alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

ActiveMQ example source code file (Page.java)

This example ActiveMQ source code file (Page.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

io, ioexception, ioexception, page, page, page_end_type, page_free_type, page_free_type, page_header_size, page_part_type, string, t, t, util

The ActiveMQ Page.java source code

/**
 * 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();
        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;
    }


}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ Page.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.