ActiveMQ example source code file (BitArrayBin.java)

This example ActiveMQ source code file (BitArrayBin.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

bitarray, bitarray, bitarraybin, bitarraybin, io, linkedlist, linkedlist, serializable, serializable, util

The ActiveMQ BitArrayBin.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.activemq.util;

import java.io.Serializable;
import java.util.LinkedList;

/**
 * Holder for many bitArrays - used for message audit
 * 
 * 
 */
public class BitArrayBin implements Serializable {

    private static final long serialVersionUID = 1L;
    private LinkedList<BitArray> list;
    private int maxNumberOfArrays;
    private int firstIndex = -1;
    private long lastInOrderBit=-1;

    /**
     * Create a BitArrayBin to a certain window size (number of messages to
     * keep)
     * 
     * @param windowSize
     */
    public BitArrayBin(int windowSize) {
        maxNumberOfArrays = ((windowSize + 1) / BitArray.LONG_SIZE) + 1;
        maxNumberOfArrays = Math.max(maxNumberOfArrays, 1);
        list = new LinkedList<BitArray>();
        for (int i = 0; i < maxNumberOfArrays; i++) {
            list.add(null);
        }
    }

    /**
     * Set a bit
     * 
     * @param index
     * @param value
     * @return true if set
     */
    public boolean setBit(long index, boolean value) {
        boolean answer = false;
        BitArray ba = getBitArray(index);
        if (ba != null) {
            int offset = getOffset(index);
            if (offset >= 0) {
                answer = ba.set(offset, value);
            }
        }
        return answer;
    }
    
    /**
     * Test if in order
     * @param index
     * @return true if next message is in order
     */
    public boolean isInOrder(long index) {
        boolean result = false;
        if (lastInOrderBit == -1) {
            result = true;
        } else {
            result = lastInOrderBit + 1 == index;
        }
        lastInOrderBit = index;
        return result;

    }

    /**
     * Get the boolean value at the index
     * 
     * @param index
     * @return true/false
     */
    public boolean getBit(long index) {
        boolean answer = index >= firstIndex;
        BitArray ba = getBitArray(index);
        if (ba != null) {
            int offset = getOffset(index);
            if (offset >= 0) {
                answer = ba.get(offset);
                return answer;
            }
        } else {
            // gone passed range for previous bins so assume set
            answer = true;
        }
        return answer;
    }

    /**
     * Get the BitArray for the index
     * 
     * @param index
     * @return BitArray
     */
    private BitArray getBitArray(long index) {
        int bin = getBin(index);
        BitArray answer = null;
        if (bin >= 0) {
            if (bin >= maxNumberOfArrays) {
                int overShoot = bin - maxNumberOfArrays + 1;
                while (overShoot > 0) {
                    list.removeFirst();
                    firstIndex += BitArray.LONG_SIZE;
                    list.add(new BitArray());
                    overShoot--;
                }
                
                bin = maxNumberOfArrays - 1;
            }
            answer = list.get(bin);
            if (answer == null) {
                answer = new BitArray();
                list.set(bin, answer);
            }
        }
        return answer;
    }

    /**
     * Get the index of the bin from the total index
     * 
     * @param index
     * @return the index of the bin
     */
    private int getBin(long index) {
        int answer = 0;
        if (firstIndex < 0) {
            firstIndex = (int) (index - (index % BitArray.LONG_SIZE));
        } else if (firstIndex >= 0) {
            answer = (int)((index - firstIndex) / BitArray.LONG_SIZE);
        }
        return answer;
    }

    /**
     * Get the offset into a bin from the total index
     * 
     * @param index
     * @return the relative offset into a bin
     */
    private int getOffset(long index) {
        int answer = 0;
        if (firstIndex >= 0) {
            answer = (int)((index - firstIndex) - (BitArray.LONG_SIZE * getBin(index)));
        }
        return answer;
    }

    public long getLastSetIndex() {
        long result = -1;
        
        if (firstIndex >=0) {
            result = firstIndex;   
            BitArray last = null;
            for (int lastBitArrayIndex = maxNumberOfArrays -1; lastBitArrayIndex >= 0; lastBitArrayIndex--) {
                last = list.get(lastBitArrayIndex);
                if (last != null) {
                    result += last.length() -1;
                    result += lastBitArrayIndex * BitArray.LONG_SIZE;
                    break;
                }
            }
        }
        return result;
    }
}