1 files changed, 139 insertions, 0 deletions
diff --git a/framework/src/onos/utils/misc/src/main/java/org/onlab/util/Counter.java b/framework/src/onos/utils/misc/src/main/java/org/onlab/util/Counter.java
new file mode 100644
index 00000000..bde28783
--- /dev/null
+++ b/framework/src/onos/utils/misc/src/main/java/org/onlab/util/Counter.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright 2014 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 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();
+    }
+}