Don't run anti-entropy when under high load

Change-Id: I9e480708b9eced73da98e5c4cb27a18aeb08f09a
diff --git a/utils/misc/src/test/java/org/onlab/util/SlidingWindowCounterTest.java b/utils/misc/src/test/java/org/onlab/util/SlidingWindowCounterTest.java
new file mode 100644
index 0000000..884606f
--- /dev/null
+++ b/utils/misc/src/test/java/org/onlab/util/SlidingWindowCounterTest.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onlab.util;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static junit.framework.TestCase.fail;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Unit tests for the sliding window counter.
+ */
+public class SlidingWindowCounterTest {
+
+    private SlidingWindowCounter counter;
+
+    @Before
+    public void setUp() {
+        counter = new SlidingWindowCounter(2);
+    }
+
+    @After
+    public void tearDown() {
+        counter.destroy();
+    }
+
+    @Test
+    public void testIncrementCount() {
+        assertEquals(0, counter.get(1));
+        assertEquals(0, counter.get(2));
+        counter.incrementCount();
+        assertEquals(1, counter.get(1));
+        assertEquals(1, counter.get(2));
+        counter.incrementCount(2);
+        assertEquals(3, counter.get(2));
+    }
+
+    @Test
+    public void testSlide() {
+        counter.incrementCount();
+        counter.advanceHead();
+        assertEquals(0, counter.get(1));
+        assertEquals(1, counter.get(2));
+        counter.incrementCount(2);
+        assertEquals(2, counter.get(1));
+        assertEquals(3, counter.get(2));
+    }
+
+    @Test
+    public void testWrap() {
+        counter.incrementCount();
+        counter.advanceHead();
+        counter.incrementCount(2);
+        counter.advanceHead();
+        assertEquals(0, counter.get(1));
+        assertEquals(2, counter.get(2));
+        counter.advanceHead();
+        assertEquals(0, counter.get(1));
+        assertEquals(0, counter.get(2));
+
+    }
+
+    @Test
+    public void testCornerCases() {
+        try {
+            counter.get(3);
+            fail("Exception should have been thrown");
+        } catch (IllegalArgumentException e) {
+            assertTrue(true);
+        }
+
+        try {
+            new SlidingWindowCounter(0);
+            fail("Exception should have been thrown");
+        } catch (IllegalArgumentException e) {
+            assertTrue(true);
+        }
+
+        try {
+            new SlidingWindowCounter(-1);
+            fail("Exception should have been thrown");
+        } catch (IllegalArgumentException e) {
+            assertTrue(true);
+        }
+    }
+}