Re: [Jastadd] Beaver + fullCopy()

From: Jesper qvist <jesper.oqvist_at_cs.lth.se>
Date: Fri, 14 Sep 2012 11:20:07 +0200

Hello!

There are some different approaches to fix this problem. We will be
discussing this within the JastAdd group next week. Hopefully we can
release a fix soon.

/Jesper

On 08/22/2012 05:16 PM, Jesper Mattsson wrote:
>
> Hi
>
> I have found a problem when using the beaver flag to JastAdd. The
> beaver.Symbol class has a final field /value/, that in the default
> constructor is set to /this/. When using copy() or fullCopy(), then
> the node is copied using clone(), and thus the /value/ field is set to
> a reference to the original node. This leads to strange memory leaks,
> where old nodes are retained because of this field.
>
> We have had huge problems in Eclipse with memory leaks, and changing
> ASTNode.clone() to set /value/ to /this/ solves those problems. Doing
> this requires using reflection (since /value/ is final). Here is one
> way to do that:
>
> *public*ASTNode<T> clone() *throws*CloneNotSupportedException {
>
> ASTNode node = (ASTNode)*super*.clone();
>
> node.in$Circle(*false*);
>
> node.is$Final(*false*);
>
> *try*{
>
> Field f = beaver.Symbol.*class*.getField("value");
>
> *new*ClearFinalFieldAction().perform(f, node);
>
> } *catch*(Exception e) {
>
> e.printStackTrace();
>
> }
>
> *return*node;
>
> }
>
> *private**static**class*ClearFinalFieldAction
> *implements*PrivilegedExceptionAction {
>
> *private*Field field;
>
> *public**void*perform(Field f, Object o) *throws*Exception {
>
> field= f;
>
> AccessController./doPrivileged/(*this*);
>
> f.set(o, o);
>
> }
>
> *public*Object run() *throws*Exception {
>
> field.setAccessible(*true*);
>
> *return**null*;
>
> }
>
> }
>
> Jesper
>
> *Jesper MATTSSON, MSc*
>
> Software Developer & IT Administrator
>
> Phone direct: +46 73 324 5909
>
> Email: jesper.mattsson_at_modelon.com <mailto:jesper.mattsson_at_modelon.com>
>
>
> Description: Description: Description: Modelon_2011_Gradient_RGB_400
>
> ------------------------------------------------------------------------
>
> Modelon AB
> Ideon Science Park
> SE-223 70 Lund, Sweden
>
>
>
> Phone: +46 46 286 2200
> Fax: +46 46 286 2201
>
>
>
>
> Web: http://www.modelon.com <http://www.modelon.com/>
>
> This email and any attachments are intended solely for the use of the
> individual or entity to whom it is addressed and may be confidential
> and/or privileged. If you are not one of the named recipients or have
> received this email in error, (i) you should not read, disclose, or
> copy it, (ii) please notify sender of your receipt by reply email and
> delete this email and all attachments, (iii) Modelon does not accept
> or assume any liability or responsibility for any use of or reliance
> on this email.
>
>
> _______________________________________________
> JastAdd mailing list
> JastAdd_at_cs.lth.se
> https://mail1.cs.lth.se/cgi-bin/mailman/listinfo/jastadd
Received on Fri Sep 14 2012 - 11:15:59 CEST

This archive was generated by hypermail 2.3.0 : Wed Apr 16 2014 - 17:19:06 CEST