RFR: JDK-8297605 DelayQueue javadoc is confusing

[Viktor Klang]

On Thu, 23 Feb 2023 21:20:27 GMT, Martin Buchholz <martin at openjdk.org> wrote:

> Here's my attempt:
> 
> ```
>  * An unbounded {@linkplain BlockingQueue blocking queue} of {@link Delayed}
>  * elements, in which an element generally becomes eligible for removal when its
>  * delay has expired.
>  *
>  * <p>An element is considered <em>expired</em> when its {@code
>  * getDelay(TimeUnit.NANOSECONDS)} method would return a value less than or
>  * equal to zero.
>  *
>  * <p>An element is considered the <em>head</em> of the queue if it is the
>  * element with the earliest expiration time, whether in the past or the future,
>  * if there is such an element.
>  *
>  * <p>An element is considered the <em>expired head</em> of the queue if it is
>  * the <em>expired</em> element with the earliest expiration time in the
>  * past, if there is such an element.
>  * The <em>expired head</em>, when present, is also the <em>head</em>.
>  *
>  * <p>While this class implements the {@code BlockingQueue} interface, it
>  * intentionally violates the general contract of {@code BlockingQueue}, in that
>  * the following methods disregard the presence of unexpired elements and only
>  * ever remove the <em>expired head</em>:
>  *
>  * <ul>
>  * <li> {@link #poll()}
>  * <li> {@link #poll(long,TimeUnit)}
>  * <li> {@link #take()}
>  * <li> {@link #remove()}
>  * </ul>
>  *
>  * <p>All other methods operate on both expired and unexpired elements.  For
>  * example, the {@code size} method returns the count of all elements.  Method
>  * {@link peek()} may return the non-null <em>head</em> even when {@code
>  * take()} would block waiting for that element to expire.
>  *
>  * <p>This queue does not permit null elements.
> ```

I think that approach sounds good. @DougLea, any opinion on this class javadoc summary?

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PR: https://git.openjdk.org/jdk/pull/12729