[GitHub] incubator-apex-malhar pull request #279: APEXMALHAR-2045: Adding bandwidth c...

[DT-Priyanka <gi...@git.apache.org>]

Github user DT-Priyanka commented on a diff in the pull request:

    https://github.com/apache/incubator-apex-malhar/pull/279#discussion_r65638954
  
    --- Diff: library/src/main/java/com/datatorrent/lib/bandwidth/BandwidthManager.java ---
    @@ -0,0 +1,137 @@
    +/**
    + * 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.bandwidth;
    +
    +import java.util.concurrent.Executors;
    +import java.util.concurrent.ScheduledExecutorService;
    +import java.util.concurrent.TimeUnit;
    +
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import com.datatorrent.api.Component;
    +import com.datatorrent.api.Context;
    +import com.datatorrent.api.Context.OperatorContext;
    +
    +/**
    + * BandwidthManager keeps track of bandwidth consumption and provides limit on maximum bandwidth that can be consumed at
    + * any moment. This accumulates bandwidth upto certain limits so that accumulated bandwidth can be used over a period of
    + * time.
    + */
    +public class BandwidthManager implements Component<Context.OperatorContext>
    +{
    +  private static final Logger LOG = LoggerFactory.getLogger(BandwidthManager.class);
    +  /**
    +   * Maximum bandwidth that can be consumed in bytes/sec
    +   */
    +  private long bandwidthLimit = Long.MAX_VALUE;
    +  private transient long currentBandwidthConsumption;
    +  private final transient ScheduledExecutorService scheduler;
    +  private final transient Object lock = new Object();
    +
    +  public BandwidthManager()
    +  {
    +    scheduler = Executors.newScheduledThreadPool(1);
    +  }
    +
    +  BandwidthManager(ScheduledExecutorService scheduler)
    +  {
    +    this.scheduler = scheduler;
    +  }
    +
    +  @Override
    +  public void setup(OperatorContext context)
    +  {
    +    scheduler.scheduleAtFixedRate(new BandwidthAccumulator(), 1, 1, TimeUnit.SECONDS);
    +  }
    +
    +  public boolean canConsumeBandwidth()
    +  {
    +    if (!isBandwidthRestricted()) {
    +      return true;
    +    }
    +    synchronized (lock) {
    +      if (currentBandwidthConsumption >= 0) {
    +        return true;
    +      }
    +    }
    +    return false;
    +  }
    +
    +  public void consumeBandwidth(long sentTupleSize)
    +  {
    +    if (isBandwidthRestricted()) {
    +      synchronized (lock) {
    +        currentBandwidthConsumption -= sentTupleSize;
    +      }
    +    }
    +  }
    +
    +  public boolean isBandwidthRestricted()
    +  {
    +    if (bandwidthLimit == Long.MAX_VALUE) {
    +      return false;
    +    }
    +    return true;
    +  }
    +
    +  /**
    +   * get maximum bandwidth that can be consumed in bytes/sec
    +   *
    +   * @return
    +   */
    +  public long getBandwidth()
    +  {
    +    return bandwidthLimit;
    +  }
    +
    +  /**
    +   * Set maximum bandwidth that can be consumed in bytes/sec
    +   *
    +   * @param bandwidth
    +   */
    +  public void setBandwidth(long bandwidth)
    +  {
    +    this.bandwidthLimit = bandwidth;
    +    LOG.info("Bandwidth limit is set to: " + bandwidth + " bytes/sec");
    +  }
    +
    +  @Override
    +  public void teardown()
    +  {
    +    scheduler.shutdownNow();
    +  }
    +
    +  class BandwidthAccumulator implements Runnable
    +  {
    +    @Override
    +    public void run()
    +    {
    +      if (isBandwidthRestricted()) {
    +        synchronized (lock) {
    +          if (currentBandwidthConsumption < 0) {
    --- End diff --
    
    Got it, updated as per your comments, setting currentBandwidth to "bandwidthLimit" when currentBandwidth is already +ve


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