RFR: 8336339: (se) SelectionKey.interestOps(int) should not throw ClosedSelectorException

[Alan Bateman]

If a Selector is closed at around the same time that a registered key's interestOps (or variants) are used to change the interest ops then interestOps may (incorrectly) throw ClosedSelectorException (CSE) These methods are only specified to throw IAE or CancelledKeyException. Related is that closing a Selector ay around the same time that a channel is initially registered that can with NPE when attempting to remove the key for the channel's registration with the selector.

The issue with interestOps dates from JDK 11 when the Selector were mostly re-implemented. The issue with register racing with close may date back further.  The Selector implementations are updated to just queue the update so that CSE is not thrown. An option here would be to not queue or remove the update when racing with close but it's not worth it. For the NPE, the AbstractSelectableChannel.removeKey checks if the keys array has been initialized, which is consistent with other access.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/20269/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20269&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336339
  Stats: 162 lines in 8 files changed: 128 ins; 25 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/20269.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20269/head:pull/20269

PR: https://git.openjdk.org/jdk/pull/20269