We don't need jdk.internal.ref.Cleaner any more

[Alan Bateman]

On 07/02/2016 22:20, Peter Levart wrote:
> :
>
> If the decision to remove sun.misc.Cleaner was partly influenced by 
> the desire to maintain just 2 instead of 3 Cleaner(s), then my 
> proposal to migrate JDK code to the public API might enable Oracle to 
> reconsider keeping sun.misc.Cleaner.

The main issue driving this is the design principles that we have listed 
in JEP 200. We don't want a standard module (java.base in this case) 
exporting a non-standard API. This means surgery to jettison the 
sun.misc package from java.base and move it to its own module 
(jdk.unsupported is the proposal in JEP 260). This is painful of course 
but we are at least in good shape for the most critical internal API, 
sun.misc.Unsafe.

For sun.misc.Cleaner then the original proposal was for it to be a 
critical internal API too but it become clear that changing the type of 
internal/private fields in the NIO buffer and channel classes would 
break libraries that have been hacking into those fields. If they are 
changing away then there seems little motive to keep sun.misc.Cleaner so 
Chris moved into into jdk.internal.ref for now. As to whether we even 
need to keep jdk.internal.ref.Cleaner then I think the only remaining 
question was whether the special handling of Cleaner in the Reference 
implementation was worth it or not. It may not be, in which case your 
current proposal to just remove seems right.

-Alan.