/*
* 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.topn;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicates;
import com.metamx.common.guava.Sequence;
import com.metamx.common.guava.Sequences;
import com.metamx.common.logger.Logger;
import io.druid.collections.StupidPool;
import io.druid.granularity.QueryGranularity;
import io.druid.query.Result;
import io.druid.query.aggregation.AggregatorFactory;
import io.druid.query.filter.Filter;
import io.druid.segment.Capabilities;
import io.druid.segment.Cursor;
import io.druid.segment.SegmentMissingException;
import io.druid.segment.StorageAdapter;
import io.druid.segment.filter.Filters;
import org.joda.time.Interval;
import java.nio.ByteBuffer;
import java.util.List;
/**
*/
public class TopNQueryEngine
{
private static final Logger log = new Logger(TopNQueryEngine.class);
private final StupidPool<ByteBuffer> bufferPool;
public TopNQueryEngine(StupidPool<ByteBuffer> bufferPool)
{
this.bufferPool = bufferPool;
}
public Sequence<Result<TopNResultValue>> query(final TopNQuery query, final StorageAdapter adapter)
{
if (adapter == null) {
throw new SegmentMissingException(
"Null storage adapter found. Probably trying to issue a query against a segment being memory unmapped."
);
}
final List<Interval> queryIntervals = query.getQuerySegmentSpec().getIntervals();
final Filter filter = Filters.convertDimensionFilters(query.getDimensionsFilter());
final QueryGranularity granularity = query.getGranularity();
final Function<Cursor, Result<TopNResultValue>> mapFn = getMapFn(query, adapter);
Preconditions.checkArgument(
queryIntervals.size() == 1, "Can only handle a single interval, got[%s]", queryIntervals
);
return Sequences.filter(
Sequences.map(
adapter.makeCursors(filter, queryIntervals.get(0), granularity),
new Function<Cursor, Result<TopNResultValue>>()
{
@Override
public Result<TopNResultValue> apply(Cursor input)
{
log.debug("Running over cursor[%s]", adapter.getInterval(), input.getTime());
return mapFn.apply(input);
}
}
),
Predicates.<Result<TopNResultValue>>notNull()
);
}
private Function<Cursor, Result<TopNResultValue>> getMapFn(TopNQuery query, final StorageAdapter adapter)
{
final Capabilities capabilities = adapter.getCapabilities();
final int cardinality = adapter.getDimensionCardinality(query.getDimensionSpec().getDimension());
int numBytesPerRecord = 0;
for (AggregatorFactory aggregatorFactory : query.getAggregatorSpecs()) {
numBytesPerRecord += aggregatorFactory.getMaxIntermediateSize();
}
final TopNAlgorithmSelector selector = new TopNAlgorithmSelector(cardinality, numBytesPerRecord);
query.initTopNAlgorithmSelector(selector);
TopNAlgorithm topNAlgorithm = null;
if (selector.isHasDimExtractionFn()) {
topNAlgorithm = new DimExtractionTopNAlgorithm(capabilities, query);
} else if (selector.isAggregateAllMetrics()) {
topNAlgorithm = new PooledTopNAlgorithm(capabilities, query, bufferPool);
} else if (selector.isAggregateTopNMetricFirst() || query.getContextValue("doAggregateTopNMetricFirst", false)) {
topNAlgorithm = new AggregateTopNMetricFirstAlgorithm(capabilities, query, bufferPool);
} else {
topNAlgorithm = new PooledTopNAlgorithm(capabilities, query, bufferPool);
}
return new TopNMapFn(query, topNAlgorithm);
}
}