Fix InterruptedException while stopping the spider

Append the messages to output tab and add the messages to History tab
asynchronously in the EDT, preventing the exceptions (and "hanging" the
spider worker threads more time than needed).

More detailed changes:
 - AuthenticationHelper, append the authentication status messages
 to the OutputPanel and add the authentication messages to the
 ExtensionHistory, asynchronously (for the latter also check if the View
 is initialised, otherwise there's no point adding it);
 - OutputPanel, add a convenience method that adds a message
 asynchronously to the panel itself.

Fix zaproxy#2429 - InterruptedExceptions while stopping the spider with user
authentication

src/org/parosproxy/paros/view/OutputPanel.java

@@ -214,4 +214,21 @@ private void doAppend(String message){
 			getTxtOutput().append(message);
 	}
 
+	/**
+	 * Appends the given {@code message} to the panel, asynchronously in the EDT.
+	 *
+	 * @param message the message to append to the output panel
+	 * @since TODO add version
+	 * @see EventQueue#invokeLater(Runnable)
+	 */
+	public void appendAsync(final String message) {
+		EventQueue.invokeLater(new Runnable() {
+
+			@Override
+			public void run() {
+				doAppend(message);
+			}
+		});
+	}
+
   }  //  @jve:decl-index=0:visual-constraint="10,10"

src/org/zaproxy/zap/authentication/AuthenticationHelper.java

@@ -1,5 +1,6 @@
 package org.zaproxy.zap.authentication;
 
+import java.awt.EventQueue;
 import java.io.IOException;
 
 import org.apache.commons.httpclient.HttpState;
@@ -57,7 +58,7 @@ public static void notifyOutputAuthSuccessful(HttpMessage msg) {
 		// Let the user know it worked
 		if (View.isInitialised()) {
 			View.getSingleton().getOutputPanel()
-					.append(Constant.messages.getString("authentication.output.success") + "\n");
+					.appendAsync(Constant.messages.getString("authentication.output.success") + "\n");
 		}
 	}
 
@@ -71,7 +72,7 @@ public static void notifyOutputAuthFailure(HttpMessage msg) {
 		// Let the user know it failed
 		if (View.isInitialised()) {
 			View.getSingleton().getOutputPanel()
-					.append(Constant.messages.getString("authentication.output.failure") + "\n");
+					.appendAsync(Constant.messages.getString("authentication.output.failure") + "\n");
 		}
 	}
 
@@ -84,13 +85,22 @@ public HttpState getCorrespondingHttpState() {
 	public static void addAuthMessageToHistory(HttpMessage msg) {
 		// Add message to history
 		try {
-			HistoryReference ref = new HistoryReference(Model.getSingleton().getSession(),
+			final HistoryReference ref = new HistoryReference(Model.getSingleton().getSession(),
 					HistoryReference.TYPE_AUTHENTICATION, msg);
 			ref.addTag(HISTORY_TAG_AUTHENTICATION);
-			ExtensionHistory extHistory = Control.getSingleton().getExtensionLoader()
-					.getExtension(ExtensionHistory.class);
-			if (extHistory != null) {
-				extHistory.addHistory(ref);
+			if (View.isInitialised()) {
+				final ExtensionHistory extHistory = Control.getSingleton()
+						.getExtensionLoader()
+						.getExtension(ExtensionHistory.class);
+				if (extHistory != null) {
+					EventQueue.invokeLater(new Runnable() {
+
+						@Override
+						public void run() {
+							extHistory.addHistory(ref);
+						}
+					});
+				}
 			}
 		} catch (Exception ex) {
 			log.error("Cannot add authentication message to History tab.", ex);