Add a dummy mutex type

ta1/Main.java

@@ -15,6 +15,8 @@ class Main {
 			sharedMutex = new MutexTypeD();
 		else if (args[0].equals("H"))
 			sharedMutex = new MutexTypeH();
+		else if (args[0].equals("N"))
+			sharedMutex = new MutexTypeN();
 		else {
 			System.err.println("ERROR : unknown mutex type : " + args[0]);
 			showUsage();
@@ -26,7 +28,7 @@ class Main {
 
 	private static void showUsage() {
 		System.out.println("Usage : java Main <mutex_type>");
-		System.out.println("Where <mutex_type> is one of D|A|H|P");
+		System.out.println("Where <mutex_type> is one of N|D|A|H|P");
 	}
 
 	private static void runExperiment() {

ta1/MutexTypeN.java

@@ -0,0 +1,16 @@
+// Nummy mutex : never refuse ownership
+
+class MutexTypeN extends Mutex {
+
+	public void p(int id) {
+		// Nothing
+	}
+
+	public void v(int id) {
+		// Nothing
+	}
+
+	public String toString() {
+		return "N";
+	}
+}