hbase-client/src/main/java/org/apache/hadoop/hbase/client/ScanResultConsumer.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.client;
  19
  20 import org.apache.hadoop.hbase.classification.InterfaceAudience;
  21 import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
  22
  23 /**
  24  * Receives {@link Result} for an asynchronous scan.
  25  */
  26 @InterfaceAudience.Public
  27 public interface ScanResultConsumer {
  28
  29   /**
  30    * @param result the data fetched from HBase service.
  31    * @return {@code false} if you want to terminate the scan process. Otherwise {@code true}
  32    */
  33   boolean onNext(Result result);
  34
  35   /**
  36    * Indicate that we hit an unrecoverable error and the scan operation is terminated.
  37    * <p>
  38    * We will not call {@link #onComplete()} after calling {@link #onError(Throwable)}.
  39    */
  40   void onError(Throwable error);
  41
  42   /**
  43    * Indicate that the scan operation is completed normally.
  44    */
  45   void onComplete();
  46
  47   /**
  48    * If {@code scan.isScanMetricsEnabled()} returns true, then this method will be called prior to
  49    * all other methods in this interface to give you the {@link ScanMetrics} instance for this scan
  50    * operation. The {@link ScanMetrics} instance will be updated on-the-fly during the scan, you can
  51    * store it somewhere to get the metrics at any time if you want.
  52    */
  53   default void onScanMetricsCreated(ScanMetrics scanMetrics) {
  54   }
  55 }