Java Component Examples

LockFreeVector Example

/*
* Copyright (c) 2008 IBM Corporation
*
* Licensed 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.amino.examples;

/*   This example shows the mainly interfaces of LockFreeVector.
*   Including : pushBack(), popBack(), get(), set().
*
*   The VectorAdder class will add different items of String from "1" to "ELEMENT_NUM".
*   The VectorRemover class will remove no more than ELEMENT_NUM items.
*   The main thread will wait for all the threads in pool to finish.
*   2009/05/22
*/
import java.util.Iterator;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.amino.ds.lockfree.LockFreeVector;

public class VectorExample {
    public static final int ELEMENT_NUM = 100;
    private static final int TASKS_NUM = 4;
    public static void main(String[] argvs) {

        ExecutorService exec = Executors.newFixedThreadPool(TASKS_NUM);

        final LockFreeVector<String> vectorStr = new LockFreeVector<String>();

        for (int i = 0; i < TASKS_NUM; ++i) {
            exec.submit(new VectorAdder(vectorStr));
            if (i%2 == 0)exec.submit(new VectorRemover(vectorStr));
        }

        exec.shutdown();

        // Wait until all the threads in pool to finish.
        try {
            while(!exec.awaitTermination(600, TimeUnit.SECONDS));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        // If the Vector is empty now, the program will exit.
        if (vectorStr.isEmpty())
        {
            System.out.println("The Vector is empty, so I will exit!");
            System.exit(1);
        }

        // Print all the elements in List.
        for (String str : vectorStr)
            System.out.println(str);

        // Let's try get() and set() here.
        String str = vectorStr.get(0);
        if ( null == str)
            vectorStr.set(0, "0");

        System.out.println("The Vector size now: " + vectorStr.size());
    }
}
/*
*  The VectorAdder class will add elements to the given Vector.
*/
class VectorAdder implements Runnable {
    LockFreeVector<String> taskVec;
    private int count = 0;

    public VectorAdder(LockFreeVector<String> taskVector)
    {
        taskVec = taskVector;
    }

    public void run(){
        while (count < VectorExample.ELEMENT_NUM)
        {
            taskVec.pushBack(Integer.toString(count++));
            System.out.println(Thread.currentThread()+ " Pushed: " + count);
        }
        Thread.yield();
    }
}

/*
*  The VectorRemover class will remove the existed elements from the given Vector.
*/
class VectorRemover implements Runnable {
    LockFreeVector<String> taskVec;

    public VectorRemover(LockFreeVector<String> taskVector)
    {
        taskVec = taskVector;
    }

    public void run(){
        int times = 0;

        while (times < VectorExample.ELEMENT_NUM)
        {
            String popped = taskVec.popBack();
            System.out.println(Thread.currentThread()+ "Popped: " + popped);
            times++;
        }
        Thread.yield();
    }
}
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