Fixes Simulator notifier shutdown

Reenables PIDTolerance tests and fixes #103

Author: ThadHouse

HAL/SimulatorHAL/HALNotifier.cs

@@ -142,6 +142,7 @@ public static void cleanNotifier(IntPtr notifier_pointer, ref int status)
                 if (notifier.next != null) notifier.next.prev = notifier.prev;
                 if (notifiers == notifier) notifiers = notifier.next;
                 Notifiers.Remove(notifier_pointer.ToInt32());
+                s_notifierCount--;
             }
 
             if (Interlocked.Decrement(ref notifierRefCount) == 0)
@@ -153,6 +154,8 @@ public static void cleanNotifier(IntPtr notifier_pointer, ref int status)
                         //Clean up alarm and manager
                         s_alarm.Dispose();
                         s_alarm = null;
+                        //Reset closest trigger to max value for next time.
+                        closestTrigger = ulong.MaxValue;
                     }
 
                 }

HAL/SimulatorHAL/NotifierAlarm.cs

@@ -62,8 +62,6 @@ public void Run()
                     m_enabled = false;
                     m_callback?.Invoke((uint)SimHooks.GetFPGATime(), IntPtr.Zero);
                 }
-
-               
             }
 
         }
@@ -94,8 +92,18 @@ public void WriteTriggerTime(ulong triggerTime)
 
         public void Dispose()
         {
-            m_continue = false;
-            m_enabled = true;
+            bool gotLock = false;
+            try
+            {
+                m_lockObject.Enter(ref gotLock);
+                m_continue = false;
+                m_enabled = true;
+            }
+            finally
+            {
+                if (gotLock) m_lockObject.Exit();
+            }
+
             m_alarmThread.Join();
         }
     }

WPILib.Tests/TestPIDTolerance.cs

@@ -8,7 +8,7 @@
 
 namespace WPILib.Tests
 {
-    //[TestFixture]
+    [TestFixture]
     public class TestPIDTolerance : TestBase
     {
         private PIDController pid;
@@ -47,7 +47,7 @@ public void PidWrite(double value)
 
         private FakeOutput output;
 
-        //[SetUp]
+        [SetUp]
         public void SetUp()
         {
             input = new FakeInput();
@@ -56,14 +56,14 @@ public void SetUp()
             pid.SetInputRange(-range/2, range/2);
         }
 
-        //[TearDown]
+        [TearDown]
         public void TearDown()
         {
             pid.Dispose();
             pid = null;
         }
 
-        //[Test]
+        [Test]
         public void TestAbsoluteTolerance()
         {
             pid.SetAbsoluteTolerance(tolerance);
@@ -79,7 +79,7 @@ public void TestAbsoluteTolerance()
             Assert.That(pid.OnTarget(), Is.False, $"Error was in tolerance when it should not have been. Error was {pid.GetAvgError()}");
         }
 
-        //[Test]
+        [Test]
         public void TestPercentTolerance()
         {
             pid.SetPercentTolerance(tolerance);