The Plugin interface currently contains 6 different methods for
adding modules. Elasticsearch has 3 different levels of injectors,
and for each of those, there are two methods. The first takes no
arguments and returns a collection of class objects to construct. The
second takes a Settings object and returns a collection of module
objects already constructed. The settings argument is unecessary because
the plugin can already get the settings from its constructor. Removing
that, the only difference between the two versions is returning an
already constructed Module, or a module Class, and there is no reason
the plugin can't construct all their modules themselves.
This change reduces the plugin api down to just 3 methods for adding
modules. Each returns a Collection<Module>. It also removes the
processModule method, which was unnecessary since onModule
implementations fullfill the same requirement. And finally, it renames
the modules() method to nodeModules() so it is clear these are created
once for each node.
the default classloader. It had all kinds of leniency in how the
classname was found, and simply cannot work with plugins having isolated
classloaders.
This change removes that method. Some of the uses of it were for custom
extension points, like custom repository or discovery types. A lot were
just there to plugin mock implementations for tests. For the settings
that were legitimate, all now support plugins adding the given setting
via onModule. For those that were specific to tests for mocks, they now
use Classes.loadClass (a helper around Class.forName). This is a
temporary measure until (in a future PR) tests can change the
implementation via package private statics.
I also removed a number of unnecessary intermediate modules, added a
"jvm-example" plugin that can be filled in in the future as a smoke test
for breaking plugins, and gave some documentation to "spawn" modules
interface.
closes#12643closes#12656
Ryan Ernst
Nik Everett