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Efficient way of loading an EMF resource at start-up? [message #1769187]

Thu, 27 July 2017 07:23

Eclipse User

I want to extend the AST of my DSL with dynamically calculated content. This additional code realize some sort of "build-in" library which is created at start-up time and is used during scoping. I have found information about attaching a resource in standalone-applications but the "build-in" lib should also be loaded in the Eclipse plugin. Loading a static DSL source code file is also not an option because I want to create the lib dynamically.

Here is what I have done so far....

class Lib {

    @Inject Provider<XtextResourceSet> resourceSetProvider

    @Inject IResourceScopeCache cache

    def Resource load() {
        val XtextResourceSet resourceSet = resourceSetProvider.get

        val resource = resourceSet.createResource(URI.createURI("dummy:/lib.mydsl"))
        cache.get("load", resource, [
                val InputStream in = new ByteArrayInputStream(" /* 'dynamic' DSL code ('build-in lib') */".getBytes("UTF8"))
                resource.load(in, resourceSet.getLoadOptions())
                return resource
            ]
        )
    }

    // called by scope provider
    def calc() {
        val resource = load()
        cache.get("calc", resource, [ /* calculations based on the loaded resource */ ]
        )
    }
}

- Is this the correct way of loading an EMF resource at runtime?
- The cache is useless. I have measured the time executing calc() with and without cache and there has been no difference. How can I cache the resource loading and the calculation?

Re: Efficient way of loading an EMF resource at start-up? [message #1769189 is a reply to message #1769187]

Thu, 27 July 2017 07:30

Eclipse User

can you elaborate on when and how this transformation can be done.
does it need any information from the ast or not?

what is the actual performance problem you face?
why not doing in the constructor / static initializer of the scope provider
or have a singleton eager binding in your module

why do you need to "load" at all if you create it programmatically?

[Updated on: Thu, 27 July 2017 07:43] by Moderator

Re: Efficient way of loading an EMF resource at start-up? [message #1769192 is a reply to message #1769189]

Thu, 27 July 2017 08:58

Eclipse User

My application creates a library for the DSL user. Due to performance issues in the Eclipse plugin (typing gets terrible slow for huge files) I want to speed-up things by putting some stuff in a build-in library for which I can pre-calculate some things. The build-in library doesn't depend on other resources (no imports) which (as I understand it correctly) makes it a perfect candidate for caching.

why not doing in the constructor / static initializer of the scope provider
or have a singleton eager binding in your module

> Do you have examples for your suggestions? I have my own scope provider and overloaded the getScope() method. If I put things in the constructor I have the problem that resourceSetProvider gets injected and injected members are null in the constructor.

I want to "load" the build-in lib because so I can handle the build-in library like any other DSL source code and I do not need to re-implement algorithms.

Re: Efficient way of loading an EMF resource at start-up? [message #1769194 is a reply to message #1769192]

Thu, 27 July 2017 09:34

Eclipse User

i think simply annotation a util with @Singleton should do the trick

Re: Efficient way of loading an EMF resource at start-up? [message #1769196 is a reply to message #1769194]

Thu, 27 July 2017 09:36

Eclipse User

adding the libary as a jar to the classapth is not an option?

Re: Efficient way of loading an EMF resource at start-up? [message #1769256 is a reply to message #1769196]

Fri, 28 July 2017 06:08

Eclipse User

Thanks Christian, @Singleton was a good tip... I now try to integrate the lib-loading in the Activator class. I have derived from the generated MyDslActivator class and extend the start() method by calling my load() method to load the build-in resource. I inject the library by

@Inject extension Lib lib

but this is the problem. The injection mechanism seams to run later and lib is null. How can I solve this problem?

Re: Efficient way of loading an EMF resource at start-up? [message #1769260 is a reply to message #1769256]

Fri, 28 July 2017 06:47

Eclipse User

no that approach would not involve the activator

in the lib you would simply do the loading on first access or on a method annoted with @Inject.

still my question: why not put a jar with lib files on the classpath?

[Updated on: Fri, 28 July 2017 06:48] by Moderator

Re: Efficient way of loading an EMF resource at start-up? [message #1769304 is a reply to message #1769260]

Fri, 28 July 2017 18:26

Eclipse User

OK, I understand. It works if I use the cache and always call load() in my calc() function but it should not be necessary. The load() function should be called once by Guice so I have rewritten my code. The problem is that the "resourceSet.createResource(..)" call triggers the load() method again and again (if the createResource() call is missing load() is executed once as expected). Do you know why is this the case and how I can circumvent this?

Regarding your question... Yes, creating the library as an external resource would be possible but I think it is cleaner to don't go the extra detour around an external file. It is also makes unit testing easier....

@Singleton
class Lib {

    @Inject Provider<XtextResourceSet> resourceSetProvider

    @Inject IResourceScopeCache cache
    
    var Resource resource

    @Inject
    def void load() {
        val XtextResourceSet resourceSet = resourceSetProvider.get

        resource = resourceSet.createResource(URI.createURI("dummy:/lib.mydsl"))
        val InputStream in = new ByteArrayInputStream(" /* 'dynamic' DSL code ('build-in lib') */".getBytes("UTF8"))
        resource.load(in, resourceSet.getLoadOptions())
    }
}

Re: Efficient way of loading an EMF resource at start-up? [message #1769307 is a reply to message #1769304]

Sat, 29 July 2017 01:15

Eclipse User

Other Utils that do that manage a loaded / is loading state

Re: Efficient way of loading an EMF resource at start-up? [message #1769308 is a reply to message #1769307]

Sat, 29 July 2017 01:17

Eclipse User

And maybe you should no load on startup but on first use.
And use a loaded / is loading state

Re: Efficient way of loading an EMF resource at start-up? [message #1769314 is a reply to message #1769308]

Sat, 29 July 2017 05:18

Eclipse User

just gave it a try and something like this could work

@Singleton
class Lib {

    @Inject Provider<XtextResourceSet> resourceSetProvider

    @Inject IResourceScopeCache cache
    
    var Resource resource

    def void load() {
        val XtextResourceSet resourceSet = resourceSetProvider.get

        resource = resourceSet.createResource(URI.createURI("dummy:/lib.mydsl"))
        val InputStream in = new ByteArrayInputStream("Hello World!".getBytes("UTF8"))
        resource.load(in, resourceSet.getLoadOptions())
    }
    
    def getAllGreetings() {
    	return (resource.contents.head as Model).greetings
    }
}

class MyDslRuntimeModule extends AbstractMyDslRuntimeModule {
	static class LibTypeListener implements TypeListener {
		override <I> void hear(TypeLiteral<I> typeLiteral, TypeEncounter<I> typeEncounter) {
			typeEncounter.register(([Object i|var Lib m = (i as Lib) m.load()] as InjectionListener<I>))
		}
	}

	def void configurePostConstructListener(Binder binder) {
		binder.bindListener(new AbstractMatcher<TypeLiteral<?>>() {
			override boolean matches(TypeLiteral<?> typeLiteral) {
				return typeof(Lib).isAssignableFrom(typeLiteral.getRawType())
			}
		}, new LibTypeListener())
	}
}

Re: Efficient way of loading an EMF resource at start-up? [message #1769328 is a reply to message #1769187]

Sat, 29 July 2017 12:06

Eclipse User

This does not work... :( The load() method is called mysteriously again and again. Do you have any idea what is happening behind the curtain. Yes, I could manage a state but I would have a better feeling to know what is going on.

Re: Efficient way of loading an EMF resource at start-up? [message #1769333 is a reply to message #1769328]

Sat, 29 July 2017 15:46

Eclipse User

Can you give a complete example of what you are doing

Re: Efficient way of loading an EMF resource at start-up? [message #1769612 is a reply to message #1769333]

Wed, 02 August 2017 04:17

Eclipse User

I have tried your example above but the load() method gets called, which calls the createResource() and this seams to trigger the load() method again...

Re: Efficient way of loading an EMF resource at start-up? [message #1769613 is a reply to message #1769612]

Wed, 02 August 2017 04:19

Eclipse User

as i said i would need a complete example and a step by step guide

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