org.commoncrawl.async.ConcurrentTask.java Source code

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Here is the source code for org.commoncrawl.async.ConcurrentTask.java

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/**
 * Copyright 2008 - CommonCrawl Foundation
 * 
 * CommonCrawl 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.commoncrawl.async;

import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * A FutureTask that runs concurrently but returns status via an async callback
 * in the specified event loop
 * 
 * @author rana
 *
 * @param <V> Value Type
 */
public class ConcurrentTask<V> extends FutureTask<V> {

    /** logging **/
    private static final Log LOG = LogFactory.getLog(ConcurrentTask.class);

    private EventLoop _eventLoop;
    private CompletionCallback<V> _callback;

    public static interface CompletionCallback<V> {

        void taskComplete(V loadResult);

        void taskFailed(Exception e);
    }

    public ConcurrentTask(EventLoop eventLoop, Callable<V> callable, CompletionCallback<V> callback) {
        super(callable);

        _eventLoop = eventLoop;
        _callback = callback;
    }

    protected void done() {

        // schedule an async event to process loaded results ...
        AsyncTask.runAsyncTask(_eventLoop, new Runnable() {

            @Override
            public void run() {
                try {
                    _callback.taskComplete(get());
                } catch (InterruptedException e) {
                    LOG.error(e);
                } catch (ExecutionException e) {
                    LOG.error(e);
                    _callback.taskFailed(e);
                } catch (CancellationException e) {
                    LOG.error(e);
                    _callback.taskFailed(e);
                }
            }

        }, false);
    }
}