This PR proposes the following changes to address wrong timeout computations in
the `com.sun.jndi.dns.DnsClient`:
- The `DnsClient` has been updated to use a monotonic high-resolution (nano)
clock. The existing `Timeout` test has also been updated to use the nano clock
to measure observed timeout value.
- The left timeout computation has been fixed to decrease the timeout value
during each retry attempt. A new test, `TimeoutWithEmptyDatagrams`, has been
added to test it.
- The `DnsClient.blockingReceive` has been updated:
- to detect if any data is received
- to avoid contention with `Selector.close()` that could be called by a
cleaner thread
- The expected timeout calculation in the `Timeout` test has been updated to
take into account the minimum retry timeout (50ms). Additionally, the max
allowed difference between the observed timeout and the expected one has been
increased from 50% to 67%. Taking into account 50 ms retry timeout decrease the
maximum allowed difference is effectively set to 61%. This change is expected
to improve the stability of the `Timeout` test which has been seen to fail
[intermittentlly](https://bugs.openjdk.org/browse/JDK-8220213). If no
objections, I'm planning to close
[JDK-8220213](https://bugs.openjdk.org/browse/JDK-8220213) as duplicate of this
one.
JNDI/DNS jtreg tests has been executed multiple times (500+) to check if the
new and the modified tests are stable. No failures been observed (so far?).
-------------
Commit messages:
- 8339538: Wrong timeout computations in DnsClient
Changes: https://git.openjdk.org/jdk/pull/20892/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20892&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8339538
Stats: 232 lines in 3 files changed: 214 ins; 2 del; 16 mod
Patch: https://git.openjdk.org/jdk/pull/20892.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/20892/head:pull/20892
PR: https://git.openjdk.org/jdk/pull/20892
