asterixdb/asterix-column/src/main/java/org/apache/asterix/column/operation/query/ColumnAssembler.java

/*
 * 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.asterix.column.operation.query;

import org.apache.asterix.column.assembler.AbstractPrimitiveValueAssembler;
import org.apache.asterix.column.assembler.AssemblerBuilderVisitor;
import org.apache.asterix.column.assembler.AssemblerState;
import org.apache.asterix.column.assembler.ObjectValueAssembler;
import org.apache.asterix.column.assembler.value.IValueGetterFactory;
import org.apache.asterix.column.bytes.stream.in.AbstractBytesInputStream;
import org.apache.asterix.column.metadata.schema.AbstractSchemaNode;
import org.apache.asterix.column.values.IColumnValuesReaderFactory;
import org.apache.asterix.om.types.ARecordType;
import org.apache.hyracks.api.exceptions.HyracksDataException;
import org.apache.hyracks.data.std.api.IValueReference;
import org.apache.hyracks.storage.am.lsm.btree.column.error.ColumnarValueException;

import com.fasterxml.jackson.databind.node.ObjectNode;

public final class ColumnAssembler {
    private final AbstractPrimitiveValueAssembler[] assemblers;
    private final ObjectValueAssembler rootAssembler;
    private final AssemblerState state;
    private int numberOfTuples;
    private int tupleIndex;
    private int numberOfSkips;

    public ColumnAssembler(AbstractSchemaNode node, ARecordType declaredType, QueryColumnMetadata columnMetadata,
            IColumnValuesReaderFactory readerFactory, IValueGetterFactory valueGetterFactory)
            throws HyracksDataException {
        AssemblerBuilderVisitor builderVisitor =
                new AssemblerBuilderVisitor(columnMetadata, readerFactory, valueGetterFactory);
        assemblers = builderVisitor.createValueAssemblers(node, declaredType);
        rootAssembler = (ObjectValueAssembler) builderVisitor.getRootAssembler();
        state = new AssemblerState();
    }

    public void reset(int numberOfTuples) {
        this.numberOfTuples = numberOfTuples;
        tupleIndex = 0;
        numberOfSkips = 0;
    }

    public void resetColumn(AbstractBytesInputStream stream, int ordinal) throws HyracksDataException {
        assemblers[ordinal].reset(stream, numberOfTuples);
    }

    public int getColumnIndex(int ordinal) {
        return assemblers[ordinal].getColumnIndex();
    }

    public boolean hasNext() {
        return tupleIndex < numberOfTuples;
    }

    public IValueReference nextValue() throws HyracksDataException {
        rootAssembler.start();
        if (tupleIndex == numberOfTuples) {
            rootAssembler.end();
            //return empty record
            return rootAssembler.getValue();
        }

        int index = 0;
        while (index < assemblers.length) {
            AbstractPrimitiveValueAssembler assembler = assemblers[index];
            int groupIndex;

            try {
                groupIndex = assembler.next(state);
            } catch (ColumnarValueException e) {
                appendInformation(e);
                throw e;
            }

            if (groupIndex != AbstractPrimitiveValueAssembler.NEXT_ASSEMBLER) {
                index = groupIndex;
            } else {
                index++;
            }
        }

        tupleIndex++;
        rootAssembler.end();
        return rootAssembler.getValue();
    }

    public int getNumberOfColumns() {
        return assemblers.length;
    }

    public int skip(int count) throws HyracksDataException {
        numberOfSkips += count;
        tupleIndex += count;
        for (int i = 0; i < assemblers.length; i++) {
            assemblers[i].skip(count);
        }
        return tupleIndex;
    }

    public void setAt(int index) throws HyracksDataException {
        skip(index - tupleIndex);
    }

    private void appendInformation(ColumnarValueException e) {
        ObjectNode assemblerNode = e.createNode(getClass().getSimpleName());
        assemblerNode.put("tupleIndex", tupleIndex);
        assemblerNode.put("numberOfTuples", numberOfTuples);
        assemblerNode.put("numberOfSkips", numberOfSkips);
        state.appendStateInfo(e);
    }
}