[
https://issues.apache.org/jira/browse/MYFACES-1820?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12792138#action_12792138
]
Leonardo Uribe commented on MYFACES-1820:
-----------------------------------------
Just as a side note, the latest code in trunk looks like this:
public ELContext getELContext()
{
// Do NOT use getCurrentInstance here. For FacesContext decorators that
// register themselves as "the current instance" that will cause an
// infinite loop. For FacesContext decorators that do not register
// themselves as "the current instance", if they are themselves wrapped
// by a decorator that *does* register itself, then an infinite loop
// also occurs.
//
// As noted above, we really want to do something like
// ctx = getWrappedInstance();
// where the subclass can return the object it is delegating to.
// As there is no such method, however, the best we can do is pass the
// method call on to the first-registered FacesContext instance. That
// instance will never be "this", as the real original FacesContext
// object will provide a proper implementation of this method.
FacesContext ctx = _firstInstance.get();
if (ctx == null)
{
throw new NullPointerException(FacesContext.class.getName());
}
ELContext elctx = ctx.getELContext();
if (elctx == null)
{
throw new UnsupportedOperationException();
}
return elctx;
}
maybe we could add an check for equals to prevent the infinite loop:
if (ctx == this)
{
throw new UnsupportedOperationException();
}
I remember this error usually happens when FacesContext instances not
implementing this method are called, but the current version should works.
> Infinite loop can occur when custom FacesContext subclass compiled against
> JSF1.1 but used with JSF1.2
> ------------------------------------------------------------------------------------------------------
>
> Key: MYFACES-1820
> URL: https://issues.apache.org/jira/browse/MYFACES-1820
> Project: MyFaces Core
> Issue Type: Bug
> Components: JSR-252
> Affects Versions: 1.2.2
> Reporter: Simon Kitching
> Attachments: FacesContext.patch.txt, patch-1820.txt
>
>
> The problem is method FacesContext.getELContext. JSF1.2 added a method to
> this base class that was not there in JSF1.1. This makes life difficult for
> existing JSF1.1 code that already subclasses that class.
> A default concrete implementation needs to exist, in order not to break
> existing JSF1.1 code, but (a) the current one gets it wrong, and (b) defining
> a correct one is difficult (impossible?)
> (1) Stan Silvert initially defined this method like this:
> // The following concrete method was added for JSF 1.2.
> // It supplies a default
> // implementation that throws UnsupportedOperationException.
> // This allows old FacesContext implementations to still work.
> public ELContext getELContext() {
> throw new UnsupportedOperationException();
> }
> (2) Dennis Byrne changed it to its current form:
> public ELContext getELContext() {
> FacesContext ctx = getCurrentInstance();
> if (ctx == null)
> throw new NullPointerException(FacesContext.class.getName());
> ELContext elctx = ctx.getELContext();
> if (elctx == null)
> throw new UnsupportedOperationException();
> return elctx;
> }
> However (2) assumes that custom subclasses never set themselves as the
> current instance, instead only ever *delegating* to the "real" instance.
> If someone's custom subclass of FacesContext ever calls
> setCurrentInstance(this), then an infinite loop will occur here.
> And in fact, this is just what we get:
> java.lang.StackOverflowError
> at java.lang.ThreadLocal$ThreadLocalMap.getEntry(ThreadLocal.java:357)
> at java.lang.ThreadLocal$ThreadLocalMap.access$000(ThreadLocal.java:242)
> at java.lang.ThreadLocal.get(ThreadLocal.java:127)
> at
> javax.faces.context.FacesContext.getCurrentInstance(FacesContext.java:98)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:35)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
> at javax.faces.context.FacesContext.getELContext(FacesContext.java:40)
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
