On Wed, 12 May 2021 at 18:41, Roger Riggs <roger.ri...@oracle.com> wrote: > Will you be posting a PR for the implementation? > It is frequently helpful to evaluate the CSR and the implementation > concurrently.
PR: https://github.com/openjdk/jdk/pull/4016 Issue: https://bugs.openjdk.java.net/browse/JDK-8266846 CSR: https://bugs.openjdk.java.net/browse/JDK-8266847 The PR takes a middle ground approach to the implementation. It is not practical to remove the existing package-scoped Clock implementation classes (SystemClock, TickClock, FixedClock, OffsetClock) despite the fact that these would be better expressed as classes that only implement `InstantSource`. However, given that "system" is the 99%+ use case, I do believe it is worth adding a dedicated `SystemInstantSource` class, as per the PR. To achieve this I moved the actual logic using `VM.getNanoAdjustment()` into a static method which can then be called directly from three places - Instant.now(), SystemClock and SystemInstantSource. Previously, every instance of SystemClock performed the VM/offset calculations separately. The new logic performs them once based on a single shared static variable. I have no reason to believe this changes the memory model or performance, but I must flag it up for reviewers. When initially discussing the proposal, I planned to add a new static method `Clock.of(InstantSource, ZoneId)`. When implementing the change I found that the method was adding no value as the instance method `InstantSource.withZone(ZoneId)` achieves the same outcome, so I omitted it. The Mac test failure appears to be unconnected to the change. Thanks for any and all reviews! Stephen
