On Fri, 19 May 2023 06:50:04 GMT, Karthik P K <k...@openjdk.org> wrote:
> could you please help me in understanding how `Util.runAndWait(() -> { });`
> help in this case
After discussing the issue with @kevinrushforth it probably won't.
The idea was to replace Thread.sleep() with something that can work reliably
even when the process takes a long time (i.e. cold boot). Simply increasing
the sleep time to 1000 ms may not be sufficient, I think.
What we need is an equivalent of java.awt.Robot.waitForIdle() which we don't
have in FX. The problem here is that all the processing involving CSS, layout
may take several pulses, and it certainly not guaranteed to be over when the
next event is processed in `Util.runAndWait()`.
We could still use Toolkit.firePulse(), but this apparently is a hack, and it
alters the normal control flow - that is something we are trying to avoid.
Another variant is to add something like that to Util and use that in place of
Thread.sleep(). This method will trigger and wait for an arbitrary number of
pulses (currently 10, but we can pick any reasonable number):
/**
* Triggers and waits for 10 pulses to complete in the specified scene.
*/
public static void waitForIdle(Scene scene) {
int count = 10;
CountDownLatch latch = new CountDownLatch(count);
Runnable pulseListener = () -> {
latch.countDown();
Platform.requestNextPulse();
};
runAndWait(() -> {
scene.addPostLayoutPulseListener(pulseListener);
});
try {
Platform.requestNextPulse();
waitForLatch(latch, 30, "waitForIdle timeout");
} finally {
runAndWait(() -> {
scene.removePostLayoutPulseListener(pulseListener);
});
}
}
I am not sure why we have Scene.addPulseListener() and not a static equivalent
of Robot.waitForIdle(), but here is some earlier work on the pulse listener:
https://bugs.openjdk.org/browse/JDK-8097917
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PR Comment: https://git.openjdk.org/jfx/pull/1091#issuecomment-1554817640
