From 68dbbc0a880133e5f2f0d7cdeb5ae43409d7059c Mon Sep 17 00:00:00 2001
From: Jonah Graham <jonah@kichwacoders.com>
Date: Mon, 30 May 2016 21:31:20 +0100
Subject: [PATCH] Bug 494650: prevent UI hang multiple launches terminated

This prevents a deadlock where two different Executor threads are both
listening to changes on the same launch configuration (e.g. when the
same launch configuration is launched twice).

See Bug 494650 for more details and information on the master branch
which has a fuller, more involved fix.

This change is a continuation of:
  commit 628389071558c43c52b666995e1eaa5c4aa67a8f
  Bug 472765: Use gdb's "set substitute-path from to"

Change-Id: I7615e34a949d7766c178025923cdab920250a591
Signed-off-by: Jonah Graham <jonah@kichwacoders.com>
---
 .../launching/GdbSourceLookupParticipant.java | 41 ++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/launching/GdbSourceLookupParticipant.java b/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/launching/GdbSourceLookupParticipant.java
index f13141ef560..12c85d3f1ce 100644
--- a/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/launching/GdbSourceLookupParticipant.java
+++ b/dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/launching/GdbSourceLookupParticipant.java
@@ -1,6 +1,18 @@
+/*******************************************************************************
+ * Copyright (c) 2015 Kichwa Coders and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Jonah Graham (Kichwa Coders) - initial API and implementation to Add support for gdb's "set substitute-path" (Bug 472765)
+ *******************************************************************************/
 package org.eclipse.cdt.dsf.gdb.launching;
 
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 
 import org.eclipse.cdt.dsf.concurrent.ConfinedToDsfExecutor;
 import org.eclipse.cdt.dsf.concurrent.DataRequestMonitor;
@@ -17,6 +29,8 @@ import org.eclipse.cdt.dsf.gdb.internal.GdbPlugin;
 import org.eclipse.cdt.dsf.gdb.service.IGDBSourceLookup;
 import org.eclipse.cdt.dsf.service.DsfServicesTracker;
 import org.eclipse.cdt.dsf.service.DsfSession;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.Status;
 import org.eclipse.debug.core.sourcelookup.ISourceLookupDirector;
 
 /**
@@ -78,7 +92,32 @@ public class GdbSourceLookupParticipant extends DsfSourceLookupParticipant {
 			};
 			fExecutor.execute(query);
 			try {
-				query.get();
+				/*
+				 * This is a workaround to prevent a deadlock due to this
+				 * blocking call. The proper solution of handling this code
+				 * atomically and being non-blocking will be in the next
+				 * release. See Bug 494650 for details.
+				 * 
+				 * Note, even though the timeout is 5 seconds here, the UI
+				 * freeze is actually worst case a 2 x 5 seconds x number of
+				 * simultaneously shutdown launches. This is because each launch
+				 * tries to save the launch configuration 2 times at shutdown
+				 * (once for the Register settings and once for the Memory
+				 * settings), and since each launch notifies all the other
+				 * launches the total UI freeze depends on the number being
+				 * terminated simultaneously.
+				 */
+				query.get(5, TimeUnit.SECONDS);
+			} catch (TimeoutException e) {
+				/*
+				 * Log the error, but with at least a bit of help for the user
+				 */
+				GdbPlugin.log(new Status(IStatus.ERROR, GdbPlugin.PLUGIN_ID,
+						"There was a timeout completing the operation. " //$NON-NLS-1$
+								+ "This is probably due to terminating two launches at the same time. " //$NON-NLS-1$
+								+ "Please consider terminating one launch at a time to avoid the UI lockup. " //$NON-NLS-1$
+								+ "See Bug 494650 for details.", //$NON-NLS-1$
+						e));
 			} catch (InterruptedException | ExecutionException e) {
 				// We have failed to update in some way, we don't really have a
 				// path to expose the failure so at least log it.