On 10/25/2016 06:10 PM, Mandy Chung wrote:
Webrev at:
http://cr.openjdk.java.net/~mchung/jdk9/webrevs/6479237/webrev.00/
Specdiff:
http://cr.openjdk.java.net/~mchung/jdk9/webrevs/6479237/specdiff/overview-summary.html
This is a long-standing RFE for adding support for class
loader names. It's #ClassLoaderNames on JSR 376 issue
list where the proposal [1] has been implemented in jake
for some time. This patch brings this change to jdk9.
A short summary:
- New constructors are added in ClassLoader, SecureClassLoader
and URLClassLoader to specify the class loader name.
- New ClassLoader::getName and StackTraceElement::getClassLoaderName
method
- StackTraceElement::toString is updated to include the name
of the class loader and module of that frame in this format:
<loader>/<module>/<fully-qualified-name>(<src>:<line>)
The detail is in StackTraceElement::buildLoaderModuleClassName
that compress the output string for cases when the loader
has no name or the module is unnamed module. Another thing
to mention is that VM sets the Class object when filling in
a stack trace of a Throwable object. Then the library will
build a String from the Class object for serialization purpose.
I am not a reviewer. I have a question though: Does this mean that you
have to establish the name of your class loader in the constructor?
If so, here's what mainly bothers me about this approach:
- With a new constructor being required, you cannot easily write a class
loader which both functions under Java 8 and has a name under Java 9
without resorting to MR JARs
- The getName() method can be overridden but doing so has no effect on
the real name of the class loader
- ... but you can't make it final or you risk breaking class loaders
that already exist
Maybe instead, the "name" field (or other internal mechanism) could
somehow be lazily populated by calling getName(), which returns null by
default but can be overridden by subclasses? This way ClassLoaders can
function the same way in Java 8 and 9, and just get extra functionality
when running under Java 9.
--
- DML
