >         that if
 >         the problem arises.
 >
 >         Thanks,
 >         David
 >
 >         On 23/09/2018 12:17 PM, JC Beyler wrote:
 >          > Hi David,
 >          >
 >          > No worries with the time to answer; I appreciate the
review!
 >          >
 >          > That's a fair point. Is it possible to "describe" to the
 >         static analysis
 >          > tool to "trust" calls made in the SafeJNIEnv class?
 >          >
 >          > Otherwise, do you have any idea on how to go forward? For
 >         what it's
 >          > worth, this current webrev does not try to replace
exception
 >         checking
 >          > with the SafeJNIEnv (it actually adds it), so for now the
 >          > question/solution could be delayed. I could continue
working
 >         on this in
 >          > the scope of both the nsk/gc/lock/jniref code base and the
 >         NSK_VERIFIER
 >          > macro removal and we can look at how to tackle the cases
 >         where the tests
 >          > are actually calling exception checking (I know my
 >         heapmonitor does for
 >          > example).
 >          >
 >          > Let me know what you think and thanks for the review,
 >          > Jc
 >          >
 >          >
 >          > On Sun, Sep 23, 2018 at 6:48 AM David Holmes
 >         mailto:david.hol...@oracle.com>
>
 >          > 
 >                   >
 >          >     Hi Jc,
 >          >
 >          >     Sorry for the delay on getting back to this but I'm
 >         travelling at the
 >          >     moment.
 >          >
 >          >     This looks quite neat. Thanks also to Alex for all the
 >         suggestions.
 >          >
 >          >     My only remaining concern is that static analysis
tools
 >         may not like
 >          >     this because they may not be able to determine that we
 >         won't make
 >          >     subsequent JNI calls when an exception happens in the
 >         first. That's not
 >          >     a reason not to do this of course, just flagging
that we
 >         may have to do
 >          >     something to deal with that problem.
 >          >
 >    

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[David Holmes]

Sorry Jc, I thought my LGTM was implicit. :)

Thanks,
David

On 26/09/2018 11:52 PM, JC Beyler wrote:
Ping on this, anybody have time to do a review and give a LGTM? Or David 
if you have time and will to provide an explicit LGTM :)


Thanks,
Jc

On Mon, Sep 24, 2018 at 9:18 AM JC Beyler > wrote:


Hi David,

Sounds good to me, Alex gave me one LGTM, so it seems I'm waiting
for an explicit LGTM from you or from someone else on this list to
do a review.

Thanks again for your help,
Jc

On Sun, Sep 23, 2018 at 9:22 AM David Holmes
mailto:david.hol...@oracle.com>> wrote:

Hi Jc,

I don't think it is an issue for this to go ahead. If the static
analysis tool has an issue then we can either find out how to
teach it
about this code structure, or else flag the issues as false
positives.
I'd be relying on one of the serviceability team here to handle
that if
the problem arises.

Thanks,
David

On 23/09/2018 12:17 PM, JC Beyler wrote:
 > Hi David,
 >
 > No worries with the time to answer; I appreciate the review!
 >
 > That's a fair point. Is it possible to "describe" to the
static analysis
 > tool to "trust" calls made in the SafeJNIEnv class?
 >
 > Otherwise, do you have any idea on how to go forward? For
what it's
 > worth, this current webrev does not try to replace exception
checking
 > with the SafeJNIEnv (it actually adds it), so for now the
 > question/solution could be delayed. I could continue working
on this in
 > the scope of both the nsk/gc/lock/jniref code base and the
NSK_VERIFIER
 > macro removal and we can look at how to tackle the cases
where the tests
 > are actually calling exception checking (I know my
heapmonitor does for
 > example).
 >
 > Let me know what you think and thanks for the review,
 > Jc
 >
 >
 > On Sun, Sep 23, 2018 at 6:48 AM David Holmes
mailto:david.hol...@oracle.com>
 > >> wrote:
 >
 >     Hi Jc,
 >
 >     Sorry for the delay on getting back to this but I'm
travelling at the
 >     moment.
 >
 >     This looks quite neat. Thanks also to Alex for all the
suggestions.
 >
 >     My only remaining concern is that static analysis tools
may not like
 >     this because they may not be able to determine that we
won't make
 >     subsequent JNI calls when an exception happens in the
first. That's not
 >     a reason not to do this of course, just flagging that we
may have to do
 >     something to deal with that problem.
 >
 >     Thanks,
 >     David
 >
 >     On 20/09/2018 11:56 AM, JC Beyler wrote:
 >      > Hi Alex,
 >      >
 >      > Done here, thanks for the review:
 >      >
 >      > Webrev:
http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.03/

 >     
 >      >

 >      > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
 >      >
 >      > Thanks again!
 >      > Jc
 >      >
 >      >
 >      > On Wed, Sep 19, 2018 at 5:13 PM Alex Menkov
 >     mailto:alexey.men...@oracle.com>
>
 >      > 
 >           >
 >      >     Hi Jc,
 >      >
 >      >     Looks good to me.
 >      >     A minor note:
 >      >     - I'd move ErrorHandler typedef to SafeJNIEnv
class to avoid
 >     global
 >      >     namespece pollution (ErrorHandler is too generic
name).
 >      >
 >      >     --alex
 >      >
 >      >     On 09/19/2018 15:56, JC Beyler wrote:
 >      >      > Hi Alex,
 >      >      >
 >      >      > I've updated the webrev to:
 >      >      > Webrev:
 > http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.02/

 >     
 >      >   
  

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[Mikael Vidstedt]

Sorry for being late to the game. Can I request a helpful comment in 
SafeJNIEnv.hpp describing what its purpose is?

Also, I don’t necessarily have a better suggestion (and don’t consider this 
blocking), but Is there another word than “Safe” to describe this wrapper? 
“Checked”? ExceptionChecking? Just something to consider.

Cheers,
Mikael

> On Sep 26, 2018, at 8:52 PM, JC Beyler  wrote:
> 
> Ping on this, anybody have time to do a review and give a LGTM? Or David if 
> you have time and will to provide an explicit LGTM :)
> 
> Thanks,
> Jc
> 
> On Mon, Sep 24, 2018 at 9:18 AM JC Beyler  > wrote:
> Hi David,
> 
> Sounds good to me, Alex gave me one LGTM, so it seems I'm waiting for an 
> explicit LGTM from you or from someone else on this list to do a review.
> 
> Thanks again for your help,
> Jc
> 
> On Sun, Sep 23, 2018 at 9:22 AM David Holmes  > wrote:
> Hi Jc,
> 
> I don't think it is an issue for this to go ahead. If the static 
> analysis tool has an issue then we can either find out how to teach it 
> about this code structure, or else flag the issues as false positives. 
> I'd be relying on one of the serviceability team here to handle that if 
> the problem arises.
> 
> Thanks,
> David
> 
> On 23/09/2018 12:17 PM, JC Beyler wrote:
> > Hi David,
> > 
> > No worries with the time to answer; I appreciate the review!
> > 
> > That's a fair point. Is it possible to "describe" to the static analysis 
> > tool to "trust" calls made in the SafeJNIEnv class?
> > 
> > Otherwise, do you have any idea on how to go forward? For what it's 
> > worth, this current webrev does not try to replace exception checking 
> > with the SafeJNIEnv (it actually adds it), so for now the 
> > question/solution could be delayed. I could continue working on this in 
> > the scope of both the nsk/gc/lock/jniref code base and the NSK_VERIFIER 
> > macro removal and we can look at how to tackle the cases where the tests 
> > are actually calling exception checking (I know my heapmonitor does for 
> > example).
> > 
> > Let me know what you think and thanks for the review,
> > Jc
> > 
> > 
> > On Sun, Sep 23, 2018 at 6:48 AM David Holmes  >  
> > >> wrote:
> > 
> > Hi Jc,
> > 
> > Sorry for the delay on getting back to this but I'm travelling at the
> > moment.
> > 
> > This looks quite neat. Thanks also to Alex for all the suggestions.
> > 
> > My only remaining concern is that static analysis tools may not like
> > this because they may not be able to determine that we won't make
> > subsequent JNI calls when an exception happens in the first. That's not
> > a reason not to do this of course, just flagging that we may have to do
> > something to deal with that problem.
> > 
> > Thanks,
> > David
> > 
> > On 20/09/2018 11:56 AM, JC Beyler wrote:
> >  > Hi Alex,
> >  >
> >  > Done here, thanks for the review:
> >  >
> >  > Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.03/ 
> > 
> >  > >
> >  >  > >
> >  > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842 
> > 
> >  >
> >  > Thanks again!
> >  > Jc
> >  >
> >  >
> >  > On Wed, Sep 19, 2018 at 5:13 PM Alex Menkov
> > mailto:alexey.men...@oracle.com> 
> > >
> >  > 
> >  > wrote:
> >  >
> >  > Hi Jc,
> >  >
> >  > Looks good to me.
> >  > A minor note:
> >  > - I'd move ErrorHandler typedef to SafeJNIEnv class to avoid
> > global
> >  > namespece pollution (ErrorHandler is too generic name).
> >  >
> >  > --alex
> >  >
> >  > On 09/19/2018 15:56, JC Beyler wrote:
> >  >  > Hi Alex,
> >  >  >
> >  >  > I've updated the webrev to:
> >  >  > Webrev:
> > http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.02/ 
> > 
> >  > >
> >  >  > >
> >  >  >  > 

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[JC Beyler]

Ping on this, anybody have time to do a review and give a LGTM? Or David if
you have time and will to provide an explicit LGTM :)

Thanks,
Jc

On Mon, Sep 24, 2018 at 9:18 AM JC Beyler  wrote:

> Hi David,
>
> Sounds good to me, Alex gave me one LGTM, so it seems I'm waiting for an
> explicit LGTM from you or from someone else on this list to do a review.
>
> Thanks again for your help,
> Jc
>
> On Sun, Sep 23, 2018 at 9:22 AM David Holmes 
> wrote:
>
>> Hi Jc,
>>
>> I don't think it is an issue for this to go ahead. If the static
>> analysis tool has an issue then we can either find out how to teach it
>> about this code structure, or else flag the issues as false positives.
>> I'd be relying on one of the serviceability team here to handle that if
>> the problem arises.
>>
>> Thanks,
>> David
>>
>> On 23/09/2018 12:17 PM, JC Beyler wrote:
>> > Hi David,
>> >
>> > No worries with the time to answer; I appreciate the review!
>> >
>> > That's a fair point. Is it possible to "describe" to the static
>> analysis
>> > tool to "trust" calls made in the SafeJNIEnv class?
>> >
>> > Otherwise, do you have any idea on how to go forward? For what it's
>> > worth, this current webrev does not try to replace exception checking
>> > with the SafeJNIEnv (it actually adds it), so for now the
>> > question/solution could be delayed. I could continue working on this in
>> > the scope of both the nsk/gc/lock/jniref code base and the NSK_VERIFIER
>> > macro removal and we can look at how to tackle the cases where the
>> tests
>> > are actually calling exception checking (I know my heapmonitor does for
>> > example).
>> >
>> > Let me know what you think and thanks for the review,
>> > Jc
>> >
>> >
>> > On Sun, Sep 23, 2018 at 6:48 AM David Holmes > > > wrote:
>> >
>> > Hi Jc,
>> >
>> > Sorry for the delay on getting back to this but I'm travelling at
>> the
>> > moment.
>> >
>> > This looks quite neat. Thanks also to Alex for all the suggestions.
>> >
>> > My only remaining concern is that static analysis tools may not like
>> > this because they may not be able to determine that we won't make
>> > subsequent JNI calls when an exception happens in the first. That's
>> not
>> > a reason not to do this of course, just flagging that we may have
>> to do
>> > something to deal with that problem.
>> >
>> > Thanks,
>> > David
>> >
>> > On 20/09/2018 11:56 AM, JC Beyler wrote:
>> >  > Hi Alex,
>> >  >
>> >  > Done here, thanks for the review:
>> >  >
>> >  > Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.03/
>> > 
>> >  > 
>> >  > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
>> >  >
>> >  > Thanks again!
>> >  > Jc
>> >  >
>> >  >
>> >  > On Wed, Sep 19, 2018 at 5:13 PM Alex Menkov
>> > mailto:alexey.men...@oracle.com>
>> >  > > > >> wrote:
>> >  >
>> >  > Hi Jc,
>> >  >
>> >  > Looks good to me.
>> >  > A minor note:
>> >  > - I'd move ErrorHandler typedef to SafeJNIEnv class to avoid
>> > global
>> >  > namespece pollution (ErrorHandler is too generic name).
>> >  >
>> >  > --alex
>> >  >
>> >  > On 09/19/2018 15:56, JC Beyler wrote:
>> >  >  > Hi Alex,
>> >  >  >
>> >  >  > I've updated the webrev to:
>> >  >  > Webrev:
>> > http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.02/
>> > 
>> >  > 
>> >  >  > <
>> http://cr.openjdk.java.net/%7Ejcbeyler/8210842/webrev.02/>
>> >  >  > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
>> >  >  >
>> >  >  > That webrev has the code that is shown here in snippets.
>> >  >  >
>> >  >  >
>> >  >  > Thanks for the reviews, I've relatively followed your
>> reviews
>> >  > except for
>> >  >  > one detail due to me wanting to handle the NSK_JNI_VERIFY
>> > macros via
>> >  >  > this system as well later down the road. For an example:
>> >  >  >
>> >  >  > We currently have in the code:
>> >  >  > if ( ! NSK_JNI_VERIFY(pEnv, (mhClass =
>> > NSK_CPP_STUB2(GetObjectClass,
>> >  >  > pEnv, mhToCall)) != NULL) )
>> >  >  >
>> >  >  > 1) The NSK_CPP_STUB2 is trivially removed with a refactor
>> >  > (JDK-8210728)
>> >  >  >  to:
>> >  >  > if ( ! NSK_JNI_VERIFY(pEnv, (mhClass =
>> > pEnv->GetObjectClass(pEnv,
>> >  >  > mhToCall)) != NULL) )
>> >  >  >
>> >  >  > 2) Then the N

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[David Holmes]

Hi Jc,

I don't think it is an issue for this to go ahead. If the static 
analysis tool has an issue then we can either find out how to teach it 
about this code structure, or else flag the issues as false positives. 
I'd be relying on one of the serviceability team here to handle that if 
the problem arises.


Thanks,
David

On 23/09/2018 12:17 PM, JC Beyler wrote:

Hi David,

No worries with the time to answer; I appreciate the review!

That's a fair point. Is it possible to "describe" to the static analysis 
tool to "trust" calls made in the SafeJNIEnv class?


Otherwise, do you have any idea on how to go forward? For what it's 
worth, this current webrev does not try to replace exception checking 
with the SafeJNIEnv (it actually adds it), so for now the 
question/solution could be delayed. I could continue working on this in 
the scope of both the nsk/gc/lock/jniref code base and the NSK_VERIFIER 
macro removal and we can look at how to tackle the cases where the tests 
are actually calling exception checking (I know my heapmonitor does for 
example).


Let me know what you think and thanks for the review,
Jc


On Sun, Sep 23, 2018 at 6:48 AM David Holmes > wrote:


Hi Jc,

Sorry for the delay on getting back to this but I'm travelling at the
moment.

This looks quite neat. Thanks also to Alex for all the suggestions.

My only remaining concern is that static analysis tools may not like
this because they may not be able to determine that we won't make
subsequent JNI calls when an exception happens in the first. That's not
a reason not to do this of course, just flagging that we may have to do
something to deal with that problem.

Thanks,
David

On 20/09/2018 11:56 AM, JC Beyler wrote:
 > Hi Alex,
 >
 > Done here, thanks for the review:
 >
 > Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.03/

 > 
 > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
 >
 > Thanks again!
 > Jc
 >
 >
 > On Wed, Sep 19, 2018 at 5:13 PM Alex Menkov
mailto:alexey.men...@oracle.com>
 > >> wrote:
 >
 >     Hi Jc,
 >
 >     Looks good to me.
 >     A minor note:
 >     - I'd move ErrorHandler typedef to SafeJNIEnv class to avoid
global
 >     namespece pollution (ErrorHandler is too generic name).
 >
 >     --alex
 >
 >     On 09/19/2018 15:56, JC Beyler wrote:
 >      > Hi Alex,
 >      >
 >      > I've updated the webrev to:
 >      > Webrev:
http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.02/

 >     
 >      > 
 >      > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
 >      >
 >      > That webrev has the code that is shown here in snippets.
 >      >
 >      >
 >      > Thanks for the reviews, I've relatively followed your reviews
 >     except for
 >      > one detail due to me wanting to handle the NSK_JNI_VERIFY
macros via
 >      > this system as well later down the road. For an example:
 >      >
 >      > We currently have in the code:
 >      > if ( ! NSK_JNI_VERIFY(pEnv, (mhClass =
NSK_CPP_STUB2(GetObjectClass,
 >      > pEnv, mhToCall)) != NULL) )
 >      >
 >      > 1) The NSK_CPP_STUB2 is trivially removed with a refactor
 >     (JDK-8210728)
 >      >  to:
 >      > if ( ! NSK_JNI_VERIFY(pEnv, (mhClass =
pEnv->GetObjectClass(pEnv,
 >      > mhToCall)) != NULL) )
 >      >
 >      > 2) Then the NSK_JNI_VERIFY, I'd like to remove it to and it
 >     becomes via
 >      > this wrapping of JNIEnv:
 >      > if ( ! (mhClass = pEnv->GetObjectClass(pEnv, mhToCall)) )
 >      >
 >      > 3) Then, via removing the assignment, we'd arrive to a:
 >      > mhClass = pEnv->GetObjectClass(pEnv, mhToCall));
 >      > if (!mhClass)
 >      >
 >      > Without any loss of checking for failures, etc.
 >      >
 >      > So that is my motivation for most of this work with a concrete
 >     example
 >      > (hopefully it helps drive this conversation).
 >      >
 >      > I inlined my answers here, let me know what you think.
 >      >
 >      > On Wed, Sep 19, 2018 at 2:30 PM Alex Menkov
 >     mailto:alexey.men...@oracle.com>
>
 >      > 
 >     

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[David Holmes]

Hi Jc,

Sorry for the delay on getting back to this but I'm travelling at the 
moment.


This looks quite neat. Thanks also to Alex for all the suggestions.

My only remaining concern is that static analysis tools may not like 
this because they may not be able to determine that we won't make 
subsequent JNI calls when an exception happens in the first. That's not 
a reason not to do this of course, just flagging that we may have to do 
something to deal with that problem.


Thanks,
David

On 20/09/2018 11:56 AM, JC Beyler wrote:

Hi Alex,

Done here, thanks for the review:

Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.03/ 


Bug: https://bugs.openjdk.java.net/browse/JDK-8210842

Thanks again!
Jc


On Wed, Sep 19, 2018 at 5:13 PM Alex Menkov > wrote:


Hi Jc,

Looks good to me.
A minor note:
- I'd move ErrorHandler typedef to SafeJNIEnv class to avoid global
namespece pollution (ErrorHandler is too generic name).

--alex

On 09/19/2018 15:56, JC Beyler wrote:
 > Hi Alex,
 >
 > I've updated the webrev to:
 > Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.02/

 > 
 > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
 >
 > That webrev has the code that is shown here in snippets.
 >
 >
 > Thanks for the reviews, I've relatively followed your reviews
except for
 > one detail due to me wanting to handle the NSK_JNI_VERIFY macros via
 > this system as well later down the road. For an example:
 >
 > We currently have in the code:
 > if ( ! NSK_JNI_VERIFY(pEnv, (mhClass = NSK_CPP_STUB2(GetObjectClass,
 > pEnv, mhToCall)) != NULL) )
 >
 > 1) The NSK_CPP_STUB2 is trivially removed with a refactor
(JDK-8210728)
 >  to:
 > if ( ! NSK_JNI_VERIFY(pEnv, (mhClass = pEnv->GetObjectClass(pEnv,
 > mhToCall)) != NULL) )
 >
 > 2) Then the NSK_JNI_VERIFY, I'd like to remove it to and it
becomes via
 > this wrapping of JNIEnv:
 > if ( ! (mhClass = pEnv->GetObjectClass(pEnv, mhToCall)) )
 >
 > 3) Then, via removing the assignment, we'd arrive to a:
 > mhClass = pEnv->GetObjectClass(pEnv, mhToCall));
 > if (!mhClass)
 >
 > Without any loss of checking for failures, etc.
 >
 > So that is my motivation for most of this work with a concrete
example
 > (hopefully it helps drive this conversation).
 >
 > I inlined my answers here, let me know what you think.
 >
 > On Wed, Sep 19, 2018 at 2:30 PM Alex Menkov
mailto:alexey.men...@oracle.com>
 > >> wrote:
 >
 >     Hi Jc,
 >
 >     Updated tests looks good.
 >     Some notes about implementation.
 >
 >     - FatalOnException implements both verification and error
handling
 >     It would be better to separate them (and this makes easy to
implement
 >     error handling different from JNIEnv::FatalError).
 >     The simplest way is to define error handler as
 >     class SafeJNIEnv {
 >     public:
 >           typedef void (*ErrorHandler)(JNIEnv *env, const char*
errorMsg);
 >           // error handler which terminates jvm by using FatalError()
 >           static void FatalError(JNIEnv *env, const char *errrorMsg);
 >
 >           SafeJNIEnv(JNIEnv* jni_env, ErrorHandler errorHandler =
 >     FatalError);
 >     (SafeJNIEnv methods should create FatalOnException objects
passing
 >     errorHandler)
 >
 >
 >
 > Agreed, I tried to keep the code simple. The concepts you talk about
 > here are generally what I reserve for when I need it (ie
extensions and
 > handling new cases). But a lot are going to be needed soon so I
think it
 > is a good time to iron the code out now on this "simple" webrev.
 >
 > So done for this.
 >
 >
 >
 >     - FatalOnException is used in SafeJNIEnv methods as
 >         FatalOnException marker(this, "msg");
 >         ret = 
 >         (optional)marker.check_for_null(ret);
 >         return ret;
 >     But actually I'd call it something like JNICallResultVerifier and
 >     create
 >     the object after JNI call. like
 >         ret = 
 >         JNICallResultVerifier(this, "msg")
 >           (optional).notNull(ret);
 >         return ret;
 >     or even (if you like such syntax sugar) you can define
 >         template
 >         T resultNotNull(T result) {
 >             notNull(result);
 >             return result;
 >         }
 >     and do
 >         ret = 
 > 

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[Alex Menkov]

Hi Jc,

Looks good to me.
A minor note:
- I'd move ErrorHandler typedef to SafeJNIEnv class to avoid global 
namespece pollution (ErrorHandler is too generic name).


--alex

On 09/19/2018 15:56, JC Beyler wrote:

Hi Alex,

I've updated the webrev to:
Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.02/ 


Bug: https://bugs.openjdk.java.net/browse/JDK-8210842

That webrev has the code that is shown here in snippets.


Thanks for the reviews, I've relatively followed your reviews except for 
one detail due to me wanting to handle the NSK_JNI_VERIFY macros via 
this system as well later down the road. For an example:


We currently have in the code:
if ( ! NSK_JNI_VERIFY(pEnv, (mhClass = NSK_CPP_STUB2(GetObjectClass, 
pEnv, mhToCall)) != NULL) )


1) The NSK_CPP_STUB2 is trivially removed with a refactor (JDK-8210728) 
 to:
if ( ! NSK_JNI_VERIFY(pEnv, (mhClass = pEnv->GetObjectClass(pEnv, 
mhToCall)) != NULL) )


2) Then the NSK_JNI_VERIFY, I'd like to remove it to and it becomes via 
this wrapping of JNIEnv:

if ( ! (mhClass = pEnv->GetObjectClass(pEnv, mhToCall)) )

3) Then, via removing the assignment, we'd arrive to a:
mhClass = pEnv->GetObjectClass(pEnv, mhToCall));
if (!mhClass)

Without any loss of checking for failures, etc.

So that is my motivation for most of this work with a concrete example 
(hopefully it helps drive this conversation).


I inlined my answers here, let me know what you think.

On Wed, Sep 19, 2018 at 2:30 PM Alex Menkov > wrote:


Hi Jc,

Updated tests looks good.
Some notes about implementation.

- FatalOnException implements both verification and error handling
It would be better to separate them (and this makes easy to implement
error handling different from JNIEnv::FatalError).
The simplest way is to define error handler as
class SafeJNIEnv {
public:
      typedef void (*ErrorHandler)(JNIEnv *env, const char* errorMsg);
      // error handler which terminates jvm by using FatalError()
      static void FatalError(JNIEnv *env, const char *errrorMsg);

      SafeJNIEnv(JNIEnv* jni_env, ErrorHandler errorHandler =
FatalError);
(SafeJNIEnv methods should create FatalOnException objects passing
errorHandler)



Agreed, I tried to keep the code simple. The concepts you talk about 
here are generally what I reserve for when I need it (ie extensions and 
handling new cases). But a lot are going to be needed soon so I think it 
is a good time to iron the code out now on this "simple" webrev.


So done for this.



- FatalOnException is used in SafeJNIEnv methods as
    FatalOnException marker(this, "msg");
    ret = 
    (optional)marker.check_for_null(ret);
    return ret;
But actually I'd call it something like JNICallResultVerifier and
create
the object after JNI call. like
    ret = 
    JNICallResultVerifier(this, "msg")
      (optional).notNull(ret);
    return ret;
or even (if you like such syntax sugar) you can define
    template
    T resultNotNull(T result) {
        notNull(result);
        return result;
    }
and do
    ret = 
    return JNICallResultVerifier(this, "msg").resultNotNull(ret);


So I renamed FatalOnException to now being JNIVerifier.

Though I like it, I don't think we can do it, except if we do it 
slightly differently:

I'm trying to solve two problems with one stone:
    - How to check for returns of JNI calls in the way that is done here
    - How to remove NSK_JNI_VERIFY* (from nsk/share/jni/jni_tools)

However, the NSK_JNI_VERIFY need to start a tracing system before the 
call to JNI, so it won't work this way. (Side question would be do we 
still care about the tracing in NSK_JNI_VERIFY, if we don't then your 
solution works well in most situations).


My vision or intuition is that we would throw a template at some point 
on SafeJNIEnv to handle both cases and have JNIVerifier become a 
specialization in certain cases and something different for the 
NSK_JNI_VERIFY case (or have a different constructor to enable tracing). 
But for now, I offer the implementation that does:


jclass SafeJNIEnv::GetObjectClass(jobject obj) {
   JNIVerifier marker(this, "GetObjectClass");
   return marker.ResultNotNull(_jni_env->GetObjectClass(obj));
}

and:

void SafeJNIEnv::SetObjectField(jobject obj, jfieldID field, jobject 
value) {

   JNIVerifier<> marker(this, "SetObjectField");
   _jni_env->SetObjectField(obj, field, value);
}




- you added #include  in the test (and you have to add it to
every test).
It would be simpler to add the include to SafeJNIEnv.hpp and define
typedef std::unique_ptr SafeJNIEnvPtr;
Then each in the test methods:
    SafeJNIEnvPtr env(new SafeJNIEnv(jni_env));
or you can add
static SafeJNIEnv::SafeJNIEnvPt

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[Alex Menkov]

Hi Jc,

Updated tests looks good.
Some notes about implementation.

- FatalOnException implements both verification and error handling
It would be better to separate them (and this makes easy to implement 
error handling different from JNIEnv::FatalError).

The simplest way is to define error handler as
class SafeJNIEnv {
public:
typedef void (*ErrorHandler)(JNIEnv *env, const char* errorMsg);
// error handler which terminates jvm by using FatalError()
static void FatalError(JNIEnv *env, const char *errrorMsg);

SafeJNIEnv(JNIEnv* jni_env, ErrorHandler errorHandler = FatalError);
(SafeJNIEnv methods should create FatalOnException objects passing 
errorHandler)



- FatalOnException is used in SafeJNIEnv methods as
  FatalOnException marker(this, "msg");
  ret = 
  (optional)marker.check_for_null(ret);
  return ret;
But actually I'd call it something like JNICallResultVerifier and create 
the object after JNI call. like

  ret = 
  JNICallResultVerifier(this, "msg")
(optional).notNull(ret);
  return ret;
or even (if you like such syntax sugar) you can define
  template
  T resultNotNull(T result) {
  notNull(result);
  return result;
  }
and do
  ret = 
  return JNICallResultVerifier(this, "msg").resultNotNull(ret);


- you added #include  in the test (and you have to add it to 
every test).

It would be simpler to add the include to SafeJNIEnv.hpp and define
typedef std::unique_ptr SafeJNIEnvPtr;
Then each in the test methods:
  SafeJNIEnvPtr env(new SafeJNIEnv(jni_env));
or you can add
static SafeJNIEnv::SafeJNIEnvPtr wrap(JNIEnv* jni_env, ErrorHandler 
errorHandler = fatalError)

and get
  SafeJNIEnvPtr env = SafeJNIEnv::wrap(jni_env);


- it would be better to wrap internal classes (FatalOnException) into 
unnamed namespace - this helps to avoid conflicts with other classes)


- FatalOnException::check_for_null(void* ptr)
should be
FatalOnException::check_for_null(const void* ptr)
And calling the method you don't need reinterpret_cast

--alex


On 09/18/2018 11:07, JC Beyler wrote:

Hi David,

Thanks for the quick review and thoughts. I have now a new version here 
that addresses your comments:


Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.01/ 


Bug:https://bugs.openjdk.java.net/browse/JDK-8210842

I've also inlined my answers/comments.



 > I've slowly started working on JDK-8191519
 > . However before
 > starting to really refactor all the tests, I thought I'd get a few
 > opinions. I am working on internalizing the error handling of JNI
calls
 > via a SafeJNIEnv class that redefines all the JNI calls to add an
error
 > checker.
 >
 > The advantage is that the test code will look and feel like
normal JNI
 > code and calls but will have the checks we want to have for our
tests.

Not sure I get that. Normal JNI code has to check for errors/exceptions
after every call. The tests need those checks too. Today they are
explicit, with this change they become implicit. Not sure what we are
gaining here ??


In my humble opinion, having the error checking out of the way allows 
the code reader to concentrate on the JNI code while maintaining error 
checking. We use something similar internally, so perhaps I'm biased to 
it :-).
If this is not a desired/helpful "feature" to simplify tests in general, 
I will backtrack it and just add the explicit tests to the native code 
of the locks for the fix 
https://bugs.openjdk.java.net/browse/JDK-8191519 instead.


Let me however try to make my case and let me know what you all think!


 > If agreed with this, we can augment the SafeJNIEnv class as needed.
 > Also, if the tests require something else than fatal errors, we
can add
 > a different marker and make it a parameter to the base class.
 >
 > Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.00/

 > 
 > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
 >
 > Let me know what you think,

Two initial suggestions:

1. FatalOnException should be constructed with a description string so
that it can report the failing operation when calling FatalError rather
than the general "Problem with a JNI call".


Agreed with you, the new webrev produces:

FATAL ERROR in native method: GetObjectClass
 at 
nsk.share.gc.lock.CriticalSectionTimedLocker.criticalSection(CriticalSectionTimedLocker.java:47)
 at nsk.share.gc.lock.jniref.JNIGlobalRefLocker.criticalNative(Native 
Method)
 at 
nsk.share.gc.lock.jniref.JNIGlobalRefLocker.criticalSection(JNIGlobalRefLocker.java:44)
 at 
nsk.share.gc.lock.CriticalSectionLocker$1.run(CriticalSectionLocker.java:56)
 at java.lang.Thread.run(java.bas

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[JC Beyler]

Hi David,

Thanks for the quick review and thoughts. I have now a new version here
that addresses your comments:

Webrev:  http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.01/
Bug: https://bugs.openjdk.java.net/browse/JDK-8210842

I've also inlined my answers/comments.


>
> > I've slowly started working on JDK-8191519
> > . However before
> > starting to really refactor all the tests, I thought I'd get a few
> > opinions. I am working on internalizing the error handling of JNI calls
> > via a SafeJNIEnv class that redefines all the JNI calls to add an error
> > checker.
> >
> > The advantage is that the test code will look and feel like normal JNI
> > code and calls but will have the checks we want to have for our tests.
>
> Not sure I get that. Normal JNI code has to check for errors/exceptions
> after every call. The tests need those checks too. Today they are
> explicit, with this change they become implicit. Not sure what we are
> gaining here ??
>

In my humble opinion, having the error checking out of the way allows the
code reader to concentrate on the JNI code while maintaining error
checking. We use something similar internally, so perhaps I'm biased to it
:-).
If this is not a desired/helpful "feature" to simplify tests in general, I
will backtrack it and just add the explicit tests to the native code of the
locks for the fix https://bugs.openjdk.java.net/browse/JDK-8191519 instead.

Let me however try to make my case and let me know what you all think!


> > If agreed with this, we can augment the SafeJNIEnv class as needed.
> > Also, if the tests require something else than fatal errors, we can add
> > a different marker and make it a parameter to the base class.
> >
> > Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.00/
> > 
> > Bug: https://bugs.openjdk.java.net/browse/JDK-8210842
> >
> > Let me know what you think,
>
> Two initial suggestions:
>
> 1. FatalOnException should be constructed with a description string so
> that it can report the failing operation when calling FatalError rather
> than the general "Problem with a JNI call".
>

Agreed with you, the new webrev produces:

FATAL ERROR in native method: GetObjectClass
at 
nsk.share.gc.lock.CriticalSectionTimedLocker.criticalSection(CriticalSectionTimedLocker.java:47)
at nsk.share.gc.lock.jniref.JNIGlobalRefLocker.criticalNative(Native
Method)
at 
nsk.share.gc.lock.jniref.JNIGlobalRefLocker.criticalSection(JNIGlobalRefLocker.java:44)
at 
nsk.share.gc.lock.CriticalSectionLocker$1.run(CriticalSectionLocker.java:56)
at java.lang.Thread.run(java.base@12-internal/Thread.java:834)


and for a return NULL in NewGlobalRef, we would get automatically:

FATAL ERROR in native method: NewGlobalRef:Return is NULL
at nsk.share.gc.lock.jniref.JNIGlobalRefLocker.criticalNative(Native
Method)

at
nsk.share.gc.lock.jniref.JNIGlobalRefLocker.criticalSection(JNIGlobalRefLocker.java:44)



Again as we port and simplify more tests (I'll only do the locks for now
and we can figure out the next steps as start working on moving tests out
of vmTestbase),
we can add, if needed, other exception handlers that don't throw or do
other things depending on the JNI method outputs.


> 2. Make the local SafeJNIEnv a pointer called env so that the change is
> less disruptive. All the env->op() calls will remain and only the local
> error checking will be removed.
>

Done, I used a unique_ptr to make the object created/destroyed/available as
a pointer do-able in one line:
std::unique_ptr env(new SafeJNIEnv(jni_env));

and then you can see that, as you mentioned, the disruption to the code is
much less:
http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.01/test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jniref/JNIGlobalRefLocker.cpp.udiff.html

Basically the tests now become internal to the SafeJNIEnv and the code now
only contains the JNI calls happening but we are protected and will fail
any test that has an exception or a NULL return for the call. Of course,
this is not 100% proof in terms of not having any error handling in the
test but in some cases like this, the new code seems to just work better:

http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.01/test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jniref/JNIGlobalRefLocker.cpp.html



>
> The switch from, e.g., checking NULL returns to checking for pending
> exceptions, need to be sure that the JNI operations clearly specify that
> NULL implies there will be an exception pending. This change may be an
> issue for static code analysis if not smart enough to understand the
> RAII wrappers.
>

Agreed, I fixed it to be more strict and say: in normal test handling, the
JNI calls should never return NULL or throw an exception. This should hold
for tests I imagine but if not we can add a different call verifier as we
go.



>
> Thanks,
> Davi

Re: RFR (S) 8210842: Handle JNIGlobalRefLocker.cpp

[David Holmes]

Hi Jc,

On 18/09/2018 1:59 PM, JC Beyler wrote:

Hi all,

I've slowly started working on JDK-8191519 
. However before 
starting to really refactor all the tests, I thought I'd get a few 
opinions. I am working on internalizing the error handling of JNI calls 
via a SafeJNIEnv class that redefines all the JNI calls to add an error 
checker.


The advantage is that the test code will look and feel like normal JNI 
code and calls but will have the checks we want to have for our tests. 


Not sure I get that. Normal JNI code has to check for errors/exceptions 
after every call. The tests need those checks too. Today they are 
explicit, with this change they become implicit. Not sure what we are 
gaining here ??


If agreed with this, we can augment the SafeJNIEnv class as needed. 
Also, if the tests require something else than fatal errors, we can add 
a different marker and make it a parameter to the base class.


Webrev: http://cr.openjdk.java.net/~jcbeyler/8210842/webrev.00/ 


Bug: https://bugs.openjdk.java.net/browse/JDK-8210842

Let me know what you think,


Two initial suggestions:

1. FatalOnException should be constructed with a description string so 
that it can report the failing operation when calling FatalError rather 
than the general "Problem with a JNI call".


2. Make the local SafeJNIEnv a pointer called env so that the change is 
less disruptive. All the env->op() calls will remain and only the local 
error checking will be removed.


The switch from, e.g., checking NULL returns to checking for pending 
exceptions, need to be sure that the JNI operations clearly specify that 
NULL implies there will be an exception pending. This change may be an 
issue for static code analysis if not smart enough to understand the 
RAII wrappers.


Thanks,
David


Jc