001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.fusesource.hawtdb.api; 018 019 import org.fusesource.hawtdb.internal.page.Extent; 020 import org.fusesource.hawtdb.internal.page.ExtentInputStream; 021 import org.fusesource.hawtdb.internal.page.ExtentOutputStream; 022 import org.fusesource.hawtdb.internal.util.Ranges; 023 024 import java.io.DataInputStream; 025 import java.io.DataOutputStream; 026 import java.io.IOException; 027 import java.util.Collections; 028 import java.util.List; 029 030 /** 031 * Abstract base class for implementations of EncoderDecoder which use stream encoding/decoding. 032 * 033 * @author <a href="http://hiramchirino.com">Hiram Chirino</a> 034 */ 035 abstract public class AbstractStreamPagedAccessor<T> implements PagedAccessor<T> { 036 037 public List<Integer> store(Paged paged, int page, T data) { 038 // The node will be stored in an extent. This allows us to easily 039 // support huge nodes. 040 // The first extent is only 1 page long, extents linked off 041 // the first page will be up to 128 pages long. 042 ExtentOutputStream eos = new ExtentOutputStream(paged, page, (short) 1, (short) 128); 043 DataOutputStream os = new DataOutputStream(eos); 044 try { 045 encode(paged, os, data); 046 os.close(); 047 } catch (IOException e) { 048 throw new IndexException(e); 049 } 050 051 Ranges pages = eos.getPages(); 052 pages.remove(page); 053 if (pages.isEmpty()) { 054 return Collections.emptyList(); 055 } 056 057 return pages.values(); 058 } 059 060 public T load(Paged paged, int page) { 061 ExtentInputStream eis = new ExtentInputStream(paged, page); 062 DataInputStream is = new DataInputStream(eis); 063 try { 064 return decode(paged, is); 065 } catch (IOException e) { 066 throw new IndexException(e); 067 } finally { 068 try { 069 is.close(); 070 } catch (Throwable ignore) { 071 } 072 } 073 074 } 075 076 public List<Integer> pagesLinked(Paged paged, int page) { 077 return Extent.pagesLinked(paged, page); 078 } 079 080 081 abstract protected void encode(Paged paged, DataOutputStream os, T data) throws IOException; 082 abstract protected T decode(Paged paged, DataInputStream is) throws IOException; 083 }