001/** 002 * 003 * Licensed to the Apache Software Foundation (ASF) under one 004 * or more contributor license agreements. See the NOTICE file 005 * distributed with this work for additional information 006 * regarding copyright ownership. The ASF licenses this file 007 * to you under the Apache License, Version 2.0 (the 008 * "License"); you may not use this file except in compliance 009 * with the License. You may obtain a copy of the License at 010 * 011 * http://www.apache.org/licenses/LICENSE-2.0 012 * 013 * Unless required by applicable law or agreed to in writing, software 014 * distributed under the License is distributed on an "AS IS" BASIS, 015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 016 * See the License for the specific language governing permissions and 017 * limitations under the License. 018 */ 019 020package org.apache.hadoop.hbase.regionserver; 021 022import org.apache.hadoop.hbase.Cell; 023import org.apache.hadoop.hbase.CellComparator; 024import org.apache.yetus.audience.InterfaceAudience; 025 026import java.io.IOException; 027import java.util.ArrayList; 028import java.util.List; 029 030/** 031 * The MemStoreMergerSegmentsIterator extends MemStoreSegmentsIterator 032 * and performs the scan for simple merge operation meaning it is NOT based on SQM 033 */ 034@InterfaceAudience.Private 035public class MemStoreMergerSegmentsIterator extends MemStoreSegmentsIterator { 036 037 // heap of scanners, lazily initialized 038 private KeyValueHeap heap = null; 039 // remember the initial version of the scanners list 040 List<KeyValueScanner> scanners = new ArrayList<KeyValueScanner>(); 041 042 private boolean closed = false; 043 044 // C-tor 045 public MemStoreMergerSegmentsIterator(List<ImmutableSegment> segments, CellComparator comparator, 046 int compactionKVMax) throws IOException { 047 super(compactionKVMax); 048 // create the list of scanners to traverse over all the data 049 // no dirty reads here as these are immutable segments 050 int order = segments.size(); 051 AbstractMemStore.addToScanners(segments, Long.MAX_VALUE, order, scanners); 052 heap = new KeyValueHeap(scanners, comparator); 053 } 054 055 @Override 056 public boolean hasNext() { 057 if (closed) { 058 return false; 059 } 060 if (this.heap != null) { 061 return (this.heap.peek() != null); 062 } 063 // Doing this way in case some test cases tries to peek directly 064 return false; 065 } 066 067 @Override 068 public Cell next() { 069 try { // try to get next 070 if (!closed && heap != null) { 071 return heap.next(); 072 } 073 } catch (IOException ie) { 074 throw new IllegalStateException(ie); 075 } 076 return null; 077 } 078 079 @Override 080 public void close() { 081 if (closed) { 082 return; 083 } 084 // Ensuring that all the segment scanners are closed 085 if (heap != null) { 086 heap.close(); 087 // It is safe to do close as no new calls will be made to this scanner. 088 heap = null; 089 } else { 090 for (KeyValueScanner scanner : scanners) { 091 scanner.close(); 092 } 093 } 094 closed = true; 095 } 096 097 @Override 098 public void remove() { 099 throw new UnsupportedOperationException(); 100 } 101}