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From: chinmaykolhatkar <git@git.apache.org>
To: dev@apex.incubator.apache.org
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References: <git-pr-157-incubator-apex-malhar@git.apache.org>
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Subject: [GitHub] incubator-apex-malhar pull request: APEXMALHAR-1963
 AbstractAsyncP...
Content-Type: text/plain
Message-Id: <20160107104740.47AD4E0C60@git1-us-west.apache.org>
Date: Thu,  7 Jan 2016 10:47:40 +0000 (UTC)

Github user chinmaykolhatkar commented on a diff in the pull request:

    https://github.com/apache/incubator-apex-malhar/pull/157#discussion_r49061423
  
    --- Diff: library/src/main/java/com/datatorrent/lib/async/AbstractAsyncProcessor.java ---
    @@ -0,0 +1,357 @@
    +/**
    + * 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 com.datatorrent.lib.async;
    +
    +import java.util.Iterator;
    +import java.util.Queue;
    +import java.util.concurrent.ExecutorService;
    +import java.util.concurrent.Executors;
    +import java.util.concurrent.Future;
    +
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import com.google.common.collect.Lists;
    +
    +import com.datatorrent.api.Context;
    +import com.datatorrent.api.DefaultInputPort;
    +import com.datatorrent.api.Operator.IdleTimeHandler;
    +import com.datatorrent.api.annotation.InputPortFieldAnnotation;
    +import com.datatorrent.common.util.BaseOperator;
    +
    +/**
    + * This base operator having a single input and tuple coming from input port are enqueued for processing asynchronously
    + * by Thread Executors.
    + *
    + * User can configure number of of threads that are required for processing. Defaulting to single thread which is
    + * different than operator thread.
    + * The user will also configure the timeout for the operations to happen.
    + *
    + * <b>Workflow is as follows:</b>
    + * <ol>
    + *   <li>Tuple of type INPUT is received on input port.</li>
    + *   <li>Tuple gets enqueued into Executors by calling <i>enqueueTupleForProcessing</i>.
    + *       Once can override <i>processTuple</i> method in which case, its users responsibility to enqueue tuple for
    + *       processing by calling <i>enqueueTupleForProcessing</i>.</li>
    + *   <li>When tuple gets its turn of execution, <i>processTupleAsync</i> gets called from thread other than
    + *       operator thread.</li>
    + *   <li>Based on maintainTupleOrder parameter, the results are consolidated at end of every window and respective call
    + *       to <i>handleProcessedTuple</i> will be made. This call will happen in operator thread.</li>
    + * </ol>
    + *
    + * This operator can be implemented to do async and parallel operations.
    + *
    + * Use case examples:
    + * <ul>
    + *   <li>Parallel reads from external datastore/database system.</li>
    + *   <li>Doing any operations which are long running tasks per tuple but DAG io should not be blocked.</li>
    + * </ul>
    + *
    + * @param <INPUT> input type of tuple
    + * @param <RESULT> Result of async processing of tuple.
    + * @since 3.3.0
    + */
    +public abstract class AbstractAsyncProcessor<INPUT, RESULT> extends BaseOperator implements IdleTimeHandler
    +{
    +  private static final Logger logger = LoggerFactory.getLogger(AbstractAsyncProcessor.class);
    +
    +  private transient ExecutorService executor;
    +  private int numProcessors = 1;
    --- End diff --
    
    Actually let me keep this to 0. This means, the threads will be created as per need.


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