001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.client;
019
020import org.apache.yetus.audience.InterfaceAudience;
021import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
022
023/**
024 * Helper class for custom client scanners.
025 */
026@InterfaceAudience.Private
027public abstract class AbstractClientScanner implements ResultScanner {
028  protected ScanMetrics scanMetrics;
029
030  /**
031   * Check and initialize if application wants to collect scan metrics
032   */
033  protected void initScanMetrics(Scan scan) {
034    // check if application wants to collect scan metrics
035    if (scan.isScanMetricsEnabled()) {
036      scanMetrics = new ScanMetrics();
037    }
038  }
039
040  /**
041   * Used internally accumulating metrics on scan. To enable collection of metrics on a Scanner,
042   * call {@link Scan#setScanMetricsEnabled(boolean)}.
043   * @return Returns the running {@link ScanMetrics} instance or null if scan metrics not enabled.
044   */
045  @Override
046  public ScanMetrics getScanMetrics() {
047    return scanMetrics;
048  }
049}