RFR: JDK-8149925 We don't need jdk.internal.ref.Cleaner any more

Roger Riggs Roger.Riggs at Oracle.com
Fri Apr 1 21:51:21 UTC 2016

Hi Peter,

Thanks for the diffs to look at.

Two observations on the changes.

- The Cleaner instance was intentionally and necessarily different than 
the CleanerImpl to enable
the CleanerImpl and its thread to terminate if the Cleaner is not longer 
Folding them into a single object breaks that.

Perhaps it is not too bad for ExtendedCleaner to subclass CleanerImpl 
with the cleanup helper/supplier behavior
and expose itself to Bits. There will be fewer moving parts.  There is 
no need for two factory methods for
ExtendedCleaner unless you are going to use  a separate ThreadFactory.

- The Deallocator (and now Allocator) nested classes are identical, and 
there is a separate copy for each
type derived from the Direct-X-template.  But it may not be worth fixing 
until the rest of it is settled to avoid
more moving parts.

I don't have an opinion on the code changes in Reference, that's 
different kettle of fish.

More next week.

Have a good weekend, Roger

On 4/1/2016 12:46 PM, Peter Levart wrote:
> On 04/01/2016 06:08 PM, Peter Levart wrote:
>> On 04/01/2016 05:18 PM, Peter Levart wrote:
>>> @Roger:
>>> ...
>>> About entanglement between nio Bits and 
>>> ExtendedCleaner.retryWhileHelpingClean(). It is the same level of 
>>> entanglement as between the DirectByteBuffer constructor and 
>>> Cleaner.register(). In both occasions an action is provided to the 
>>> Cleaner. Cleaner.register() takes a cleanup action and 
>>> ExtendedCleaner.retryWhileHelpingClean() takes a retriable 
>>> "allocating" or "reservation" action. "allocation" or "reservation" 
>>> is the opposite of cleanup. Both methods are encapsulated in the 
>>> same object because those two functions must be coordinated. So I 
>>> think that collocating them together makes sense. What do you think?
>> ...to illustrate what I mean, here's a variant that totally untangles 
>> Bits from Cleaner and moves the whole Cleaner interaction into the 
>> DirectByteBuffer itself:
>> http://cr.openjdk.java.net/~plevart/jdk9-dev/removeInternalCleaner/webrev.13.part2/ 
>> Notice the symmetry between Cleaner.retryWhileHelpingClean : 
>> Cleaner.register and Allocator : Deallocator ?
>> Regards, Peter
> And here's also a diff between webrev.12.part2 and webrev.13.part2:
> http://cr.openjdk.java.net/~plevart/jdk9-dev/removeInternalCleaner/webrev.diff.12to13.part2/ 
> Regards, Peter

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