Real-world scm or wagon <extensions> won't trigger maven2-compat code path [1]. To avoid that obscure code path we can either make the test more elaborate (i.e. add dependencies to extjar1/extjar2) or we can use extensions <plugin>. Either way I don't think we should spend time on the code path unlikely to be used in real life.
[1] https://github.com/apache/maven/blob/maven-3.5.1/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuildingHelper.java#L210-L219 -- Regards, Igor On Wed, Sep 20, 2017, at 03:29 AM, Robert Scholte wrote: > On Wed, 20 Sep 2017 09:12:47 +0200, Stephen Connolly > <stephen.alan.conno...@gmail.com> wrote: > > > On Wed 20 Sep 2017 at 01:29, Igor Fedorenko <i...@ifedorenko.com> wrote: > > > >> In that case, can I suggest couple of changes to the test project > >> > >> * I thinks it makes more sense to configure extjar1 and extjar2 as > >> extensions <plugin> elements in probleN pom.xml files. First, there is > >> no meaningful order between <extensions> and <plugins> elements. More > >> importantly, though, simple <extensions> are treated in special > >> maven2-compat mode and are not representative of likely real-world > >> extensions. > > > > Not sure I agree with this. I think there are jars worth sharing across > multiple plugins, but where making the plugin an extension is a bit > weird. > I'm thinking of scm and wagon in this case. > > > > > That sounds like we need documentation updated then. None of that is > > obvious to me. > > > > > >> > >> * I think we should introduce META-INF/maven/extension.xml to the test > >> extensions. This metadata what introduced to configure classpath > >> visibility, so lets use it. > > > > > > Again, not obvious to me, if that file allows control of classpath > > visibility then it may be that the only issue *with* 3.5.1 is the lack of > > documentation... now previous versions would have been adding breaking > > changes from my PoV but that is the past and should not affect the 3.5.1 > > release. > > > > PRs for the probe project welcome. I am happy to try and write docs once > > I > > have an understanding of what the expected behaviours are > > > > > >> > >> -- > >> Regards, > >> Igor > >> > >> On Tue, Sep 19, 2017, at 05:12 PM, Stephen Connolly wrote: > >> > Yes, the expectations are key. Depending on what they are we may > >> either > >> > drop 3.5.1 or go ahead as it depends on whether this is more correct > >> than > >> > 3.5.0 or swapping one fix for a bug > >> > > >> > On Tue 19 Sep 2017 at 21:39, Igor Fedorenko <i...@ifedorenko.com> > >> wrote: > >> > > >> > > Just to confirm I understand what we are trying to establish here. > >> We > >> > > want to decide the expected/desired component injection behaviour > >> and > >> > > classpath visibility in the absence of package and artifact export > >> > > configuration (i.e. META-INF/maven/extension.xml file). Did I get > >> this > >> > > right? > >> > > > >> > > -- > >> > > Regards, > >> > > Igor > >> > > > >> > > On Tue, Sep 19, 2017, at 03:52 PM, Robert Scholte wrote: > >> > > > Let's do it like this: > >> > > > > >> > > > >> https://cwiki.apache.org/confluence/download/attachments/2329841/classrealms.pdf?api=v2 > >> > > > > >> > > > Robert > >> > > > > >> > > > On Tue, 19 Sep 2017 21:08:39 +0200, Stephen Connolly > >> > > > <stephen.alan.conno...@gmail.com> wrote: > >> > > > > >> > > > > I think you will need a link to the PDF as attachments are > >> stripped > >> > > from > >> > > > > the ML > >> > > > > > >> > > > > On Tue 19 Sep 2017 at 19:57, Robert Scholte > >> <rfscho...@apache.org> > >> > > wrote: > >> > > > > > >> > > > >> Attached a single page overview. > >> > > > >> > >> > > > >> Per block you'll see in the upper left corner the executed > >> plugin > >> > > > >> The left column contains the extensions and plugin in orderas > >> > > specified > >> > > > >> in > >> > > > >> the pom.xml > >> > > > >> In every classloadercolumn you'll see numbers which represent > >> the > >> > > order. > >> > > > >> > >> > > > >> I hope I didn't make any mistakes. > >> > > > >> Tomorrow I have enough time to see if I understand what's > >> happening > >> > > > >> here. > >> > > > >> > >> > > > >> I will come back with my conclusions. > >> > > > >> > >> > > > >> Robert > >> > > > >> > >> > > > >> On Tue, 19 Sep 2017 06:55:08 +0200, Igor Fedorenko < > >> > > i...@ifedorenko.com> > >> > > > >> wrote: > >> > > > >> > >> > > > >> > TL;DR your test project exposed two existing bugs, one > >> change in > >> > > > >> > behaviour and one quirk I can't explain > >> > > > >> > > >> > > > >> > * Build `<extensions>` are loaded by two classloaders, which > >> is > >> a > >> > > bug > >> > > > >> in > >> > > > >> > DefaultProjectBuildingHelper#createProjectRealm and explains > >> why you > >> > > > >> see > >> > > > >> > extjar1/extjar2 in the output > >> > > > >> > * ClassRealm does not allow same foreign-import from multiple > >> > > > >> > classloaders, which is a bug and explains why it is not > >> possible to > >> > > > >> load > >> > > > >> > same resource from multiple plugins/extensions > >> > > > >> > * TCCL does not have access to private (i.e. not exported) > >> resources > >> > > > >> of > >> > > > >> > this extensions plugin, which is a change of behaviour > >> introduced by > >> > > > >> > mng-6209 fix > >> > > > >> > * Also, component injection order appears to be backwards, > >> but > >> maybe > >> > > > >> > Stuart can explain why. > >> > > > >> > > >> > > > >> > > >> > > > >> > Below is more detailed explanation of expected and observed > >> > > behaviour > >> > > > >> > > >> > > > >> > > >> > > > >> > ## Component injection depends on the currently running > >> plugin > >> and > >> > > the > >> > > > >> > injection site > >> > > > >> > > >> > > > >> > Currently running plugins have access to the following > >> component > >> > > > >> > implementations: > >> > > > >> > > >> > > > >> > * Regular plugin has access to components implemented by the > >> plugin, > >> > > > >> > project build extensions, if any (via project class realm > >> foreign > >> > > > >> > import) and Maven Core. > >> > > > >> > * Extension plugin has access to components implemented by > >> the > >> > > project > >> > > > >> > build extensions and Maven Core. > >> > > > >> > * Without a running plugin (e.g., during project dependency > >> > > > >> resolution), > >> > > > >> > components implemented by the project build extensions and > >> Maven > >> > > Core > >> > > > >> > are accessible. > >> > > > >> > > >> > > > >> > Different injection sites have access to the following > >> component > >> > > > >> > interfaces: > >> > > > >> > > >> > > > >> > * Maven Core has access to component interfaces defined by > >> the > >> core > >> > > > >> > itself (obviously) > >> > > > >> > * Project build extensions have access to **public** > >> component > >> > > > >> > interfaces defined by Maven Core and component interfaces > >> defined by > >> > > > >> the > >> > > > >> > build extension itself (there is no way to access component > >> > > interfaces > >> > > > >> > defined in other extensions) > >> > > > >> > * Regular plugins have access to **public** component > >> interfaces > >> > > > >> defined > >> > > > >> > by Maven Core, component interfaces **exported** by build > >> extensions > >> > > > >> and > >> > > > >> > component interfaces defined in the plugin itself > >> > > > >> > > >> > > > >> > For injection to work, injection site has to have access to > >> the > >> > > > >> > component interface and the component implementation must be > >> > > > >> accessible > >> > > > >> > through the current context. > >> > > > >> > > >> > > > >> > From what I can tell, in your example all plugins have access > >> to the > >> > > > >> > right components when using current 3.5.2-SNAPSHOT. The > >> injection > >> > > > >> order > >> > > > >> > does appear to be backwards from what I expected, however. > >> > > > >> > > >> > > > >> > > >> > > > >> > ## Resources lookup fully depends on classpath visibility, > >> > > > >> specifically > >> > > > >> > > >> > > > >> > * Regular plugin class realm has access to resources from the > >> plugin > >> > > > >> > itself, from **exported** packages of the project build > >> extensions > >> > > and > >> > > > >> > **public** Maven Core packages > >> > > > >> > * Extensions plugin class realm has access to the resources > >> from the > >> > > > >> > extensions plugin itself and from **public** Maven Core > >> packages > >> > > > >> > * Project class realm has access to classes and resources > >> > > **exported** > >> > > > >> > by project build extensions and **public** Maven Core > >> packages > >> > > > >> > > >> > > > >> > I see three problems here > >> > > > >> > > >> > > > >> > * Maven adds build single-jar `<extensions>` elements > >> directly > >> to > >> > > > >> > project class realm **and** creates separate extensions class > >> realms > >> > > > >> for > >> > > > >> > them. Which results in duplicate classes/resources loaded by > >> two > >> > > > >> > classloaders and explains why you see extjar1/extjar2 output > >> (which > >> > > > >> you > >> > > > >> > shouldn't according to the explanation above) > >> > > > >> > * ClassRealm does not allow foreign-import of the same > >> package > >> from > >> > > > >> > multiple classloaders. This makes it impossible to load the > >> same > >> > > > >> > resource from multiple plugins/extensions. > >> > > > >> > * Extensions plugins cannot access their own private (i.e. > >> not > >> > > > >> exported) > >> > > > >> > resources via TCCL, this is change in behaviour introduced by > >> > > mng-6209 > >> > > > >> > fix > >> > > > >> > > >> > > > >> > Hope this helps > >> > > > >> > >> > > > >> > >> --------------------------------------------------------------------- > >> > > > >> To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > >> > > > >> For additional commands, e-mail: dev-h...@maven.apache.org > >> > > > > >> > > > > >> --------------------------------------------------------------------- > >> > > > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > >> > > > For additional commands, e-mail: dev-h...@maven.apache.org > >> > > > > >> > > > >> > > > >> --------------------------------------------------------------------- > >> > > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > >> > > For additional commands, e-mail: dev-h...@maven.apache.org > >> > > > >> > > -- > >> > Sent from my phone > >> > >> --------------------------------------------------------------------- > >> To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > >> For additional commands, e-mail: dev-h...@maven.apache.org > >> > >> -- > > Sent from my phone > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org > For additional commands, e-mail: dev-h...@maven.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@maven.apache.org For additional commands, e-mail: dev-h...@maven.apache.org
