RFR: 8346952 : GetGraphicsStressTest.java fails: Native resources unavailable

[Anass Baya]

**Analysis:**

We are encountering a race condition in the native code. While retrieving the screen number by calling _getScreenImOn(), the window is disposed. As a result, the AWT-Windows event loop processes the Dispose() call, which triggers UnlinkObjects().
The race condition between the execution paths of these two native methods sometimes causes an exception

**Proposed Fix:**

While it's possible to introduce a synchronization mechanism, it would not offer any real benefit. The window will be disposed regardless, and we’ll fall back to the default screen. This behavior is already handled in WWindowPeer.java, where a workaround is in place to use the default device when getScreenImOn() returns a non-existent screen number


public void updateGC() {

    int scrn = getScreenImOn();

    if (screenLog.isLoggable(PlatformLogger.Level.FINER)) {
        log.finer("Screen number: " + scrn);
    }

    // get current GD
    Win32GraphicsDevice oldDev = winGraphicsConfig.getDevice();

    Win32GraphicsDevice newDev;
    GraphicsDevice[] devs = GraphicsEnvironment
        .getLocalGraphicsEnvironment()
        .getScreenDevices();

    // Occasionally during device addition/removal getScreenImOn can return
    // a non-existing screen number. Use the default device in this case.
    if (scrn >= devs.length) {
        newDev = (Win32GraphicsDevice) GraphicsEnvironment
            .getLocalGraphicsEnvironment().getDefaultScreenDevice();
    } else {
        newDev = (Win32GraphicsDevice) devs[scrn];
    }
}


Therefore, I propose modifying the native method getScreenImOn to return the default device if the peer is being disposed :

jint AwtWindow::_GetScreenImOn(void *param)
{
...
    jboolean destroyed = JNI_GET_DESTROYED(self);
    if (destroyed == JNI_TRUE){
        env->DeleteGlobalRef(self);
        return AwtWin32GraphicsDevice::GetDefaultDeviceIndex();
    }
...


**Tests Summary:**

  GetGraphicsStressTest (existing test):

        Fails intermittently without the fix

        Consistently passes with the fix

  NotifyStressTest (newly added test):

         Consistently fails without the fix

         Consistently passes with the fix

-------------

Commit messages:
 - Handle white spaces
 - remove extra-space
 - Update copyright
 - Return the default device if the peer is beeing disposed
 - Add Test for JDK-8346952

Changes: https://git.openjdk.org/jdk/pull/25619/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25619&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346952
  Stats: 66 lines in 2 files changed: 66 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/25619.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25619/head:pull/25619

PR: https://git.openjdk.org/jdk/pull/25619