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.util.Iterator; 021import org.apache.hadoop.hbase.Cell; 022import org.apache.yetus.audience.InterfaceAudience; 023 024/** 025 * A basic SegmentScanner used against an ImmutableScanner snapshot Used flushing where we do a 026 * single pass, no reverse scanning or inserts happening. Its a dumbed-down Scanner that can go 027 * fast. Like {@link org.apache.hadoop.hbase.util.CollectionBackedScanner} (but making it know about 028 * Segments was onerous). 029 */ 030@InterfaceAudience.Private 031public class SnapshotSegmentScanner extends NonReversedNonLazyKeyValueScanner { 032 private final ImmutableSegment segment; 033 private Iterator<Cell> iter; 034 private Cell current; 035 036 public SnapshotSegmentScanner(ImmutableSegment segment) { 037 this.segment = segment; 038 this.segment.incScannerCount(); 039 this.iter = createIterator(this.segment); 040 if (this.iter.hasNext()) { 041 this.current = this.iter.next(); 042 } 043 } 044 045 private static Iterator<Cell> createIterator(Segment segment) { 046 return segment.getCellSet().iterator(); 047 } 048 049 @Override 050 public Cell peek() { 051 return current; 052 } 053 054 @Override 055 public Cell next() { 056 Cell oldCurrent = current; 057 if (iter.hasNext()) { 058 current = iter.next(); 059 } else { 060 current = null; 061 } 062 return oldCurrent; 063 } 064 065 @Override 066 public boolean seek(Cell seekCell) { 067 // restart iterator 068 this.iter = createIterator(this.segment); 069 return reseek(seekCell); 070 } 071 072 @Override 073 public boolean reseek(Cell seekCell) { 074 while (this.iter.hasNext()) { 075 Cell next = this.iter.next(); 076 int ret = this.segment.getComparator().compare(next, seekCell); 077 if (ret >= 0) { 078 this.current = next; 079 return true; 080 } 081 } 082 return false; 083 } 084 085 /** 086 * @see KeyValueScanner#getScannerOrder() 087 */ 088 @Override 089 public long getScannerOrder() { 090 return 0; 091 } 092 093 @Override 094 public void close() { 095 this.segment.decScannerCount(); 096 } 097}