algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/physical/EmptyTupleSourcePOperator.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
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 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
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package org.apache.hyracks.algebricks.core.algebra.operators.physical;

import java.util.LinkedList;

import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
import org.apache.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
import org.apache.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
import org.apache.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
import org.apache.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
import org.apache.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
import org.apache.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
import org.apache.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
import org.apache.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
import org.apache.hyracks.algebricks.core.jobgen.impl.JobGenContext;
import org.apache.hyracks.algebricks.runtime.operators.std.EmptyTupleSourceRuntimeFactory;
import org.apache.hyracks.api.dataflow.value.ISerializerDeserializer;
import org.apache.hyracks.api.dataflow.value.RecordDescriptor;

public class EmptyTupleSourcePOperator extends AbstractPhysicalOperator {

    @Override
    public PhysicalOperatorTag getOperatorTag() {
        return PhysicalOperatorTag.EMPTY_TUPLE_SOURCE;
    }

    @Override
    public boolean isMicroOperator() {
        return true;
    }

    @Override
    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
        deliveredProperties = new StructuralPropertiesVector(IPartitioningProperty.UNPARTITIONED,
                new LinkedList<ILocalStructuralProperty>());
    }

    @Override
    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
            IPhysicalPropertiesVector reqdByParent) {
        return null;
    }

    @Override
    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
            throws AlgebricksException {
        EmptyTupleSourceRuntimeFactory runtime = new EmptyTupleSourceRuntimeFactory();
        RecordDescriptor recDesc = new RecordDescriptor(new ISerializerDeserializer[] {});
        builder.contributeMicroOperator(op, runtime, recDesc);
    }

    @Override
    public boolean expensiveThanMaterialization() {
        return false;
    }
}