processing/src/main/java/io/druid/query/timeseries/TimeseriesQueryEngine.java

/*
 * Druid - a distributed column store.
 * Copyright (C) 2012, 2013  Metamarkets Group Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package io.druid.query.timeseries;

import com.google.common.base.Function;
import com.metamx.common.guava.BaseSequence;
import com.metamx.common.guava.Sequence;
import io.druid.query.QueryRunnerHelper;
import io.druid.query.Result;
import io.druid.query.aggregation.Aggregator;
import io.druid.query.aggregation.AggregatorFactory;
import io.druid.query.aggregation.PostAggregator;
import io.druid.segment.Cursor;
import io.druid.segment.StorageAdapter;
import io.druid.segment.filter.Filters;

import java.util.Iterator;
import java.util.List;

/**
 */
public class TimeseriesQueryEngine
{
  public Sequence<Result<TimeseriesResultValue>> process(final TimeseriesQuery query, final StorageAdapter adapter)
  {
    return new BaseSequence<Result<TimeseriesResultValue>, Iterator<Result<TimeseriesResultValue>>>(
        new BaseSequence.IteratorMaker<Result<TimeseriesResultValue>, Iterator<Result<TimeseriesResultValue>>>()
        {
          @Override
          public Iterator<Result<TimeseriesResultValue>> make()
          {
            return QueryRunnerHelper.makeCursorBasedQuery(
                adapter,
                query.getQuerySegmentSpec().getIntervals(),
                Filters.convertDimensionFilters(query.getDimensionsFilter()),
                query.getGranularity(),
                new Function<Cursor, Result<TimeseriesResultValue>>()
                {
                  private final List<AggregatorFactory> aggregatorSpecs = query.getAggregatorSpecs();
                  private final List<PostAggregator> postAggregatorSpecs = query.getPostAggregatorSpecs();

                  @Override
                  public Result<TimeseriesResultValue> apply(Cursor cursor)
                  {
                    Aggregator[] aggregators = QueryRunnerHelper.makeAggregators(cursor, aggregatorSpecs);

                    while (!cursor.isDone()) {
                      for (Aggregator aggregator : aggregators) {
                        aggregator.aggregate();
                      }
                      cursor.advance();
                    }

                    TimeseriesResultBuilder bob = new TimeseriesResultBuilder(cursor.getTime());

                    for (Aggregator aggregator : aggregators) {
                      bob.addMetric(aggregator);
                    }

                    Result<TimeseriesResultValue> retVal = bob.build();

                    // cleanup
                    for (Aggregator agg : aggregators) {
                      agg.close();
                    }

                    return retVal;
                  }
                }
            ).iterator();
          }

          @Override
          public void cleanup(Iterator<Result<TimeseriesResultValue>> toClean)
          {
            // https://github.com/metamx/druid/issues/128
            while (toClean.hasNext()) {
              toClean.next();
            }
          }
        }
    );
  }
}