I've updated https://issues.apache.org/jira/browse/LOG4J2-2803 with a better overview of the existing systems, the idea behind the new system, and some other details. I have some written notes about the state of the mean-bean-machine branch relating to what's left to integrate which is essentially the following:
* Format for bean metadata * Strategy for loading bean metadata * Annotation processor for generating bean metadata * Implementing a configuration scope * Transforming plugin attribute names into generated qualifier names based on configuration node location * Lazy initialization of required beans * Determine if and how bean managers should communicate (i.e., one bean manager per LoggerContext, or one per LoggerContextFactory?) * Refactor plugins to use new API On Sat, 29 May 2021 at 20:58, Ralph Goers <ralph.go...@dslextreme.com> wrote: > > While you could write the ServiceLoader class by hand, I wouldn’t want anyone > to. > That would be error prone. > > I have though about creating a Maven plugin to generate the class, but all > that > would do is replace the proc=only compile step, so there isn’t much point. > > Ralph > > > On May 29, 2021, at 5:40 PM, Ralph Goers <ralph.go...@dslextreme.com> wrote: > > > > We do need better docs on this. 3.0 is going to be a mixed bag. It will be > > easier > > for “normal” applications because plugins now use ServiceLoader instead of > > the Log4jPlugins.dat file. However, it is going to be more challenging for > > those > > developing plugins if they use the Java Platform Module System. > > > > As one might imagine, the compiler now has a modulePath in addition to a > > classPath. When no module-info.java is present Maven will set things up to > > only use the classPath, which will work as normal. However, when a > > module-info.java > > file is present than Maven will configure the project and its tests to use > > the > > modulePath. By itself this isn’t a problem. However, the Java compiler ONLY > > looks for Annotation processors automatically on the classPath. This means > > anyone using JPMS while compiling plugins will have to explicitly configure > > the annotation processor. > > > > There is a second issue when using JPMS. While our annotation processor > > generates the service class and service definition file, JPMS requires that > > the > > Log4jPlugins service class must be declared in module-info.java. This is > > somewhat of a problem because the compiler will fail if it finds the > > module-info.java references the Log4jPlugins service class because the > > annotation processor hasn’t generated it yet. > > > > The only recourse to this is to do a proc=only compile that does not include > > the module-info.java class followed by a full compile with proc=none. > > Personally, > > I think this is a but in javac but I suspect it would be a major change to > > fix it. > > > > I have meant to write a blog post on all of this basically to ask the > > question, > > “Is JPMS really worth it”? > > > > Ralph > > > >> On May 29, 2021, at 11:06 AM, Matt Sicker <boa...@gmail.com> wrote: > >> > >> Hey all, that itch is back to figure out how to complete my previous > >> attempt at the plugin system updates (started a little over a year ago > >> and put on pause at some point). I'm currently working on getting that > >> branch back up to working again with master (mostly needing to update > >> module-info files), and I'm hoping to map out and figure out the path > >> forward on completing it. > >> > >> With that being said, one major aspect of this project will be > >> explaining how the 2.x plugin system works, how it relates to the 3.x > >> system, and the gist of how I'd like to restructure things. Does > >> anyone here have any preferences on how I share some docs about this? > >> I could record some videos that go over code and such, or I could > >> write things up blog style. Note that these docs would be focused at > >> fellow log4j developers and not necessarily the user manual. I still > >> plan to have proper API docs and manual pages for the system, but > >> those would be targeted for users writing their own extensions mainly. > >> > >> Link for background info: > >> https://issues.apache.org/jira/browse/LOG4J2-2803 > >> > > > > > > > >
