1 files changed, 163 insertions, 0 deletions
diff --git a/qpid/java/broker/src/main/java/org/apache/qpid/server/stats/StatisticsCounter.java b/qpid/java/broker/src/main/java/org/apache/qpid/server/stats/StatisticsCounter.java
new file mode 100644
index 0000000000..b732121180
--- /dev/null
+++ b/qpid/java/broker/src/main/java/org/apache/qpid/server/stats/StatisticsCounter.java
@@ -0,0 +1,163 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.qpid.server.stats;
+
+import java.util.Date;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This class collects statistics and counts the total, rate per second and
+ * peak rate per second values for the events that are registered with it. 
+ */
+public class StatisticsCounter
+{
+    private static final Logger _log = LoggerFactory.getLogger(StatisticsCounter.class);
+    
+    public static final long DEFAULT_SAMPLE_PERIOD = Long.getLong("qpid.statistics.samplePeriod", 2000L); // 2s
+    public static final boolean DISABLE_STATISTICS = Boolean.getBoolean("qpid.statistics.disable");
+    
+    private static final String COUNTER = "counter";
+    private static final AtomicLong _counterIds = new AtomicLong(0L);
+    
+    private long _peak = 0L;
+    private long _total = 0L;
+    private long _temp = 0L;
+    private long _last = 0L;
+    private long _rate = 0L;
+
+    private long _start;
+    
+    private final long _period;
+    private final String _name;
+
+    public StatisticsCounter()
+    {
+        this(COUNTER);
+    }
+    
+    public StatisticsCounter(String name)
+    {
+        this(name, DEFAULT_SAMPLE_PERIOD);
+    }
+
+    public StatisticsCounter(String name, long period)
+    {
+        _period = period;
+        _name = name + "-" + + _counterIds.incrementAndGet();
+        reset();
+    }
+    
+    public void registerEvent()
+    {
+        registerEvent(1L);
+    }
+
+    public void registerEvent(long value)
+    {
+        registerEvent(value, System.currentTimeMillis());
+    }
+
+    public void registerEvent(long value, long timestamp)
+    {
+        if (DISABLE_STATISTICS)
+        {
+            return;
+        }
+        
+        long thisSample = (timestamp / _period);
+        synchronized (this)
+        {
+            if (thisSample > _last)
+            {
+                _last = thisSample;
+                _rate = _temp;
+                _temp = 0L;
+                if (_rate > _peak)
+                {
+                    _peak = _rate;
+                }
+            }
+            
+            _total += value;
+            _temp += value;
+        }
+    }
+    
+    /**
+     * Update the current rate and peak - may reset rate to zero if a new
+     * sample period has started.
+     */
+    private void update()
+    {
+        registerEvent(0L, System.currentTimeMillis());
+    }
+
+    /**
+     * Reset 
+     */
+    public void reset()
+    {
+        _log.info("Resetting statistics for counter: " + _name);
+        _peak = 0L;
+        _rate = 0L;
+        _total = 0L;
+        _start = System.currentTimeMillis();
+        _last = _start / _period;
+    }
+
+    public double getPeak()
+    {
+        update();
+        return (double) _peak / ((double) _period / 1000.0d);
+    }
+
+    public double getRate()
+    {
+        update();
+        return (double) _rate / ((double) _period / 1000.0d);
+    }
+
+    public long getTotal()
+    {
+        return _total;
+    }
+
+    public long getStart()
+    {
+        return _start;
+    }
+
+    public Date getStartTime()
+    {
+        return new Date(_start);
+    }
+    
+    public String getName()
+    {
+        return _name;
+    }
+    
+    public long getPeriod()
+    {
+        return _period;
+    }
+}