KeyOnlyFilter.java

/*
 * Copyright (C) 2014  The Async HBase Authors.  All rights reserved.
 * This file is part of Async HBase.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *   - Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   - Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *   - Neither the name of the StumbleUpon nor the names of its contributors
 *     may be used to endorse or promote products derived from this software
 *     without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package org.hbase.async;

import java.lang.UnsupportedOperationException;

import org.jboss.netty.buffer.ChannelBuffer;
import org.hbase.async.generated.FilterPB;

/**
 * A filter that will only return the key component of each KV (the value will
 * be rewritten as empty).
 * <p>
 * This filter can be used to grab all of the keys without having to also grab
 * the values.
 */
public final class KeyOnlyFilter extends ScanFilter {
  private static final byte[] NAME = Bytes.UTF8("org.apache.hadoop"
      + ".hbase.filter.KeyOnlyFilter");

  private boolean lenAsVal;

  public KeyOnlyFilter() {
    this(false);
  }

  public KeyOnlyFilter(boolean lenAsVal) {
    this.lenAsVal = lenAsVal;
  }

  @Override
  byte[] serialize() {
    final FilterPB.KeyOnlyFilter.Builder builder =
        FilterPB.KeyOnlyFilter.newBuilder();
    builder.setLenAsVal(this.lenAsVal);
    return builder.build().toByteArray();
  }

  @Override
  byte[] name() {
    return NAME;
  }

  @Override
  int predictSerializedSize() {
    int size = 1 + NAME.length
        + 1; //lenAsVal
    return size;
  }

  @Override
  void serializeOld(final ChannelBuffer buf) {
    buf.writeByte((byte) NAME.length);     // 1
    buf.writeBytes(NAME);                  // 44
    buf.writeByte(lenAsVal ? 1 : 0);       // 1
  }

  @Override
  public String toString() {
    return this.getClass().getSimpleName() + " "
        + "lenAsVal: " + (lenAsVal ? "true" : "false");
  }
}