Description Karsten Thoms 2013-08-26 10:16:53 EDT

The extension point org.eclipse.ui.decorators in plugin org.eclipse.xtend.shared.ui does only filter for the project nature. It is necessary to extend the enablement expression to apply only in IProject. Otherwise the expression will be evaluated on every object in the navigator view.

The issue came up in a customer project which has a very large tree (>100.000 items) in a custom navigator view. The items presented in this tree are EObjects, which adapt to org.eclipse.core.resources.mapping. On changes (filter) of the view all decorators for the elements were queried. This caused the decoration job running very long in the background (5 minutes with profiling).

The objectClass filtering helps the UI to complete much faster (1:19 with profiling).

Change enablement to:
         <enablement>
            <and>
              <objectClass
                  name="org.eclipse.core.resources.IProject"/>
              <objectState
                    name="nature"
                    value="org.eclipse.xtend.shared.ui.xtendXPandNature">
              </objectState>
            </and>
         </enablement>