Fix LT-21934: fork task to stop parser so control returns to user

Src/LexText/ParserCore/ParseFiler.cs

@@ -77,6 +77,16 @@ public class ParseFiler
 
 		#region Properties
 
+		/// <summary>
+		/// Are we in the process of stopping the thread this is running in?
+		/// </summary>
+		public bool Stopping;
+
+		/// <summary>
+		/// Are we updating word forms?
+		/// </summary>
+		public bool UpdatingWordforms;
+
 		#endregion Properties
 
 		#region Construction and Disposal
@@ -108,6 +118,9 @@ public ParseFiler(LcmCache cache, Action<TaskReport> taskUpdateHandler, IdleQueu
 			m_baseAnnotationRepository = servLoc.GetInstance<ICmBaseAnnotationRepository>();
 			m_baseAnnotationFactory = servLoc.GetInstance<ICmBaseAnnotationFactory>();
 			m_userAgent = m_cache.LanguageProject.DefaultUserAgent;
+
+			Stopping = false;
+			UpdatingWordforms = false;
 		}
 
 		#endregion Construction and Disposal
@@ -145,6 +158,12 @@ private bool UpdateWordforms(object parameter)
 			if (!((IActionHandlerExtensions) m_cache.ActionHandlerAccessor).CanStartUow)
 				return false;
 
+			// Don't update words if we are stopping.
+			if (Stopping)
+				return false;
+			// Don't stop if we are updating words.
+			UpdatingWordforms = true;
+
 			// update all of the wordforms in a batch, this might slow down the UI thread a little, if it causes too much unresponsiveness
 			// we can bail out early if there is a message in the Win32 message queue
 			IEnumerable<WordformUpdateWork> results;
@@ -208,6 +227,7 @@ from ann in m_baseAnnotationRepository.AllInstances()
 					FireWordformUpdated(work.Wordform, work.Priority, work.ParseResult, work.CheckParser);
 				}
 			});
+			UpdatingWordforms = false;
 			return true;
 		}
 

Src/LexText/ParserCore/ParserScheduler.cs

@@ -12,6 +12,7 @@
 using SIL.LCModel;
 using SIL.ObjectModel;
 using XCore;
+using System.Threading;
 
 namespace SIL.FieldWorks.WordWorks.Parser
 {
@@ -196,6 +197,20 @@ public bool TryAWordDialogIsRunning
 		}
 
 		protected override void DisposeManagedResources()
+		{
+			// Wait until wordforms aren't being updated.
+			m_parserWorker.ParseFiler.Stopping = true;
+			while (m_parserWorker.ParseFiler.UpdatingWordforms)
+				Thread.Sleep(1);
+			// It should be safe to stop the thread now.
+			// (Thread.Stop aborts after 60 seconds, which can leave things in a funny state.)
+			System.Threading.Tasks.Task.Run(() =>
+			{
+				FinishDisposeManagedResources();
+			});
+		}
+
+		private void FinishDisposeManagedResources()
 		{
 			m_thread.Stop();
 			m_thread.Dispose();

Src/LexText/ParserUI/ParserUIStrings.resx

@@ -344,7 +344,4 @@
   <data name="ksEnterComment" xml:space="preserve">
     <value>Please enter a comment for the parser report</value>
   </data>
-  <data name="ksStoppingParser" xml:space="preserve">
-    <value>Stopping the Parser (may take up to a minute)</value>
-  </data>
 </root>

Src/LexText/ParserUI/TryAWordDlg.cs

@@ -369,7 +369,6 @@ protected override void OnClosed(EventArgs ea)
 			m_persistProvider.PersistWindowSettings(PersistProviderID, this);
 			if (m_parserListener.Connection != null)
 			{
-				this.Text = ParserUIStrings.ksStoppingParser;
 				m_parserListener.Connection.TryAWordDialogIsRunning = false;
 				m_parserListener.DisconnectFromParser();
 			}