com.aitusoftware.flute.server.http.SlaPercentileChartHandler Maven / Gradle / Ivy

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/*
 * Copyright 2016 Aitu Software Limited.
 *
 * 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 com.aitusoftware.flute.server.http;

import com.aitusoftware.flute.server.cache.HistogramCache;
import com.aitusoftware.flute.server.dao.jdbc.HistogramRetrievalDao;
import com.aitusoftware.flute.server.dao.jdbc.MetricIdentifierDao;
import com.aitusoftware.flute.server.query.FullHistogramHandler;
import com.aitusoftware.flute.server.query.Query;
import org.HdrHistogram.Histogram;
import org.HdrHistogram.HistogramIterationValue;
import org.HdrHistogram.PercentileIterator;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.handler.DefaultHandler;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Optional;
import java.util.Set;
import java.util.function.Supplier;

import static java.lang.String.format;
import static java.util.Collections.singleton;

public final class SlaPercentileChartHandler extends DefaultHandler
{
    private final HistogramRetrievalDao histogramRetrievalDao;
    private final MetricIdentifierDao metricIdentifierDao;
    private final boolean isAggregator;
    private final HistogramCache histogramCache;

    public SlaPercentileChartHandler(final HistogramRetrievalDao histogramRetrievalDao,
                                     final MetricIdentifierDao metricIdentifierDao,
                                     final boolean isAggregator, final Supplier histogramSupplier)
    {
        this.histogramRetrievalDao = histogramRetrievalDao;
        this.metricIdentifierDao = metricIdentifierDao;
        this.isAggregator = isAggregator;
        this.histogramCache = new HistogramCache(100, histogramRetrievalDao, System::currentTimeMillis, histogramSupplier);
    }

    @Override
    public void handle(final String target, final Request baseRequest, final HttpServletRequest request, final HttpServletResponse response) throws IOException, ServletException
    {
        response.setContentType("application/javascript; charset=utf-8");
        final Optional parseResult = QueryParser.parseQuery(request.getPathInfo());

        if(!parseResult.isPresent())
        {
            response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            baseRequest.setHandled(true);
            return;
        }
        final Query query = parseResult.get();

        final PrintWriter writer = response.getWriter();

        final Set metricIdentifiers;
        if(isAggregator)
        {

            metricIdentifiers = metricIdentifierDao.getIdentifiersMatching(query.getMetricKey());
        }
        else
        {
            metricIdentifiers = singleton(query.getMetricKey());
        }

        if(!query.hasExplicitEndTime())
        {
            loadFromCache(query, writer, metricIdentifiers, query.getMetricKey());
        }
        else
        {
            histogramRetrievalDao.selectCompositeHistogram(metricIdentifiers,
                    query, new PercentileHistogramHandler(writer));
        }



        response.setStatus(HttpServletResponse.SC_OK);
        baseRequest.setHandled(true);

        writer.flush();
    }

    private void loadFromCache(
            final Query query, final PrintWriter writer,
            final Set metricIdentifiers,
            final String metricKey)
    {
        final Histogram histogram = histogramCache.getCurrentHistogram(metricIdentifiers,
                query.getDuration(), query.getDurationUnit(), metricKey);
        new PercentileHistogramHandler(writer).onRecord(query.getMetricKey(), histogram.getStartTimeStamp(), histogram);
    }

    private static class PercentileHistogramHandler implements FullHistogramHandler
    {
        private final PrintWriter writer;

        public PercentileHistogramHandler(final PrintWriter writer)
        {
            this.writer = writer;
        }

        @Override
        public void onRecord(final String identifier, final long timestamp, final Histogram histogram)
        {
            final int numberOfSignificantValueDigits = histogram.getNumberOfSignificantValueDigits();
            final PercentileIterator iterator = new PercentileIterator(histogram, 5);
            writer.append("[");
            boolean first = true;
            while (iterator.hasNext())
            {
                final HistogramIterationValue iterationValue = iterator.next();
                final boolean isMaxEntry = iterationValue.getPercentileLevelIteratedTo() == 100.0D;

                if(isMaxEntry)
                {
                    continue;
                }

                if(first)
                {
                    first = false;
                }
                else
                {
                    writer.append(',');
                }
                writer.append('{');


                ReportingConfigSerialiser.appendValue("value", format("%." + numberOfSignificantValueDigits + "f", (double) iterationValue.getValueIteratedTo()), false, writer);
                writer.append(',');
                ReportingConfigSerialiser.appendValue("percentile", format("%2.12f", iterationValue.getPercentileLevelIteratedTo()/100.0D), false, writer);
                writer.append(',');
                ReportingConfigSerialiser.appendValue("total", Long.toString(iterationValue.getTotalCountToThisValue()), false, writer);
                writer.append(',');


                final double ratio = 1 / (1.0D - (iterationValue.getPercentileLevelIteratedTo() / 100.0D));
                ReportingConfigSerialiser.appendValue("ratio",
                        format("%.2f", ratio), false, writer);
                writer.append('}');
            }

            writer.append("]");
        }
    }
}