> On Feb 21, 2016, at 10:55 AM, Peter Levart <peter.lev...@gmail.com> wrote:
>
> Hi Kim, Roger,
>
> I have prepared another webrev which addresses your outstanding concerns:
>
> http://cr.openjdk.java.net/~plevart/jdk9-dev/removeInternalCleaner/webrev.04/
>
MethodHandleNatives.java
line 71-74 Nit: can you break the long lines
> I added new method to Cleaner:
>
> public boolean helpClean() { }
>
I’m in two minds of making this a public method. An explicit way to enqueue
pending references as well as invoke Cleanable::clean. If it goes in, the
method name needs to be renamed.
The existing way to do that is to register phantom references in your own
ReferenceQueue and then drain the queue at appropriate point. Would you
consider having a method to return ReferenceQueue maintained by the cleaner
instead?
Other than this new method, the change looks good to me.
Mandy
> I think this form of method that just does one quantum of work and returns a
> boolean indicating whether there's more work waiting is a better fit for some
> clients that might want to do just a limited amount of work at once (like for
> example sun.java2d.Disposer.pollRemove that you mentioned). This method also
> deals with helping the ReferenceHandler thread, which is necessary to be able
> to "squeeze" out all outstanding work. As Cleaner is in the same package as
> Reference and helping ReferenceHandler thread is implicitly included in
> Cleaner.helpClean(), the JavaLangRefAccess interface and a field in
> SharedSecrets can be removed.
>
> I also simplified the API in sun.nio.fs.NativeBuffer and replaced the
> accessor of Cleanable with a simple void free() method (called free because
> it deallocates memory).
>
> I think this will have to be submitted to CCC for approval, right? Can you
> help me with it?
>
>
> Regards, Peter
>
> On 02/17/2016 11:34 PM, Kim Barrett wrote:
>>> On Feb 17, 2016, at 4:06 AM, Peter Levart <peter.lev...@gmail.com> wrote:
>>>
>>> Hi Kim,
>>>
>>> Thanks for looking into this. Answers inline…
>> Peter,
>>
>> Thanks for the explanations.
>>
>>> On 02/17/2016 01:20 AM, Kim Barrett wrote:
>>>>> However, I recall Roger saying there were existing tests that
>>>> failed when certain uses of sun.misc.Cleaner were replaced with
>>>> java.lang.ref.Cleaner. I don't remember the details, but maybe Roger
>>>> does.
>>> If the failing test was the following:
>>>
>>> java/nio/Buffer/DirectBufferAllocTest.java
>>>
>>> ...then it has been taken care of (see Bits.java).
>> That looks familiar. And yes, I see what you did there, and I don't
>> think Roger's initial prototype testing did anything similar, so
>> indeed this is likely the failure he encountered.
>>
>> Though I'm still inclined to object to that form of drainQueue (see
>> below).
>>
>>>> I don't understand why CleanerImpl needs to be changed to public in
>>>> order to provide access to the new drainQueue. Wouldn't it be better
>>>> to add Cleaner.drainQueue?
>>> An interesting idea. But I don't know if such functionality is generally
>>> useful enough to commit to it in a public API.
>> java.desktop:sun.java2d.Disposer.pollRemove seems to me to be
>> addressing an essentially similar requirement, with
>> java.desktop:sun.font.StrikeCache being the user of that API.
>>
>> Of course, that's already got all the scaffolding for using phantom
>> references, and there's no need to rewrite it to use
>> java.lang.ref.Cleaner. But maybe there are others like this?
>>
>> In any case, I really dislike the approach of exposing the CleanerImpl
>> object to get at this functionality.
>>
>>>> Some of the other changes here don't seem related to the problem at
>>>> hand. ...
>>> One thing that this change unfortunately requires is to get rid of lambdas
>>> and method references in the implementation and dependencies of
>>> java.land.ref.Cleaner API, because it gets used early in the boot-up
>>> sequence when java.lang.invoke infrastructure is not ready yet.
>> Oh, right! Bootstrapping issues!
>>
>>> The alternative to CleanerCleanable is a no-op Runnable implementation
>>> passed to PhantomCleanableRef constructor. …
>> OK. Now I understand.
>>
>>> Making CleanerImpl implement Runnable …
>> I'd be fine with this if the CleanerImpl wasn't exposed as part of the
>> drainQueue functionality.
>>
>>>> ------------------------------------------------------------------------------
>>>> src/java.base/share/classes/sun/nio/fs/NativeBuffer.java
>>>> 76 Cleaner.Cleanable cleanable() {
>>>> 77 return cleanable;
>>>> 78 }
>>>>
>>>> [pre-existing, but if we're changing things anyway...]
>>>>
>>>> I'm kind of surprised by an accessor function (both here and in the
>>>> original code) rather than a cleanup function. Is there a use case
>>>> for anything other than buffer.cleanable().clean()?
>>> It can't be, since both old Cleaner and new Cleanable have only got a
>>> single method - clean().
>> So this could be replaced with
>>
>> void clean() {
>> cleanable.clean();
>> }
>>
>> To me, that seems better.
>>
>>>> Similarly for the DirectBuffer interface.
>>> This one is a critical method, used by various 3rd party softwares...
>> I want to cover my ears when people start talking about some of the
>> things that have done… OK.
>>
>>
>>
>>
>
