OpenSimMirror/OpenSim/Framework/Monitoring/Stats/CounterStat.cs

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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;
    }

    public OSDMap GetHistogramAsOSDMap()
    {
        OSDMap ret = new OSDMap();

        ret.Add("Buckets", OSD.FromInteger(m_numBuckets));
        ret.Add("BucketMilliseconds", OSD.FromInteger(m_bucketMilliseconds));
        ret.Add("TotalMilliseconds", OSD.FromInteger(m_totalHistogramMilliseconds));

        // Compute a number for the first bucket in the histogram.
        // This will allow readers to know how this histogram relates to any previously read histogram.
        int baseBucketNum = (m_timeBase / m_bucketMilliseconds) + m_lastBucket + 1;
        ret.Add("BaseNumber", OSD.FromInteger(baseBucketNum));

        ret.Add("Values", GetHistogramAsOSDArray());

        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);
            }
        }
    }

    // CounterStat is a basic stat plus histograms
    public override OSDMap ToOSDMap()
    {
        // Get the foundational instance
        OSDMap map = base.ToOSDMap();

        map["StatType"] = "CounterStat";

        // If there are any histograms, add a new field that is an array of histograms as OSDMaps
        if (m_histograms.Count > 0)
        {
            OSDArray histos = new OSDArray();
            foreach (EventHistogram histo in m_histograms.Values)
            {
                histos.Add(histo.GetHistogramAsOSDMap());
            }
            map.Add("Histograms", histos);
        }
        return map;
    }
}
}