TrimAggregator.java

package org.kairosdb.core.aggregator;

import org.kairosdb.core.DataPoint;
import org.kairosdb.core.aggregator.annotation.AggregatorName;
import org.kairosdb.core.aggregator.annotation.AggregatorProperty;
import org.kairosdb.core.datastore.DataPointGroup;

/**
 Trims off the first, last or both (first and last) data points.  When aggregating
 the first and last data points may not represent a full range and you may want
 to remove them for displaying in a graph or in conjunction with the save_as
 aggregator to save rollup data.

 Created by bhawkins on 8/28/15.
 */
@AggregatorName(
        name = "trim",
        description = "Trims off the first, last or both (first and last) data points from the results.",
        properties = {
                @AggregatorProperty(name = "trim", type = "enum", values={"first", "last", "both"})
        }
)
public class TrimAggregator implements Aggregator
{
	public enum Trim
	{
		FIRST, LAST, BOTH
	};

	public TrimAggregator()
	{
	}

	public TrimAggregator(Trim trim)
	{
		m_trim = trim;
	}

	private Trim m_trim;

	@Override
	public DataPointGroup aggregate(DataPointGroup dataPointGroup)
	{
		return new TimDataPointAggregator(dataPointGroup);
	}

	/**
	 Sets which data points to trim off. Values can be FIRST, LAST or BOTH.
	 Setting to trim FIRST will trim off the oldest data point unless order is
	 descending.
	 @param trim
	 */
	public void setTrim(Trim trim)
	{
		m_trim = trim;
	}

	@Override
	public boolean canAggregate(String groupType)
	{
		return true;
	}

	@Override
	public String getAggregatedGroupType(String groupType)
	{
		return groupType;
	}

	private class TimDataPointAggregator extends AggregatedDataPointGroupWrapper
	{
		public TimDataPointAggregator(DataPointGroup innerDataPointGroup)
		{
			super(innerDataPointGroup);

			if (m_trim == Trim.FIRST || m_trim == Trim.BOTH)
			{
				if (innerDataPointGroup.hasNext())
					currentDataPoint = innerDataPointGroup.next();
				else
					currentDataPoint = null;
			}
		}

		@Override
		public boolean hasNext()
		{
			if (m_trim == Trim.BOTH || m_trim == Trim.LAST)
			{
				return currentDataPoint != null && hasNextInternal();
			}
			else
				return super.hasNext();
		}

		@Override
		public DataPoint next()
		{
			DataPoint ret = currentDataPoint;
			if (hasNextInternal())
				currentDataPoint = nextInternal();
			else
				currentDataPoint = null;

			return ret;
		}


	}
}