org.apache.hadoop.hbase.client.Append Maven / Gradle / Ivy

Go to download
/*
 * 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.hadoop.hbase.client;

import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.KeyValueUtil;
import org.apache.hadoop.hbase.util.Bytes;

/**
 * Performs Append operations on a single row.
 * 
 * Note that this operation does not appear atomic to readers. Appends are done
 * under a single row lock, so write operations to a row are synchronized, but
 * readers do not take row locks so get and scan operations can see this
 * operation partially completed.
 * 

 * To append to a set of columns of a row, instantiate an Append object with the
 * row to append to. At least one column to append must be specified using the
 * {@link #add(byte[], byte[], byte[])} method.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class Append extends Mutation {
  private static final String RETURN_RESULTS = "_rr_";
  /**
   * @param returnResults
   *          True (default) if the append operation should return the results.
   *          A client that is not interested in the result can save network
   *          bandwidth setting this to false.
   */
  public void setReturnResults(boolean returnResults) {
    setAttribute(RETURN_RESULTS, Bytes.toBytes(returnResults));
  }

  /**
   * @return current setting for returnResults
   */
  public boolean isReturnResults() {
    byte[] v = getAttribute(RETURN_RESULTS);
    return v == null ? true : Bytes.toBoolean(v);
  }

  /**
   * Create a Append operation for the specified row.
   * 

   * At least one column must be appended to.
   * @param row row key; makes a local copy of passed in array.
   */
  public Append(byte[] row) {
    this(row, 0, row.length);
  }

  /** Create a Append operation for the specified row.
   * 
   * At least one column must be appended to.
   * @param rowArray Makes a copy out of this buffer.
   * @param rowOffset
   * @param rowLength
   */
  public Append(final byte [] rowArray, final int rowOffset, final int rowLength) {
    checkRow(rowArray, rowOffset, rowLength);
    this.row = Bytes.copy(rowArray, rowOffset, rowLength);
  }

  /**
   * Add the specified column and value to this Append operation.
   * @param family family name
   * @param qualifier column qualifier
   * @param value value to append to specified column
   * @return this
   */
  public Append add(byte [] family, byte [] qualifier, byte [] value) {
    KeyValue kv = new KeyValue(this.row, family, qualifier, this.ts, KeyValue.Type.Put, value);
    return add(kv);
  }

  /**
   * Add column and value to this Append operation.
   * @param cell
   * @return This instance
   */
  @SuppressWarnings("unchecked")
  public Append add(final Cell cell) {
    // Presume it is KeyValue for now.
    KeyValue kv = KeyValueUtil.ensureKeyValue(cell);
    byte [] family = kv.getFamily();
    List list = this.familyMap.get(family);
    if (list == null) {
      list  = new ArrayList();
    }
    // find where the new entry should be placed in the List
    list.add(kv);
    this.familyMap.put(family, list);
    return this;
  }
}