RFR: 8060130: Simplify the synchronization of defining and getting java.lang.Package

[Claes Redestad]

Hi Mandy,

  thanks for the review!

On 10/15/2014 03:07 AM, Mandy Chung wrote:
> Claes, Peter,
>
>   Thanks for the revised webrev and Peter's thorough review. webrev.05
> looks much better.  My comment is mostly minor.
>
>
> ClassLoader.java
>
> line 1582-1586 - I suggest to get rid of the "oldpkg" variable
> (it's really the package to be used and not an old pkg).
>
>     pkg = new Package(name, specTitle, specVersion, specVendor,
>                             implTitle, implVersion, implVendor,
>                             sealBase, this);
>     if (packages.putIfAbsent(name, pkg) != null) {
>         throw new IllegalArgumentException(name + " already defined");
>     }
>     return pkg;
>
> line 1634-1635: nit: the pkgName variable is not really needed.
>    it's in the existing code and probably good to remove it.
>    Package.java
>
> line 473: maybe better to leave the ClassLoader parameter in the 
> constructor.
>    I thought about adding a comment saying that this private constructor
>    is only used for system package but keeping the loader parameter makes
>    it more explicit.
>
> line 569: nit: formatting - indent to the right to align the first 
> parameter
>    to new Package(...)

Fixed.

>
> line 621-623: is this really needed?  Uncontended case seems to be
>    the common case.  It seems the synchronized overhead would be
>    insignificant.

I'd prefer sticking to the double-checked idiom here, unless you insist.

I've cleaned up the code to avoid assignment in if-clauses, which 
according to
anonymous sources makes the code more readable. Perhaps this addresses
some of your concerns?

>
> line 624: a space is missing between synchronized and "("

Fixed.

>
> Looks like there is one test 
> jdk/test/java/lang/ClassLoader/GetPackage.java
> about packages.  Can you add a new test to verify the system packages 
> as that
> is one major change in your patch?

http://cr.openjdk.java.net/~redestad/8060130/webrev.06

Since I don't want to add binary JAR files, I opted to add a test which 
creates two JAR files,
each with a single class (with/without manifest) and then proceeds to 
spawn processes
to verify that:

- when the JAR with manifest is on bootclasspath, the package can be 
found via
Package.getSystemPackage and the package object reflects values added to 
the manifest
- when the JAR without manifest is on bootclaspath, the package can be 
found via
Package.getSystemPackage but is empty apart from name
- adding the test.classes directory to bootclasspath behaves the same as 
adding the JAR
without manifest
- for any case where the class/package is not on the bootclasspath, the 
package information
can not be found via Package.getSystemPackage().

Does this cover everything?

I guess there might be a way to make @run main/othervm or 
main/bootclasspath pick
up a dynamically generated JAR file, but I've failed to find a way that 
would make this work without
pregenerating the JARs. Suggestions on how this can be simplified are 
welcome.

/Claes

>
> Thanks
> Mandy
>