| # Building Log4j Core |
| |
| Log4j 2 supports the Java Platform Module System. JPMS has requirements that conflict with several things |
| Log4j also tries to support: |
| 1. OSGi - OSGi frameworks are not packaged as OSGi modules. Including an OSGi implementation will cause |
| compiler errors while resolving the JPMS module inforation. |
| 2. Garbage Free - The Google tool Log4j uses to verify that Log4j core is garbage free violates JPMS rules. The test |
| compilations fail when it is included as a dependency. |
| 3. Compiler bugs - When compiling with module-info.java included the classes in the appender, layout, and filter |
| directories get "duplicate class" errors. For some reason these directory names are being interpreted as starting |
| with upper case letters even though they are not. For some reason the compiler is showing an error |
| that the class cannot be found even though it is being generated. See |
| [JDK-8265826](https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8265826). |
| 4. Test classes that are used by other modules - Several test classes are used by other log4j modules and need |
| to be passed to them. This requires these classes exist in a package that is not used in log4j-core. |
| 5. Test classes used by log4j-core must use the same package space to be able to access some methods in the classes |
| being tested. |
| 6. Once Java has compiled the main module with a module-info.java all test compiles also require one. Likewise, |
| a test compile with a module-info.java is not allowed if the main compile doesn't have one. |
| |
| For these reasons the build will need to be processed as follows: |
| 1. Move the Garbage Free tests to their own module. This will require copying all the test resources. |
| 1. Compile all the main classes except module-info.java with the Plugin preprocessor. |
| 1. Compile the main module-info.java. |
| 1. Compile the test classes used by other modules with module-info.java and with the plugin preprocessor. |
| 1. Package these test classes in a test jar. |
| 1. Delete the module-info and generated source for the test classes. |
| 1. Move the main module-info to a temp location. |
| 1. Compile the unit test classes without module-info.java. |
| 1. Move the main module-info back to the classes directory. |
| 1. Compile module-info.java for unit tests. |
| 1. Run the unit tests. |
| 1. Create the main jar if the unit tests pass. |
| |
| Once the JDK bug is fixed this process can be simplified quite a bit since the components will all be able to be |
| compiled once with the module-info.java file. |
| |
