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.util; 019 020import java.util.AbstractCollection; 021import java.util.ArrayList; 022import java.util.List; 023import java.util.NoSuchElementException; 024import org.apache.yetus.audience.InterfaceAudience; 025 026/** 027 * A collection class that contains multiple sub-lists, which allows us to not copy lists. This 028 * class does not support modification. The derived classes that add modifications are not 029 * thread-safe. NOTE: Doesn't implement list as it is not necessary for current usage, feel free to 030 * add. 031 */ 032@InterfaceAudience.Private 033public class ConcatenatedLists<T> extends AbstractCollection<T> { 034 protected final ArrayList<List<T>> components = new ArrayList<>(); 035 protected int size = 0; 036 037 public void addAllSublists(List<? extends List<T>> items) { 038 for (List<T> list : items) { 039 addSublist(list); 040 } 041 } 042 043 public void addSublist(List<T> items) { 044 if (!items.isEmpty()) { 045 this.components.add(items); 046 this.size += items.size(); 047 } 048 } 049 050 @Override 051 public int size() { 052 return this.size; 053 } 054 055 @Override 056 public java.util.Iterator<T> iterator() { 057 return new Iterator(); 058 } 059 060 @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD", 061 justification = "nextWasCalled is using by StripeStoreFileManager") 062 public class Iterator implements java.util.Iterator<T> { 063 protected int currentComponent = 0; 064 protected int indexWithinComponent = -1; 065 protected boolean nextWasCalled = false; 066 067 @Override 068 public boolean hasNext() { 069 return (currentComponent + 1) < components.size() 070 || ((currentComponent + 1) == components.size() 071 && ((indexWithinComponent + 1) < components.get(currentComponent).size())); 072 } 073 074 @Override 075 public T next() { 076 if (!components.isEmpty()) { 077 this.nextWasCalled = true; 078 List<T> src = components.get(currentComponent); 079 if (++indexWithinComponent < src.size()) { 080 return src.get(indexWithinComponent); 081 } 082 083 if (++currentComponent < components.size()) { 084 indexWithinComponent = 0; 085 src = components.get(currentComponent); 086 assert src.size() > 0; 087 return src.get(indexWithinComponent); 088 } 089 } 090 this.nextWasCalled = false; 091 throw new NoSuchElementException(); 092 } 093 094 @Override 095 public void remove() { 096 throw new UnsupportedOperationException(); 097 } 098 } 099}