Re: RFR: JDK-8225056 VM support for sealed classes
Hi Harold,
On 22/05/2020 4:33 am, Harold Seigel wrote:
Hi David,
Thanks for looking at this! Please review this new webrev:
http://cr.openjdk.java.net/~hseigel/webrev.01/webrev/
I'll list all relevant commens here rather than interspersing below so
that it is easier to track. Mostly nits below, other than the
is_permitted_subclass check in the VM, and the use of ReflectionData in
java.lang.Class.
--
src/hotspot/share/classfile/classFileParser.cpp
+ bool ClassFileParser::supports_sealed_types() {
+ return _major_version == JVM_CLASSFILE_MAJOR_VERSION &&
+ _minor_version == JAVA_PREVIEW_MINOR_VERSION &&
+ Arguments::enable_preview();
+ }
Nowe there is too little indentation - the subclauses of the conjunction
expression should align[1]
+ bool ClassFileParser::supports_sealed_types() {
+ return _major_version == JVM_CLASSFILE_MAJOR_VERSION &&
+ _minor_version == JAVA_PREVIEW_MINOR_VERSION &&
+ Arguments::enable_preview();
+ }
3791 if (parsed_permitted_subclasses_attribute) {
3792 classfile_parse_error("Multiple
PermittedSubclasses attributes in class file %s", CHECK);
3793 // Classes marked ACC_FINAL cannot have a
PermittedSubclasses attribute.
3794 } else if (_access_flags.is_final()) {
3795 classfile_parse_error("PermittedSubclasses
attribute in final class file %s", CHECK);
3796 } else {
3797 parsed_permitted_subclasses_attribute = true;
3798 }
The indent of the comment at L3793 is wrong, and its placement is
awkward because it relates to the next condition. But we don't have to
use if-else here as any parse error results in immediate return due to
the CHECK macro. So the above can be reformatted as:
3791 if (parsed_permitted_subclasses_attribute) {
3792 classfile_parse_error("Multiple
PermittedSubclasses attributes in class file %s", CHECK);
3793 }
3794 // Classes marked ACC_FINAL cannot have a
PermittedSubclasses attribute.
3795 if (_access_flags.is_final()) {
3796 classfile_parse_error("PermittedSubclasses
attribute in final class file %s", CHECK);
3797 }
3798 parsed_permitted_subclasses_attribute = true;
---
src/hotspot/share/oops/instanceKlass.cpp
The logic in InstanceKlass::has_as_permitted_subclass still does not
implement the rules specified in the JVMS. It only implements a "same
module" check, whereas the JVMS specifies an accessibility requirement
as well.
730 bool InstanceKlass::is_sealed() const {
731 return _permitted_subclasses != NULL &&
732 _permitted_subclasses != Universe::the_empty_short_array() &&
733 _permitted_subclasses->length() > 0;
734 }
Please align subclauses.
---
src/hotspot/share/prims/jvm.cpp
2159 objArrayHandle result (THREAD, r);
Please remove space after "result".
As we will always create and return an arry, if you reverse these two
statements:
2156 if (length != 0) {
2157 objArrayOop r =
oopFactory::new_objArray(SystemDictionary::String_klass(),
2158length, CHECK_NULL);
and these two:
2169 return (jobjectArray)JNIHandles::make_local(THREAD, result());
2170 }
then you can delete
2172 // if it gets to here return an empty array, cases will be: the
class is primitive, or an array, or just not sealed
2173 objArrayOop result =
oopFactory::new_objArray(SystemDictionary::String_klass(), 0, CHECK_NULL);
2174 return (jobjectArray)JNIHandles::make_local(env, result);
The comment there is no longer accurate anyway.
---
src/hotspot/share/prims/jvmtiRedefineClasses.cpp
857 static jvmtiError
check_permitted_subclasses_attribute(InstanceKlass* the_class,
858 InstanceKlass*
scratch_class) {
Please align.
---
src/hotspot/share/prims/jvmtiRedefineClasses.cpp
2007 if (permitted_subclasses != NULL) {
permitted_subclasses cannot be NULL. I initially thought the bug was in
the nest_members version of this code, but they both have the same
properties: the member is initialized to NULL when the InstanceKlass is
constructed, and set to either the proper array or the empty_array()
when classfile parsing is complete. So redefinition cannot encounter a
NULL value here.
---
src/java.base/share/classes/java/lang/Class.java
The use of ReflectionData is not correctly implemented. The
ReflectionData instance is not constant but can be replaced when class
redefinition operates. So you cannot do this:
if (rd.permittedSubclasses != null) {
return rd.permittedSubclasses;
}
because you may be returning the permittedSubclasses field of a
different Reflectiondata instance. You need to read the field once into
a local and thereafter use it. Similarly with:
Re: RFR: 8244993: Revert changes to OutputAnalyzer stderrShouldBeEmptyIgnoreVMWarnings() that allow version strings
On 24/05/2020 3:06 am, Chris Plummer wrote:
On 5/23/20 6:03 AM, David Holmes wrote:
Hi Chris,
On 23/05/2020 4:50 am, Chris Plummer wrote:
Hi Daniil,
There is one reference to "jvmwarningmsg" that occurs before it is
declared while all the rest all come after. It probably would make
sense to move its declaration up near the top of the file.
92 private static void matchListedProcesses(OutputAnalyzer
output) {
93 output.stdoutShouldMatchByLine(JCMD_LIST_REGEX)
94 .stderrShouldBeEmptyIgnoreVMWarnings();
95 }
We probably use this coding pattern all over the place, but I think
it just leads to less readable code. Any reason not to use:
92 private static void matchListedProcesses(OutputAnalyzer
output) {
93 output.stdoutShouldMatchByLine(JCMD_LIST_REGEX);
94 output.stderrShouldBeEmptyIgnoreVMWarnings();
95 }
I just don't see the point of the chaining, and don't understand why
all these OutputAnalyzer methods return the "this" object in the
first place. Maybe I'm missing something.
They return "this" precisely so that you can chain. The API was
designed for a style that allows:
output.shouldContain(x).shouldNotContain(y).shouldContain(z) ...
to avoid the repetition of "output".
Yeah, I get that, but I never did like this pattern. I just don't find
it as readable. For one, there's no conveyance of the method return
type, not just because of the chaining, but also because the method name
does not imply a return type. Chaining like
getMethod().getClass().getName() is fine, because there are implied
return types in the method names, and they clearly are being called for
the purpose of returning a type. But when the return type is there
solely for the purpose of chaining, it's not as obvious what is going on.
Your example is easier to read because the method names are short,
readily identified as related, and you made them all fit on one line
with shortened arguments.
Which is really an anti-pattern for this style of API :)
That's not the case with Daniil's code. I just
don't see the argument for saying that:
93 output.stdoutShouldMatchByLine(JCMD_LIST_REGEX)
94 .stderrShouldBeEmptyIgnoreVMWarnings();
Note the '.' should line up
Is somehow better than:
93 output.stdoutShouldMatchByLine(JCMD_LIST_REGEX);
94 output.stderrShouldBeEmptyIgnoreVMWarnings();
I don't have to look twice at the second version (or be familiar with
the APIs being used) to know what's going on.
All a matter of personal preference. :)
Cheers,
David
Chris
David
-
I guess maybe there are cases where
the OutputAnalyzer object is not already in a local variable, adding
some value to the chaining, but that's not the case here, and I think
if it were the case it would be more readable just to stick the
OutputAnalyzer object in a local. There one other case of this:
154 private static void matchPerfCounters(OutputAnalyzer output) {
155 output.stdoutShouldMatchByLine(PERF_COUNTER_REGEX,null,
156 PERF_COUNTER_REGEX)
157 .stderrShouldBeEmptyIgnoreVMWarnings();
158 }
I think you can also add spaces after the commas, and probably make
the first stdoutShouldMatchByLine() one line.
thanks,
Chris
On 5/21/20 10:06 PM, Daniil Titov wrote:
Please review a webrev [1] that reverts the changes done in
jdk.test.lib.process.OutputAnalyzer in [3].
Change [3] modified OutputAnalyzer
stderrShouldBeEmptyIgnoreVMWarnings() methods to ignore also VM
version strings . The current webrev [1] reverts this change and
instead makes the tests that expects an empty stderr from launched
j-* tools to filter out '-showversion' from test options when
forwarding test VM option to j*-tools.
Testing: Mach5 tier1-tier5 tests passed successfully. Tier6-tier7
tests are in progress.
[1] Webrev: http://cr.openjdk.java.net/~dtitov/8244993/webrev.01
[2] Jira issue: https://bugs.openjdk.java.net/browse/JDK-8244993
[3] https://bugs.openjdk.java.net/browse/JDK-8242009
Thank you,
Daniil
