Bug 531634 - [GTK] Linux: Handle logoff / shutdown events from session manager

Hotfix for first version of the patch.

Using System.exit() from Shell's 'SWT.Close' event caused deadlock,
because main thread held 'Platform.lock' in its event loop and waited
for shutdown hook, which waited for the lock - see also Bug 546743.

Since multiple Displays are not possible currently (there's only dead
code pretending to support it), it should be OK to have non-static
object. Having it non-static removes the need for shutdown hook.

Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug531634_LogoffListener.java b/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug531634_LogoffListener.java
index 8187df05c2..4e75c0a3be 100644
--- a/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug531634_LogoffListener.java
+++ b/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug531634_LogoffListener.java
@@ -19,6 +19,8 @@ import org.eclipse.swt.layout.FillLayout;
 import org.eclipse.swt.widgets.*;

 

 public class Bug531634_LogoffListener {

+	private static boolean isUserClosed = false;

+

 	public static void main (String [] args) {

 		Display display = new Display ();

 

@@ -34,7 +36,7 @@ public class Bug531634_LogoffListener {
 		});

 

 		display.addListener(SWT.Dispose, event -> {

-			if (!shell.isDisposed()) {

+			if (!isUserClosed && !shell.isDisposed()) {

 				MessageBox dialog = new MessageBox(shell, SWT.ICON_INFORMATION);

 				dialog.setMessage("EndSession received.\nI will exit when you close this box. Time limit is 10 sec.");

 				dialog.open();

@@ -44,6 +46,15 @@ public class Bug531634_LogoffListener {
 		final Label label = new Label(shell, SWT.WRAP | SWT.CENTER);

 		label.setText("\n\n\nWhen you logoff/shutdown, I will give you messages on 'QueryEndSession' and 'EndSession'");

 

+		// The first version of the patch had deadlock when System.exit() was called in response to UI action.

+		// This happened because 'SWT.Close' is called from inside 'OS.g_main_context_iteration' and

+		// Platform.lock is held by main thread, locking all OS.xxx calls from other threads.

+		shell.addListener(SWT.Close, event -> {

+			isUserClosed = true;

+			display.dispose();

+			System.exit(0);

+		});

+

 		shell.open ();

 

 		while (!shell.isDisposed()) {