org.apache.lens.server.query.collect.IntersectingWaitingQueriesSelector.java Source code

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Here is the source code for org.apache.lens.server.query.collect.IntersectingWaitingQueriesSelector.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.lens.server.query.collect;

import java.util.List;
import java.util.Set;

import org.apache.lens.server.api.query.FinishedLensQuery;
import org.apache.lens.server.api.query.QueryContext;
import org.apache.lens.server.api.query.collect.EstimatedImmutableQueryCollection;
import org.apache.lens.server.api.query.collect.WaitingQueriesSelectionPolicy;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import lombok.NonNull;

/**
 * Selects queries eligible by all {@link WaitingQueriesSelectionPolicy} to move them out of waiting state.
 *
 */
public class IntersectingWaitingQueriesSelector implements WaitingQueriesSelector {

    private final ImmutableSet<WaitingQueriesSelectionPolicy> selectionPolicies;

    public IntersectingWaitingQueriesSelector(
            @NonNull final ImmutableSet<WaitingQueriesSelectionPolicy> selectionPolicies) {
        this.selectionPolicies = selectionPolicies;
    }

    /**
     * Selects queries eligible by all {@link WaitingQueriesSelectionPolicy} to move them out of waiting state.
     *
     * @see WaitingQueriesSelector#selectQueries(FinishedLensQuery, EstimatedImmutableQueryCollection)
     *
     * @param finishedQuery
     * @param waitingQueries
     * @return
     */
    @Override
    public Set<QueryContext> selectQueries(final FinishedLensQuery finishedQuery,
            final EstimatedImmutableQueryCollection waitingQueries) {

        Set<WaitingQueriesSelectionPolicy> allSelectionPolicies = prepareAllSelectionPolicies(finishedQuery);

        List<Set<QueryContext>> candiateQueriesSets = getAllCandidateQueriesSets(finishedQuery, waitingQueries,
                allSelectionPolicies);

        return findCommonQueries(candiateQueriesSets);
    }

    @VisibleForTesting
    Set<WaitingQueriesSelectionPolicy> prepareAllSelectionPolicies(final FinishedLensQuery finishedQuery) {

        /* Get the selection policies of driver on which this query was run */
        ImmutableSet<WaitingQueriesSelectionPolicy> driverSelectionPolicies = finishedQuery
                .getDriverSelectionPolicies();

        return Sets.union(this.selectionPolicies, driverSelectionPolicies);
    }

    private List<Set<QueryContext>> getAllCandidateQueriesSets(final FinishedLensQuery finishedQuery,
            final EstimatedImmutableQueryCollection waitingQueries,
            final Set<WaitingQueriesSelectionPolicy> allSelectionPolicies) {

        List<Set<QueryContext>> candidateQueriesSets = Lists.newLinkedList();

        for (final WaitingQueriesSelectionPolicy selectionPolicy : allSelectionPolicies) {

            Set<QueryContext> candiateQueries = selectionPolicy.selectQueries(finishedQuery, waitingQueries);
            candidateQueriesSets.add(candiateQueries);
        }
        return candidateQueriesSets;
    }

    @VisibleForTesting
    Set<QueryContext> findCommonQueries(final List<Set<QueryContext>> candiateQueriesSets) {

        Set<QueryContext> commonQueries = Sets.newLinkedHashSet();

        if (!candiateQueriesSets.isEmpty()) {
            commonQueries = Iterables.get(candiateQueriesSets, 0);

            for (Set<QueryContext> candidateEligibleQueries : candiateQueriesSets) {
                commonQueries.retainAll(candidateEligibleQueries);
            }
        }
        return commonQueries;
    }
}