Confusing startLock.wait()/finishLock.wait() calls in WindowsSelectorImpl

[Andrey Turbanov]

Hello.
I found confusing calls to Object.wait() in 2 methods:
1. sun.nio.ch.WindowsSelectorImpl.StartLock#waitForStart
https://github.com/openjdk/jdk/blob/4df67426ed02f18af0757897acb28b636a317a91/src/java.base/windows/classes/sun/nio/ch/WindowsSelectorImpl.java#L252
2. sun.nio.ch.WindowsSelectorImpl.FinishLock#waitForHelperThreads
https://github.com/openjdk/jdk/blob/4df67426ed02f18af0757897acb28b636a317a91/src/java.base/windows/classes/sun/nio/ch/WindowsSelectorImpl.java#L304

Methods 'sun.nio.ch.WindowsSelectorImpl.FinishLock#waitForHelperThreads'
and 'sun.nio.ch.WindowsSelectorImpl.StartLock#waitForStart'
are synchronized. It means they are synchronized on 'this'.
But, somewhy, this methods calls to 'wait()' via reference fields in
outer class:

private synchronized boolean waitForStart(SelectThread thread) {
   ...
  startLock.wait();

private synchronized void waitForHelperThreads() {
   ...
  finishLock.wait();


It seems confusing to me. I would expect that method 'wait()' to be
called directly on 'this' too.
For StartLock it even allows to mark it as a 'static' nested class
(minus one redundant field).
Is it intentional to call 'wait()' like this?


Andrey Turbanov