On Sun, 28 Jul 2024 22:25:52 GMT, Phil Race <p...@openjdk.org> wrote:
>> When a printjob is cancelled midway, `PrinterAbortException `was not thrown
>> in macos. because
>> firstly,` cancelCheck` invokes` LWCToolkit.invokeLater` with null as
>> parameter causing it to fail with NPE and
>> secondly PrinterAbortException was consumed silently when `printLoop` throws
>> any exception
>> which is rectified to throw the PrinterAbortException when encountered..
>
> src/java.desktop/macosx/classes/sun/lwawt/macosx/CPrinterJob.java line 756:
>
>> 754: boolean cancelled = (performingPrinting && userCancelled);
>> 755: if (cancelled) {
>> 756: cancelDoc();
>
> The comments about deadlock refer to isCancelled() but is that not also why
> there was an invokeLater() ?
> It is not at all clear to me. Perhaps you can explain how the deadlock would
> occur and why it is not a problem for calling cancelDoc() ?
This comment was there from initial macosx port. Since
RasterPrinterJob.`isCancelled` relies on `synchronized` block and since this
`cancelCheck` method was called from native, it might have been suspected that
it might block the native AppKit thread, so `invokeLater` was added.
But the problem was `LWCToolkit.invokeLater` is called with `null` argument,
which was not a problem in initial macosx port but
[JDK-8042087](https://bugs.openjdk.org/browse/JDK-8042087) got it modified in
jdk9 to throw an exception if component argument is null, which is the case in
`CPrinterJob.m#cancelCheck`
> LWCToolkit.inokeAndWait is called on the Appkit thread, but if the component
> argument is null it uses EventQueue.invokeLater which would fail with an NPE
> in plugin mode. The method should be updated to throw an exception in case
> the provided component is null.
Coming to your question, I guess if there is a deadlock, calling `cancelDoc`
directly will also face the same issue as it also relies on same
`synchronized(this)` block but I could not find any deadlock issue with the
printing for which this `invokeLater` safeguard was added...
So, Is the above comment " fail with an NPE in plugin mode" still applicable
i.e do we still support plugin mode?
If not, we can restore invokeLater call in this code and use
`Toolkit.getToolkit` if the component is null as it was[ previously to
JDK-8042087
](https://github.com/openjdk/jdk/commit/bb2698cfa6f2bdc92c197f17a7d2f90003db05fa)
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20027#discussion_r1694942392
