How automatically update EMF ResourceSet on file change?

Question

I need to have always up to date content of some file in my program. I've created an EMF resource set.

Because resourceSet.getResource(resourceURI, true) takes a lot of time to complete I store the resource set in a static field, so files can be cached.

I.e. once resourceSet.getResource(resourceURI, true) is called for some URI the file is cached in resourceSet.

The problem is that resourceSet doesn't update it's cache automatically:

I.e.:

resourceSet.getResource(resourceURI, true);
// delete resourceURI from file system

// Here I expect null, but old version of the file is returned
resourceSet.getResource(resourceURI, true);

How to force resourceSet to update cache if needed?

I'm using org.eclipse.emf.ecore.resource.impl.ResourceSetImpl, but probably I need another version of ResourceSet that takes modification stamps into account?

Answer 1

Two things: first if you want to reload the resource, you'll have to call

aResource.unload([..]);
aResource.load([..])

As EMF is not requiring Eclipse in any way the Resource and ResourceSet classes are not the same as the Eclipse workspace IResource subclasses, which mean changing a file on the file system will not cause the EMF Resources to be reloaded.

It's pretty easy to do though, have a look on the XxxxEditor EMF generated for you, the class instantiate a IResourceChangeListener which will receive deltas from the Eclipse workspace when a file is being modified. The generated listener process these deltas by reloading the resources.

protected IResourceChangeListener resourceChangeListener = new IResourceChangeListener() {
    public void resourceChanged(IResourceChangeEvent event) {
        IResourceDelta delta = event.getDelta();
        //find out which EMF Resource matches with the IResource and reload it
    }
}