com.hazelcast.jet.sql.impl.connector.map.JoinScanProcessorSupplier Maven / Gradle / Ivy

/*
 * Copyright 2021 Hazelcast Inc.
 *
 * Licensed under the Hazelcast Community License (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://hazelcast.com/hazelcast-community-license
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.hazelcast.jet.sql.impl.connector.map;

import com.hazelcast.function.FunctionEx;
import com.hazelcast.jet.Traverser;
import com.hazelcast.jet.core.Processor;
import com.hazelcast.jet.core.ProcessorSupplier;
import com.hazelcast.jet.impl.processor.TransformBatchedP;
import com.hazelcast.jet.sql.impl.ExpressionUtil;
import com.hazelcast.jet.sql.impl.JetJoinInfo;
import com.hazelcast.jet.sql.impl.SimpleExpressionEvalContext;
import com.hazelcast.jet.sql.impl.connector.keyvalue.KvRowProjector;
import com.hazelcast.jet.sql.impl.connector.keyvalue.KvRowProjector.Supplier;
import com.hazelcast.map.IMap;
import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.DataSerializable;
import com.hazelcast.projection.Projection;
import com.hazelcast.security.permission.MapPermission;
import com.hazelcast.sql.impl.expression.Expression;
import com.hazelcast.sql.impl.expression.ExpressionEvalContext;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;

import javax.annotation.Nonnull;
import java.io.IOException;
import java.security.Permission;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map.Entry;

import static com.hazelcast.jet.Traversers.traverseIterable;
import static com.hazelcast.jet.impl.util.Util.extendArray;
import static com.hazelcast.security.permission.ActionConstants.ACTION_CREATE;
import static com.hazelcast.security.permission.ActionConstants.ACTION_READ;
import static java.util.Collections.singletonList;

@SuppressFBWarnings(
        value = {"SE_BAD_FIELD", "SE_NO_SERIALVERSIONID"},
        justification = "the class is never java-serialized"
)
final class JoinScanProcessorSupplier implements ProcessorSupplier, DataSerializable {

    private JetJoinInfo joinInfo;
    private String mapName;
    private KvRowProjector.Supplier rightRowProjectorSupplier;

    private transient IMap map;
    private transient ExpressionEvalContext evalContext;

    @SuppressWarnings("unused")
    private JoinScanProcessorSupplier() {
    }

    JoinScanProcessorSupplier(
            JetJoinInfo joinInfo,
            String mapName,
            KvRowProjector.Supplier rightRowProjectorSupplier
    ) {
        this.joinInfo = joinInfo;
        this.mapName = mapName;
        this.rightRowProjectorSupplier = rightRowProjectorSupplier;
    }

    @Override
    public void init(@Nonnull Context context) {
        map = context.hazelcastInstance().getMap(mapName);
        evalContext = SimpleExpressionEvalContext.from(context);
    }

    @Nonnull
    @Override
    public Collection get(int count) {
        List processors = new ArrayList<>(count);
        for (int i = 0; i < count; i++) {
            Processor processor =
                    new TransformBatchedP(
                            joinFn(joinInfo, map, rightRowProjectorSupplier, evalContext)
                    ) {
                        @Override
                        public boolean isCooperative() {
                            return false;
                        }
                    };
            processors.add(processor);
        }
        return processors;
    }

    private static FunctionEx, Traverser> joinFn(
            @Nonnull JetJoinInfo joinInfo,
            @Nonnull IMap map,
            @Nonnull Supplier rightRowProjectorSupplier,
            @Nonnull ExpressionEvalContext evalContext
    ) {
        Projection, Object[]> projection =
                QueryUtil.toProjection(rightRowProjectorSupplier, evalContext);

        return lefts -> {
            List rights = new ArrayList<>();
            // TODO it would be nice if we executed the project() with the predicate that the rightRowProjector
            //  uses, maybe the majority of rows are rejected. In general it's good to do filtering as closely to the
            //  source as possible. However, the predicate has state. Without a state the predicate will have to
            //  create QueryTargets and extractors for each row.

            // current rules pull projects up, hence project() cardinality won't be greater than the source's
            // changing the rules might require revisiting
            for (Object[] right : map.project(projection)) {
                if (right != null) {
                    rights.add(right);
                }
            }

            List rows = new ArrayList<>();
            for (Object[] left : lefts) {
                boolean joined = join(rows, left, rights, joinInfo.condition(), evalContext);
                if (!joined && joinInfo.isLeftOuter()) {
                    rows.add(extendArray(left, rightRowProjectorSupplier.columnCount()));
                }
            }
            return traverseIterable(rows);
        };
    }

    private static boolean join(
            @Nonnull List rows,
            @Nonnull Object[] left,
            @Nonnull List rights,
            @Nonnull Expression condition,
            @Nonnull ExpressionEvalContext evalContext
    ) {
        boolean matched = false;
        for (Object[] right : rights) {
            Object[] joined = ExpressionUtil.join(left, right, condition, evalContext);
            if (joined != null) {
                rows.add(joined);
                matched = true;
            }
        }
        return matched;
    }

    @Override
    public List permissions() {
        return singletonList(new MapPermission(mapName, ACTION_CREATE, ACTION_READ));
    }

    @Override
    public void writeData(ObjectDataOutput out) throws IOException {
        out.writeObject(joinInfo);
        out.writeObject(mapName);
        out.writeObject(rightRowProjectorSupplier);
    }

    @Override
    public void readData(ObjectDataInput in) throws IOException {
        joinInfo = in.readObject();
        mapName = in.readObject();
        rightRowProjectorSupplier = in.readObject();
    }
}