[OpenJDK 2D-Dev] FileCacheImageOutputStream.close() is not idempotent

Joe Darcy joe.darcy at oracle.com
Tue Jun 19 19:11:27 UTC 2012

On 6/14/2012 10:37 AM, Phil Race wrote:
> On 6/14/2012 10:09 AM, Martin Desruisseaux wrote:
>> Le 14/06/12 18:59, Phil Race a écrit :
>>> Perhaps the real issue is that the interface Closeable should not 
>>> have made
>>> claims about what all the existing close methods it was added to do 
>>> in all cases.
>>> FileInputStream.close() made no such claim.
>> AutoCloseable makes no such claim, but Closeable does. If the intend 
>> was to support ARM without complying with the idempotent criterion, 
>> then ImageInputStream should have extended AutoCloseable rather than 
>> Closeable...
> The list of classes implementing each of these looks to be the same 
> and I'm not sure if there
> was careful consideration. But its a very long list and I've not 
> examined it closely.
> I just assume that it would not make sense for either of these to add 
> requirements beyond
> what FileInputStream.close() already did. But its too late to undo 
> this in any case.

Mea culpa; when I retrofitted Closeable/AutoCloseable to this batch of 
classes, since the close methods are not idempoent, the *Image*Stream 
types should have been marked AutoCloseable rather than Closeable, a 
policy recommended elsewhere:

     "Project Coin: Bringing it to a Close(able)"

Since JDK 7 has already shipped, changing the implemented interface from 
Closeable to AutoCloseble would be a binary incompatible change and 
those strongly recommended against.  If possible, I think the best way 
to address this problem would be to make the methods idempotent.


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