RFR: 8355301: Simplify Throwable::printStackTrace by using record [v4]

[Johannes Döbler]

On Fri, 25 Apr 2025 07:06:05 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>>> What should we replace it with? Do you have any suggestions?
>> 
>> The wrapper classes were needed when there were was a mix of synchronized and j.u.concurrent locks in use. With JEP 491 integrated it meant that the java.io classes could be changed back to use synchronized.  Yes, we could do some cleanup in Throwable too. Changing PrintStreamOrWriter to be an interface should be fine but the rest of these changes in this PR doesn't seem necessary. As others have already asked, I think it would be useful to understand what issue you are running into and why you want to change this code.
>
>> @AlanBateman I have modified it to use interface + record. Is this what you want?
> 
> I don't object to changing it to interface + record but it feels more like needless code churn. I really disliked the next version that used printStackTrace0(Object printer) as it immediately invites another re-write.

The record has fewer source lines but doesn't the generated record class have a getter, toString(), hashCode() and equals(Object) which are not needed here?
What about using a lock parameter and a method handle to pass in the required features of PrintStream and PrintWriter:

public void printStackTrace(PrintWriter pw) {
    printStackTrace(pw, pw::println);
}

public void printStackTrace(PrintStream ps) {
    printStackTrace(ps, ps::println);
}

private void printStackTrace(Object lock, Consumer<Object> println) {
    synchronized(lock) {
    	...
        println.accept(this);
    	...
    }
}

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PR Review Comment: https://git.openjdk.org/jdk/pull/24795#discussion_r2059745913