Java Component Examples

LockFreeEBStack 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;

/*   The Stack is a FILO data structure.
*   This example shows the mainly interfaces of EBStack which adds
*   elimination mechanism to deal with high contention rate scenario.
*   Including : push(), pop(), peek()
*
*   The StackAdder class will add items of String from "1" to "ELEMENT_NUM".
*   The StackRemover 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.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.amino.ds.lockfree.EBStack;
import org.amino.ds.lockfree.IStack;

public class EBStackExample {

    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 IStack<String> stackStr = new EBStack<String>();

        for (int i = 0; i < TASKS_NUM; ++i) {
            exec.submit(new StackAdder(stackStr));
            exec.submit(new StackRemover(stackStr));
        }

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

        System.out.println("The top element: "+stackStr.peek());
    }
}

/*
*  The StackAdder class will add elements to the given Stack.
*/
class StackAdder implements Runnable {
    IStack<String> taskDq;
    private int count = 0;

    public StackAdder(IStack<String> taskStack)
    {
        taskDq = taskStack;
    }

    public void run(){
        while (count < EBDequeExample.ELEMENT_NUM)
        {
            // The add* functions have no return value.
            taskDq.push(Integer.toString(count++));
            System.out.println(Thread.currentThread()+ " Pushed:" + count);
        }
        Thread.yield();
    }
}

/*
*  The ListRemover class will remove the existed elements from the given Stack.
*/
class StackRemover implements Runnable {
    IStack<String> taskDq;

    public StackRemover(IStack<String> taskStack)
    {
        taskDq = taskStack;
    }

    public void run(){
        int times = 0;

        while (times < EBDequeExample.ELEMENT_NUM)
        {
            String toPop = taskDq.pop();
            System.out.println(Thread.currentThread()+ " Popped: " + toPop);
            times++;
        }
        Thread.yield();
    }
}

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