Add CounterStat which is a wrapper for a counter stat but, because

the 'count' event is internal, historical data can be built it.
Also includes EventHistogram class for building time based,
bucketed history of event occurances.
Make Stat implement IDisposable for subclasses that might need it.

OpenSim/Framework/Monitoring/Stats/CounterStat.cs

@@ -0,0 +1,211 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+using OpenMetaverse.StructuredData;
+
+namespace OpenSim.Framework.Monitoring
+{
+// Create a time histogram of events. The histogram is built in a wrap-around
+//   array of equally distributed buckets.
+// For instance, a minute long histogram of second sized buckets would be:
+//          new EventHistogram(60, 1000)
+public class EventHistogram
+{
+    private int m_timeBase;
+    private int m_numBuckets;
+    private int m_bucketMilliseconds;
+    private int m_lastBucket;
+    private int m_totalHistogramMilliseconds;
+    private long[] m_histogram;
+    private object histoLock = new object();
+
+    public EventHistogram(int numberOfBuckets, int millisecondsPerBucket)
+    {
+        m_numBuckets = numberOfBuckets;
+        m_bucketMilliseconds = millisecondsPerBucket;
+        m_totalHistogramMilliseconds = m_numBuckets * m_bucketMilliseconds;
+
+        m_histogram = new long[m_numBuckets];
+        Zero();
+        m_lastBucket = 0;
+        m_timeBase = Util.EnvironmentTickCount();
+    }
+
+    public void Event()
+    {
+        this.Event(1);
+    }
+
+    // Record an event at time 'now' in the histogram.
+    public void Event(int cnt)
+    {
+        lock (histoLock)
+        {
+            // The time as displaced from the base of the histogram
+            int bucketTime = Util.EnvironmentTickCountSubtract(m_timeBase);
+
+            // If more than the total time of the histogram, we just start over
+            if (bucketTime > m_totalHistogramMilliseconds)
+            {
+                Zero();
+                m_lastBucket = 0;
+                m_timeBase = Util.EnvironmentTickCount();
+            }
+            else
+            {
+                // To which bucket should we add this event?
+                int bucket = bucketTime / m_bucketMilliseconds;
+
+                // Advance m_lastBucket to the new bucket. Zero any buckets skipped over.
+                while (bucket != m_lastBucket)
+                {
+                    // Zero from just after the last bucket to the new bucket or the end
+                    for (int jj = m_lastBucket + 1; jj <= Math.Min(bucket, m_numBuckets - 1); jj++)
+                    {
+                        m_histogram[jj] = 0;
+                    }
+                    m_lastBucket = bucket;
+                    // If the new bucket is off the end, wrap around to the beginning
+                    if (bucket > m_numBuckets)
+                    {
+                        bucket -= m_numBuckets;
+                        m_lastBucket = 0;
+                        m_histogram[m_lastBucket] = 0;
+                        m_timeBase += m_totalHistogramMilliseconds;
+                    }
+                }
+            }
+            m_histogram[m_lastBucket] += cnt;
+        }
+    }
+
+    // Get a copy of the current histogram
+    public long[] GetHistogram()
+    {
+        long[] ret = new long[m_numBuckets];
+        lock (histoLock)
+        {
+            int indx = m_lastBucket + 1;
+            for (int ii = 0; ii < m_numBuckets; ii++, indx++)
+            {
+                if (indx >= m_numBuckets)
+                    indx = 0;
+                ret[ii] = m_histogram[indx];
+            }
+        }
+        return ret;
+    }
+
+    // Get a copy of the current histogram
+    public OSDArray GetHistogramAsOSDArray()
+    {
+        OSDArray ret = new OSDArray(m_numBuckets);
+        lock (histoLock)
+        {
+            int indx = m_lastBucket + 1;
+            for (int ii = 0; ii < m_numBuckets; ii++, indx++)
+            {
+                if (indx >= m_numBuckets)
+                    indx = 0;
+                ret[ii] = OSD.FromLong(m_histogram[indx]);
+            }
+        }
+        return ret;
+    }
+
+    // Zero out the histogram
+    public void Zero()
+    {
+        lock (histoLock)
+        {
+            for (int ii = 0; ii < m_numBuckets; ii++)
+                m_histogram[ii] = 0;
+        }
+    }
+}
+
+// A statistic that wraps a counter.
+// Built this way mostly so histograms and history can be created.
+public class CounterStat : Stat
+{
+    private SortedDictionary<string, EventHistogram> m_histograms;
+    private object counterLock = new object();
+
+    public CounterStat(
+                        string shortName,
+                        string name,
+                        string description,
+                        string unitName,
+                        string category,
+                        string container,
+                        StatVerbosity verbosity)
+        : base(shortName, name, description, unitName, category, container, StatType.Push, null, verbosity)
+    {
+        m_histograms = new SortedDictionary<string, EventHistogram>();
+    }
+
+    // Histograms are presumably added at intialization time and the list does not change thereafter.
+    // Thus no locking of the histogram list.
+    public void AddHistogram(string histoName, EventHistogram histo)
+    {
+        m_histograms.Add(histoName, histo);
+    }
+
+    public delegate void ProcessHistogram(string name, EventHistogram histo);
+    public void ForEachHistogram(ProcessHistogram process)
+    {
+        foreach (KeyValuePair<string, EventHistogram> kvp in m_histograms)
+        {
+            process(kvp.Key, kvp.Value);
+        }
+    }
+
+    public void Event()
+    {
+        this.Event(1);
+    }
+
+    // Count the underlying counter.
+    public void Event(int cnt)
+    {
+        lock (counterLock)
+        {
+            base.Value += cnt;
+
+            foreach (EventHistogram histo in m_histograms.Values)
+            {
+                histo.Event(cnt);
+            }
+        }
+    }
+}
+}

OpenSim/Framework/Monitoring/Stats/Stat.cs

@@ -34,7 +34,7 @@ namespace OpenSim.Framework.Monitoring
     /// <summary>
     /// Holds individual statistic details
     /// </summary>
-    public class Stat
+    public class Stat : IDisposable
     {
         /// <summary>
         /// Category of this stat (e.g. cache, scene, etc).
@@ -181,6 +181,12 @@ namespace OpenSim.Framework.Monitoring
             Verbosity = verbosity;
         }
 
+        // IDisposable.Dispose()
+        public virtual void Dispose()
+        {
+            return;
+        }
+
         /// <summary>
         /// Record a value in the sample set.
         /// </summary>