Hi Roger,
On 12/04/2017 03:09 PM, Peter Levart wrote:
On 12/04/2017 02:25 PM, Peter Levart wrote:
Hi Rogger,
On 12/04/2017 02:17 PM, Peter Levart wrote:
Hi Rogger,
Interesting approach. Conditional finalization. You use finalization
to support cases where user overrides finalize() and/or close() and
Cleaner when he doesn't.
I wonder if it is the right thing to use AltFinalizer when user
overrides finalize() method. In that case the method is probably not
empty and calls super.finalize() (if it is empty or doesn't call
super, user probably doesn't want the finalization to close the
stream) and so normal finalization applies. If you register
AltFinalizer for such case, close() will be called twice.
Ah, scrap that. I forgot that XXXStream.finalize() is now empty, so
user overriding it and calling super does not in fact close the
stream. You have to register AltFinalizer in that case. But now I
wonder if the logic should still be 3-state and do the following:
- if user overrides finalize() - use AltFinalizer to call both: first
finalize() and then close(); else
- if user overrides close() - use AltFinalizer to call close(); else
- use Cleaner
What do you think?
Regards, Peter
I just realized that in the above case when finalize is overridden, it
would be called twice. once by finalization and once by AltFinalizer.
So your logic is as correct as it can be for that case (to just call
close() with AltFinalizer). The only problem is order which is
arbitrary, so it may happen that AltFinalizer calls close() 1st and
then finalization calls overridden finalize() method which might
expect the stream to still be open until it calls super.finalize().
Regards, Peter
Final refinement... (hopefully!)
If user overrides just finalize() and does not override close(), then it
might be best to employ Cleaner to close the stream. Cleaner is Phantom
based and will get fired after finalization invokes overridden
finalize(), enabling the finalize() method to still access the stream in
that case. So this is the final logic (I think):
- if user overrides close(), use AltFinalizer to call close(); else
- use Cleaner to close the stream
The above logic in action:
finalize() close() action
not overridden not overridden Cleaner closes stream
not overridden overridden AltFinalizer calls close()
overridden not overridden finalization calls
finalize() then Cleaner closes stream
overridden overridden finalization calls
finalize() and AltFinalizer calls close() (in arbitrary order)
Regards, Peter
