RFR 8195059: Update java.net Socket and DatagramSocket implementations to use Cleaner

[Roger Riggs]

Hi Chris,

Thanks for the review and suggestion.

Webrev updated:
    http://cr.openjdk.java.net/~rriggs/webrev-net-cleanup-8195059/

  * Refactored SocketCleanup into a java.net package private SocketCleanable
  * Moved register and unregister into static methods in SocketCleanable
  * Simplified the test by retaining the checking for GC reclaimed
    objects but
    removed checking fd counts, since they were unreliable in testing
    and not consistent across OS's

Thanks, Roger

On 2/1/2018 10:11 AM, Chris Hegarty wrote:
> Hi Roger,
>
>> On 31 Jan 2018, at 15:52, Roger Riggs <Roger.Riggs at oracle.com> wrote:
>>
>> Adding net-dev at openjdk.java.net
>>
>> On 1/30/2018 5:08 PM, Roger Riggs wrote:
>>> Please review changes to replace finalizers in socket, datagram, and multicast networking
>>> with Cleaner based release of the raw file descriptors.  Each FileDescriptor is registered
>>> for cleanup after the raw fd (or handle) is assigned.  Normal calls to close unregister the
>>> cleaner before using the current logic to close the raw fd/handle. Windows networking
>>> uses fd's with the Windows socket_ API requiring a special cased Cleanable.
>>>
>>> The tests check that the implementation objects including FileDescriptors are reclaimed
>>> and for Linux that the raw fd counts are reduced as expected.
>>>
>>> Webrev:
>>>     http://cr.openjdk.java.net/~rriggs/webrev-net-cleanup-8195059/
> I think this is good. One small comment; could SocketCleanup be a
> top-level package-private class, since it is shared by the three
> different socket types.
>
> I didn’t look too hard at the tests, other than to note that they seem
> to verify expected behaviour, which is good.
>
> -Chris.