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LiveScope and new Resources [message #1828391] Tue, 09 June 2020 06:36 Go to next message
Konrad Jünemann is currently offline Konrad JünemannFriend
Messages: 55
Registered: December 2018
Member
Hi,

My DSL generates new DSL files when building. These files must be able to refer to already existing DSL-files. For example, if A.dsl compiles, it should generate B.dsl, which has a cross reference to A.dsl.

I should mention, I am talking about building under Eclipse, so not standalone.

I currently do it this way:
- I use the MyDslGenerator generated by Xtext
- XText calls
doGenerate(Resource resource, IFileSystemAccess2 fsa, IGeneratorContext context)
. Let's call the provided resource resource "A".
- My implementation constructs the new EObjects using the EMF factories. Let's call the created EObject "B".
- The new EObjects are added to the ResourceSet of resource A, like this:
//val A a;
//val B b;
val bPath = getPath(b)
val uri = fsa.getURI(bPath, MyOutputConfigurationProvider.OUTPUT_FOLDER)
val rset = a.eResource.resourceSet
res = rset.createResource(uri)
res.contents.add(b)

- then, I serialize B by using the XText Serializer:
//val B b;
val Serializer ser = gsp.findService(b, Serializer)
val content = ser.serialize(b)
fsa.generateFile(bPath, MyOutputConfigurationProvider.OUTPUT_FOLDER, content)


Unfortunately, this does not work, as B does not see A and the serializer can thus not generate the cross-reference from B to A. The Serializer throws a RunTimeException:
java.lang.RuntimeException: No EObjectDescription could be found in Scope <SoAndSo>
EStructuralFeature: commonmetamodel::Import.member
	at org.eclipse.xtext.serializer.diagnostic.ISerializationDiagnostic$ExceptionThrowingAcceptor.accept(ISerializationDiagnostic.java:132)
	at org.eclipse.xtext.serializer.tokens.CrossReferenceSerializer.getCrossReferenceNameFromScope(CrossReferenceSerializer.java:139)
	at org.eclipse.xtext.serializer.tokens.CrossReferenceSerializer.serializeCrossRef(CrossReferenceSerializer.java:112)
	at org.eclipse.xtext.serializer.acceptor.SequenceFeeder.getToken(SequenceFeeder.java:483)
	at org.eclipse.xtext.serializer.acceptor.SequenceFeeder.accept(SequenceFeeder.java:240)


Now, what I learned is that I should use LiveScopeResourceSetInitializer in order to allow the target resourceSet (which in my case is the same as the source resourceSet) "see" dirty resources. How is this properly done?

What I tried so far:
1. Just using the A-resourceSet and initializing it using the LiveScopeResourceSetInitializer. This does not work as I get the following exception when running a full build:
java.lang.IllegalStateException: Ambiguous scope for the resource set. Can't combine org.eclipse.xtext.scoping.namespaces.DefaultGlobalScopeProvider.BUILDER_SCOPE and org.eclipse.xtext.scoping.LIVE_SCOPE

2. Creating a new resourceSet (using an IResourceSetProvider) each time my generator is called, initializing the newly created rset (just using the XtextLiveScopeResourceSetProvider works fine, too), and adding all resources from the A-resourceSet to the B-resourceSet.
This approach kinda works, but the performance is really bad. The performance is bad, because in a full build, a new resourceSet is created for every single compiled EObject and the
JavaProjectResourceSetInitializer
calls
EcorePlugin.computePlatformPluginToPlatformResourceMap
every time. I can provide the call tree of my profiler, if helpful.

I imagine I am missing something fundamentally. What is the correct way construct my own EObjects in a generator (with incremental and full build)? Do I add add the EObjects to the incoming resourceSet, create a new resourceSet for each built resource (how to tackle the performance issue then?), or do I use a completey different approach?
Re: LiveScope and new Resources [message #1828399 is a reply to message #1828391] Tue, 09 June 2020 08:02 Go to previous messageGo to next message
Karsten Thoms is currently offline Karsten ThomsFriend
Messages: 739
Registered: July 2009
Location: Dortmund, Germany
Senior Member

When I had a similar issue I solved that by triggering a second build job. We added a small delay and then the project builder took up the new resources and just run the builder again as if you would have written the resources manually. IIRC we collected all generated DSL resources and touched them after the delay.
Re: LiveScope and new Resources [message #1828400 is a reply to message #1828399] Tue, 09 June 2020 08:12 Go to previous messageGo to next message
Konrad Jünemann is currently offline Konrad JünemannFriend
Messages: 55
Registered: December 2018
Member
OK, not sure that I fully understand. Are you saying you did not call the serializer explicitely (cause that's where I already get the error) and you did not persists the files manually using the fsa, but instead just pumped the EObjects into the resources and waited?

Re: LiveScope and new Resources [message #1828407 is a reply to message #1828400] Tue, 09 June 2020 10:11 Go to previous messageGo to next message
Christian Dietrich is currently offline Christian DietrichFriend
Messages: 13641
Registered: July 2009
Senior Member
Why no simply added the resource you need to the second resourcesset?

Need professional support for Xtext, Xpand, EMF?
Go to: https://www.itemis.com/en/it-services/methods-and-tools/xtext
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Re: LiveScope and new Resources [message #1828410 is a reply to message #1828407] Tue, 09 June 2020 10:37 Go to previous messageGo to next message
Konrad Jünemann is currently offline Konrad JünemannFriend
Messages: 55
Registered: December 2018
Member
Hi Christian,

That was my second approach (see post above). I basically created a fresh resourceSet every time the generator got called and added the required resources. This worked, but (as it turned out) is incredibly slow when running a FULL_BUILD, as a new resourceSet gets created for every file parsed. Is that a known problem ? Maybe I just use a bad setting?

My DSL Project (that contains the user files, i.e., A and B, not my xtend-sourcecode) has the JavaNature and a plugin dependency to one of my plugins, as I provide some static, "well known" DSL-files through this mechanic. Not sure if this might affect performance.

I uploaded an image of my profiler run here:
https://ibb.co/Lv478w3

As you can see, the performance issue mainly arises as EcorePlugin keeps calculating its
computePlatformPluginToPlatformResourceMap
, triggered by
JavaProjectResourceSetInitializer
.

I am trying to resolve this performance issue, as this way a full build takes ~8 min when it should be way under 1 min.




Re: LiveScope and new Resources [message #1828418 is a reply to message #1828410] Tue, 09 June 2020 13:29 Go to previous messageGo to next message
Christian Dietrich is currently offline Christian DietrichFriend
Messages: 13641
Registered: July 2009
Senior Member
I don't know what you algorithmic do. But you have the control which resourcesets you create

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Twitter : @chrdietrich
Blog : https://www.dietrich-it.de
Re: LiveScope and new Resources [message #1828419 is a reply to message #1828418] Tue, 09 June 2020 13:31 Go to previous messageGo to next message
Christian Dietrich is currently offline Christian DietrichFriend
Messages: 13641
Registered: July 2009
Senior Member
P.s.

computePlatformPluginToPlatformResourceMap

Might be affected by a slow virus scanner

The respective code can also be customized
To skip that call by overriding the Boolean map,
But depending on the usecase this,might affect all dsls in your env


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Re: LiveScope and new Resources [message #1828424 is a reply to message #1828419] Tue, 09 June 2020 13:56 Go to previous messageGo to next message
Konrad Jünemann is currently offline Konrad JünemannFriend
Messages: 55
Registered: December 2018
Member
Quote:
I don't know what you algorithmic do. But you have the control which resourcesets you create


So what is the recommended procedure if I want to create a new DSL File using the XText Serializer? Should I create a new ResourceSet for each call of my Generator the XText Framework makes? This would mean I create many ResourceSets during a typical clean-build procedure.

Re: LiveScope and new Resources [message #1828436 is a reply to message #1828424] Tue, 09 June 2020 15:14 Go to previous messageGo to next message
Christian Dietrich is currently offline Christian DietrichFriend
Messages: 13641
Registered: July 2009
Senior Member
The cleanest would be a fresh es
Or one fresh es for the whole generation
Well it's hard to find a general answer
Maybe a n:1 solution for the generator could help too
Or you simply avoid the serializer and create text
Or you adapt the serializer not to check the
Scope (depends if you have wired shadowing rules or if you have straight forward naming


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[Updated on: Tue, 09 June 2020 15:15]

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Re: LiveScope and new Resources [message #1828449 is a reply to message #1828436] Wed, 10 June 2020 06:47 Go to previous messageGo to next message
Konrad Jünemann is currently offline Konrad JünemannFriend
Messages: 55
Registered: December 2018
Member
Hi Christian,

For documentation purposes, I understand there at least the following approaches:


  1. Creating a new ResourceSet on each Generator Call (so multiple resourceSets on a single full build)
  2. Creating a new ResourceSet on each Generator Call, but deviate on full builds: create only one resourceSet in this case (not sure how I would achive that)
  3. <I don't understand your n:1 proposal> Edit: Create a new Generator-Interface that allows to compile multiple Resources at once, as described here:
    https://kthoms.wordpress.com/2011/07/12/xtend-generating-from-multiple-input-models/
  4. Avoid the serializer all together and create text (I chose this approach in a former project, which worked well, but was a bit redundant to the grammar)
  5. Adapt the serializer (not to check the Scope) -> I guess this will become a bit dirty quickly


Thank you very much for this insight. I thought mayby one of these solution was the clearly prefered way to do it. I think I will first try to stick to option 1 first while trying to tackle the mentioned performance issue. If that fails, I will try to get option 2 working. If that also fails I will use option 4 (text generation), as I know this will work properly.

Many thanks!

[Updated on: Wed, 10 June 2020 11:44]

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Re: LiveScope and new Resources [message #1828453 is a reply to message #1828449] Wed, 10 June 2020 07:11 Go to previous messageGo to next message
Christian Dietrich is currently offline Christian DietrichFriend
Messages: 13641
Registered: July 2009
Senior Member
Regarding 3

https://www.google.de/amp/s/kthoms.wordpress.com/2011/07/12/xtend-generating-from-multiple-input-models/amp/

Don't know if there is an updated version somewhere


Need professional support for Xtext, Xpand, EMF?
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Twitter : @chrdietrich
Blog : https://www.dietrich-it.de
Re: LiveScope and new Resources [message #1828457 is a reply to message #1828453] Wed, 10 June 2020 07:30 Go to previous messageGo to next message
Karsten Thoms is currently offline Karsten ThomsFriend
Messages: 739
Registered: July 2009
Location: Dortmund, Germany
Senior Member

Quote:
Don't know if there is an updated version somewhere


No, but the basic idea is still applicable.
Re: LiveScope and new Resources [message #1828472 is a reply to message #1828457] Wed, 10 June 2020 11:46 Go to previous message
Konrad Jünemann is currently offline Konrad JünemannFriend
Messages: 55
Registered: December 2018
Member
Wow, great input here, guys. Thanks for the link to Karsten's Blog, this might be excactly what I need. I will try to remember to update this post when I got it working.

Many thanks!
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