io.druid.query.UnionQueryRunner.java Source code

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Here is the source code for io.druid.query.UnionQueryRunner.java

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/*
 * Druid - a distributed column store.
 * Copyright 2012 - 2015 Metamarkets Group Inc.
 *
 * 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 io.druid.query;

import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.metamx.common.guava.Sequence;
import com.metamx.common.guava.Sequences;

import java.util.Map;

public class UnionQueryRunner<T> implements QueryRunner<T> {
    private final QueryRunner<T> baseRunner;
    private final QueryToolChest<T, Query<T>> toolChest;

    public UnionQueryRunner(QueryRunner<T> baseRunner, QueryToolChest<T, Query<T>> toolChest) {
        this.baseRunner = baseRunner;
        this.toolChest = toolChest;
    }

    @Override
    public Sequence<T> run(final Query<T> query, final Map<String, Object> responseContext) {
        DataSource dataSource = query.getDataSource();
        if (dataSource instanceof UnionDataSource) {
            return toolChest.mergeSequencesUnordered(Sequences.simple(Lists.transform(
                    ((UnionDataSource) dataSource).getDataSources(), new Function<DataSource, Sequence<T>>() {
                        @Override
                        public Sequence<T> apply(DataSource singleSource) {
                            return baseRunner.run(query.withDataSource(singleSource), responseContext);
                        }
                    })));
        } else {
            return baseRunner.run(query, responseContext);
        }
    }

}