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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
> > > >>
> > > >>
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> >
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