Sorry .. this got lost ..
I don't understand this line :
253 jobjectArray emptyArray = env->NewObjectArray(1, clazz, NULL);
This is returning an array of length 1 and element 0 is NULL.
I think you want
env->NewObjectArray(0, clazz, NULL); and I don't see why you need to
create it there instead you can just have 304 if (nameArray != NULL) {
305 return nameArray;
306 } else {
307 return env->NewObjectArray(0, clazz, NULL);
308 } 449 if (prevRemotePrinters != null) { shouldn't this be 449 if
(prevRemotePrinters != null && prevRemotePrinters.length > 0) { ? -phil.
On 12/10/18 10:19 PM, Shashidhara Veerabhadraiah wrote:
Hi Phil, I have updated with small code updates:
http://cr.openjdk.java.net/~sveerabhadra/8212202/webrev.04/
Thanks and regards,
Shashi
*From:*Shashidhara Veerabhadraiah
*Sent:* Monday, December 10, 2018 3:19 PM
*To:* Philip Race <[email protected]>
*Cc:* Prasanta Sadhukhan <[email protected]>;
[email protected]
*Subject:* RE: [OpenJDK 2D-Dev] [12] JDK-8212202: NPE in the print
tests after JDK-8153732
Hi Phil, Please find the updated Webrev.
http://cr.openjdk.java.net/~sveerabhadra/8212202/webrev.03/
Thanks and regards,
Shashi
*From:*Philip Race
*Sent:* Friday, December 7, 2018 8:54 PM
*To:* Shashidhara Veerabhadraiah
<[email protected]
<mailto:[email protected]>>
*Cc:* Prasanta Sadhukhan <[email protected]
<mailto:[email protected]>>; [email protected]
<mailto:[email protected]>
*Subject:* Re: [OpenJDK 2D-Dev] [12] JDK-8212202: NPE in the print
tests after JDK-8153732
First off, I think the high order bit is that if a non-null array
reference is returned there are NO
null String entries in it. Whether a zero length or null array is
returned when there are no printers
is the less important issue.
However an empty array also tells you there are no printers, and you
are less likely to get an NPE from that.
It is arguably easier for the caller, if they don't need the extra
null check first.
FWIW the javax.print public APIs return zero length arrays instead of
null and applications seem to survive :-)
I don't know what you mean by :
> (And anyway we need to handle the first null string reference)?
If you are referring to a small matter of coding in the native layer,
then that is not an insurmountable problem.
Basically if there are problems getting names or whatever in the
native layer, handle it THERE, don't make
everyone else have to deal with it.
One caveat: JNI calls can theoretically fail due to OOME .. in such a
case we are doomed and
the main goal is to not crash in native and to obey all JNI rules.
What is returned in that case
can be a null array reference and an NPE in a Java-level user of that
reference in such a case is not a big deal.
-phil
On 12/6/18, 8:10 PM, Shashidhara Veerabhadraiah wrote:
Hi Phil, Is it advisable to return zero length array from native?
The null return from native is telling the caller that there are
no printers connected to the system. To tell this should we
allocate a zero length array containing null back to the
caller(And anyway we need to handle the first null string
reference)? Handling the null on the caller isn’t an easier option?
Thanks and regards,
Shashi
*From:*Phil Race
*Sent:* Thursday, December 6, 2018 2:35 AM
*To:* Shashidhara Veerabhadraiah
<[email protected]>
<mailto:[email protected]>; Prasanta Sadhukhan
<[email protected]>
<mailto:[email protected]>; [email protected]
<mailto:[email protected]>
*Subject:* Re: [OpenJDK 2D-Dev] [12] JDK-8212202: NPE in the print
tests after JDK-8153732
But what I am saying is we should not return a NULL string reference
from native. You are still allowing that and then having to handle
it in Java code.
And FWIW you can return a zero length array as well so there
isn't a NULL array reference to deal with either.
-phil.
On 12/3/18 8:29 AM, Shashidhara Veerabhadraiah wrote:
Hi Phil, There were 2 problems earlier. One is that, from the
native it is possible to have no printers being associated
with the system(causing to return null reference) and other
problem in the implementation was that there may be no network
printers and still return a valid array reference containing a
null string. The first problem is fixed by handling null
references returned from this function and other problem was
that earlier there were different base conditions, for
updating the reference and use it to create the printer name
array which could produce a valid reference pointing to null
string. Here is the updated Webrev which fixes these problems:
http://cr.openjdk.java.net/~sveerabhadra/8212202/webrev.02/
<http://cr.openjdk.java.net/%7Esveerabhadra/8212202/webrev.02/>
The big problem was that I was not able to reproduce this
problem neither at my end nor at the systems used for PIT
testing. Only Sergey had produced this NPE till now.
Thanks and regards,
Shashi
*From:*Phil Race
*Sent:* Wednesday, November 28, 2018 11:19 PM
*To:* Shashidhara Veerabhadraiah
<[email protected]>
<mailto:[email protected]>; Prasanta
Sadhukhan <[email protected]>
<mailto:[email protected]>;
[email protected] <mailto:[email protected]>
*Subject:* Re: [OpenJDK 2D-Dev] [12] JDK-8212202: NPE in the
print tests after JDK-8153732
I am not understanding you. I thought the problem to be we got
an array of (say) 3 values
(ie printer names) returned from native where some or all of
the *values* were NULL.
And I am saying we should in such a case in the native code,
before returning,
remove from the returned array all values that are NULL.
That could result in an empty (zero length) array being
returned from native but
no null names ..
-phil.
On 11/26/18 10:23 PM, Shashidhara Veerabhadraiah wrote:
The windows function EnumPrinters() returns a value that
could be zero or greater. If it is zero we have no other
option but to return null from the function. I do not
think there is a way where we can always make sure we get
a non-zero value considering the various system scenarios.
So we should handle the null return values as well in the
caller of this function I think.
Here is the updated Webrev for test fix:
http://cr.openjdk.java.net/~sveerabhadra/8212202/webrev.01/
<http://cr.openjdk.java.net/%7Esveerabhadra/8212202/webrev.01/>
Thanks and regards,
Shashi
*From:*Phil Race
*Sent:* Tuesday, November 27, 2018 1:52 AM
*To:* Prasanta Sadhukhan <[email protected]>
<mailto:[email protected]>; Shashidhara
Veerabhadraiah <[email protected]>
<mailto:[email protected]>;
[email protected] <mailto:[email protected]>
*Subject:* Re: [OpenJDK 2D-Dev] [12] JDK-8212202: NPE in
the print tests after JDK-8153732
[Removed swing-dev as this as nothing to do with swing].
You mention in the bug eval that you don't need a new test
because this
is already covered by the test for 8153732. If that is the
case then this
bugid should be added to that test.
Although it also looks like there are plenty of tests that
provoke this ..
if all you need is a system without any printers then this
is a serious regression.
I am not sure I am following why doCompare() is the place
to fix this.
If getRemotePrinterNames() is returning NULL strings, then
maybe it should not !
I suggest to fix it there.
-phil.
On 11/26/18 7:51 AM, Prasanta Sadhukhan wrote:
I am not against doCompare() changes. I am just saying
run() changes are not needed.
Regards
Prasanta
On 26-Nov-18 9:15 PM, Shashidhara Veerabhadraiah wrote:
There is a possible case and that is the reason
for this fix. The possible states for
prevRemotePinters and currentRemotePrinters are
null and valid values and they can reach those
states at any time either because of network
disconnect or any other OS related changes. With
that in mind, this fix tries to eliminate the
possible NPE cases.
Thanks and regards,
Shashi
*From:*Prasanta Sadhukhan
*Sent:* Monday, November 26, 2018 8:01 PM
*To:* Shashidhara Veerabhadraiah
<[email protected]>
<mailto:[email protected]>;
[email protected]
<mailto:[email protected]>;
[email protected]
<mailto:[email protected]>
*Subject:* Re: [OpenJDK 2D-Dev] [12] JDK-8212202:
NPE in the print tests after JDK-8153732
On 26-Nov-18 6:51 PM,
[email protected]
<mailto:[email protected]> wrote:
Hi Prasanta, I think we should not create a
behavior across the functions. doCompare()
does only the comparison and it may be used
for other purposes and is complete with
respect to the comparison functionality.
run() function has a different behavior as it
needs to populate the prevRemotePrinters and
then the currentRemotePrinters and then use
the comparison functionality. I think this is
a good way to do.
Even without the if-else check, it does populates
the prevRemotePrinters, no?
if "prevRemotePrinters" is null and
currentRemotePrinters is null, then no need to
update. If currentRemotePrinters is null, then
what is the point of using
getRemotePrintersNames() to update
prevRemotePrinters as currentRemotePrinters is
also obtained from getRemotePrintersNames!!
If "prevRemotePrinters" is null and
currentRemotePrinters is not null, then
doCompare() called from run() will be true and
prevRemotePrinters will be populated with
currentRemotePrinters.
If "prevRemotePrinters" is not null and
currentRemotePrinters is null, then also
prevRemotePrinters will be populated with
currentRemotePrinters.
Regards
Prasanta
Thanks and regards,
Shashi
On 26/11/18 6:03 PM, Prasanta Sadhukhan wrote:
Hi Shashi,
I think l437 check of if-else *if
(prevRemotePrinters != null) {*
is not required. prevRemotePrinters null
check is addressed in str1==null case in
doCompare().
If prevRemotePrinters is null and
currentRemotePrinters is not null, then
you update prevRemotePrinters to
currentRemotePrinters as per l415 where
doCompare returns true.
Also, If prevRemotePrinters is not null
and currentRemotePrinters is null, then
also you update prevRemotePrinters to
currentRemotePrinters which is the output
of getRemotePrintersNames().
Regards
Prasanta
On 26-Nov-18 2:33 PM, Shashidhara
Veerabhadraiah wrote:
Hi All, Please review a NPE fix for
the below bug.
Bug:
https://bugs.openjdk.java.net/browse/JDK-8212202
Webrev:
http://cr.openjdk.java.net/~sveerabhadra/8212202/webrev.00/
<http://cr.openjdk.java.net/%7Esveerabhadra/8212202/webrev.00/>
Function getRemotePrintersNames() may
return null values and hence they need
to be handled from the caller of that
function which was missing earlier.
This fix handles the null return
values of the said function.
Thanks and regards,
Shashi
