path: root/exec/vector/src/main/codegen/templates/VariableLengthVectors.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.
 */
import java.lang.Override;
import java.util.Set;

import org.apache.drill.exec.exception.OutOfMemoryException;
import org.apache.drill.exec.memory.AllocationManager.BufferLedger;
import org.apache.drill.exec.vector.BaseDataValueVector;
import org.apache.drill.exec.vector.BaseValueVector;
import org.apache.drill.exec.vector.VariableWidthVector;

<@pp.dropOutputFile />
<#list vv.types as type>
<#list type.minor as minor>

<#assign friendlyType = (minor.friendlyType!minor.boxedType!type.boxedType) />

<#if type.major == "VarLen">
<@pp.changeOutputFile name="/org/apache/drill/exec/vector/${minor.class}Vector.java" />

<#include "/@includes/license.ftl" />

package org.apache.drill.exec.vector;

<#include "/@includes/vv_imports.ftl" />

/**
 * ${minor.class}Vector implements a vector of variable width values.  Elements in the vector
 * are accessed by position from the logical start of the vector.  A fixed width offsetVector
 * is used to convert an element's position to it's offset from the start of the (0-based)
 * DrillBuf. Size is inferred from adjacent elements.
 * <ul>
 * <li>The width of each element is ${type.width} byte(s). Note that the actual width is
 * variable, this width is used as a guess for certain calculations.</li>
 * <li>The equivalent Java primitive is '${minor.javaType!type.javaType}'<li>
 * </ul>
 * NB: this class is automatically generated from <tt>${.template_name}</tt>
 * and <tt>ValueVectorTypes.tdd</tt> using FreeMarker.
 */

public final class ${minor.class}Vector extends BaseDataValueVector implements VariableWidthVector {

  private static final int INITIAL_BYTE_COUNT = Math.min(INITIAL_VALUE_ALLOCATION * DEFAULT_RECORD_BYTE_COUNT, MAX_BUFFER_SIZE);
  
  private final UInt${type.width}Vector offsetVector = new UInt${type.width}Vector(offsetsField, allocator);
  private final FieldReader reader = new ${minor.class}ReaderImpl(${minor.class}Vector.this);

  private final Accessor accessor;
  private final Mutator mutator;

  private int allocationSizeInBytes = INITIAL_BYTE_COUNT;
  private int allocationMonitor = 0;

  public ${minor.class}Vector(MaterializedField field, BufferAllocator allocator) {
    super(field, allocator);
    this.accessor = new Accessor();
    this.mutator = new Mutator();
  }

  @Override
  public FieldReader getReader() {
    return reader;
  }

  @Override
  public int getBufferSize(){
    if (getAccessor().getValueCount() == 0) {
      return 0;
    }
    return offsetVector.getBufferSize() + data.writerIndex();
  }

  @Override
  public int getAllocatedSize() {
    return offsetVector.getAllocatedSize() + data.capacity();
  }

  @Override
  public int getBufferSizeFor(final int valueCount) {
    if (valueCount == 0) {
      return 0;
    }

    final int idx = offsetVector.getAccessor().get(valueCount);
    return offsetVector.getBufferSizeFor(valueCount + 1) + idx;
  }

  @Override
  public int getValueCapacity() {
    return Math.max(offsetVector.getValueCapacity() - 1, 0);
  }

  @Override
  public int getByteCapacity() {
    return data.capacity();
  }

  /**
  * Return the number of bytes contained in the current var len byte vector.
  * TODO: Remove getVarByteLength with it's implementation after all client's are moved to using getCurrentSizeInBytes.
  * It's kept as is to preserve backward compatibility
  * @return
  */
  @Override
  public int getCurrentSizeInBytes() {
    return getVarByteLength();
  }

  /**
   * Return the number of bytes contained in the current var len byte vector.
   * @return
   */
  public int getVarByteLength(){
    final int valueCount = getAccessor().getValueCount();
    if (valueCount == 0) {
      return 0;
    }
    return offsetVector.getAccessor().get(valueCount);
  }

  @Override
  public SerializedField getMetadata() {
    return getMetadataBuilder()
             .addChild(offsetVector.getMetadata())
             .setValueCount(getAccessor().getValueCount())
             .setBufferLength(getBufferSize())
             .build();
  }

  @Override
  public void load(SerializedField metadata, DrillBuf buffer) {
    // the bits vector is the first child (the order in which the children are added in getMetadataBuilder is significant)
    final SerializedField offsetField = metadata.getChild(0);
    offsetVector.load(offsetField, buffer);

    final int capacity = buffer.capacity();
    final int offsetsLength = offsetField.getBufferLength();
    data = buffer.slice(offsetsLength, capacity - offsetsLength);
    data.retain();
  }

  @Override
  public void clear() {
    super.clear();
    offsetVector.clear();
  }

  @Override
  public DrillBuf[] getBuffers(boolean clear) {
    final DrillBuf[] buffers = ObjectArrays.concat(offsetVector.getBuffers(false), super.getBuffers(false), DrillBuf.class);
    if (clear) {
      // does not make much sense but we have to retain buffers even when clear is set. refactor this interface.
      for (final DrillBuf buffer:buffers) {
        buffer.retain(1);
      }
      clear();
    }
    return buffers;
  }

  public long getOffsetAddr() {
    return offsetVector.getBuffer().memoryAddress();
  }

  @Override
  public UInt${type.width}Vector getOffsetVector() {
    return offsetVector;
  }

  @Override
  public TransferPair getTransferPair(BufferAllocator allocator) {
    return new TransferImpl(getField(), allocator);
  }

  @Override
  public TransferPair getTransferPair(String ref, BufferAllocator allocator) {
    return new TransferImpl(getField().withPath(ref), allocator);
  }

  @Override
  public TransferPair makeTransferPair(ValueVector to) {
    return new TransferImpl((${minor.class}Vector) to);
  }

  public void transferTo(${minor.class}Vector target) {
    target.clear();
    this.offsetVector.transferTo(target.offsetVector);
    target.data = data.transferOwnership(target.allocator).buffer;
    target.data.writerIndex(data.writerIndex());
    clear();
  }

  public void splitAndTransferTo(int startIndex, int length, ${minor.class}Vector target) {
    UInt${type.width}Vector.Accessor offsetVectorAccessor = this.offsetVector.getAccessor();
    final int startPoint = offsetVectorAccessor.get(startIndex);
    final int sliceLength = offsetVectorAccessor.get(startIndex + length) - startPoint;
    target.clear();
    target.offsetVector.allocateNew(length + 1);
    offsetVectorAccessor = this.offsetVector.getAccessor();
    final UInt4Vector.Mutator targetOffsetVectorMutator = target.offsetVector.getMutator();
    for (int i = 0; i < length + 1; i++) {
      targetOffsetVectorMutator.set(i, offsetVectorAccessor.get(startIndex + i) - startPoint);
    }
    target.data = data.slice(startPoint, sliceLength).transferOwnership(target.allocator).buffer;
    target.getMutator().setValueCount(length);
}

  protected void copyFrom(int fromIndex, int thisIndex, ${minor.class}Vector from){
    final UInt4Vector.Accessor fromOffsetVectorAccessor = from.offsetVector.getAccessor();
    final int start = fromOffsetVectorAccessor.get(fromIndex);
    final int end = fromOffsetVectorAccessor.get(fromIndex + 1);
    final int len = end - start;

    final int outputStart = offsetVector.data.get${(minor.javaType!type.javaType)?cap_first}(thisIndex * ${type.width});
    from.data.getBytes(start, data, outputStart, len);
    offsetVector.data.set${(minor.javaType!type.javaType)?cap_first}( (thisIndex+1) * ${type.width}, outputStart + len);
  }

  public boolean copyFromSafe(int fromIndex, int thisIndex, ${minor.class}Vector from){
    final UInt${type.width}Vector.Accessor fromOffsetVectorAccessor = from.offsetVector.getAccessor();
    final int start = fromOffsetVectorAccessor.get(fromIndex);
    final int end =   fromOffsetVectorAccessor.get(fromIndex + 1);
    final int len = end - start;
    final int outputStart = offsetVector.data.get${(minor.javaType!type.javaType)?cap_first}(thisIndex * ${type.width});

    while(data.capacity() < outputStart + len) {
        reAlloc();
    }

    offsetVector.getMutator().setSafe(thisIndex + 1, outputStart + len);
    from.data.getBytes(start, data, outputStart, len);
    return true;
  }

  @Override
  public void copyEntry(int toIndex, ValueVector from, int fromIndex) {
    copyFromSafe(fromIndex, toIndex, (${minor.class}Vector) from);
  }

  @Override
  public void collectLedgers(Set<BufferLedger> ledgers) {
    offsetVector.collectLedgers(ledgers);
    super.collectLedgers(ledgers);
  }

  @Override
  public int getPayloadByteCount(int valueCount) {
    if (valueCount == 0) {
      return 0;
    }
    // If 1 or more values, then the last value is set to
    // the offset of the next value, which is the same as
    // the length of existing values.
    // In addition to the actual data bytes, we must also
    // include the "overhead" bytes: the offset vector entries
    // that accompany each column value. Thus, total payload
    // size is consumed text bytes + consumed offset vector
    // bytes.
    return offsetVector.getAccessor().get(valueCount) +
           offsetVector.getPayloadByteCount(valueCount);
  }

  private class TransferImpl implements TransferPair{
    private final ${minor.class}Vector to;

    public TransferImpl(MaterializedField field, BufferAllocator allocator){
      to = new ${minor.class}Vector(field, allocator);
    }

    public TransferImpl(${minor.class}Vector to) {
      this.to = to;
    }

    @Override
    public ${minor.class}Vector getTo() {
      return to;
    }

    @Override
    public void transfer() {
      transferTo(to);
    }

    @Override
    public void splitAndTransfer(int startIndex, int length) {
      splitAndTransferTo(startIndex, length, to);
    }

    @Override
    public void copyValueSafe(int fromIndex, int toIndex) {
      to.copyFromSafe(fromIndex, toIndex, ${minor.class}Vector.this);
    }
  }

  @Override
  public void setInitialCapacity(final int valueCount) {
    final long size = 1L * valueCount * ${type.width};
    if (size > MAX_ALLOCATION_SIZE) {
      throw new OversizedAllocationException("Requested amount of memory is more than max allowed allocation size");
    }
    allocationSizeInBytes = (int)size;
    offsetVector.setInitialCapacity(valueCount + 1);
  }

  @Override
  public void allocateNew() {
    if(!allocateNewSafe()){
      throw new OutOfMemoryException("Failure while allocating buffer.");
    }
  }

  @Override
  public boolean allocateNewSafe() {
    long curAllocationSize = allocationSizeInBytes;
    if (allocationMonitor > 10) {
      curAllocationSize = Math.max(MIN_BYTE_COUNT, curAllocationSize / 2);
      allocationMonitor = 0;
    } else if (allocationMonitor < -2) {
      curAllocationSize = curAllocationSize * 2L;
      allocationMonitor = 0;
    }

    if (curAllocationSize > MAX_ALLOCATION_SIZE) {
      return false;
    }

    clear();
    /* Boolean to keep track if all the memory allocations were successful
     * Used in the case of composite vectors when we need to allocate multiple
     * buffers for multiple vectors. If one of the allocations failed we need to
     * clear all the memory that we allocated
     */
    try {
      final int requestedSize = (int)curAllocationSize;
      data = allocator.buffer(requestedSize);
      allocationSizeInBytes = requestedSize;
      offsetVector.allocateNew();
    } catch (OutOfMemoryException e) {
      clear();
      return false;
    }
    data.readerIndex(0);
    offsetVector.zeroVector();
    return true;
  }

  @Override
  public void allocateNew(int totalBytes, int valueCount) {
    clear();
    assert totalBytes >= 0;
    try {
      data = allocator.buffer(totalBytes);
      offsetVector.allocateNew(valueCount + 1);
    } catch (RuntimeException e) {
      clear();
      throw e;
    }
    data.readerIndex(0);
    allocationSizeInBytes = totalBytes;
    offsetVector.zeroVector();
  }

  @Override
  public void reset() {
    allocationSizeInBytes = INITIAL_BYTE_COUNT;
    allocationMonitor = 0;
    data.readerIndex(0);
    offsetVector.zeroVector();
    super.reset();
  }

  public void reAlloc() {
    final long newAllocationSize = allocationSizeInBytes*2L;
    if (newAllocationSize > MAX_ALLOCATION_SIZE)  {
      throw new OversizedAllocationException("Unable to expand the buffer. Max allowed buffer size is reached.");
    }

    reallocRaw((int) newAllocationSize);
  }

  @Override
  public DrillBuf reallocRaw(int newAllocationSize) {
    final DrillBuf newBuf = allocator.buffer(newAllocationSize);
    newBuf.setBytes(0, data, 0, data.capacity());
    data.release();
    data = newBuf;
    allocationSizeInBytes = newAllocationSize;
    return data;
  }

  public void decrementAllocationMonitor() {
    if (allocationMonitor > 0) {
      allocationMonitor = 0;
    }
    --allocationMonitor;
  }

  private void incrementAllocationMonitor() {
    ++allocationMonitor;
  }

  @Override
  public Accessor getAccessor(){
    return accessor;
  }

  @Override
  public Mutator getMutator() {
    return mutator;
  }

  @Override
  public void exchange(ValueVector other) {
    super.exchange(other);
    ${minor.class}Vector target = (${minor.class}Vector) other;
    offsetVector.exchange(target.offsetVector);
  }

  @Override
  public void toNullable(ValueVector nullableVector) {
    Nullable${minor.class}Vector dest = (Nullable${minor.class}Vector) nullableVector;
    dest.getMutator().fromNotNullable(this);
  }

  public final class Accessor extends BaseValueVector.BaseAccessor implements VariableWidthAccessor {
    final UInt${type.width}Vector.Accessor oAccessor = offsetVector.getAccessor();
    
    public long getStartEnd(int index){
      return oAccessor.getTwoAsLong(index);
    }

    public byte[] get(int index) {
      assert index >= 0;
      final int startIdx = oAccessor.get(index);
      final int length = oAccessor.get(index + 1) - startIdx;
      assert length >= 0;
      final byte[] dst = new byte[length];
      data.getBytes(startIdx, dst, 0, length);
      return dst;
    }

    @Override
    public int getValueLength(int index) {
      final UInt${type.width}Vector.Accessor offsetVectorAccessor = offsetVector.getAccessor();
      return offsetVectorAccessor.get(index + 1) - offsetVectorAccessor.get(index);
    }

    public void get(int index, ${minor.class}Holder holder){
      holder.start = oAccessor.get(index);
      holder.end = oAccessor.get(index + 1);
      holder.buffer = data;
      <#if minor.class.contains("Decimal")>
      holder.scale = field.getScale();
      holder.precision = field.getPrecision();
      </#if>
    }

    public void get(int index, Nullable${minor.class}Holder holder){
      holder.isSet = 1;
      holder.start = oAccessor.get(index);
      holder.end = oAccessor.get(index + 1);
      holder.buffer = data;
      <#if minor.class.contains("Decimal")>
      holder.scale = field.getScale();
      holder.precision = field.getPrecision();
      </#if>
    }

    <#switch minor.class>
    <#case "VarDecimal">
    @Override
    public ${friendlyType} getObject(int index) {
      byte[] b = get(index);
      BigInteger bi = b.length == 0 ? BigInteger.ZERO : new BigInteger(b);
      BigDecimal bd = new BigDecimal(bi, getField().getScale());
      return bd;
    }
    <#break>
    <#case "VarChar">
    @Override
    public ${friendlyType} getObject(int index) {
      Text text = new Text();
      text.set(get(index));
      return text;
    }
    <#break>
    <#case "Var16Char">
    @Override
    public ${friendlyType} getObject(int index) {
      return new String(get(index), Charsets.UTF_16);
    }
    <#break>
    <#default>
    @Override
    public ${friendlyType} getObject(int index) {
      return get(index);
    }
    </#switch>

    @Override
    public int getValueCount() {
      return Math.max(offsetVector.getAccessor().getValueCount()-1, 0);
    }

    @Override
    public boolean isNull(int index){
      return false;
    }

    public UInt${type.width}Vector getOffsetVector(){
      return offsetVector;
    }
  }

  /**
   * <h4>Overview</h4>
   * <p>
   * Mutable${minor.class} implements a vector of variable width values.  Elements in the vector
   * are accessed by position from the logical start of the vector.  A fixed width offsetVector
   * is used to convert an element's position to it's offset from the start of the (0-based)
   * DrillBuf.  Size is inferred by adjacent elements.
   *   The width of each element is ${type.width} byte(s)
   *   The equivalent Java primitive is '${minor.javaType!type.javaType}'
   *
   * NB: this class is automatically generated from ValueVectorTypes.tdd using FreeMarker.
   * </p>
   * <h4>Contract</h4>
   * <p>
   *   <ol>
   *     <li>
   *       <b>Supported Writes:</b> {@link VariableWidthVector}s do not support random writes. In contrast {@link org.apache.drill.exec.vector.FixedWidthVector}s do
   *       allow random writes but special care is needed.
   *       </li>
   *     <li>
   *       <b>Writing Values:</b> All set methods must be called with a consecutive sequence of indices. With a few exceptions:
   *       <ol>
   *         <li>You can update the last index you just set.</li>
   *         <li>You can reset a previous index (call it Idx), but you must assume all the data after Idx is corrupt. Also
   *         note that the memory consumed by data that came after Idx is not released.</li>
   *       </ol>
   *     </li>
   *     <li>
   *       <b>Setting Value Count:</b> Vectors aren't explicitly aware of how many values they contain. So you must keep track of the
   *       number of values you've written to the vector and once you are done writing to the vector you must call {@link Mutator#setValueCount(int)}.
   *       It is possible to trim the vector by setting the value count to be less than the number of values currently contained in the vector. Note the extra memory consumed in
   *       the data buffer is not freed when this is done.
   *     </li>
   *     <li>
   *       <b>Memory Allocation:</b> When setting a value at an index you must do one of the following to ensure you do not get an {@link IndexOutOfBoundsException}.
   *       <ol>
   *         <li>
   *           Allocate the exact amount of memory you need when using the {@link Mutator#set(int, byte[])} methods. If you do not
   *           manually allocate sufficient memory an {@link IndexOutOfBoundsException} can be thrown when the data buffer runs out of space.
   *         </li>
   *         <li>
   *           Or you can use the {@link Mutator#setSafe(int, byte[])} methods, which will automatically grow your data buffer to
   *           fit your data.
   *         </li>
   *       </ol>
   *     </li>
   *     <li>
   *       <b>Immutability:</b> Once a vector has been populated with data and {@link #setValueCount(int)} has been called, it should be considered immutable.
   *     </li>
   *   </ol>
   * </p>
   */
  public final class Mutator extends BaseValueVector.BaseMutator implements VariableWidthVector.VariableWidthMutator {

    /**
     * Set the variable length element at the specified index to the supplied byte array.
     *
     * @param index   position of the bit to set
     * @param bytes   array of bytes to write
     */
    protected void set(int index, byte[] bytes) {
      assert index >= 0;
      final int currentOffset = offsetVector.getAccessor().get(index);
      offsetVector.getMutator().set(index + 1, currentOffset + bytes.length);
      data.setBytes(currentOffset, bytes, 0, bytes.length);
    }

    public void setSafe(int index, byte[] bytes) {
      assert index >= 0;

      final int currentOffset = offsetVector.getAccessor().get(index);
      while (data.capacity() < currentOffset + bytes.length) {
        reAlloc();
      }
      offsetVector.getMutator().setSafe(index + 1, currentOffset + bytes.length);
      data.setBytes(currentOffset, bytes, 0, bytes.length);
    }

    /**
     * Set the variable length element at the specified index to the supplied byte array.
     *
     * @param index   position of the bit to set
     * @param bytes   array of bytes to write
     * @param start   start index of bytes to write
     * @param length  length of bytes to write
     */
    protected void set(int index, byte[] bytes, int start, int length) {
      assert index >= 0;
      final int currentOffset = offsetVector.getAccessor().get(index);
      offsetVector.getMutator().set(index + 1, currentOffset + length);
      data.setBytes(currentOffset, bytes, start, length);
    }

    public void setSafe(int index, ByteBuffer bytes, int start, int length) {
      assert index >= 0;

      final int currentOffset = offsetVector.getAccessor().get(index);

      while (data.capacity() < currentOffset + length) {
        reAlloc();
      }
      offsetVector.getMutator().setSafe(index + 1, currentOffset + length);
      data.setBytes(currentOffset, bytes, start, length);
    }

    public void setSafe(int index, byte[] bytes, int start, int length) {
      assert index >= 0;

      final int currentOffset = offsetVector.getAccessor().get(index);

      while (data.capacity() < currentOffset + length) {
        reAlloc();
      }
      offsetVector.getMutator().setSafe(index + 1, currentOffset + length);
      data.setBytes(currentOffset, bytes, start, length);
    }

    @Override
    public void setValueLengthSafe(int index, int length) {
      final int offset = offsetVector.getAccessor().get(index);
      while(data.capacity() < offset + length ) {
        reAlloc();
      }
      offsetVector.getMutator().setSafe(index + 1, offsetVector.getAccessor().get(index) + length);
    }

    public void setSafe(int index, int start, int end, DrillBuf buffer) {
      final int len = end - start;
      final int outputStart = offsetVector.data.get${(minor.javaType!type.javaType)?cap_first}(index * ${type.width});

      while (data.capacity() < outputStart + len) {
        reAlloc();
      }
      offsetVector.getMutator().setSafe(index + 1, outputStart + len);
      buffer.getBytes(start, data, outputStart, len);
    }

    public void setSafe(int index, Nullable${minor.class}Holder holder) {
      assert holder.isSet == 1;

      final int start = holder.start;
      final int end =   holder.end;
      final int len = end - start;

      final int outputStart = offsetVector.data.get${(minor.javaType!type.javaType)?cap_first}(index * ${type.width});

      while (data.capacity() < outputStart + len) {
        reAlloc();
      }
      holder.buffer.getBytes(start, data, outputStart, len);
      offsetVector.getMutator().setSafe(index + 1, outputStart + len);
    }

    <#if minor.class == "VarDecimal">
    public void set(int index, BigDecimal value) {
      byte[] bytes = value.unscaledValue().toByteArray();
      set(index, bytes, 0, bytes.length);
    }

    public void setSafe(int index, BigDecimal value) {
      byte[] bytes = value.unscaledValue().toByteArray();
      setSafe(index, bytes, 0, bytes.length);
    }
    </#if>

    public void setSafe(int index, ${minor.class}Holder holder) {
      final int start = holder.start;
      final int end =   holder.end;
      final int len = end - start;
      final int outputStart = offsetVector.data.get${(minor.javaType!type.javaType)?cap_first}(index * ${type.width});

      while(data.capacity() < outputStart + len) {
        reAlloc();
      }
      holder.buffer.getBytes(start, data, outputStart, len);
      offsetVector.getMutator().setSafe(index + 1, outputStart + len);
    }

    /**
     * Backfill missing offsets from the given last written position to the
     * given current write position. Used by the "new" size-safe column
     * writers to allow skipping values. The <tt>set()</tt> and <tt>setSafe()</tt>
     * <b>do not</b> fill empties. See DRILL-5529.
     * @param lastWrite the position of the last valid write: the offset
     * to be copied forward
     * @param index the current write position filling occurs up to,
     * but not including, this position
     */

    public void fillEmpties(int lastWrite, int index) {
      // If last write was 2, offsets are [0, 3, 6]
      // If next write is 4, offsets must be: [0, 3, 6, 6, 6]
      // Remember the offsets are one more than row count.

      final int fillOffset = offsetVector.getAccessor().get(lastWrite+1);
      final UInt4Vector.Mutator offsetMutator = offsetVector.getMutator();
      for (int i = lastWrite; i < index; i++) {
        offsetMutator.setSafe(i + 1, fillOffset);
      }
    }

    protected void set(int index, int start, int length, DrillBuf buffer) {
      assert index >= 0;
      final int currentOffset = offsetVector.getAccessor().get(index);
      offsetVector.getMutator().set(index + 1, currentOffset + length);
      final DrillBuf bb = buffer.slice(start, length);
      data.setBytes(currentOffset, bb);
    }

    protected void set(int index, Nullable${minor.class}Holder holder) {
      final int length = holder.end - holder.start;
      final int currentOffset = offsetVector.getAccessor().get(index);
      offsetVector.getMutator().set(index + 1, currentOffset + length);
      data.setBytes(currentOffset, holder.buffer, holder.start, length);
    }

    protected void set(int index, ${minor.class}Holder holder) {
      final int length = holder.end - holder.start;
      final int currentOffset = offsetVector.getAccessor().get(index);
      offsetVector.getMutator().set(index + 1, currentOffset + length);
      data.setBytes(currentOffset, holder.buffer, holder.start, length);
    }

    /**
     * <h4>Notes on Usage</h4>
     * <p>
     * For {@link VariableWidthVector}s this method can be used in the following cases:
     * <ul>
     *   <li>Setting the actual number of elements currently contained in the vector.</li>
     *   <li>Trimming the vector to have fewer elements than it current does.</li>
     * </ul>
     * </p>
     * <h4>Caveats</h4>
     * <p>
     *   It is important to note that for {@link org.apache.drill.exec.vector.FixedWidthVector}s this method can also be used to expand the vector.
     *   However, {@link VariableWidthVector} do not support this usage and this method will throw an {@link IndexOutOfBoundsException} if you attempt
     *   to use it in this way. Expansion of valueCounts is not supported mainly because there is no benefit, since you would still have to rely on the setSafe
     *   methods to appropriatly expand the data buffer and populate the vector anyway (since by definition we do not know the width of elements). See DRILL-6234 for details.
     * </p>
     * <h4>Method Documentation</h4>
     * {@inheritDoc}
     */
    @Override
    public void setValueCount(int valueCount) {
      final int currentByteCapacity = getByteCapacity();
      // Check if valueCount to be set is zero and current capacity is also zero. If yes then
      // we should not call get to read start index from offset vector at that value count.
      final int idx = (valueCount == 0 && currentByteCapacity == 0)
        ? 0
        : offsetVector.getAccessor().get(valueCount);
      data.writerIndex(idx);
      if (valueCount > 0 && currentByteCapacity > idx * 2) {
        incrementAllocationMonitor();
      } else if (allocationMonitor > 0) {
        allocationMonitor = 0;
      }
      VectorTrimmer.trim(data, idx);
      offsetVector.getMutator().setValueCount(valueCount == 0 ? 0 : valueCount+1);
    }

    @Override
    public void generateTestData(int size){
      boolean even = true;
      <#switch minor.class>
      <#case "Var16Char">
      final java.nio.charset.Charset charset = Charsets.UTF_16;
      <#break>
      <#case "VarChar">
      <#default>
      final java.nio.charset.Charset charset = Charsets.UTF_8;
      </#switch>
      final byte[] evenValue = new String("aaaaa").getBytes(charset);
      final byte[] oddValue = new String("bbbbbbbbbb").getBytes(charset);
      for(int i =0; i < size; i++, even = !even){
        set(i, even ? evenValue : oddValue);
        }
      setValueCount(size);
    }
  }
}
</#if> <#-- type.major -->
</#list>
</#list>