RFR [9] 8071472: Add field setter API for setting final fields in readObject

[Peter Levart]

On 03/23/2015 04:45 PM, Chris Hegarty wrote:
> Here is an updated version of the FieldSetter API, with all comments 
> to date incorporated.
>
>
> http://cr.openjdk.java.net/~chegar/8071472/02/specdiff/overview-summary.html 
>
>
> Final spec comments welcome, after which I intend to submit a CCC 
> request.
>
> -Chris.

Hi Chris,

Recent bug "JDK-8068721 - RMI-IIOP communication fails when 
ConcurrentHashMap is passed to remote method" made me thinking...

ObjectInputStream is an extensible API. There are subclasses of 
ObjectInputStream out there. For example, there is an abstract 
"com.sun.corba.se.impl.io.InputStreamHook" with concrete implementation 
"com.sun.corba.se.impl.io.IIOPInputStream". The InputStreamHook 
overrides ObjectInputStream.defaultReadObject() with it's own 
implementation which doesn call ObjectInputStream.defaultReadObject(), 
which means that FieldSetterContext.checkPersistentFinalsNotSet() and 
FieldSetterContext.markPersistentFinalsSet() is not called for 
InputStreamHook based subclasses when user's readObject() calls 
defaultReadObject(), which further means that 
FieldSetter.checkAllFinalsSet() that is eventually called as last thing 
in user's readObject() method might find any persistent finals as not 
set and throw InvalidObjectException.

I have been thinking about this and I see several solutions:

1. provide protected final methods 
ObjectInputStream.checkPersistentFinalsNotSet() and 
markPersistentFinalsSet() that just delegate to FieldSetterContext for 
ObjectInputStream classes to call as part of their own overriden 
defaultReadObject() method. We should make sure those methods are called 
in JDK's corba InputStreamHook and document they should be called in 3rd 
party subclasses.

2. in ObjectInputStream constructor, detect if defaultReadObject() is 
overridden and set a flag that makes FieldSetter.checkAllFinalsSet() 
effectively a no-op.

3. 1 + 2 + enable for ObjectInputStream subclasses to declare that they 
obey the contract and that they call markPersistentFinalsSet() from 
overridden defaultReadObject() so checkAllFinalsSet() can be enabled.


What do you think?

Regards, Peter