1 /** 2 * Copyright 2010 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 package org.apache.hadoop.hbase.regionserver; 21 22 import org.apache.hadoop.hbase.KeyValue; 23 24 import java.io.Closeable; 25 import java.io.IOException; 26 import java.util.List; 27 28 /** 29 * Internal scanners differ from client-side scanners in that they operate on 30 * HStoreKeys and byte[] instead of RowResults. This is because they are 31 * actually close to how the data is physically stored, and therefore it is more 32 * convenient to interact with them that way. It is also much easier to merge 33 * the results across SortedMaps than RowResults. 34 * 35 * <p>Additionally, we need to be able to determine if the scanner is doing 36 * wildcard column matches (when only a column family is specified or if a 37 * column regex is specified) or if multiple members of the same column family 38 * were specified. If so, we need to ignore the timestamp to ensure that we get 39 * all the family members, as they may have been last updated at different 40 * times. 41 */ 42 public interface InternalScanner extends Closeable { 43 /** 44 * Grab the next row's worth of values. 45 * @param results return output array 46 * @return true if more rows exist after this one, false if scanner is done 47 * @throws IOException e 48 */ 49 public boolean next(List<KeyValue> results) throws IOException; 50 51 /** 52 * Grab the next row's worth of values. 53 * @param results return output array 54 * @param metric the metric name 55 * @return true if more rows exist after this one, false if scanner is done 56 * @throws IOException e 57 */ 58 public boolean next(List<KeyValue> results, String metric) throws IOException; 59 60 /** 61 * Grab the next row's worth of values with a limit on the number of values 62 * to return. 63 * @param result return output array 64 * @param limit limit on row count to get 65 * @return true if more rows exist after this one, false if scanner is done 66 * @throws IOException e 67 */ 68 public boolean next(List<KeyValue> result, int limit) throws IOException; 69 70 /** 71 * Grab the next row's worth of values with a limit on the number of values 72 * to return. 73 * @param result return output array 74 * @param limit limit on row count to get 75 * @param metric the metric name 76 * @return true if more rows exist after this one, false if scanner is done 77 * @throws IOException e 78 */ 79 public boolean next(List<KeyValue> result, int limit, String metric) throws IOException; 80 81 /** 82 * Closes the scanner and releases any resources it has allocated 83 * @throws IOException 84 */ 85 public void close() throws IOException; 86 }