Java Component Examples

LockFreeDictionary 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;

import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.amino.ds.lockfree.LockFreeDictionary;

/*   The Dictionary is a map contains elements with key and value pairs.
*   This example show the main interfaces of LockFreePriorityDictionary.
*   Including : put(), deleteValue(), size(), isEmpty()
*
*   The DictAdder class will add items of String from "1" to "ELEMENT_NUM".
*   The DictRemover 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
*/

public class DictionaryExample {
    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 Map<String, String> dictionaryStr = new LockFreeDictionary<String, String>();

        for (int i = 0; i < TASKS_NUM; ++i) {
            exec.submit(new DictAdder(dictionaryStr));
            if (i % 2 == 0)
                exec.submit(new DictRemover(dictionaryStr));
        }

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

        System.out.println("Dictionary size: " + dictionaryStr.size());
    }
}

/*
* The DictAdder class will add elements to the given Dictionary.
*/
class DictAdder implements Runnable {
    Map<String, String> taskDict;
    private int count = 0;

    public DictAdder(Map<String, String> taskMap) {
        taskDict = taskMap;
    }

    public void run() {
        while (count < DictionaryExample.ELEMENT_NUM) {
            String putStr = taskDict.put(Integer.toString(count++), Integer
                    .toString(count++));
            System.out.println(Thread.currentThread() + " Put:" + putStr);
        }
        Thread.yield();
    }
}

/*
* The DictRemover class will remove the existed elements from the given Dictionary.
*/
class DictRemover implements Runnable {
    Map<String, String> taskDict;
    private int count = 0;

    public DictRemover(Map<String, String> taskMap) {
        taskDict = taskMap;
    }

    public void run() {
        int times = 0;

        while (times < DictionaryExample.ELEMENT_NUM) {
            String key = ((LockFreeDictionary<String, String>) taskDict)
                    .deleteValue(Integer.toString(count++));
            System.out.println(Thread.currentThread() + " Removed key:" + key);
            times++;
        }
        Thread.yield();
    }
}
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