| [m2e-dev] Improve project configurators execution order |
Currently, for any given Mojo execution in the Maven Lifecycle, you can have one "primary" configurator and an unlimited number of "secondary" configurators, that would run in an undefined order, after the primary one. And BTW, having 2 "primary" configurators is forbidden : eg. for the maven-war-plugin:war goal, m2e-wtp and m2eclipse-webby provide competing "primary" configurators that m2e will reject. In m2e-wtp, I intend to drop the current, legacy org.maven.ide.eclipse.configuration.wtp configurator that basically handles all javaee types (war, ejb, ear...) and replace it with specialized, public configurators for each type. That will allow 3rd party plugins to reuse and extend them more easily (See https://bugs.eclipse.org/bugs/show_bug.cgi?id=412213). But in order to keep backward compatibility with existing plugins depending on it, (I know of JBoss Tools and the Google Plugin for Eclipse), I want to keep org.maven.ide.eclipse.configuration.wtp for a little longer. So I need to be able to chain configurator execution in a more precise way, eg : org.eclipse.m2e.javaee.web.configurator -> org.maven.ide.eclipse.configuration.wtp.configurator (empty configurator) -> com.google.gdt.eclipse.maven.googleProjectConfigurator My plan is to be able to perform a topological sort of a Directed Acyclic Graph (DAG) of project configurators, similar to what we currently use for Project converters. Introducing 2 new attributes to the org.eclipse.m2e.core.projectConfigurators extension point : - runsAfter : a comma-separated list of configuratorIds a given configurator should run after. ids suffixed with an exclamation mark would be optional. - runsBefore : a comma-separated list of configuratorIds a given configurator should run before. ids suffixed with a star would be required So for instance : runsAfter="A,B?" means this configurator X needs to run after A. If A is missing, X will be ignored. If B is present, X will run after. If B is missing we don't care and execute X anyway (For instance the seam configurator needs to run after the web project one for wars or the ear project one for ears, but both are never found at the same time for a given Mojo execution) runsBefore="C,D*" means this configurator X needs to before C, *if* it's present. In this case D *must* be present, or else X will be ignored. Obviously, cyclic dependencies are forbidden and will result in an error. We can still check only 1 "primary" configurator is declared per MojoExecution, by checking only one configurator has no parent in the DAG. The changes required to implement this new feature are fairly self contained in LifecycleMappingFactory, the projectConfigurators.exsd schema and a new sorter class. Existing "secondaryTo" attribute will still be supported for now, but deprecated. All existing plugins will still work as-is. Only the plugins requiring to leverage the new sorting feature will require a dependency to m2e 1.6. Ideally, I would like to be able to sort configurators not only per mojoexecution, but rather per project, see https://bugs.eclipse.org/bugs/show_bug.cgi?id=348791, but that will require a whole lot of work I'm not sure I can do right now. But this is a first step in that direction. Gerrit patch will follow