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.regionserver; 019 020import java.io.IOException; 021import java.util.List; 022import org.apache.hadoop.hbase.Cell; 023import org.apache.hadoop.hbase.DoNotRetryIOException; 024import org.apache.hadoop.hbase.HConstants; 025import org.apache.hadoop.hbase.PrivateCellUtil; 026import org.apache.hadoop.hbase.client.Scan; 027import org.apache.hadoop.hbase.util.Bytes; 028import org.apache.yetus.audience.InterfaceAudience; 029 030/** 031 * ReversibleRegionScannerImpl extends from RegionScannerImpl, and is used to support reversed 032 * scanning. 033 */ 034@InterfaceAudience.Private 035class ReversedRegionScannerImpl extends RegionScannerImpl { 036 037 ReversedRegionScannerImpl(Scan scan, List<KeyValueScanner> additionalScanners, HRegion region, 038 long nonceGroup, long nonce) throws IOException { 039 super(scan, additionalScanners, region, nonceGroup, nonce); 040 } 041 042 @Override 043 protected void initializeKVHeap(List<KeyValueScanner> scanners, 044 List<KeyValueScanner> joinedScanners, HRegion region) throws IOException { 045 this.storeHeap = new ReversedKeyValueHeap(scanners, comparator); 046 if (!joinedScanners.isEmpty()) { 047 throw new DoNotRetryIOException("Reverse scan with loading CFs on demand is not supported"); 048 } 049 } 050 051 @Override 052 protected boolean shouldStop(Cell currentRowCell) { 053 if (currentRowCell == null) { 054 return true; 055 } 056 if (stopRow == null || Bytes.equals(stopRow, HConstants.EMPTY_START_ROW)) { 057 return false; 058 } 059 int c = comparator.compareRows(currentRowCell, stopRow, 0, stopRow.length); 060 return c < 0 || (c == 0 && !includeStopRow); 061 } 062 063 @Override 064 protected boolean nextRow(ScannerContext scannerContext, Cell curRowCell) throws IOException { 065 assert super.joinedContinuationRow == null : "Trying to go to next row during joinedHeap read."; 066 this.storeHeap.seekToPreviousRow(PrivateCellUtil.createFirstOnRow(curRowCell)); 067 resetFilters(); 068 // Calling the hook in CP which allows it to do a fast forward 069 if (this.region.getCoprocessorHost() != null) { 070 return this.region.getCoprocessorHost().postScannerFilterRow(this, curRowCell); 071 } 072 return true; 073 } 074 075}