Code review for jigsaw/jake -> jdk9/dev sync up

Maurizio Cimadamore maurizio.cimadamore at
Mon Nov 28 16:01:05 UTC 2016

On 28/11/16 14:53, Jan Lahoda wrote:
> Thanks for the comments Maurizio.
> On 28.11.2016 12:28, Maurizio Cimadamore wrote:
>> Hi,
>> the langtools code looks generally ok. Few questions:
>> * Why doesn't 'open' get its own directive in - instead
>> of relying on a 'mode' set on an export directive?
> It seemed to me that having two directive interfaces in the API for 
> directives that have the same structure was unnecessary (as we don't 
> have MethodElement and ConstructorElement, but just ExecutableElement, 
> or TypeElement that represents a class, an interface, an annotation 
> type or an enum type).
> If you think it would be better to have separate interfaces for 
> exports and opens, I am OK with that as well.
I agree that it would be redundant - perhaps the two directive can both 
share a common superclass which defines the common fields? I said that 
because it looks like for everything else, 'opens' and 'exports' are 
really two separate directives, with separate bytecode encodings and 
such (that is, the Module attribute has separate entries for 'opens' and 
>> * ClassReader: should we have checks regarding an open module containing
>> no open directives in the classfile? This seems to be called out in the
>> spec [1] - see section 2.2
> I think such checks would be fine, working on a patch.
>> * At some point we should investigate better sharing strategy between
>> ClassReader and ModuleNameReader
>> * Names.dynamic seems unused
> Fixed:

> Jan
>> * I note that the classfile attribute name changes are not captured in
>> the spec (but I might be referring to a slightly older version).
>> Maurizio
>> [1] -
>> On 24/11/16 15:25, Alan Bateman wrote:
>>> Folks on jigsaw-dev will know that we are on a mission to bring the
>>> changes accumulated in the jake forest to jdk9/dev. We can think of
>>> this as a refresh of the module system in JDK 9, the last big refresh
>>> was in May with many small updates since then.
>>> The focus this time is to bring the changes that are tied to JSR
>>> issues into jdk9/dev, specifically the issues that are tracked on the
>>> JSR issues list [1] as:
>>> #CompileTimeDependences
>>> #AddExportsInManifest
>>> #ClassFileModuleName
>>> #ClassFileAccPublic
>>> #ServiceLoaderEnhancements
>>> #ResourceEncapsulation/#ClassFilesAsResources
>>> #ReflectiveAccessToNonExportedTypes
>>> #AwkwardStrongEncapsulation
>>> #ReadabilityAddedByLayerCreator
>>> #IndirectQualifiedReflectiveAccess (partial)
>>> #VersionsInModuleNames
>>> #NonHierarchicalLayers
>>> #ModuleAnnotations/#ModuleDeprecation
>>> #ReflectiveAccessByInstrumentationAgents
>>> Some of these issues are not "Resolved" yet, meaning there is still
>>> ongoing discussion on the EG mailing list. That is okay, there is
>>> nothing final here. If there are changes to these proposals then the
>>> implementation changes will follow. Also, as I said in a mail to
>>> jigsaw-dev yesterday [2], is that we will keep the jake forest open
>>> for ongoing prototyping and iteration, also ongoing implementation
>>> improvements where iteration or bake time is important.
>>> For the code review then the focus is therefore on sanity checking the
>>> changes that we would like to bring into jdk9/dev. We will not use
>>> this review thread to debate alternative designs or other big
>>> implementation changes that are more appropriate to bake in jake.
>>> To get going, I've put the webrevs with a snapshot of the changes in
>>> jake here:
>>> The changes are currently sync'ed against jdk-9+146 and will be
>>> rebased (and re-tested) against jdk9/dev prior to integration. There
>>> are a number of small changes that need to be added to this in the
>>> coming days, I will refresh the webrev every few days to take account
>>> of these updates.
>>> A few important points to mention, even if you aren't reviewing the
>>> changes:
>>> 1. This refresh requires a new version of jtreg to run the tests. The
>>> changes for this new version are in the code-tools/jtreg repository
>>> and the plan is to tag a new build (jtreg4.2-b04) next week. Once the
>>> tag has been added then we'll update the requiredVersion property in
>>> each TEST.ROOT to force everyone to update.
>>> 2. For developers trying out modules with the main line JDK 9 builds
>>> then be aware that `requires public` changes to `requires transitive`
>>> and the `provides` clause changes to require all providers for a
>>> specific service type to be in the same clause. Also be aware that the
>>> binary form of the module declaration (module-info.class) changes so
>>> you will need to recompile any modules.
>>> 3. Those running existing code on JDK 9 and ignoring modules will need
>>> to be aware of a disruptive change in this refresh. The disruptive
>>> change is #AwkwardStrongEncapsulation where setAccessible(true) is
>>> changed so that it can't be used to break into non-public
>>> fields/methods of JDK classes. This change is going to expose a lot of
>>> hacks in existing code. We plan to send mail to jdk9-dev in advance of
>>> this integration to create awareness of this change. As per the
>>> original introduction of strong encapsulation then command line
>>> options (and now the manifest of application JAR files) can be used to
>>> keep existing code working. The new option is `--add-opens` to open a
>>> package in a module for deep reflection by other modules. As an
>>> example, if you find yourself with code that hacks into the private
>>> `comparator` field in java.util.TreeMap then running with `--add-opens
>>> java.base/java.util=ALL-UNNAMED` will keep that code working.
>>> A few miscellaneous notes for those that are reviewing:
>>> 1. We have some temporary/transition code in the top-level repo to
>>> deal with the importing of the JavaFX modules. This will be removed
>>> once the changes are in JDK 9 for the OpenJFX project to use.
>>> 2. In the jdk repo then it's important to understand that the module
>>> system is initialized at startup and there are many places where we
>>> need to keep startup performance in mind. This sometimes means less
>>> elegant code than might be used if startup wasn't such a big concern.
>>> 3. The changes in the jaxws repo make use of new APIs that means the
>>> code doesn't compile with JDK 7 or JDK 8. Our intention is to work
>>> with the JAXB and JAX-WS maintainers to address the issues in the
>>> upstream project and then bring those changes into jdk9/dev to replace
>>> the patches that we are forced to push for the short term.
>>> 4. You will see several tests where the value of the @modules tag has
>>> `:open` or `:+open`. This is new jtreg speak. The former means the
>>> test is run with --add-opens to open the package, the latter means the
>>> test is exported at compile-time and exported + open at run-time (the
>>> latter usage will be rare, it's where tests have static references to
>>> JDK internal types and are also doing deep reflection with
>>> setAccessible).
>>> In terms of dates then we are aiming to integrate these changes into
>>> jdk9/dev in early December. I will send a follow-up mail next week on
>>> this as we work through the logistics.
>>> -Alan
>>> [1]
>>> [2]

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