content: /*
   * 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.calcite.adapter.enumerable;
  
  import org.apache.calcite.linq4j.tree.BlockBuilder;
  import org.apache.calcite.linq4j.tree.Expression;
  import org.apache.calcite.linq4j.tree.Expressions;
  import org.apache.calcite.plan.DeriveMode;
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelOptCost;
  import org.apache.calcite.plan.RelOptPlanner;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelCollationTraitDef;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.RelNodes;
  import org.apache.calcite.rel.core.CorrelationId;
  import org.apache.calcite.rel.core.Join;
  import org.apache.calcite.rel.core.JoinRelType;
  import org.apache.calcite.rel.metadata.RelMdCollation;
  import org.apache.calcite.rel.metadata.RelMdUtil;
  import org.apache.calcite.rel.metadata.RelMetadataQuery;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.rex.RexUtil;
  import org.apache.calcite.util.BuiltInMethod;
  import org.apache.calcite.util.ImmutableIntList;
  import org.apache.calcite.util.Pair;
  import org.apache.calcite.util.Util;
  
  import com.google.common.collect.ImmutableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.lang.reflect.Method;
  import java.util.List;
  import java.util.Set;
  
  /** Implementation of {@link org.apache.calcite.rel.core.Join} in
   * {@link org.apache.calcite.adapter.enumerable.EnumerableConvention enumerable calling convention}. */
  public class EnumerableHashJoin extends Join implements EnumerableRel {
    /** Creates an EnumerableHashJoin.
     *
     * <p>Use {@link #create} unless you know what you're doing. */
    protected EnumerableHashJoin(
        RelOptCluster cluster,
        RelTraitSet traits,
        RelNode left,
        RelNode right,
        RexNode condition,
        Set<CorrelationId> variablesSet,
        JoinRelType joinType) {
      super(
          cluster,
          traits,
          ImmutableList.of(),
          left,
          right,
          condition,
          variablesSet,
          joinType);
    }
  
    @Deprecated // to be removed before 2.0
    protected EnumerableHashJoin(RelOptCluster cluster, RelTraitSet traits,
        RelNode left, RelNode right, RexNode condition, ImmutableIntList leftKeys,
        ImmutableIntList rightKeys, JoinRelType joinType,
        Set<String> variablesStopped) {
      this(cluster, traits, left, right, condition, CorrelationId.setOf(variablesStopped), joinType);
    }
  
    /** Creates an EnumerableHashJoin. */
    public static EnumerableHashJoin create(
        RelNode left,
        RelNode right,
        RexNode condition,
        Set<CorrelationId> variablesSet,
        JoinRelType joinType) {
      final RelOptCluster cluster = left.getCluster();
      final RelMetadataQuery mq = cluster.getMetadataQuery();
      final RelTraitSet traitSet =
          cluster.traitSetOf(EnumerableConvention.INSTANCE)
              .replaceIfs(RelCollationTraitDef.INSTANCE,
                  () -> RelMdCollation.enumerableHashJoin(mq, left, right, joinType));
      return new EnumerableHashJoin(cluster, traitSet, left, right, condition,
          variablesSet, joinType);
    }
  
    @Override public EnumerableHashJoin copy(RelTraitSet traitSet, RexNode condition,
        RelNode left, RelNode right, JoinRelType joinType,
        boolean semiJoinDone) {
      return new EnumerableHashJoin(getCluster(), traitSet, left, right,
          condition, variablesSet, joinType);
    }
  
    @Override public @Nullable Pair<RelTraitSet, List<RelTraitSet>> passThroughTraits(
        final RelTraitSet required) {
      return EnumerableTraitsUtils.passThroughTraitsForJoin(
          required, joinType, left.getRowType().getFieldCount(), getTraitSet());
    }
  
    @Override public @Nullable Pair<RelTraitSet, List<RelTraitSet>> deriveTraits(
        final RelTraitSet childTraits, final int childId) {
      // should only derive traits (limited to collation for now) from left join input.
      return EnumerableTraitsUtils.deriveTraitsForJoin(
          childTraits, childId, joinType, getTraitSet(), right.getTraitSet());
    }
  
    @Override public DeriveMode getDeriveMode() {
      if (joinType == JoinRelType.FULL || joinType == JoinRelType.RIGHT) {
        return DeriveMode.PROHIBITED;
      }
  
      return DeriveMode.LEFT_FIRST;
    }
  
    @Override public @Nullable RelOptCost computeSelfCost(RelOptPlanner planner,
        RelMetadataQuery mq) {
      double rowCount = mq.getRowCount(this);
  
      // Joins can be flipped, and for many algorithms, both versions are viable
      // and have the same cost. To make the results stable between versions of
      // the planner, make one of the versions slightly more expensive.
      switch (joinType) {
      case SEMI:
      case ANTI:
        // SEMI and ANTI join cannot be flipped
        break;
      case RIGHT:
        rowCount = RelMdUtil.addEpsilon(rowCount);
        break;
      default:
        if (RelNodes.COMPARATOR.compare(left, right) > 0) {
          rowCount = RelMdUtil.addEpsilon(rowCount);
        }
      }
  
      // Cheaper if the smaller number of rows is coming from the LHS.
      // Model this by adding L log L to the cost.
      final double rightRowCount = mq.getRowCount(right);
      final double leftRowCount = mq.getRowCount(left);
      if (Double.isInfinite(leftRowCount)) {
        rowCount = leftRowCount;
      } else {
        rowCount += Util.nLogN(leftRowCount);
      }
      if (Double.isInfinite(rightRowCount)) {
        rowCount = rightRowCount;
      } else {
        rowCount += rightRowCount;
      }
      if (isSemiJoin()) {
        return planner.getCostFactory().makeCost(rowCount, 0, 0).multiplyBy(.01d);
      } else {
        return planner.getCostFactory().makeCost(rowCount, 0, 0);
      }
    }
  
    @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
      switch (joinType) {
      case SEMI:
      case ANTI:
        return implementHashSemiJoin(implementor, pref);
      default:
        return implementHashJoin(implementor, pref);
      }
    }
  
    private Result implementHashSemiJoin(EnumerableRelImplementor implementor, Prefer pref) {
      assert joinType == JoinRelType.SEMI || joinType == JoinRelType.ANTI;
      final Method method = joinType == JoinRelType.SEMI
          ? BuiltInMethod.SEMI_JOIN.method
          : BuiltInMethod.ANTI_JOIN.method;
      BlockBuilder builder = new BlockBuilder();
      final Result leftResult =
          implementor.visitChild(this, 0, (EnumerableRel) left, pref);
      Expression leftExpression =
          builder.append(
              "left", leftResult.block);
      final Result rightResult =
          implementor.visitChild(this, 1, (EnumerableRel) right, pref);
      Expression rightExpression =
          builder.append(
              "right", rightResult.block);
      final PhysType physType = leftResult.physType;
      final PhysType keyPhysType =
          leftResult.physType.project(
              joinInfo.leftKeys, JavaRowFormat.LIST);
      Expression predicate = Expressions.constant(null);
      if (!joinInfo.nonEquiConditions.isEmpty()) {
        RexNode nonEquiCondition =
            RexUtil.composeConjunction(getCluster().getRexBuilder(),
                joinInfo.nonEquiConditions, true);
        if (nonEquiCondition != null) {
          predicate =
              EnumUtils.generatePredicate(implementor,
                  getCluster().getRexBuilder(), left, right, leftResult.physType,
                  rightResult.physType, nonEquiCondition);
        }
      }
      return implementor.result(
          physType,
          builder.append(
              Expressions.call(
                  method,
                  Expressions.list(
                      leftExpression,
                      rightExpression,
                      leftResult.physType.generateAccessorWithoutNulls(joinInfo.leftKeys),
                      rightResult.physType.generateAccessorWithoutNulls(joinInfo.rightKeys),
                      Util.first(keyPhysType.comparer(),
                          Expressions.constant(null)),
                      predicate)))
              .toBlock());
    }
  
    private Result implementHashJoin(EnumerableRelImplementor implementor, Prefer pref) {
      BlockBuilder builder = new BlockBuilder();
      final Result leftResult =
          implementor.visitChild(this, 0, (EnumerableRel) left, pref);
      Expression leftExpression =
          builder.append(
              "left", leftResult.block);
      final Result rightResult =
          implementor.visitChild(this, 1, (EnumerableRel) right, pref);
      Expression rightExpression =
          builder.append(
              "right", rightResult.block);
      final PhysType physType =
          PhysTypeImpl.of(
              implementor.getTypeFactory(), getRowType(), pref.preferArray());
      final PhysType keyPhysType =
          leftResult.physType.project(
              joinInfo.leftKeys, JavaRowFormat.LIST);
      Expression predicate = Expressions.constant(null);
      if (!joinInfo.nonEquiConditions.isEmpty()) {
        RexNode nonEquiCondition =
            RexUtil.composeConjunction(getCluster().getRexBuilder(),
                joinInfo.nonEquiConditions, true);
        if (nonEquiCondition != null) {
          predicate =
              EnumUtils.generatePredicate(implementor,
                  getCluster().getRexBuilder(), left, right, leftResult.physType,
                  rightResult.physType, nonEquiCondition);
        }
      }
      return implementor.result(
          physType,
          builder.append(
              Expressions.call(
                  leftExpression,
                  BuiltInMethod.HASH_JOIN.method,
                  Expressions.list(
                      rightExpression,
                      leftResult.physType.generateAccessorWithoutNulls(joinInfo.leftKeys),
                      rightResult.physType.generateAccessorWithoutNulls(joinInfo.rightKeys),
                      EnumUtils.joinSelector(joinType,
                          physType,
                          ImmutableList.of(
                              leftResult.physType, rightResult.physType)))
                      .append(
                          Util.first(keyPhysType.comparer(),
                              Expressions.constant(null)))
                      .append(
                          Expressions.constant(joinType.generatesNullsOnLeft()))
                      .append(
                          Expressions.constant(
                              joinType.generatesNullsOnRight()))
                      .append(predicate)))
              .toBlock());
    }
  }
  