cn.patterncat.metrics.codahale.LatencyUtilsReservoir Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of springboot-metrics-starter Show documentation
springboot-metrics-starter
The newest version!
package cn.patterncat.metrics.codahale;

import com.codahale.metrics.Reservoir;
import com.codahale.metrics.Snapshot;
import org.HdrHistogram.Histogram;
import org.LatencyUtils.LatencyStats;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.concurrent.ThreadSafe;
import java.io.OutputStream;
import java.io.PrintStream;

/**
 * A {@link Reservoir} which utilizes {@link LatencyStats} for tracking latencies.
 *
 * This reservoir will reset every time a snapshot is taken, so it should not be used with multiple
 * scheduled reporters.
 */
@ThreadSafe
public final class LatencyUtilsReservoir implements Reservoir {
    private static final Logger LOG = LoggerFactory.getLogger(LatencyUtilsReservoir.class);

    private final LatencyStats mLatencyStats;

    /**
     * Construct a new latency utils reservoir.
     *
     * @param latencyStats The LatencyStats backing the reservoir.
     */
    private LatencyUtilsReservoir(final LatencyStats latencyStats) {
        mLatencyStats = latencyStats;
    }

    /**
     * Create a new latency utils reservoir.
     *
     * @param latencyStats The LatencyStats backing the reservoir.
     * @return a new latency utils reservoir.
     */
    public static LatencyUtilsReservoir create(final LatencyStats latencyStats) {
        return new LatencyUtilsReservoir(latencyStats);
    }

    /**
     * Create a new latency utils reservoir with the default settings.
     *
     * @return a new latency utils reservoir.
     */
    public static LatencyUtilsReservoir create() {
        return new LatencyUtilsReservoir(new LatencyStats());
    }

    /**
     * Throws {@link UnsupportedOperationException}.  This method is not currently used by the
     * metrics library, and would be difficult to implement for LatencyUtils.
     *
     * @return Nothing.
     */
    @Override
    public int size() {
        throw new UnsupportedOperationException();
    }

    /** {@inheritDoc} */
    @Override
    public void update(final long value) {
        mLatencyStats.recordLatency(value);
    }

    /** {@inheritDoc} */
    @Override
    public Snapshot getSnapshot() {
        return new HistogramSnapshot(mLatencyStats.getIntervalHistogram());
    }

    /**
     * An implementation of {@link Snapshot} for {@link LatencyStats}.
     *
     * Package private for use by the HDR histogram reservoir.
     */
    static final class HistogramSnapshot extends Snapshot {
        private final Histogram mHistogram;

        /**
         * Create a new latency utils reservoir snapshot.
         *
         * @param histogram The histogram backing the snapshot.
         */
        public HistogramSnapshot(final Histogram histogram) {
            mHistogram = histogram;
        }

        /** {@inheritDoc} */
        @Override
        public double getValue(final double quantile) {
            try {
                return mHistogram.getValueAtPercentile(quantile * 100);
            } catch (IndexOutOfBoundsException e) {
                return Double.NaN;
            }
        }

        /**
         * Throws {@link UnsupportedOperationException}.  This method is not currently used by the
         * metrics library, and would be difficult to implement for LatencyUtils.
         *
         * @return Nothing.
         */
        @Override
        public long[] getValues() {
            throw new UnsupportedOperationException();
        }

        /** {@inheritDoc} */
        @Override
        public int size() {
            return (int) mHistogram.getTotalCount();
        }

        /** {@inheritDoc} */
        @Override
        public long getMax() {
            return mHistogram.getMaxValue();
        }

        /** {@inheritDoc} */
        @Override
        public double getMean() {
            return mHistogram.getMean();
        }

        /** {@inheritDoc} */
        @Override
        public long getMin() {
            return mHistogram.getMinValue();
        }

        /** {@inheritDoc} */
        @Override
        public double getStdDev() {
            return mHistogram.getStdDeviation();
        }

        /** {@inheritDoc} */
        @Override
        public void dump(final OutputStream output) {
            mHistogram.outputPercentileDistribution(new PrintStream(output), 1.0);
        }
    }
}