Working on IO loop stuff.
diff --git a/utils/misc/pom.xml b/utils/misc/pom.xml
index 899edcf..b451b50 100644
--- a/utils/misc/pom.xml
+++ b/utils/misc/pom.xml
@@ -20,7 +20,10 @@
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava-testlib</artifactId>
-            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.onlab.onos</groupId>
+            <artifactId>onlab-junit</artifactId>
         </dependency>
         <dependency>
             <groupId>io.netty</groupId>
diff --git a/utils/misc/src/main/java/org/onlab/util/Counter.java b/utils/misc/src/main/java/org/onlab/util/Counter.java
new file mode 100644
index 0000000..ae97b76
--- /dev/null
+++ b/utils/misc/src/main/java/org/onlab/util/Counter.java
@@ -0,0 +1,124 @@
+package org.onlab.util;
+
+import java.util.Objects;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkArgument;
+
+/**
+ * Counting mechanism capable of tracking occurrences and rates.
+ */
+public class Counter {
+
+    private long total = 0;
+    private long start = System.currentTimeMillis();
+    private long end = 0;
+
+    /**
+     * Creates a new counter.
+     */
+    public Counter() {
+    }
+
+    /**
+     * Creates a new counter in a specific state. If non-zero end time is
+     * specified, the counter will be frozen.
+     *
+     * @param start start time
+     * @param total total number of items to start with
+     * @param end   end time; if non-ze
+     */
+    public Counter(long start, long total, long end) {
+        checkArgument(start <= end, "Malformed interval: start > end");
+        checkArgument(total >= 0, "Total must be non-negative");
+        this.start = start;
+        this.total = total;
+        this.end = end;
+    }
+
+    /**
+     * Resets the counter, by zeroing out the count and restarting the timer.
+     */
+    public synchronized void reset() {
+        end = 0;
+        total = 0;
+        start = System.currentTimeMillis();
+    }
+
+    /**
+     * Freezes the counter in the current state including the counts and times.
+     */
+    public synchronized void freeze() {
+        end = System.currentTimeMillis();
+    }
+
+    /**
+     * Adds the specified number of occurrences to the counter.  No-op if the
+     * counter has been frozen.
+     *
+     * @param count number of occurrences
+     */
+    public synchronized void add(long count) {
+        checkArgument(count >= 0, "Count must be non-negative");
+        if (end == 0L) {
+            total += count;
+        }
+    }
+
+    /**
+     * Returns the number of occurrences per second.
+     *
+     * @return throughput in occurrences per second
+     */
+    public synchronized double throughput() {
+        return total / duration();
+    }
+
+    /**
+     * Returns the total number of occurrences counted.
+     *
+     * @return number of counted occurrences
+     */
+    public synchronized long total() {
+        return total;
+    }
+
+    /**
+     * Returns the duration expressed in fractional number of seconds.
+     *
+     * @return fractional number of seconds since the last reset
+     */
+    public synchronized double duration() {
+        //  Protect against 0 return by artificially setting duration to 1ms
+        long duration = (end == 0L ? System.currentTimeMillis() : end) - start;
+        return (duration == 0 ? 1 : duration) / 1000.0;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(total, start, end);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof Counter) {
+            final Counter other = (Counter) obj;
+            return Objects.equals(this.total, other.total) &&
+                    Objects.equals(this.start, other.start) &&
+                    Objects.equals(this.end, other.end);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("total", total)
+                .add("start", start)
+                .add("end", end)
+                .toString();
+    }
+}
diff --git a/utils/misc/src/test/java/org/onlab/util/CounterTest.java b/utils/misc/src/test/java/org/onlab/util/CounterTest.java
new file mode 100644
index 0000000..4b7c954
--- /dev/null
+++ b/utils/misc/src/test/java/org/onlab/util/CounterTest.java
@@ -0,0 +1,71 @@
+package org.onlab.util;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.onlab.junit.TestTools.delay;
+
+/**
+ * Tests of the Counter utility.
+ */
+public class CounterTest {
+
+    @Test
+    public void basics() {
+        Counter tt = new Counter();
+        assertEquals("incorrect number of bytes", 0L, tt.total());
+        assertEquals("incorrect throughput", 0.0, tt.throughput(), 0.0001);
+        tt.add(1234567890L);
+        assertEquals("incorrect number of bytes", 1234567890L, tt.total());
+        assertTrue("incorrect throughput", 1234567890.0 < tt.throughput());
+        delay(1500);
+        tt.add(1L);
+        assertEquals("incorrect number of bytes", 1234567891L, tt.total());
+        assertTrue("incorrect throughput", 1234567891.0 > tt.throughput());
+        tt.reset();
+        assertEquals("incorrect number of bytes", 0L, tt.total());
+        assertEquals("incorrect throughput", 0.0, tt.throughput(), 0.0001);
+    }
+
+    @Test
+    public void freeze() {
+        Counter tt = new Counter();
+        tt.add(123L);
+        assertEquals("incorrect number of bytes", 123L, tt.total());
+        delay(1000);
+        tt.freeze();
+        tt.add(123L);
+        assertEquals("incorrect number of bytes", 123L, tt.total());
+
+        double d = tt.duration();
+        double t = tt.throughput();
+        assertEquals("incorrect duration", d, tt.duration(), 0.0001);
+        assertEquals("incorrect throughput", t, tt.throughput(), 0.0001);
+        assertEquals("incorrect number of bytes", 123L, tt.total());
+    }
+
+    @Test
+    public void reset() {
+        Counter tt = new Counter();
+        tt.add(123L);
+        assertEquals("incorrect number of bytes", 123L, tt.total());
+
+        double d = tt.duration();
+        double t = tt.throughput();
+        assertEquals("incorrect duration", d, tt.duration(), 0.0001);
+        assertEquals("incorrect throughput", t, tt.throughput(), 0.0001);
+        assertEquals("incorrect number of bytes", 123L, tt.total());
+
+        tt.reset();
+        assertEquals("incorrect throughput", 0.0, tt.throughput(), 0.0001);
+        assertEquals("incorrect number of bytes", 0, tt.total());
+    }
+
+    @Test
+    public void syntheticTracker() {
+        Counter tt = new Counter(5000, 1000, 6000);
+        assertEquals("incorrect duration", 1, tt.duration(), 0.1);
+        assertEquals("incorrect throughput", 1000, tt.throughput(), 1.0);
+    }
+}