| /** |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.kahadb.page; |
| |
| import java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.apache.kahadb.util.ByteSequence; |
| import org.apache.kahadb.util.DataByteArrayInputStream; |
| import org.apache.kahadb.util.DataByteArrayOutputStream; |
| import org.apache.kahadb.util.Marshaller; |
| |
| /** |
| * A Page within a file. |
| * |
| * |
| */ |
| public class Page<T> { |
| |
| public static final int PAGE_HEADER_SIZE = 21; |
| |
| public static final byte PAGE_FREE_TYPE = 0; |
| public static final byte PAGE_PART_TYPE = 1; |
| public static final byte PAGE_END_TYPE = 2; |
| |
| long pageId; |
| |
| // The following fields are persisted |
| byte type = PAGE_FREE_TYPE; |
| long txId; |
| // A field reserved to hold checksums.. Not in use (yet) |
| int checksum; |
| |
| // Points to the next page in the chunk stream |
| long next; |
| T data; |
| |
| public Page() { |
| } |
| |
| public Page(long pageId) { |
| this.pageId=pageId; |
| } |
| |
| public void copy(Page<T> other) { |
| this.pageId = other.pageId; |
| this.txId = other.txId; |
| this.type = other.type; |
| this.next = other.next; |
| this.data = other.data; |
| } |
| |
| Page<T> copy() { |
| Page<T> rc = new Page<T>(); |
| rc.copy(this); |
| return rc; |
| } |
| |
| void makeFree(long txId) { |
| this.type = Page.PAGE_FREE_TYPE; |
| this.txId = txId; |
| this.data = null; |
| this.next = 0; |
| } |
| |
| public void makePagePart(long next, long txId) { |
| this.type = Page.PAGE_PART_TYPE; |
| this.next = next; |
| this.txId = txId; |
| } |
| |
| public void makePageEnd(long size, long txId) { |
| this.type = Page.PAGE_END_TYPE; |
| this.next = size; |
| this.txId = txId; |
| } |
| |
| void write(DataOutput os) throws IOException { |
| os.writeByte(type); |
| os.writeLong(txId); |
| os.writeLong(next); |
| os.writeInt(checksum); |
| } |
| |
| void read(DataInput is) throws IOException { |
| type = is.readByte(); |
| txId = is.readLong(); |
| next = is.readLong(); |
| checksum = is.readInt(); |
| } |
| |
| public long getPageId() { |
| return pageId; |
| } |
| |
| public long getTxId() { |
| return txId; |
| } |
| |
| public T get() { |
| return data; |
| } |
| |
| public void set(T data) { |
| this.data = data; |
| } |
| |
| public short getType() { |
| return type; |
| } |
| |
| public long getNext() { |
| return next; |
| } |
| |
| public String toString() { |
| return "[Page:" + getPageId()+", type: "+type+"]"; |
| } |
| |
| public int getChecksum() { |
| return checksum; |
| } |
| |
| public void setChecksum(int checksum) { |
| this.checksum = checksum; |
| } |
| |
| |
| } |