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RE: [cdt-dev] PDom locking, lifecycle of PDom objects 
Oh, I'm pretty sure the lock acquisition is fairly random and probably
missing in places. Feel free to fix it up as you see necessary.

Cheers,
Doug Schaefer
QNX Software Systems
Eclipse CDT Project Lead
http://cdtdoug.blogspot.com
 

-----Original Message-----
From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On
Behalf Of Schorn, Markus
Sent: Wednesday, September 06, 2006 9:29 AM
To: CDT General developers list.
Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects

Hi,
I just figured out that having read-locks on multiple PDOMs should not
be a problem, as long as no-one tries to obtain write-locks or a
combination of write- and read-locks on multiple PDOM databases. I will
put a note into the documentation of IPDOM.acquireWriteLock().

With that I have a safe solution for computing the Call Hierarchy, which
makes me happy :-)!

---------------------------------------------
On the other hand there is a remaining issue:
---------------------------------------------
When you obtain an IASTTranslationUnit by using the method
'ILanguage.getASTTranslationUnit(...)' with the option
'ILanguage.AST_USE_INDEX' you need to obtain a read-lock, as the
resulting translation unit can contain elements from the PDOM. This is
far from obvious and is not done in various places of the CDT source
code:

ASTProvider.java - org/eclipse/cdt/internal/ui/editor
OpenDefinitionAction.java - org/eclipse/cdt/internal/ui/search/actions
PDOMFastHandleDelta.java -
org/eclipse/cdt/internal/core/pdom/indexer/fast
PDOMFastIndexerJob.java -
org/eclipse/cdt/internal/core/pdom/indexer/fast
PDOMSearchElementQuery.java - org/eclipse/cdt/internal/ui/search
PDOMSearchTextSelectionQuery.java - org/eclipse/cdt/internal/ui/search

Markus.
 

> -----Original Message-----
> From: cdt-dev-bounces@xxxxxxxxxxx 
> [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Doug Schaefer
> Sent: Dienstag, 05. September 2006 16:48
> To: CDT General developers list.
> Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects
> 
> Interesting idea. I've never used adaptBinding that way (I 
> don't think...).
> 
> At any rate, once you get the new binding, you can release 
> the old one and
> the unlock the old PDOM.
> 
> Doug Schaefer
> QNX Software Systems
> Eclipse CDT Project Lead
> http://cdtdoug.blogspot.com
>  
> 
> -----Original Message-----
> From: cdt-dev-bounces@xxxxxxxxxxx 
> [mailto:cdt-dev-bounces@xxxxxxxxxxx] On
> Behalf Of Schorn, Markus
> Sent: Tuesday, September 05, 2006 10:31 AM
> To: CDT General developers list.
> Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects
> 
> The point is that definitions for references are not necessarily
> part of the same project:
> 
> Project A:
>   File: library.h:  void lib_func();
>   File: library.c:  void lib_func() {}
>   File: testLibrary.c: int main(int argc, char** argv) { lib_func();} 
> 
> Project B:
>   File: main.c:  int main(int argc, char** argv) { lib_func();}
> 
> In case I want to show the call hierarchy for 'lib_func', I need to
> search the PDom of project A and B.
> 
> I currently make this happen by using PDOMLinkage.adaptBinding() to
> convert the PDOMBinding from the one PDOM to the other. 
> 
> Markus.
> 
> > -----Original Message-----
> > From: cdt-dev-bounces@xxxxxxxxxxx 
> > [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Doug Schaefer
> > Sent: Dienstag, 05. September 2006 15:19
> > To: CDT General developers list.
> > Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects
> > 
> > Hmm, I'm a little confused. PDOM's don't know about 
> > eachother. So I'm not
> > sure what you meant by (c). Once you have the IASTName, you ask the
> > IPDOMResolver to resolve the IBinding, then from there you 
> > can navigate to
> > references or definitions or declarations. You would have to 
> > do that for
> > each PDOM. It certainly wasn't my intention that you can use 
> > PDOM objects
> > from one PDOM to navigate to objects in another PDOM. Given 
> > that, you would
> > only need to lock one PDOM at a time.
> > 
> > Doug Schaefer
> > QNX Software Systems
> > Eclipse CDT Project Lead
> > http://cdtdoug.blogspot.com
> >  
> > 
> > -----Original Message-----
> > From: cdt-dev-bounces@xxxxxxxxxxx 
> > [mailto:cdt-dev-bounces@xxxxxxxxxxx] On
> > Behalf Of Schorn, Markus
> > Sent: Tuesday, September 05, 2006 8:15 AM
> > To: CDT General developers list.
> > Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects
> > 
> > Doug,
> > 
> > I avoided using PDom objects in the model of the Call Hierarchy,
> > so that should be ok. 
> > Yet I work with the PDOM to find the references. For that I have
> > to access multiple PDOMs and I can see a problem with that, because
> > I cannot obtain the locks on multiple PDOMs without taking the risk
> > of a deadlock. 
> > 
> > Here is what I do
> > (a) convert input from ICElement to IASTName.
> > (b) find references for the IASTName in PDom.
> > (c) find definitions for references in multiple PDoms
> > (d) convert definitions to ICElements.
> > 
> > (c) is the problematic step as I have to use the reference found in
> >     a PDom to search for definitions in all other PDoms.
> > 
> > I'll be happy to discuss this at the summit.
> > 
> > Markus.
> > 
> > > -----Original Message-----
> > > From: cdt-dev-bounces@xxxxxxxxxxx 
> > > [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Doug Schaefer
> > > Sent: Dienstag, 05. September 2006 13:42
> > > To: CDT General developers list.
> > > Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects
> > > 
> > > Sorry, Markus, I was trying very hard not to work on the 
> > > holiday yesterday
> > > ;). 
> > > The PDOM is probably immature in this area, which is one 
> > > reason why the
> > > Index View is hidden and not recommended for heavy use. The 
> > > PDOM does have a
> > > read/write lock on it. While you are looking at objects you 
> > > should have the
> > > read lock turned on. You shouldn't keep them around long 
> > > term. That is the
> > > role of the ICElement objects. That comes back to the need to 
> > > be able to
> > > create ICElement objects from the PDOM and to update them 
> > > based on PDOM
> > > updates. That would probably make your life easier.
> > > 
> > > This is something we need to talk about at the Summit. I'll have a
> > > presentation there that will hopefully clarify what the 
> > > architecture is
> > > supposed to be.
> > > 
> > > Doug Schaefer
> > > QNX Software Systems
> > > Eclipse CDT Project Lead
> > > http://cdtdoug.blogspot.com
> > >  
> > > 
> > > -----Original Message-----
> > > From: cdt-dev-bounces@xxxxxxxxxxx 
> > > [mailto:cdt-dev-bounces@xxxxxxxxxxx] On
> > > Behalf Of Schorn, Markus
> > > Sent: Tuesday, September 05, 2006 4:19 AM
> > > To: CDT General developers list.
> > > Subject: RE: [cdt-dev] PDom locking, lifecycle of PDom objects
> > > 
> > > Hi Doug,
> > > please help me out on this, I really need to understand how 
> > > to correctly
> > > use locks on the PDom. I try to restate my question:
> > > 
> > > The implementation of the Call Hierarchy has the need to work 
> > > with multiple PDoms, because such hierarchies may span 
> over multiple
> > > projects. I must not simultaneously hold locks of multiple PDoms
> > > as this would lead to dead-locks. So I have to avoid locks where
> > > possible and I have to understand under which circumstances this
> > > is reasonable to do.
> > > 
> > > If there is no safe way to work with multiple PDoms we should
> > > make changes to our architecture. That's why I'd like to 
> understand
> > > this as soon as possible.
> > > 
> > > Markus.
> > > 
> > > > -----Original Message-----
> > > > From: cdt-dev-bounces@xxxxxxxxxxx 
> > > > [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Schorn, Markus
> > > > Sent: Montag, 04. September 2006 15:26
> > > > To: CDT General developers list.
> > > > Subject: [cdt-dev] PDom locking, lifecycle of PDom objects
> > > > 
> > > > Hi,
> > > > I am trying to understand how to safely use the PDom. I have 
> > > > a bunch of
> > > > questions. I can only ask the first one, as the next one will 
> > > > depend on
> > > > the first answer. 
> > > > 
> > > > Objects obtained by the PDOM (e.g. PDOMName) will actually 
> > > access the
> > > > database when I invoke methods (e.g. 
> > > PDOMName.toCharArray()) on them.
> > > > What happens if the database was modified after the PDOM 
> > object was
> > > > handed to me?
> > > > 
> > > > Markus.
> > > > _______________________________________________
> > > > cdt-dev mailing list
> > > > cdt-dev@xxxxxxxxxxx
> > > > https://dev.eclipse.org/mailman/listinfo/cdt-dev
> > > > 
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