Package io.crate.operation.collect

Source Code of io.crate.operation.collect.SystemCollectService

/*
* Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
* license agreements.  See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.  Crate 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.
*
* However, if you have executed another commercial license agreement
* with Crate these terms will supersede the license and you may use the
* software solely pursuant to the terms of the relevant commercial agreement.
*/

package io.crate.operation.collect;

import com.google.common.collect.ImmutableMap;
import io.crate.metadata.Functions;
import io.crate.metadata.RowContextCollectorExpression;
import io.crate.metadata.sys.SysJobsLogTableInfo;
import io.crate.metadata.sys.SysJobsTableInfo;
import io.crate.metadata.sys.SysOperationsLogTableInfo;
import io.crate.metadata.sys.SysOperationsTableInfo;
import io.crate.operation.Input;
import io.crate.operation.projectors.Projector;
import io.crate.operation.reference.sys.job.RowContextDocLevelReferenceResolver;
import io.crate.planner.node.dql.CollectNode;
import io.crate.planner.symbol.Literal;
import org.apache.lucene.search.CollectionTerminatedException;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.discovery.DiscoveryService;

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

/**
* this collect service can be used to retrieve a collector for system tables (which don't contain shards)
*/
public class SystemCollectService implements CollectService {

    private final CollectInputSymbolVisitor<RowContextCollectorExpression<?, ?>> docInputSymbolVisitor;
    private final ImmutableMap<String, StatsTables.IterableGetter> iterableGetters;
    private final DiscoveryService discoveryService;


    @Inject
    public SystemCollectService(DiscoveryService discoveryService, Functions functions, StatsTables statsTables) {
        docInputSymbolVisitor = new CollectInputSymbolVisitor<>(functions,
                RowContextDocLevelReferenceResolver.INSTANCE);

        iterableGetters = ImmutableMap.<String, StatsTables.IterableGetter>of(
                SysJobsTableInfo.IDENT.fqn(), statsTables.jobsGetter(),
                SysJobsLogTableInfo.IDENT.fqn(), statsTables.jobsLogGetter(),
                SysOperationsTableInfo.IDENT.fqn(), statsTables.operationsGetter(),
                SysOperationsLogTableInfo.IDENT.fqn(), statsTables.operationsLogGetter()
        );
        this.discoveryService = discoveryService;
    }

    @Override
    public CrateCollector getCollector(CollectNode collectNode, Projector downstream) {
        if (collectNode.whereClause().noMatch()) {
            return CrateCollector.NOOP;
        }
        Set<String> tables = collectNode.routing().locations().get(discoveryService.localNode().id()).keySet();
        assert tables.size() == 1;
        StatsTables.IterableGetter iterableGetter = iterableGetters.get(tables.iterator().next());
        assert iterableGetter != null;
        CollectInputSymbolVisitor.Context ctx = docInputSymbolVisitor.process(collectNode);

        Input<Boolean> condition;
        if (collectNode.whereClause().hasQuery()) {
            // TODO: single arg method
            condition = (Input<Boolean>) docInputSymbolVisitor.process(collectNode.whereClause().query(), ctx);
        } else {
            condition = Literal.newLiteral(true);
        }

        return new SystemTableCollector(
                ctx.topLevelInputs(), ctx.docLevelExpressions(), downstream, iterableGetter.getIterable(), condition);
    }

    static class SystemTableCollector<R> implements CrateCollector {

        private final List<Input<?>> inputs;
        private final List<RowContextCollectorExpression<R, ?>> collectorExpressions;
        private Projector downstream;
        private final Iterable<R> rows;
        private final Input<Boolean> condition;

        protected SystemTableCollector(List<Input<?>> inputs,
                                       List<RowContextCollectorExpression<R, ?>> collectorExpressions,
                                       Projector downstream,
                                       Iterable<R> rows,
                                       Input<Boolean> condition) {
            this.inputs = inputs;
            this.collectorExpressions = collectorExpressions;
            this.rows = rows;
            this.condition = condition;
            assert downstream != null;
            downstream(downstream);
        }

        @Override
        public void doCollect() throws Exception {
            for (R row : rows) {
                for (RowContextCollectorExpression<R, ?> collectorExpression : collectorExpressions) {
                    collectorExpression.setNextRow(row);
                }
                Boolean match = condition.value();
                if (match == null || !match) {
                    // no match
                    continue;
                }

                Object[] newRow = new Object[inputs.size()];
                int i = 0;
                for (Input<?> input : inputs) {
                    newRow[i++] = input.value();
                }
                if (!downstream.setNextRow(newRow)) {
                    // no more rows required, we can stop here
                    downstream.upstreamFinished();
                    throw new CollectionTerminatedException();
                }
            }
            downstream.upstreamFinished();
        }

        @Override
        public void downstream(Projector downstream) {
            downstream.registerUpstream(this);
            this.downstream = downstream;
        }

        @Override
        public Projector downstream() {
            return downstream;
        }
    }
}
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